ScaleFrameLayout.java revision a9f6062bd2dd02b3de253b57c69302893bf1f2e3 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.widget;
15
16import android.content.Context;
17import android.graphics.drawable.Drawable;
18import android.util.AttributeSet;
19import android.view.Gravity;
20import android.view.View;
21import android.view.ViewGroup;
22import android.widget.FrameLayout;
23
24/**
25 * Subclass of FrameLayout that support scale layout area size for children.
26 * @hide
27 */
28public class ScaleFrameLayout extends FrameLayout {
29
30    private static final int DEFAULT_CHILD_GRAVITY = Gravity.TOP | Gravity.START;
31
32    private float mLayoutScaleX = 1f;
33    private float mLayoutScaleY = 1f;
34
35    private float mChildScale = 1f;
36
37    public ScaleFrameLayout(Context context) {
38        this(context ,null);
39    }
40
41    public ScaleFrameLayout(Context context, AttributeSet attrs) {
42        this(context, attrs, 0);
43    }
44
45    public ScaleFrameLayout(Context context, AttributeSet attrs,
46            int defStyle) {
47        super(context, attrs, defStyle);
48    }
49
50    public void setLayoutScaleX(float scaleX) {
51        if (scaleX != mLayoutScaleX) {
52            mLayoutScaleX = scaleX;
53            requestLayout();
54        }
55    }
56
57    public void setLayoutScaleY(float scaleY) {
58        if (scaleY != mLayoutScaleY) {
59            mLayoutScaleY = scaleY;
60            requestLayout();
61        }
62    }
63
64    public void setChildScale(float scale) {
65        if (mChildScale != scale) {
66            mChildScale = scale;
67            for (int i = 0; i < getChildCount(); i++) {
68                getChildAt(i).setScaleX(scale);
69                getChildAt(i).setScaleY(scale);
70            }
71        }
72    }
73
74    @Override
75    public void addView(View child, int index, ViewGroup.LayoutParams params) {
76        super.addView(child, index, params);
77        child.setScaleX(mChildScale);
78        child.setScaleY(mChildScale);
79    }
80
81    @Override
82    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
83        final int count = getChildCount();
84
85        final int parentLeft, parentRight;
86        final int layoutDirection = getLayoutDirection();
87        final float pivotX = (layoutDirection == View.LAYOUT_DIRECTION_RTL) ?
88                getWidth() - getPivotX() :
89                getPivotX();
90        if (mLayoutScaleX != 1f) {
91            parentLeft = getPaddingLeft() + (int)(pivotX - pivotX / mLayoutScaleX + 0.5f);
92            parentRight = (int)(pivotX + (right - left - pivotX) / mLayoutScaleX + 0.5f)
93                    - getPaddingRight();
94        } else {
95            parentLeft = getPaddingLeft();
96            parentRight = right - left - getPaddingRight();
97        }
98
99        final int parentTop, parentBottom;
100        final float pivotY = getPivotY();
101        if (mLayoutScaleY != 1f) {
102            parentTop = getPaddingTop() + (int)(pivotY - pivotY / mLayoutScaleY + 0.5f);
103            parentBottom = (int)(pivotY + (bottom - top - pivotY) / mLayoutScaleY + 0.5f)
104                    - getPaddingBottom();
105        } else {
106            parentTop = getPaddingTop();
107            parentBottom = bottom - top - getPaddingBottom();
108        }
109
110        for (int i = 0; i < count; i++) {
111            final View child = getChildAt(i);
112            if (child.getVisibility() != GONE) {
113                final LayoutParams lp = (LayoutParams) child.getLayoutParams();
114
115                final int width = child.getMeasuredWidth();
116                final int height = child.getMeasuredHeight();
117
118                int childLeft;
119                int childTop;
120
121                int gravity = lp.gravity;
122                if (gravity == -1) {
123                    gravity = DEFAULT_CHILD_GRAVITY;
124                }
125
126                final int absoluteGravity = Gravity.getAbsoluteGravity(gravity, layoutDirection);
127                final int verticalGravity = gravity & Gravity.VERTICAL_GRAVITY_MASK;
128
129                switch (absoluteGravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
130                    case Gravity.CENTER_HORIZONTAL:
131                        childLeft = parentLeft + (parentRight - parentLeft - width) / 2 +
132                                lp.leftMargin - lp.rightMargin;
133                        break;
134                    case Gravity.RIGHT:
135                        childLeft = parentRight - width - lp.rightMargin;
136                        break;
137                    case Gravity.LEFT:
138                    default:
139                        childLeft = parentLeft + lp.leftMargin;
140                }
141
142                switch (verticalGravity) {
143                    case Gravity.TOP:
144                        childTop = parentTop + lp.topMargin;
145                        break;
146                    case Gravity.CENTER_VERTICAL:
147                        childTop = parentTop + (parentBottom - parentTop - height) / 2 +
148                                lp.topMargin - lp.bottomMargin;
149                        break;
150                    case Gravity.BOTTOM:
151                        childTop = parentBottom - height - lp.bottomMargin;
152                        break;
153                    default:
154                        childTop = parentTop + lp.topMargin;
155                }
156
157                child.layout(childLeft, childTop, childLeft + width, childTop + height);
158                // synchronize child pivot to be same as ScaleFrameLayout's pivot
159                child.setPivotX(pivotX - childLeft);
160                child.setPivotY(pivotY - childTop);
161            }
162        }
163    }
164
165    private static int getScaledMeasureSpec(int measureSpec, float scale) {
166        return scale == 1f ? measureSpec : MeasureSpec.makeMeasureSpec(
167                (int) (MeasureSpec.getSize(measureSpec) / scale + 0.5f),
168                MeasureSpec.getMode(measureSpec));
169    }
170
171    @Override
172    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
173        if (mLayoutScaleX != 1f || mLayoutScaleY != 1f) {
174            final int scaledWidthMeasureSpec =
175                    getScaledMeasureSpec(widthMeasureSpec, mLayoutScaleX);
176            final int scaledHeightMeasureSpec =
177                    getScaledMeasureSpec(heightMeasureSpec, mLayoutScaleY);
178            super.onMeasure(scaledWidthMeasureSpec, scaledHeightMeasureSpec);
179            setMeasuredDimension((int)(getMeasuredWidth() * mLayoutScaleX + 0.5f),
180                    (int)(getMeasuredHeight() * mLayoutScaleY + 0.5f));
181        } else {
182            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
183        }
184    }
185
186    /**
187     * setForeground() is not supported,  throws UnsupportedOperationException() when called.
188     */
189    @Override
190    public void setForeground(Drawable d) {
191        throw new UnsupportedOperationException();
192    }
193
194}
195