LinearLayout.java revision 6c5664ac58463fefb580acd0d9b5550b25511f85
1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.widget;
18
19import com.android.internal.R;
20
21import android.content.Context;
22import android.content.res.TypedArray;
23import android.util.AttributeSet;
24import android.view.Gravity;
25import android.view.View;
26import android.view.ViewDebug;
27import android.view.ViewGroup;
28import android.widget.RemoteViews.RemoteView;
29
30
31/**
32 * A Layout that arranges its children in a single column or a single row. The direction of
33 * the row can be set by calling {@link #setOrientation(int) setOrientation()}.
34 * You can also specify gravity, which specifies the alignment of all the child elements by
35 * calling {@link #setGravity(int) setGravity()} or specify that specific children
36 * grow to fill up any remaining space in the layout by setting the <em>weight</em> member of
37 * {@link android.widget.LinearLayout.LayoutParams LinearLayout.LayoutParams}.
38 * The default orientation is horizontal.
39 *
40 * <p>
41 * Also see {@link LinearLayout.LayoutParams android.widget.LinearLayout.LayoutParams}
42 * for layout attributes </p>
43 */
44@RemoteView
45public class LinearLayout extends ViewGroup {
46    public static final int HORIZONTAL = 0;
47    public static final int VERTICAL = 1;
48
49    /**
50     * Whether the children of this layout are baseline aligned.  Only applicable
51     * if {@link #mOrientation} is horizontal.
52     */
53    @ViewDebug.ExportedProperty
54    private boolean mBaselineAligned = true;
55
56    /**
57     * If this layout is part of another layout that is baseline aligned,
58     * use the child at this index as the baseline.
59     *
60     * Note: this is orthogonal to {@link #mBaselineAligned}, which is concerned
61     * with whether the children of this layout are baseline aligned.
62     */
63    @ViewDebug.ExportedProperty
64    private int mBaselineAlignedChildIndex = -1;
65
66    /**
67     * The additional offset to the child's baseline.
68     * We'll calculate the baseline of this layout as we measure vertically; for
69     * horizontal linear layouts, the offset of 0 is appropriate.
70     */
71    @ViewDebug.ExportedProperty
72    private int mBaselineChildTop = 0;
73
74    @ViewDebug.ExportedProperty
75    private int mOrientation;
76    @ViewDebug.ExportedProperty(mapping = {
77            @ViewDebug.IntToString(from =  -1,                       to = "NONE"),
78            @ViewDebug.IntToString(from = Gravity.NO_GRAVITY,        to = "NONE"),
79            @ViewDebug.IntToString(from = Gravity.TOP,               to = "TOP"),
80            @ViewDebug.IntToString(from = Gravity.BOTTOM,            to = "BOTTOM"),
81            @ViewDebug.IntToString(from = Gravity.LEFT,              to = "LEFT"),
82            @ViewDebug.IntToString(from = Gravity.RIGHT,             to = "RIGHT"),
83            @ViewDebug.IntToString(from = Gravity.CENTER_VERTICAL,   to = "CENTER_VERTICAL"),
84            @ViewDebug.IntToString(from = Gravity.FILL_VERTICAL,     to = "FILL_VERTICAL"),
85            @ViewDebug.IntToString(from = Gravity.CENTER_HORIZONTAL, to = "CENTER_HORIZONTAL"),
86            @ViewDebug.IntToString(from = Gravity.FILL_HORIZONTAL,   to = "FILL_HORIZONTAL"),
87            @ViewDebug.IntToString(from = Gravity.CENTER,            to = "CENTER"),
88            @ViewDebug.IntToString(from = Gravity.FILL,              to = "FILL")
89        })
90    private int mGravity = Gravity.LEFT | Gravity.TOP;
91    @ViewDebug.ExportedProperty
92    private int mTotalLength;
93
94    @ViewDebug.ExportedProperty
95    private float mWeightSum;
96
97    @ViewDebug.ExportedProperty
98    private boolean mUseLargestChild;
99
100    private int[] mMaxAscent;
101    private int[] mMaxDescent;
102
103    private static final int VERTICAL_GRAVITY_COUNT = 4;
104
105    private static final int INDEX_CENTER_VERTICAL = 0;
106    private static final int INDEX_TOP = 1;
107    private static final int INDEX_BOTTOM = 2;
108    private static final int INDEX_FILL = 3;
109
110    public LinearLayout(Context context) {
111        super(context);
112    }
113
114    public LinearLayout(Context context, AttributeSet attrs) {
115        super(context, attrs);
116
117        TypedArray a =
118            context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.LinearLayout);
119
120        int index = a.getInt(com.android.internal.R.styleable.LinearLayout_orientation, -1);
121        if (index >= 0) {
122            setOrientation(index);
123        }
124
125        index = a.getInt(com.android.internal.R.styleable.LinearLayout_gravity, -1);
126        if (index >= 0) {
127            setGravity(index);
128        }
129
130        boolean baselineAligned = a.getBoolean(R.styleable.LinearLayout_baselineAligned, true);
131        if (!baselineAligned) {
132            setBaselineAligned(baselineAligned);
133        }
134
135        mWeightSum = a.getFloat(R.styleable.LinearLayout_weightSum, -1.0f);
136
137        mBaselineAlignedChildIndex =
138                a.getInt(com.android.internal.R.styleable.LinearLayout_baselineAlignedChildIndex, -1);
139
140        // TODO: Better name, add Java APIs, make it public
141        mUseLargestChild = a.getBoolean(R.styleable.LinearLayout_useLargestChild, false);
142
143        a.recycle();
144    }
145
146    /**
147     * <p>Indicates whether widgets contained within this layout are aligned
148     * on their baseline or not.</p>
149     *
150     * @return true when widgets are baseline-aligned, false otherwise
151     */
152    public boolean isBaselineAligned() {
153        return mBaselineAligned;
154    }
155
156    /**
157     * <p>Defines whether widgets contained in this layout are
158     * baseline-aligned or not.</p>
159     *
160     * @param baselineAligned true to align widgets on their baseline,
161     *         false otherwise
162     *
163     * @attr ref android.R.styleable#LinearLayout_baselineAligned
164     */
165    @android.view.RemotableViewMethod
166    public void setBaselineAligned(boolean baselineAligned) {
167        mBaselineAligned = baselineAligned;
168    }
169
170    @Override
171    public int getBaseline() {
172        if (mBaselineAlignedChildIndex < 0) {
173            return super.getBaseline();
174        }
175
176        if (getChildCount() <= mBaselineAlignedChildIndex) {
177            throw new RuntimeException("mBaselineAlignedChildIndex of LinearLayout "
178                    + "set to an index that is out of bounds.");
179        }
180
181        final View child = getChildAt(mBaselineAlignedChildIndex);
182        final int childBaseline = child.getBaseline();
183
184        if (childBaseline == -1) {
185            if (mBaselineAlignedChildIndex == 0) {
186                // this is just the default case, safe to return -1
187                return -1;
188            }
189            // the user picked an index that points to something that doesn't
190            // know how to calculate its baseline.
191            throw new RuntimeException("mBaselineAlignedChildIndex of LinearLayout "
192                    + "points to a View that doesn't know how to get its baseline.");
193        }
194
195        // TODO: This should try to take into account the virtual offsets
196        // (See getNextLocationOffset and getLocationOffset)
197        // We should add to childTop:
198        // sum([getNextLocationOffset(getChildAt(i)) / i < mBaselineAlignedChildIndex])
199        // and also add:
200        // getLocationOffset(child)
201        int childTop = mBaselineChildTop;
202
203        if (mOrientation == VERTICAL) {
204            final int majorGravity = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
205            if (majorGravity != Gravity.TOP) {
206               switch (majorGravity) {
207                   case Gravity.BOTTOM:
208                       childTop = mBottom - mTop - mPaddingBottom - mTotalLength;
209                       break;
210
211                   case Gravity.CENTER_VERTICAL:
212                       childTop += ((mBottom - mTop - mPaddingTop - mPaddingBottom) -
213                               mTotalLength) / 2;
214                       break;
215               }
216            }
217        }
218
219        LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
220        return childTop + lp.topMargin + childBaseline;
221    }
222
223    /**
224     * @return The index of the child that will be used if this layout is
225     *   part of a larger layout that is baseline aligned, or -1 if none has
226     *   been set.
227     */
228    public int getBaselineAlignedChildIndex() {
229        return mBaselineAlignedChildIndex;
230    }
231
232    /**
233     * @param i The index of the child that will be used if this layout is
234     *          part of a larger layout that is baseline aligned.
235     *
236     * @attr ref android.R.styleable#LinearLayout_baselineAlignedChildIndex
237     */
238    @android.view.RemotableViewMethod
239    public void setBaselineAlignedChildIndex(int i) {
240        if ((i < 0) || (i >= getChildCount())) {
241            throw new IllegalArgumentException("base aligned child index out "
242                    + "of range (0, " + getChildCount() + ")");
243        }
244        mBaselineAlignedChildIndex = i;
245    }
246
247    /**
248     * <p>Returns the view at the specified index. This method can be overriden
249     * to take into account virtual children. Refer to
250     * {@link android.widget.TableLayout} and {@link android.widget.TableRow}
251     * for an example.</p>
252     *
253     * @param index the child's index
254     * @return the child at the specified index
255     */
256    View getVirtualChildAt(int index) {
257        return getChildAt(index);
258    }
259
260    /**
261     * <p>Returns the virtual number of children. This number might be different
262     * than the actual number of children if the layout can hold virtual
263     * children. Refer to
264     * {@link android.widget.TableLayout} and {@link android.widget.TableRow}
265     * for an example.</p>
266     *
267     * @return the virtual number of children
268     */
269    int getVirtualChildCount() {
270        return getChildCount();
271    }
272
273    /**
274     * Returns the desired weights sum.
275     *
276     * @return A number greater than 0.0f if the weight sum is defined, or
277     *         a number lower than or equals to 0.0f if not weight sum is
278     *         to be used.
279     */
280    public float getWeightSum() {
281        return mWeightSum;
282    }
283
284    /**
285     * Defines the desired weights sum. If unspecified the weights sum is computed
286     * at layout time by adding the layout_weight of each child.
287     *
288     * This can be used for instance to give a single child 50% of the total
289     * available space by giving it a layout_weight of 0.5 and setting the
290     * weightSum to 1.0.
291     *
292     * @param weightSum a number greater than 0.0f, or a number lower than or equals
293     *        to 0.0f if the weight sum should be computed from the children's
294     *        layout_weight
295     */
296    @android.view.RemotableViewMethod
297    public void setWeightSum(float weightSum) {
298        mWeightSum = Math.max(0.0f, weightSum);
299    }
300
301    @Override
302    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
303        if (mOrientation == VERTICAL) {
304            measureVertical(widthMeasureSpec, heightMeasureSpec);
305        } else {
306            measureHorizontal(widthMeasureSpec, heightMeasureSpec);
307        }
308    }
309
310    /**
311     * Measures the children when the orientation of this LinearLayout is set
312     * to {@link #VERTICAL}.
313     *
314     * @param widthMeasureSpec Horizontal space requirements as imposed by the parent.
315     * @param heightMeasureSpec Vertical space requirements as imposed by the parent.
316     *
317     * @see #getOrientation()
318     * @see #setOrientation(int)
319     * @see #onMeasure(int, int)
320     */
321    void measureVertical(int widthMeasureSpec, int heightMeasureSpec) {
322        mTotalLength = 0;
323        int maxWidth = 0;
324        int alternativeMaxWidth = 0;
325        int weightedMaxWidth = 0;
326        boolean allFillParent = true;
327        float totalWeight = 0;
328
329        final int count = getVirtualChildCount();
330
331        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
332        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
333
334        boolean matchWidth = false;
335
336        final int baselineChildIndex = mBaselineAlignedChildIndex;
337        final boolean useLargestChild = mUseLargestChild;
338
339        int largestChildHeight = Integer.MIN_VALUE;
340
341        // See how tall everyone is. Also remember max width.
342        for (int i = 0; i < count; ++i) {
343            final View child = getVirtualChildAt(i);
344
345            if (child == null) {
346                mTotalLength += measureNullChild(i);
347                continue;
348            }
349
350            if (child.getVisibility() == View.GONE) {
351               i += getChildrenSkipCount(child, i);
352               continue;
353            }
354
355            LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
356
357            totalWeight += lp.weight;
358
359            if (heightMode == MeasureSpec.EXACTLY && lp.height == 0 && lp.weight > 0) {
360                // Optimization: don't bother measuring children who are going to use
361                // leftover space. These views will get measured again down below if
362                // there is any leftover space.
363                final int totalLength = mTotalLength;
364                mTotalLength = Math.max(totalLength, totalLength + lp.topMargin + lp.bottomMargin);
365            } else {
366                int oldHeight = Integer.MIN_VALUE;
367
368                if (lp.height == 0 && lp.weight > 0) {
369                    // heightMode is either UNSPECIFIED or AT_MOST, and this
370                    // child wanted to stretch to fill available space.
371                    // Translate that to WRAP_CONTENT so that it does not end up
372                    // with a height of 0
373                    oldHeight = 0;
374                    lp.height = LayoutParams.WRAP_CONTENT;
375                }
376
377                // Determine how big this child would like to be. If this or
378                // previous children have given a weight, then we allow it to
379                // use all available space (and we will shrink things later
380                // if needed).
381                measureChildBeforeLayout(
382                       child, i, widthMeasureSpec, 0, heightMeasureSpec,
383                       totalWeight == 0 ? mTotalLength : 0);
384
385                if (oldHeight != Integer.MIN_VALUE) {
386                   lp.height = oldHeight;
387                }
388
389                final int childHeight = child.getMeasuredHeight();
390                final int totalLength = mTotalLength;
391                mTotalLength = Math.max(totalLength, totalLength + childHeight + lp.topMargin +
392                       lp.bottomMargin + getNextLocationOffset(child));
393
394                if (useLargestChild) {
395                    largestChildHeight = Math.max(childHeight, largestChildHeight);
396                }
397            }
398
399            /**
400             * If applicable, compute the additional offset to the child's baseline
401             * we'll need later when asked {@link #getBaseline}.
402             */
403            if ((baselineChildIndex >= 0) && (baselineChildIndex == i + 1)) {
404               mBaselineChildTop = mTotalLength;
405            }
406
407            // if we are trying to use a child index for our baseline, the above
408            // book keeping only works if there are no children above it with
409            // weight.  fail fast to aid the developer.
410            if (i < baselineChildIndex && lp.weight > 0) {
411                throw new RuntimeException("A child of LinearLayout with index "
412                        + "less than mBaselineAlignedChildIndex has weight > 0, which "
413                        + "won't work.  Either remove the weight, or don't set "
414                        + "mBaselineAlignedChildIndex.");
415            }
416
417            boolean matchWidthLocally = false;
418            if (widthMode != MeasureSpec.EXACTLY && lp.width == LayoutParams.MATCH_PARENT) {
419                // The width of the linear layout will scale, and at least one
420                // child said it wanted to match our width. Set a flag
421                // indicating that we need to remeasure at least that view when
422                // we know our width.
423                matchWidth = true;
424                matchWidthLocally = true;
425            }
426
427            final int margin = lp.leftMargin + lp.rightMargin;
428            final int measuredWidth = child.getMeasuredWidth() + margin;
429            maxWidth = Math.max(maxWidth, measuredWidth);
430
431            allFillParent = allFillParent && lp.width == LayoutParams.MATCH_PARENT;
432            if (lp.weight > 0) {
433                /*
434                 * Widths of weighted Views are bogus if we end up
435                 * remeasuring, so keep them separate.
436                 */
437                weightedMaxWidth = Math.max(weightedMaxWidth,
438                        matchWidthLocally ? margin : measuredWidth);
439            } else {
440                alternativeMaxWidth = Math.max(alternativeMaxWidth,
441                        matchWidthLocally ? margin : measuredWidth);
442            }
443
444            i += getChildrenSkipCount(child, i);
445        }
446
447        if (useLargestChild && heightMode == MeasureSpec.AT_MOST) {
448            mTotalLength = 0;
449
450            for (int i = 0; i < count; ++i) {
451                final View child = getVirtualChildAt(i);
452
453                if (child == null) {
454                    mTotalLength += measureNullChild(i);
455                    continue;
456                }
457
458                if (child.getVisibility() == GONE) {
459                    i += getChildrenSkipCount(child, i);
460                    continue;
461                }
462
463                final LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)
464                        child.getLayoutParams();
465                // Account for negative margins
466                final int totalLength = mTotalLength;
467                mTotalLength = Math.max(totalLength, totalLength + largestChildHeight +
468                        lp.topMargin + lp.bottomMargin + getNextLocationOffset(child));
469            }
470        }
471
472        // Add in our padding
473        mTotalLength += mPaddingTop + mPaddingBottom;
474
475        int heightSize = mTotalLength;
476
477        // Check against our minimum height
478        heightSize = Math.max(heightSize, getSuggestedMinimumHeight());
479
480        // Reconcile our calculated size with the heightMeasureSpec
481        heightSize = resolveSize(heightSize, heightMeasureSpec);
482
483        // Either expand children with weight to take up available space or
484        // shrink them if they extend beyond our current bounds
485        int delta = heightSize - mTotalLength;
486        if (delta != 0 && totalWeight > 0.0f) {
487            float weightSum = mWeightSum > 0.0f ? mWeightSum : totalWeight;
488
489            mTotalLength = 0;
490
491            for (int i = 0; i < count; ++i) {
492                final View child = getVirtualChildAt(i);
493
494                if (child.getVisibility() == View.GONE) {
495                    continue;
496                }
497
498                LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
499
500                float childExtra = lp.weight;
501                if (childExtra > 0) {
502                    // Child said it could absorb extra space -- give him his share
503                    int share = (int) (childExtra * delta / weightSum);
504                    weightSum -= childExtra;
505                    delta -= share;
506
507                    final int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
508                            mPaddingLeft + mPaddingRight +
509                                    lp.leftMargin + lp.rightMargin, lp.width);
510
511                    // TODO: Use a field like lp.isMeasured to figure out if this
512                    // child has been previously measured
513                    if ((lp.height != 0) || (heightMode != MeasureSpec.EXACTLY)) {
514                        // child was measured once already above...
515                        // base new measurement on stored values
516                        int childHeight = child.getMeasuredHeight() + share;
517                        if (childHeight < 0) {
518                            childHeight = 0;
519                        }
520
521                        child.measure(childWidthMeasureSpec,
522                                MeasureSpec.makeMeasureSpec(childHeight, MeasureSpec.EXACTLY));
523                    } else {
524                        // child was skipped in the loop above.
525                        // Measure for this first time here
526                        child.measure(childWidthMeasureSpec,
527                                MeasureSpec.makeMeasureSpec(share > 0 ? share : 0,
528                                        MeasureSpec.EXACTLY));
529                    }
530                }
531
532                final int margin =  lp.leftMargin + lp.rightMargin;
533                final int measuredWidth = child.getMeasuredWidth() + margin;
534                maxWidth = Math.max(maxWidth, measuredWidth);
535
536                boolean matchWidthLocally = widthMode != MeasureSpec.EXACTLY &&
537                        lp.width == LayoutParams.MATCH_PARENT;
538
539                alternativeMaxWidth = Math.max(alternativeMaxWidth,
540                        matchWidthLocally ? margin : measuredWidth);
541
542                allFillParent = allFillParent && lp.width == LayoutParams.MATCH_PARENT;
543
544                final int totalLength = mTotalLength;
545                mTotalLength = Math.max(totalLength, totalLength + child.getMeasuredHeight() +
546                        lp.topMargin + lp.bottomMargin + getNextLocationOffset(child));
547            }
548
549            // Add in our padding
550            mTotalLength += mPaddingTop + mPaddingBottom;
551            // TODO: Should we recompute the heightSpec based on the new total length?
552        } else {
553            alternativeMaxWidth = Math.max(alternativeMaxWidth,
554                                           weightedMaxWidth);
555        }
556
557        if (!allFillParent && widthMode != MeasureSpec.EXACTLY) {
558            maxWidth = alternativeMaxWidth;
559        }
560
561        maxWidth += mPaddingLeft + mPaddingRight;
562
563        // Check against our minimum width
564        maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
565
566        setMeasuredDimension(resolveSize(maxWidth, widthMeasureSpec), heightSize);
567
568        if (matchWidth) {
569            forceUniformWidth(count, heightMeasureSpec);
570        }
571    }
572
573    private void forceUniformWidth(int count, int heightMeasureSpec) {
574        // Pretend that the linear layout has an exact size.
575        int uniformMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth(),
576                MeasureSpec.EXACTLY);
577        for (int i = 0; i< count; ++i) {
578           final View child = getVirtualChildAt(i);
579           if (child.getVisibility() != GONE) {
580               LinearLayout.LayoutParams lp = ((LinearLayout.LayoutParams)child.getLayoutParams());
581
582               if (lp.width == LayoutParams.MATCH_PARENT) {
583                   // Temporarily force children to reuse their old measured height
584                   // FIXME: this may not be right for something like wrapping text?
585                   int oldHeight = lp.height;
586                   lp.height = child.getMeasuredHeight();
587
588                   // Remeasue with new dimensions
589                   measureChildWithMargins(child, uniformMeasureSpec, 0, heightMeasureSpec, 0);
590                   lp.height = oldHeight;
591               }
592           }
593        }
594    }
595
596    /**
597     * Measures the children when the orientation of this LinearLayout is set
598     * to {@link #HORIZONTAL}.
599     *
600     * @param widthMeasureSpec Horizontal space requirements as imposed by the parent.
601     * @param heightMeasureSpec Vertical space requirements as imposed by the parent.
602     *
603     * @see #getOrientation()
604     * @see #setOrientation(int)
605     * @see #onMeasure(int, int)
606     */
607    void measureHorizontal(int widthMeasureSpec, int heightMeasureSpec) {
608        mTotalLength = 0;
609        int maxHeight = 0;
610        int alternativeMaxHeight = 0;
611        int weightedMaxHeight = 0;
612        boolean allFillParent = true;
613        float totalWeight = 0;
614
615        final int count = getVirtualChildCount();
616
617        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
618        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
619
620        boolean matchHeight = false;
621
622        if (mMaxAscent == null || mMaxDescent == null) {
623            mMaxAscent = new int[VERTICAL_GRAVITY_COUNT];
624            mMaxDescent = new int[VERTICAL_GRAVITY_COUNT];
625        }
626
627        final int[] maxAscent = mMaxAscent;
628        final int[] maxDescent = mMaxDescent;
629
630        maxAscent[0] = maxAscent[1] = maxAscent[2] = maxAscent[3] = -1;
631        maxDescent[0] = maxDescent[1] = maxDescent[2] = maxDescent[3] = -1;
632
633        final boolean baselineAligned = mBaselineAligned;
634        final boolean useLargestChild = mUseLargestChild;
635
636        int largestChildWidth = Integer.MIN_VALUE;
637
638        // See how wide everyone is. Also remember max height.
639        for (int i = 0; i < count; ++i) {
640            final View child = getVirtualChildAt(i);
641
642            if (child == null) {
643                mTotalLength += measureNullChild(i);
644                continue;
645            }
646
647            if (child.getVisibility() == GONE) {
648                i += getChildrenSkipCount(child, i);
649                continue;
650            }
651
652            final LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)
653                    child.getLayoutParams();
654
655            totalWeight += lp.weight;
656
657            if (widthMode == MeasureSpec.EXACTLY && lp.width == 0 && lp.weight > 0) {
658                // Optimization: don't bother measuring children who are going to use
659                // leftover space. These views will get measured again down below if
660                // there is any leftover space.
661                mTotalLength += lp.leftMargin + lp.rightMargin;
662
663                // Baseline alignment requires to measure widgets to obtain the
664                // baseline offset (in particular for TextViews). The following
665                // defeats the optimization mentioned above. Allow the child to
666                // use as much space as it wants because we can shrink things
667                // later (and re-measure).
668                if (baselineAligned) {
669                    final int freeSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
670                    child.measure(freeSpec, freeSpec);
671                }
672            } else {
673                int oldWidth = Integer.MIN_VALUE;
674
675                if (lp.width == 0 && lp.weight > 0) {
676                    // widthMode is either UNSPECIFIED or AT_MOST, and this
677                    // child
678                    // wanted to stretch to fill available space. Translate that to
679                    // WRAP_CONTENT so that it does not end up with a width of 0
680                    oldWidth = 0;
681                    lp.width = LayoutParams.WRAP_CONTENT;
682                }
683
684                // Determine how big this child would like to be. If this or
685                // previous children have given a weight, then we allow it to
686                // use all available space (and we will shrink things later
687                // if needed).
688                measureChildBeforeLayout(child, i, widthMeasureSpec,
689                        totalWeight == 0 ? mTotalLength : 0,
690                        heightMeasureSpec, 0);
691
692                if (oldWidth != Integer.MIN_VALUE) {
693                    lp.width = oldWidth;
694                }
695
696                final int childWidth = child.getMeasuredWidth();
697                mTotalLength += childWidth + lp.leftMargin + lp.rightMargin +
698                        getNextLocationOffset(child);
699
700                if (useLargestChild) {
701                    largestChildWidth = Math.max(childWidth, largestChildWidth);
702                }
703            }
704
705            boolean matchHeightLocally = false;
706            if (heightMode != MeasureSpec.EXACTLY && lp.height == LayoutParams.MATCH_PARENT) {
707                // The height of the linear layout will scale, and at least one
708                // child said it wanted to match our height. Set a flag indicating that
709                // we need to remeasure at least that view when we know our height.
710                matchHeight = true;
711                matchHeightLocally = true;
712            }
713
714            final int margin = lp.topMargin + lp.bottomMargin;
715            final int childHeight = child.getMeasuredHeight() + margin;
716
717            if (baselineAligned) {
718                final int childBaseline = child.getBaseline();
719                if (childBaseline != -1) {
720                    // Translates the child's vertical gravity into an index
721                    // in the range 0..VERTICAL_GRAVITY_COUNT
722                    final int gravity = (lp.gravity < 0 ? mGravity : lp.gravity)
723                            & Gravity.VERTICAL_GRAVITY_MASK;
724                    final int index = ((gravity >> Gravity.AXIS_Y_SHIFT)
725                            & ~Gravity.AXIS_SPECIFIED) >> 1;
726
727                    maxAscent[index] = Math.max(maxAscent[index], childBaseline);
728                    maxDescent[index] = Math.max(maxDescent[index], childHeight - childBaseline);
729                }
730            }
731
732            maxHeight = Math.max(maxHeight, childHeight);
733
734            allFillParent = allFillParent && lp.height == LayoutParams.MATCH_PARENT;
735            if (lp.weight > 0) {
736                /*
737                 * Heights of weighted Views are bogus if we end up
738                 * remeasuring, so keep them separate.
739                 */
740                weightedMaxHeight = Math.max(weightedMaxHeight,
741                        matchHeightLocally ? margin : childHeight);
742            } else {
743                alternativeMaxHeight = Math.max(alternativeMaxHeight,
744                        matchHeightLocally ? margin : childHeight);
745            }
746
747            i += getChildrenSkipCount(child, i);
748        }
749
750        // Check mMaxAscent[INDEX_TOP] first because it maps to Gravity.TOP,
751        // the most common case
752        if (maxAscent[INDEX_TOP] != -1 ||
753                maxAscent[INDEX_CENTER_VERTICAL] != -1 ||
754                maxAscent[INDEX_BOTTOM] != -1 ||
755                maxAscent[INDEX_FILL] != -1) {
756            final int ascent = Math.max(maxAscent[INDEX_FILL],
757                    Math.max(maxAscent[INDEX_CENTER_VERTICAL],
758                    Math.max(maxAscent[INDEX_TOP], maxAscent[INDEX_BOTTOM])));
759            final int descent = Math.max(maxDescent[INDEX_FILL],
760                    Math.max(maxDescent[INDEX_CENTER_VERTICAL],
761                    Math.max(maxDescent[INDEX_TOP], maxDescent[INDEX_BOTTOM])));
762            maxHeight = Math.max(maxHeight, ascent + descent);
763        }
764
765        if (useLargestChild && widthMode == MeasureSpec.AT_MOST) {
766            mTotalLength = 0;
767
768            for (int i = 0; i < count; ++i) {
769                final View child = getVirtualChildAt(i);
770
771                if (child == null) {
772                    mTotalLength += measureNullChild(i);
773                    continue;
774                }
775
776                if (child.getVisibility() == GONE) {
777                    i += getChildrenSkipCount(child, i);
778                    continue;
779                }
780
781                final LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)
782                        child.getLayoutParams();
783                mTotalLength += largestChildWidth + lp.leftMargin + lp.rightMargin +
784                        getNextLocationOffset(child);
785            }
786        }
787
788        // Add in our padding
789        mTotalLength += mPaddingLeft + mPaddingRight;
790
791        int widthSize = mTotalLength;
792
793        // Check against our minimum width
794        widthSize = Math.max(widthSize, getSuggestedMinimumWidth());
795
796        // Reconcile our calculated size with the widthMeasureSpec
797        widthSize = resolveSize(widthSize, widthMeasureSpec);
798
799        // Either expand children with weight to take up available space or
800        // shrink them if they extend beyond our current bounds
801        int delta = widthSize - mTotalLength;
802        if (delta != 0 && totalWeight > 0.0f) {
803            float weightSum = mWeightSum > 0.0f ? mWeightSum : totalWeight;
804
805            maxAscent[0] = maxAscent[1] = maxAscent[2] = maxAscent[3] = -1;
806            maxDescent[0] = maxDescent[1] = maxDescent[2] = maxDescent[3] = -1;
807            maxHeight = -1;
808
809            mTotalLength = 0;
810
811            for (int i = 0; i < count; ++i) {
812                final View child = getVirtualChildAt(i);
813
814                if (child == null || child.getVisibility() == View.GONE) {
815                    continue;
816                }
817
818                final LinearLayout.LayoutParams lp =
819                        (LinearLayout.LayoutParams) child.getLayoutParams();
820
821                float childExtra = lp.weight;
822                if (childExtra > 0) {
823                    // Child said it could absorb extra space -- give him his share
824                    int share = (int) (childExtra * delta / weightSum);
825                    weightSum -= childExtra;
826                    delta -= share;
827
828                    final int childHeightMeasureSpec = getChildMeasureSpec(
829                            heightMeasureSpec,
830                            mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin,
831                            lp.height);
832
833                    // TODO: Use a field like lp.isMeasured to figure out if this
834                    // child has been previously measured
835                    if ((lp.width != 0) || (widthMode != MeasureSpec.EXACTLY)) {
836                        // child was measured once already above ... base new measurement
837                        // on stored values
838                        int childWidth = child.getMeasuredWidth() + share;
839                        if (childWidth < 0) {
840                            childWidth = 0;
841                        }
842
843                        child.measure(
844                            MeasureSpec.makeMeasureSpec(childWidth, MeasureSpec.EXACTLY),
845                            childHeightMeasureSpec);
846                    } else {
847                        // child was skipped in the loop above. Measure for this first time here
848                        child.measure(MeasureSpec.makeMeasureSpec(
849                                share > 0 ? share : 0, MeasureSpec.EXACTLY),
850                                childHeightMeasureSpec);
851                    }
852                }
853
854                mTotalLength += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin +
855                        getNextLocationOffset(child);
856
857                boolean matchHeightLocally = heightMode != MeasureSpec.EXACTLY &&
858                        lp.height == LayoutParams.MATCH_PARENT;
859
860                final int margin = lp.topMargin + lp .bottomMargin;
861                int childHeight = child.getMeasuredHeight() + margin;
862                maxHeight = Math.max(maxHeight, childHeight);
863                alternativeMaxHeight = Math.max(alternativeMaxHeight,
864                        matchHeightLocally ? margin : childHeight);
865
866                allFillParent = allFillParent && lp.height == LayoutParams.MATCH_PARENT;
867
868                if (baselineAligned) {
869                    final int childBaseline = child.getBaseline();
870                    if (childBaseline != -1) {
871                        // Translates the child's vertical gravity into an index in the range 0..2
872                        final int gravity = (lp.gravity < 0 ? mGravity : lp.gravity)
873                                & Gravity.VERTICAL_GRAVITY_MASK;
874                        final int index = ((gravity >> Gravity.AXIS_Y_SHIFT)
875                                & ~Gravity.AXIS_SPECIFIED) >> 1;
876
877                        maxAscent[index] = Math.max(maxAscent[index], childBaseline);
878                        maxDescent[index] = Math.max(maxDescent[index],
879                                childHeight - childBaseline);
880                    }
881                }
882            }
883
884            // Add in our padding
885            mTotalLength += mPaddingLeft + mPaddingRight;
886            // TODO: Should we update widthSize with the new total length?
887
888            // Check mMaxAscent[INDEX_TOP] first because it maps to Gravity.TOP,
889            // the most common case
890            if (maxAscent[INDEX_TOP] != -1 ||
891                    maxAscent[INDEX_CENTER_VERTICAL] != -1 ||
892                    maxAscent[INDEX_BOTTOM] != -1 ||
893                    maxAscent[INDEX_FILL] != -1) {
894                final int ascent = Math.max(maxAscent[INDEX_FILL],
895                        Math.max(maxAscent[INDEX_CENTER_VERTICAL],
896                        Math.max(maxAscent[INDEX_TOP], maxAscent[INDEX_BOTTOM])));
897                final int descent = Math.max(maxDescent[INDEX_FILL],
898                        Math.max(maxDescent[INDEX_CENTER_VERTICAL],
899                        Math.max(maxDescent[INDEX_TOP], maxDescent[INDEX_BOTTOM])));
900                maxHeight = Math.max(maxHeight, ascent + descent);
901            }
902        } else {
903            alternativeMaxHeight = Math.max(alternativeMaxHeight, weightedMaxHeight);
904        }
905
906        if (!allFillParent && heightMode != MeasureSpec.EXACTLY) {
907            maxHeight = alternativeMaxHeight;
908        }
909
910        maxHeight += mPaddingTop + mPaddingBottom;
911
912        // Check against our minimum height
913        maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
914
915        setMeasuredDimension(widthSize, resolveSize(maxHeight, heightMeasureSpec));
916
917        if (matchHeight) {
918            forceUniformHeight(count, widthMeasureSpec);
919        }
920    }
921
922    private void forceUniformHeight(int count, int widthMeasureSpec) {
923        // Pretend that the linear layout has an exact size. This is the measured height of
924        // ourselves. The measured height should be the max height of the children, changed
925        // to accomodate the heightMesureSpec from the parent
926        int uniformMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredHeight(),
927                MeasureSpec.EXACTLY);
928        for (int i = 0; i < count; ++i) {
929           final View child = getVirtualChildAt(i);
930           if (child.getVisibility() != GONE) {
931               LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
932
933               if (lp.height == LayoutParams.MATCH_PARENT) {
934                   // Temporarily force children to reuse their old measured width
935                   // FIXME: this may not be right for something like wrapping text?
936                   int oldWidth = lp.width;
937                   lp.width = child.getMeasuredWidth();
938
939                   // Remeasure with new dimensions
940                   measureChildWithMargins(child, widthMeasureSpec, 0, uniformMeasureSpec, 0);
941                   lp.width = oldWidth;
942               }
943           }
944        }
945    }
946
947    /**
948     * <p>Returns the number of children to skip after measuring/laying out
949     * the specified child.</p>
950     *
951     * @param child the child after which we want to skip children
952     * @param index the index of the child after which we want to skip children
953     * @return the number of children to skip, 0 by default
954     */
955    int getChildrenSkipCount(View child, int index) {
956        return 0;
957    }
958
959    /**
960     * <p>Returns the size (width or height) that should be occupied by a null
961     * child.</p>
962     *
963     * @param childIndex the index of the null child
964     * @return the width or height of the child depending on the orientation
965     */
966    int measureNullChild(int childIndex) {
967        return 0;
968    }
969
970    /**
971     * <p>Measure the child according to the parent's measure specs. This
972     * method should be overriden by subclasses to force the sizing of
973     * children. This method is called by {@link #measureVertical(int, int)} and
974     * {@link #measureHorizontal(int, int)}.</p>
975     *
976     * @param child the child to measure
977     * @param childIndex the index of the child in this view
978     * @param widthMeasureSpec horizontal space requirements as imposed by the parent
979     * @param totalWidth extra space that has been used up by the parent horizontally
980     * @param heightMeasureSpec vertical space requirements as imposed by the parent
981     * @param totalHeight extra space that has been used up by the parent vertically
982     */
983    void measureChildBeforeLayout(View child, int childIndex,
984            int widthMeasureSpec, int totalWidth, int heightMeasureSpec,
985            int totalHeight) {
986        measureChildWithMargins(child, widthMeasureSpec, totalWidth,
987                heightMeasureSpec, totalHeight);
988    }
989
990    /**
991     * <p>Return the location offset of the specified child. This can be used
992     * by subclasses to change the location of a given widget.</p>
993     *
994     * @param child the child for which to obtain the location offset
995     * @return the location offset in pixels
996     */
997    int getLocationOffset(View child) {
998        return 0;
999    }
1000
1001    /**
1002     * <p>Return the size offset of the next sibling of the specified child.
1003     * This can be used by subclasses to change the location of the widget
1004     * following <code>child</code>.</p>
1005     *
1006     * @param child the child whose next sibling will be moved
1007     * @return the location offset of the next child in pixels
1008     */
1009    int getNextLocationOffset(View child) {
1010        return 0;
1011    }
1012
1013    @Override
1014    protected void onLayout(boolean changed, int l, int t, int r, int b) {
1015        if (mOrientation == VERTICAL) {
1016            layoutVertical();
1017        } else {
1018            layoutHorizontal();
1019        }
1020    }
1021
1022    /**
1023     * Position the children during a layout pass if the orientation of this
1024     * LinearLayout is set to {@link #VERTICAL}.
1025     *
1026     * @see #getOrientation()
1027     * @see #setOrientation(int)
1028     * @see #onLayout(boolean, int, int, int, int)
1029     */
1030    void layoutVertical() {
1031        final int paddingLeft = mPaddingLeft;
1032
1033        int childTop = mPaddingTop;
1034        int childLeft;
1035
1036        // Where right end of child should go
1037        final int width = mRight - mLeft;
1038        int childRight = width - mPaddingRight;
1039
1040        // Space available for child
1041        int childSpace = width - paddingLeft - mPaddingRight;
1042
1043        final int count = getVirtualChildCount();
1044
1045        final int majorGravity = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
1046        final int minorGravity = mGravity & Gravity.HORIZONTAL_GRAVITY_MASK;
1047
1048        if (majorGravity != Gravity.TOP) {
1049           switch (majorGravity) {
1050               case Gravity.BOTTOM:
1051                   // mTotalLength contains the padding already, we add the top
1052                   // padding to compensate
1053                   childTop = mBottom - mTop + mPaddingTop - mTotalLength;
1054                   break;
1055
1056               case Gravity.CENTER_VERTICAL:
1057                   childTop += ((mBottom - mTop)  - mTotalLength) / 2;
1058                   break;
1059           }
1060
1061        }
1062
1063        for (int i = 0; i < count; i++) {
1064            final View child = getVirtualChildAt(i);
1065            if (child == null) {
1066                childTop += measureNullChild(i);
1067            } else if (child.getVisibility() != GONE) {
1068                final int childWidth = child.getMeasuredWidth();
1069                final int childHeight = child.getMeasuredHeight();
1070
1071                final LinearLayout.LayoutParams lp =
1072                        (LinearLayout.LayoutParams) child.getLayoutParams();
1073
1074                int gravity = lp.gravity;
1075                if (gravity < 0) {
1076                    gravity = minorGravity;
1077                }
1078
1079                switch (gravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
1080                    case Gravity.LEFT:
1081                        childLeft = paddingLeft + lp.leftMargin;
1082                        break;
1083
1084                    case Gravity.CENTER_HORIZONTAL:
1085                        childLeft = paddingLeft + ((childSpace - childWidth) / 2)
1086                                + lp.leftMargin - lp.rightMargin;
1087                        break;
1088
1089                    case Gravity.RIGHT:
1090                        childLeft = childRight - childWidth - lp.rightMargin;
1091                        break;
1092                    default:
1093                        childLeft = paddingLeft;
1094                        break;
1095                }
1096
1097
1098                childTop += lp.topMargin;
1099                setChildFrame(child, childLeft, childTop + getLocationOffset(child),
1100                        childWidth, childHeight);
1101                childTop += childHeight + lp.bottomMargin + getNextLocationOffset(child);
1102
1103                i += getChildrenSkipCount(child, i);
1104            }
1105        }
1106    }
1107
1108    /**
1109     * Position the children during a layout pass if the orientation of this
1110     * LinearLayout is set to {@link #HORIZONTAL}.
1111     *
1112     * @see #getOrientation()
1113     * @see #setOrientation(int)
1114     * @see #onLayout(boolean, int, int, int, int)
1115     */
1116    void layoutHorizontal() {
1117        final int paddingTop = mPaddingTop;
1118
1119        int childTop;
1120        int childLeft = mPaddingLeft;
1121
1122        // Where bottom of child should go
1123        final int height = mBottom - mTop;
1124        int childBottom = height - mPaddingBottom;
1125
1126        // Space available for child
1127        int childSpace = height - paddingTop - mPaddingBottom;
1128
1129        final int count = getVirtualChildCount();
1130
1131        final int majorGravity = mGravity & Gravity.HORIZONTAL_GRAVITY_MASK;
1132        final int minorGravity = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
1133
1134        final boolean baselineAligned = mBaselineAligned;
1135
1136        final int[] maxAscent = mMaxAscent;
1137        final int[] maxDescent = mMaxDescent;
1138
1139        if (majorGravity != Gravity.LEFT) {
1140            switch (majorGravity) {
1141                case Gravity.RIGHT:
1142                    // mTotalLength contains the padding already, we add the left
1143                    // padding to compensate
1144                    childLeft = mRight - mLeft + mPaddingLeft - mTotalLength;
1145                    break;
1146
1147                case Gravity.CENTER_HORIZONTAL:
1148                    childLeft += ((mRight - mLeft) - mTotalLength) / 2;
1149                    break;
1150            }
1151       }
1152
1153        for (int i = 0; i < count; i++) {
1154            final View child = getVirtualChildAt(i);
1155
1156            if (child == null) {
1157                childLeft += measureNullChild(i);
1158            } else if (child.getVisibility() != GONE) {
1159                final int childWidth = child.getMeasuredWidth();
1160                final int childHeight = child.getMeasuredHeight();
1161                int childBaseline = -1;
1162
1163                final LinearLayout.LayoutParams lp =
1164                        (LinearLayout.LayoutParams) child.getLayoutParams();
1165
1166                if (baselineAligned && lp.height != LayoutParams.MATCH_PARENT) {
1167                    childBaseline = child.getBaseline();
1168                }
1169
1170                int gravity = lp.gravity;
1171                if (gravity < 0) {
1172                    gravity = minorGravity;
1173                }
1174
1175                switch (gravity & Gravity.VERTICAL_GRAVITY_MASK) {
1176                    case Gravity.TOP:
1177                        childTop = paddingTop + lp.topMargin;
1178                        if (childBaseline != -1) {
1179                            childTop += maxAscent[INDEX_TOP] - childBaseline;
1180                        }
1181                        break;
1182
1183                    case Gravity.CENTER_VERTICAL:
1184                        // Removed support for baseline alignment when layout_gravity or
1185                        // gravity == center_vertical. See bug #1038483.
1186                        // Keep the code around if we need to re-enable this feature
1187                        // if (childBaseline != -1) {
1188                        //     // Align baselines vertically only if the child is smaller than us
1189                        //     if (childSpace - childHeight > 0) {
1190                        //         childTop = paddingTop + (childSpace / 2) - childBaseline;
1191                        //     } else {
1192                        //         childTop = paddingTop + (childSpace - childHeight) / 2;
1193                        //     }
1194                        // } else {
1195                        childTop = paddingTop + ((childSpace - childHeight) / 2)
1196                                + lp.topMargin - lp.bottomMargin;
1197                        break;
1198
1199                    case Gravity.BOTTOM:
1200                        childTop = childBottom - childHeight - lp.bottomMargin;
1201                        if (childBaseline != -1) {
1202                            int descent = child.getMeasuredHeight() - childBaseline;
1203                            childTop -= (maxDescent[INDEX_BOTTOM] - descent);
1204                        }
1205                        break;
1206                    default:
1207                        childTop = paddingTop;
1208                        break;
1209                }
1210
1211                childLeft += lp.leftMargin;
1212                setChildFrame(child, childLeft + getLocationOffset(child), childTop,
1213                        childWidth, childHeight);
1214                childLeft += childWidth + lp.rightMargin +
1215                        getNextLocationOffset(child);
1216
1217                i += getChildrenSkipCount(child, i);
1218            }
1219        }
1220    }
1221
1222    private void setChildFrame(View child, int left, int top, int width, int height) {
1223        child.layout(left, top, left + width, top + height);
1224    }
1225
1226    /**
1227     * Should the layout be a column or a row.
1228     * @param orientation Pass HORIZONTAL or VERTICAL. Default
1229     * value is HORIZONTAL.
1230     *
1231     * @attr ref android.R.styleable#LinearLayout_orientation
1232     */
1233    public void setOrientation(int orientation) {
1234        if (mOrientation != orientation) {
1235            mOrientation = orientation;
1236            requestLayout();
1237        }
1238    }
1239
1240    /**
1241     * Returns the current orientation.
1242     *
1243     * @return either {@link #HORIZONTAL} or {@link #VERTICAL}
1244     */
1245    public int getOrientation() {
1246        return mOrientation;
1247    }
1248
1249    /**
1250     * Describes how the child views are positioned. Defaults to GRAVITY_TOP. If
1251     * this layout has a VERTICAL orientation, this controls where all the child
1252     * views are placed if there is extra vertical space. If this layout has a
1253     * HORIZONTAL orientation, this controls the alignment of the children.
1254     *
1255     * @param gravity See {@link android.view.Gravity}
1256     *
1257     * @attr ref android.R.styleable#LinearLayout_gravity
1258     */
1259    @android.view.RemotableViewMethod
1260    public void setGravity(int gravity) {
1261        if (mGravity != gravity) {
1262            if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == 0) {
1263                gravity |= Gravity.LEFT;
1264            }
1265
1266            if ((gravity & Gravity.VERTICAL_GRAVITY_MASK) == 0) {
1267                gravity |= Gravity.TOP;
1268            }
1269
1270            mGravity = gravity;
1271            requestLayout();
1272        }
1273    }
1274
1275    @android.view.RemotableViewMethod
1276    public void setHorizontalGravity(int horizontalGravity) {
1277        final int gravity = horizontalGravity & Gravity.HORIZONTAL_GRAVITY_MASK;
1278        if ((mGravity & Gravity.HORIZONTAL_GRAVITY_MASK) != gravity) {
1279            mGravity = (mGravity & ~Gravity.HORIZONTAL_GRAVITY_MASK) | gravity;
1280            requestLayout();
1281        }
1282    }
1283
1284    @android.view.RemotableViewMethod
1285    public void setVerticalGravity(int verticalGravity) {
1286        final int gravity = verticalGravity & Gravity.VERTICAL_GRAVITY_MASK;
1287        if ((mGravity & Gravity.VERTICAL_GRAVITY_MASK) != gravity) {
1288            mGravity = (mGravity & ~Gravity.VERTICAL_GRAVITY_MASK) | gravity;
1289            requestLayout();
1290        }
1291    }
1292
1293    @Override
1294    public LayoutParams generateLayoutParams(AttributeSet attrs) {
1295        return new LinearLayout.LayoutParams(getContext(), attrs);
1296    }
1297
1298    /**
1299     * Returns a set of layout parameters with a width of
1300     * {@link android.view.ViewGroup.LayoutParams#MATCH_PARENT}
1301     * and a height of {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT}
1302     * when the layout's orientation is {@link #VERTICAL}. When the orientation is
1303     * {@link #HORIZONTAL}, the width is set to {@link LayoutParams#WRAP_CONTENT}
1304     * and the height to {@link LayoutParams#WRAP_CONTENT}.
1305     */
1306    @Override
1307    protected LayoutParams generateDefaultLayoutParams() {
1308        if (mOrientation == HORIZONTAL) {
1309            return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
1310        } else if (mOrientation == VERTICAL) {
1311            return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
1312        }
1313        return null;
1314    }
1315
1316    @Override
1317    protected LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
1318        return new LayoutParams(p);
1319    }
1320
1321
1322    // Override to allow type-checking of LayoutParams.
1323    @Override
1324    protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
1325        return p instanceof LinearLayout.LayoutParams;
1326    }
1327
1328    /**
1329     * Per-child layout information associated with ViewLinearLayout.
1330     *
1331     * @attr ref android.R.styleable#LinearLayout_Layout_layout_weight
1332     * @attr ref android.R.styleable#LinearLayout_Layout_layout_gravity
1333     */
1334    public static class LayoutParams extends ViewGroup.MarginLayoutParams {
1335        /**
1336         * Indicates how much of the extra space in the LinearLayout will be
1337         * allocated to the view associated with these LayoutParams. Specify
1338         * 0 if the view should not be stretched. Otherwise the extra pixels
1339         * will be pro-rated among all views whose weight is greater than 0.
1340         */
1341        @ViewDebug.ExportedProperty
1342        public float weight;
1343
1344        /**
1345         * Gravity for the view associated with these LayoutParams.
1346         *
1347         * @see android.view.Gravity
1348         */
1349        @ViewDebug.ExportedProperty(mapping = {
1350            @ViewDebug.IntToString(from =  -1,                       to = "NONE"),
1351            @ViewDebug.IntToString(from = Gravity.NO_GRAVITY,        to = "NONE"),
1352            @ViewDebug.IntToString(from = Gravity.TOP,               to = "TOP"),
1353            @ViewDebug.IntToString(from = Gravity.BOTTOM,            to = "BOTTOM"),
1354            @ViewDebug.IntToString(from = Gravity.LEFT,              to = "LEFT"),
1355            @ViewDebug.IntToString(from = Gravity.RIGHT,             to = "RIGHT"),
1356            @ViewDebug.IntToString(from = Gravity.CENTER_VERTICAL,   to = "CENTER_VERTICAL"),
1357            @ViewDebug.IntToString(from = Gravity.FILL_VERTICAL,     to = "FILL_VERTICAL"),
1358            @ViewDebug.IntToString(from = Gravity.CENTER_HORIZONTAL, to = "CENTER_HORIZONTAL"),
1359            @ViewDebug.IntToString(from = Gravity.FILL_HORIZONTAL,   to = "FILL_HORIZONTAL"),
1360            @ViewDebug.IntToString(from = Gravity.CENTER,            to = "CENTER"),
1361            @ViewDebug.IntToString(from = Gravity.FILL,              to = "FILL")
1362        })
1363        public int gravity = -1;
1364
1365        /**
1366         * {@inheritDoc}
1367         */
1368        public LayoutParams(Context c, AttributeSet attrs) {
1369            super(c, attrs);
1370            TypedArray a =
1371                    c.obtainStyledAttributes(attrs, com.android.internal.R.styleable.LinearLayout_Layout);
1372
1373            weight = a.getFloat(com.android.internal.R.styleable.LinearLayout_Layout_layout_weight, 0);
1374            gravity = a.getInt(com.android.internal.R.styleable.LinearLayout_Layout_layout_gravity, -1);
1375
1376            a.recycle();
1377        }
1378
1379        /**
1380         * {@inheritDoc}
1381         */
1382        public LayoutParams(int width, int height) {
1383            super(width, height);
1384            weight = 0;
1385        }
1386
1387        /**
1388         * Creates a new set of layout parameters with the specified width, height
1389         * and weight.
1390         *
1391         * @param width the width, either {@link #MATCH_PARENT},
1392         *        {@link #WRAP_CONTENT} or a fixed size in pixels
1393         * @param height the height, either {@link #MATCH_PARENT},
1394         *        {@link #WRAP_CONTENT} or a fixed size in pixels
1395         * @param weight the weight
1396         */
1397        public LayoutParams(int width, int height, float weight) {
1398            super(width, height);
1399            this.weight = weight;
1400        }
1401
1402        /**
1403         * {@inheritDoc}
1404         */
1405        public LayoutParams(ViewGroup.LayoutParams p) {
1406            super(p);
1407        }
1408
1409        /**
1410         * {@inheritDoc}
1411         */
1412        public LayoutParams(MarginLayoutParams source) {
1413            super(source);
1414        }
1415
1416        @Override
1417        public String debug(String output) {
1418            return output + "LinearLayout.LayoutParams={width=" + sizeToString(width) +
1419                    ", height=" + sizeToString(height) + " weight=" + weight +  "}";
1420        }
1421    }
1422}
1423