1/*
2 * Copyright (C) 2007 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.graphics;
18
19import android.content.res.AssetManager;
20import android.content.res.Resources;
21import android.os.Trace;
22import android.util.DisplayMetrics;
23import android.util.Log;
24import android.util.TypedValue;
25
26import java.io.FileDescriptor;
27import java.io.FileInputStream;
28import java.io.IOException;
29import java.io.InputStream;
30
31/**
32 * Creates Bitmap objects from various sources, including files, streams,
33 * and byte-arrays.
34 */
35public class BitmapFactory {
36    private static final int DECODE_BUFFER_SIZE = 16 * 1024;
37
38    public static class Options {
39        /**
40         * Create a default Options object, which if left unchanged will give
41         * the same result from the decoder as if null were passed.
42         */
43        public Options() {
44            inDither = false;
45            inScaled = true;
46            inPremultiplied = true;
47        }
48
49        /**
50         * If set, decode methods that take the Options object will attempt to
51         * reuse this bitmap when loading content. If the decode operation
52         * cannot use this bitmap, the decode method will return
53         * <code>null</code> and will throw an IllegalArgumentException. The
54         * current implementation necessitates that the reused bitmap be
55         * mutable, and the resulting reused bitmap will continue to remain
56         * mutable even when decoding a resource which would normally result in
57         * an immutable bitmap.</p>
58         *
59         * <p>You should still always use the returned Bitmap of the decode
60         * method and not assume that reusing the bitmap worked, due to the
61         * constraints outlined above and failure situations that can occur.
62         * Checking whether the return value matches the value of the inBitmap
63         * set in the Options structure will indicate if the bitmap was reused,
64         * but in all cases you should use the Bitmap returned by the decoding
65         * function to ensure that you are using the bitmap that was used as the
66         * decode destination.</p>
67         *
68         * <h3>Usage with BitmapFactory</h3>
69         *
70         * <p>As of {@link android.os.Build.VERSION_CODES#KITKAT}, any
71         * mutable bitmap can be reused by {@link BitmapFactory} to decode any
72         * other bitmaps as long as the resulting {@link Bitmap#getByteCount()
73         * byte count} of the decoded bitmap is less than or equal to the {@link
74         * Bitmap#getAllocationByteCount() allocated byte count} of the reused
75         * bitmap. This can be because the intrinsic size is smaller, or its
76         * size post scaling (for density / sample size) is smaller.</p>
77         *
78         * <p class="note">Prior to {@link android.os.Build.VERSION_CODES#KITKAT}
79         * additional constraints apply: The image being decoded (whether as a
80         * resource or as a stream) must be in jpeg or png format. Only equal
81         * sized bitmaps are supported, with {@link #inSampleSize} set to 1.
82         * Additionally, the {@link android.graphics.Bitmap.Config
83         * configuration} of the reused bitmap will override the setting of
84         * {@link #inPreferredConfig}, if set.</p>
85         *
86         * <h3>Usage with BitmapRegionDecoder</h3>
87         *
88         * <p>BitmapRegionDecoder will draw its requested content into the Bitmap
89         * provided, clipping if the output content size (post scaling) is larger
90         * than the provided Bitmap. The provided Bitmap's width, height, and
91         * {@link Bitmap.Config} will not be changed.
92         *
93         * <p class="note">BitmapRegionDecoder support for {@link #inBitmap} was
94         * introduced in {@link android.os.Build.VERSION_CODES#JELLY_BEAN}. All
95         * formats supported by BitmapRegionDecoder support Bitmap reuse via
96         * {@link #inBitmap}.</p>
97         *
98         * @see Bitmap#reconfigure(int,int, android.graphics.Bitmap.Config)
99         */
100        public Bitmap inBitmap;
101
102        /**
103         * If set, decode methods will always return a mutable Bitmap instead of
104         * an immutable one. This can be used for instance to programmatically apply
105         * effects to a Bitmap loaded through BitmapFactory.
106         */
107        @SuppressWarnings({"UnusedDeclaration"}) // used in native code
108        public boolean inMutable;
109
110        /**
111         * If set to true, the decoder will return null (no bitmap), but
112         * the out... fields will still be set, allowing the caller to query
113         * the bitmap without having to allocate the memory for its pixels.
114         */
115        public boolean inJustDecodeBounds;
116
117        /**
118         * If set to a value > 1, requests the decoder to subsample the original
119         * image, returning a smaller image to save memory. The sample size is
120         * the number of pixels in either dimension that correspond to a single
121         * pixel in the decoded bitmap. For example, inSampleSize == 4 returns
122         * an image that is 1/4 the width/height of the original, and 1/16 the
123         * number of pixels. Any value <= 1 is treated the same as 1. Note: the
124         * decoder uses a final value based on powers of 2, any other value will
125         * be rounded down to the nearest power of 2.
126         */
127        public int inSampleSize;
128
129        /**
130         * If this is non-null, the decoder will try to decode into this
131         * internal configuration. If it is null, or the request cannot be met,
132         * the decoder will try to pick the best matching config based on the
133         * system's screen depth, and characteristics of the original image such
134         * as if it has per-pixel alpha (requiring a config that also does).
135         *
136         * Image are loaded with the {@link Bitmap.Config#ARGB_8888} config by
137         * default.
138         */
139        public Bitmap.Config inPreferredConfig = Bitmap.Config.ARGB_8888;
140
141        /**
142         * If true (which is the default), the resulting bitmap will have its
143         * color channels pre-multipled by the alpha channel.
144         *
145         * <p>This should NOT be set to false for images to be directly drawn by
146         * the view system or through a {@link Canvas}. The view system and
147         * {@link Canvas} assume all drawn images are pre-multiplied to simplify
148         * draw-time blending, and will throw a RuntimeException when
149         * un-premultiplied are drawn.</p>
150         *
151         * <p>This is likely only useful if you want to manipulate raw encoded
152         * image data, e.g. with RenderScript or custom OpenGL.</p>
153         *
154         * <p>This does not affect bitmaps without an alpha channel.</p>
155         *
156         * <p>Setting this flag to false while setting {@link #inScaled} to true
157         * may result in incorrect colors.</p>
158         *
159         * @see Bitmap#hasAlpha()
160         * @see Bitmap#isPremultiplied()
161         * @see #inScaled
162         */
163        public boolean inPremultiplied;
164
165        /**
166         * If dither is true, the decoder will attempt to dither the decoded
167         * image.
168         */
169        public boolean inDither;
170
171        /**
172         * The pixel density to use for the bitmap.  This will always result
173         * in the returned bitmap having a density set for it (see
174         * {@link Bitmap#setDensity(int) Bitmap.setDensity(int)}).  In addition,
175         * if {@link #inScaled} is set (which it is by default} and this
176         * density does not match {@link #inTargetDensity}, then the bitmap
177         * will be scaled to the target density before being returned.
178         *
179         * <p>If this is 0,
180         * {@link BitmapFactory#decodeResource(Resources, int)},
181         * {@link BitmapFactory#decodeResource(Resources, int, android.graphics.BitmapFactory.Options)},
182         * and {@link BitmapFactory#decodeResourceStream}
183         * will fill in the density associated with the resource.  The other
184         * functions will leave it as-is and no density will be applied.
185         *
186         * @see #inTargetDensity
187         * @see #inScreenDensity
188         * @see #inScaled
189         * @see Bitmap#setDensity(int)
190         * @see android.util.DisplayMetrics#densityDpi
191         */
192        public int inDensity;
193
194        /**
195         * The pixel density of the destination this bitmap will be drawn to.
196         * This is used in conjunction with {@link #inDensity} and
197         * {@link #inScaled} to determine if and how to scale the bitmap before
198         * returning it.
199         *
200         * <p>If this is 0,
201         * {@link BitmapFactory#decodeResource(Resources, int)},
202         * {@link BitmapFactory#decodeResource(Resources, int, android.graphics.BitmapFactory.Options)},
203         * and {@link BitmapFactory#decodeResourceStream}
204         * will fill in the density associated the Resources object's
205         * DisplayMetrics.  The other
206         * functions will leave it as-is and no scaling for density will be
207         * performed.
208         *
209         * @see #inDensity
210         * @see #inScreenDensity
211         * @see #inScaled
212         * @see android.util.DisplayMetrics#densityDpi
213         */
214        public int inTargetDensity;
215
216        /**
217         * The pixel density of the actual screen that is being used.  This is
218         * purely for applications running in density compatibility code, where
219         * {@link #inTargetDensity} is actually the density the application
220         * sees rather than the real screen density.
221         *
222         * <p>By setting this, you
223         * allow the loading code to avoid scaling a bitmap that is currently
224         * in the screen density up/down to the compatibility density.  Instead,
225         * if {@link #inDensity} is the same as {@link #inScreenDensity}, the
226         * bitmap will be left as-is.  Anything using the resulting bitmap
227         * must also used {@link Bitmap#getScaledWidth(int)
228         * Bitmap.getScaledWidth} and {@link Bitmap#getScaledHeight
229         * Bitmap.getScaledHeight} to account for any different between the
230         * bitmap's density and the target's density.
231         *
232         * <p>This is never set automatically for the caller by
233         * {@link BitmapFactory} itself.  It must be explicitly set, since the
234         * caller must deal with the resulting bitmap in a density-aware way.
235         *
236         * @see #inDensity
237         * @see #inTargetDensity
238         * @see #inScaled
239         * @see android.util.DisplayMetrics#densityDpi
240         */
241        public int inScreenDensity;
242
243        /**
244         * When this flag is set, if {@link #inDensity} and
245         * {@link #inTargetDensity} are not 0, the
246         * bitmap will be scaled to match {@link #inTargetDensity} when loaded,
247         * rather than relying on the graphics system scaling it each time it
248         * is drawn to a Canvas.
249         *
250         * <p>BitmapRegionDecoder ignores this flag, and will not scale output
251         * based on density. (though {@link #inSampleSize} is supported)</p>
252         *
253         * <p>This flag is turned on by default and should be turned off if you need
254         * a non-scaled version of the bitmap.  Nine-patch bitmaps ignore this
255         * flag and are always scaled.
256         *
257         * <p>If {@link #inPremultiplied} is set to false, and the image has alpha,
258         * setting this flag to true may result in incorrect colors.
259         */
260        public boolean inScaled;
261
262        /**
263         * If this is set to true, then the resulting bitmap will allocate its
264         * pixels such that they can be purged if the system needs to reclaim
265         * memory. In that instance, when the pixels need to be accessed again
266         * (e.g. the bitmap is drawn, getPixels() is called), they will be
267         * automatically re-decoded.
268         *
269         * <p>For the re-decode to happen, the bitmap must have access to the
270         * encoded data, either by sharing a reference to the input
271         * or by making a copy of it. This distinction is controlled by
272         * inInputShareable. If this is true, then the bitmap may keep a shallow
273         * reference to the input. If this is false, then the bitmap will
274         * explicitly make a copy of the input data, and keep that. Even if
275         * sharing is allowed, the implementation may still decide to make a
276         * deep copy of the input data.</p>
277         *
278         * <p>While inPurgeable can help avoid big Dalvik heap allocations (from
279         * API level 11 onward), it sacrifices performance predictability since any
280         * image that the view system tries to draw may incur a decode delay which
281         * can lead to dropped frames. Therefore, most apps should avoid using
282         * inPurgeable to allow for a fast and fluid UI. To minimize Dalvik heap
283         * allocations use the {@link #inBitmap} flag instead.</p>
284         *
285         * <p class="note"><strong>Note:</strong> This flag is ignored when used
286         * with {@link #decodeResource(Resources, int,
287         * android.graphics.BitmapFactory.Options)} or {@link #decodeFile(String,
288         * android.graphics.BitmapFactory.Options)}.</p>
289         */
290        public boolean inPurgeable;
291
292        /**
293         * This field works in conjuction with inPurgeable. If inPurgeable is
294         * false, then this field is ignored. If inPurgeable is true, then this
295         * field determines whether the bitmap can share a reference to the
296         * input data (inputstream, array, etc.) or if it must make a deep copy.
297         */
298        public boolean inInputShareable;
299
300        /**
301         * If inPreferQualityOverSpeed is set to true, the decoder will try to
302         * decode the reconstructed image to a higher quality even at the
303         * expense of the decoding speed. Currently the field only affects JPEG
304         * decode, in the case of which a more accurate, but slightly slower,
305         * IDCT method will be used instead.
306         */
307        public boolean inPreferQualityOverSpeed;
308
309        /**
310         * The resulting width of the bitmap, set independent of the state of
311         * inJustDecodeBounds. However, if there is an error trying to decode,
312         * outWidth will be set to -1.
313         */
314
315        public int outWidth;
316
317        /**
318         * The resulting height of the bitmap, set independent of the state of
319         * inJustDecodeBounds. However, if there is an error trying to decode,
320         * outHeight will be set to -1.
321         */
322        public int outHeight;
323
324        /**
325         * If known, this string is set to the mimetype of the decoded image.
326         * If not know, or there is an error, it is set to null.
327         */
328        public String outMimeType;
329
330        /**
331         * Temp storage to use for decoding.  Suggest 16K or so.
332         */
333        public byte[] inTempStorage;
334
335        private native void requestCancel();
336
337        /**
338         * Flag to indicate that cancel has been called on this object.  This
339         * is useful if there's an intermediary that wants to first decode the
340         * bounds and then decode the image.  In that case the intermediary
341         * can check, inbetween the bounds decode and the image decode, to see
342         * if the operation is canceled.
343         */
344        public boolean mCancel;
345
346        /**
347         *  This can be called from another thread while this options object is
348         *  inside a decode... call. Calling this will notify the decoder that
349         *  it should cancel its operation. This is not guaranteed to cancel
350         *  the decode, but if it does, the decoder... operation will return
351         *  null, or if inJustDecodeBounds is true, will set outWidth/outHeight
352         *  to -1
353         */
354        public void requestCancelDecode() {
355            mCancel = true;
356            requestCancel();
357        }
358    }
359
360    /**
361     * Decode a file path into a bitmap. If the specified file name is null,
362     * or cannot be decoded into a bitmap, the function returns null.
363     *
364     * @param pathName complete path name for the file to be decoded.
365     * @param opts null-ok; Options that control downsampling and whether the
366     *             image should be completely decoded, or just is size returned.
367     * @return The decoded bitmap, or null if the image data could not be
368     *         decoded, or, if opts is non-null, if opts requested only the
369     *         size be returned (in opts.outWidth and opts.outHeight)
370     */
371    public static Bitmap decodeFile(String pathName, Options opts) {
372        Bitmap bm = null;
373        InputStream stream = null;
374        try {
375            stream = new FileInputStream(pathName);
376            bm = decodeStream(stream, null, opts);
377        } catch (Exception e) {
378            /*  do nothing.
379                If the exception happened on open, bm will be null.
380            */
381            Log.e("BitmapFactory", "Unable to decode stream: " + e);
382        } finally {
383            if (stream != null) {
384                try {
385                    stream.close();
386                } catch (IOException e) {
387                    // do nothing here
388                }
389            }
390        }
391        return bm;
392    }
393
394    /**
395     * Decode a file path into a bitmap. If the specified file name is null,
396     * or cannot be decoded into a bitmap, the function returns null.
397     *
398     * @param pathName complete path name for the file to be decoded.
399     * @return the resulting decoded bitmap, or null if it could not be decoded.
400     */
401    public static Bitmap decodeFile(String pathName) {
402        return decodeFile(pathName, null);
403    }
404
405    /**
406     * Decode a new Bitmap from an InputStream. This InputStream was obtained from
407     * resources, which we pass to be able to scale the bitmap accordingly.
408     */
409    public static Bitmap decodeResourceStream(Resources res, TypedValue value,
410            InputStream is, Rect pad, Options opts) {
411
412        if (opts == null) {
413            opts = new Options();
414        }
415
416        if (opts.inDensity == 0 && value != null) {
417            final int density = value.density;
418            if (density == TypedValue.DENSITY_DEFAULT) {
419                opts.inDensity = DisplayMetrics.DENSITY_DEFAULT;
420            } else if (density != TypedValue.DENSITY_NONE) {
421                opts.inDensity = density;
422            }
423        }
424
425        if (opts.inTargetDensity == 0 && res != null) {
426            opts.inTargetDensity = res.getDisplayMetrics().densityDpi;
427        }
428
429        return decodeStream(is, pad, opts);
430    }
431
432    /**
433     * Synonym for opening the given resource and calling
434     * {@link #decodeResourceStream}.
435     *
436     * @param res   The resources object containing the image data
437     * @param id The resource id of the image data
438     * @param opts null-ok; Options that control downsampling and whether the
439     *             image should be completely decoded, or just is size returned.
440     * @return The decoded bitmap, or null if the image data could not be
441     *         decoded, or, if opts is non-null, if opts requested only the
442     *         size be returned (in opts.outWidth and opts.outHeight)
443     */
444    public static Bitmap decodeResource(Resources res, int id, Options opts) {
445        Bitmap bm = null;
446        InputStream is = null;
447
448        try {
449            final TypedValue value = new TypedValue();
450            is = res.openRawResource(id, value);
451
452            bm = decodeResourceStream(res, value, is, null, opts);
453        } catch (Exception e) {
454            /*  do nothing.
455                If the exception happened on open, bm will be null.
456                If it happened on close, bm is still valid.
457            */
458        } finally {
459            try {
460                if (is != null) is.close();
461            } catch (IOException e) {
462                // Ignore
463            }
464        }
465
466        if (bm == null && opts != null && opts.inBitmap != null) {
467            throw new IllegalArgumentException("Problem decoding into existing bitmap");
468        }
469
470        return bm;
471    }
472
473    /**
474     * Synonym for {@link #decodeResource(Resources, int, android.graphics.BitmapFactory.Options)}
475     * will null Options.
476     *
477     * @param res The resources object containing the image data
478     * @param id The resource id of the image data
479     * @return The decoded bitmap, or null if the image could not be decode.
480     */
481    public static Bitmap decodeResource(Resources res, int id) {
482        return decodeResource(res, id, null);
483    }
484
485    /**
486     * Decode an immutable bitmap from the specified byte array.
487     *
488     * @param data byte array of compressed image data
489     * @param offset offset into imageData for where the decoder should begin
490     *               parsing.
491     * @param length the number of bytes, beginning at offset, to parse
492     * @param opts null-ok; Options that control downsampling and whether the
493     *             image should be completely decoded, or just is size returned.
494     * @return The decoded bitmap, or null if the image data could not be
495     *         decoded, or, if opts is non-null, if opts requested only the
496     *         size be returned (in opts.outWidth and opts.outHeight)
497     */
498    public static Bitmap decodeByteArray(byte[] data, int offset, int length, Options opts) {
499        if ((offset | length) < 0 || data.length < offset + length) {
500            throw new ArrayIndexOutOfBoundsException();
501        }
502
503        Bitmap bm;
504
505        Trace.traceBegin(Trace.TRACE_TAG_GRAPHICS, "decodeBitmap");
506        try {
507            bm = nativeDecodeByteArray(data, offset, length, opts);
508
509            if (bm == null && opts != null && opts.inBitmap != null) {
510                throw new IllegalArgumentException("Problem decoding into existing bitmap");
511            }
512            setDensityFromOptions(bm, opts);
513        } finally {
514            Trace.traceEnd(Trace.TRACE_TAG_GRAPHICS);
515        }
516
517        return bm;
518    }
519
520    /**
521     * Decode an immutable bitmap from the specified byte array.
522     *
523     * @param data byte array of compressed image data
524     * @param offset offset into imageData for where the decoder should begin
525     *               parsing.
526     * @param length the number of bytes, beginning at offset, to parse
527     * @return The decoded bitmap, or null if the image could not be decode.
528     */
529    public static Bitmap decodeByteArray(byte[] data, int offset, int length) {
530        return decodeByteArray(data, offset, length, null);
531    }
532
533    /**
534     * Set the newly decoded bitmap's density based on the Options.
535     */
536    private static void setDensityFromOptions(Bitmap outputBitmap, Options opts) {
537        if (outputBitmap == null || opts == null) return;
538
539        final int density = opts.inDensity;
540        if (density != 0) {
541            outputBitmap.setDensity(density);
542            final int targetDensity = opts.inTargetDensity;
543            if (targetDensity == 0 || density == targetDensity || density == opts.inScreenDensity) {
544                return;
545            }
546
547            byte[] np = outputBitmap.getNinePatchChunk();
548            final boolean isNinePatch = np != null && NinePatch.isNinePatchChunk(np);
549            if (opts.inScaled || isNinePatch) {
550                outputBitmap.setDensity(targetDensity);
551            }
552        } else if (opts.inBitmap != null) {
553            // bitmap was reused, ensure density is reset
554            outputBitmap.setDensity(Bitmap.getDefaultDensity());
555        }
556    }
557
558    /**
559     * Decode an input stream into a bitmap. If the input stream is null, or
560     * cannot be used to decode a bitmap, the function returns null.
561     * The stream's position will be where ever it was after the encoded data
562     * was read.
563     *
564     * @param is The input stream that holds the raw data to be decoded into a
565     *           bitmap.
566     * @param outPadding If not null, return the padding rect for the bitmap if
567     *                   it exists, otherwise set padding to [-1,-1,-1,-1]. If
568     *                   no bitmap is returned (null) then padding is
569     *                   unchanged.
570     * @param opts null-ok; Options that control downsampling and whether the
571     *             image should be completely decoded, or just is size returned.
572     * @return The decoded bitmap, or null if the image data could not be
573     *         decoded, or, if opts is non-null, if opts requested only the
574     *         size be returned (in opts.outWidth and opts.outHeight)
575     *
576     * <p class="note">Prior to {@link android.os.Build.VERSION_CODES#KITKAT},
577     * if {@link InputStream#markSupported is.markSupported()} returns true,
578     * <code>is.mark(1024)</code> would be called. As of
579     * {@link android.os.Build.VERSION_CODES#KITKAT}, this is no longer the case.</p>
580     */
581    public static Bitmap decodeStream(InputStream is, Rect outPadding, Options opts) {
582        // we don't throw in this case, thus allowing the caller to only check
583        // the cache, and not force the image to be decoded.
584        if (is == null) {
585            return null;
586        }
587
588        Bitmap bm = null;
589
590        Trace.traceBegin(Trace.TRACE_TAG_GRAPHICS, "decodeBitmap");
591        try {
592            if (is instanceof AssetManager.AssetInputStream) {
593                final int asset = ((AssetManager.AssetInputStream) is).getAssetInt();
594                bm = nativeDecodeAsset(asset, outPadding, opts);
595            } else {
596                bm = decodeStreamInternal(is, outPadding, opts);
597            }
598
599            if (bm == null && opts != null && opts.inBitmap != null) {
600                throw new IllegalArgumentException("Problem decoding into existing bitmap");
601            }
602
603            setDensityFromOptions(bm, opts);
604        } finally {
605            Trace.traceEnd(Trace.TRACE_TAG_GRAPHICS);
606        }
607
608        return bm;
609    }
610
611    /**
612     * Private helper function for decoding an InputStream natively. Buffers the input enough to
613     * do a rewind as needed, and supplies temporary storage if necessary. is MUST NOT be null.
614     */
615    private static Bitmap decodeStreamInternal(InputStream is, Rect outPadding, Options opts) {
616        // ASSERT(is != null);
617        byte [] tempStorage = null;
618        if (opts != null) tempStorage = opts.inTempStorage;
619        if (tempStorage == null) tempStorage = new byte[DECODE_BUFFER_SIZE];
620        return nativeDecodeStream(is, tempStorage, outPadding, opts);
621    }
622
623    /**
624     * Decode an input stream into a bitmap. If the input stream is null, or
625     * cannot be used to decode a bitmap, the function returns null.
626     * The stream's position will be where ever it was after the encoded data
627     * was read.
628     *
629     * @param is The input stream that holds the raw data to be decoded into a
630     *           bitmap.
631     * @return The decoded bitmap, or null if the image data could not be decoded.
632     */
633    public static Bitmap decodeStream(InputStream is) {
634        return decodeStream(is, null, null);
635    }
636
637    /**
638     * Decode a bitmap from the file descriptor. If the bitmap cannot be decoded
639     * return null. The position within the descriptor will not be changed when
640     * this returns, so the descriptor can be used again as-is.
641     *
642     * @param fd The file descriptor containing the bitmap data to decode
643     * @param outPadding If not null, return the padding rect for the bitmap if
644     *                   it exists, otherwise set padding to [-1,-1,-1,-1]. If
645     *                   no bitmap is returned (null) then padding is
646     *                   unchanged.
647     * @param opts null-ok; Options that control downsampling and whether the
648     *             image should be completely decoded, or just its size returned.
649     * @return the decoded bitmap, or null
650     */
651    public static Bitmap decodeFileDescriptor(FileDescriptor fd, Rect outPadding, Options opts) {
652        Bitmap bm;
653
654        Trace.traceBegin(Trace.TRACE_TAG_GRAPHICS, "decodeFileDescriptor");
655        try {
656            if (nativeIsSeekable(fd)) {
657                bm = nativeDecodeFileDescriptor(fd, outPadding, opts);
658            } else {
659                FileInputStream fis = new FileInputStream(fd);
660                try {
661                    bm = decodeStreamInternal(fis, outPadding, opts);
662                } finally {
663                    try {
664                        fis.close();
665                    } catch (Throwable t) {/* ignore */}
666                }
667            }
668
669            if (bm == null && opts != null && opts.inBitmap != null) {
670                throw new IllegalArgumentException("Problem decoding into existing bitmap");
671            }
672
673            setDensityFromOptions(bm, opts);
674        } finally {
675            Trace.traceEnd(Trace.TRACE_TAG_GRAPHICS);
676        }
677        return bm;
678    }
679
680    /**
681     * Decode a bitmap from the file descriptor. If the bitmap cannot be decoded
682     * return null. The position within the descriptor will not be changed when
683     * this returns, so the descriptor can be used again as is.
684     *
685     * @param fd The file descriptor containing the bitmap data to decode
686     * @return the decoded bitmap, or null
687     */
688    public static Bitmap decodeFileDescriptor(FileDescriptor fd) {
689        return decodeFileDescriptor(fd, null, null);
690    }
691
692    private static native Bitmap nativeDecodeStream(InputStream is, byte[] storage,
693            Rect padding, Options opts);
694    private static native Bitmap nativeDecodeFileDescriptor(FileDescriptor fd,
695            Rect padding, Options opts);
696    private static native Bitmap nativeDecodeAsset(int asset, Rect padding, Options opts);
697    private static native Bitmap nativeDecodeByteArray(byte[] data, int offset,
698            int length, Options opts);
699    private static native boolean nativeIsSeekable(FileDescriptor fd);
700}
701