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1 /*
2  * Copyright (C) 2013 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 
17 package com.android.photos.views;
18 
19 import android.content.Context;
20 import android.graphics.Bitmap;
21 import android.graphics.Rect;
22 import android.graphics.RectF;
23 import android.util.LongSparseArray;
24 import android.util.DisplayMetrics;
25 import android.util.Log;
26 import android.util.Pools.Pool;
27 import android.util.Pools.SynchronizedPool;
28 import android.view.View;
29 import android.view.WindowManager;
30 
31 import com.android.gallery3d.common.Utils;
32 import com.android.gallery3d.glrenderer.BasicTexture;
33 import com.android.gallery3d.glrenderer.GLCanvas;
34 import com.android.gallery3d.glrenderer.UploadedTexture;
35 
36 /**
37  * Handles laying out, decoding, and drawing of tiles in GL
38  */
39 public class TiledImageRenderer {
40     public static final int SIZE_UNKNOWN = -1;
41 
42     private static final String TAG = "TiledImageRenderer";
43     private static final int UPLOAD_LIMIT = 1;
44 
45     /*
46      *  This is the tile state in the CPU side.
47      *  Life of a Tile:
48      *      ACTIVATED (initial state)
49      *              --> IN_QUEUE - by queueForDecode()
50      *              --> RECYCLED - by recycleTile()
51      *      IN_QUEUE --> DECODING - by decodeTile()
52      *               --> RECYCLED - by recycleTile)
53      *      DECODING --> RECYCLING - by recycleTile()
54      *               --> DECODED  - by decodeTile()
55      *               --> DECODE_FAIL - by decodeTile()
56      *      RECYCLING --> RECYCLED - by decodeTile()
57      *      DECODED --> ACTIVATED - (after the decoded bitmap is uploaded)
58      *      DECODED --> RECYCLED - by recycleTile()
59      *      DECODE_FAIL -> RECYCLED - by recycleTile()
60      *      RECYCLED --> ACTIVATED - by obtainTile()
61      */
62     private static final int STATE_ACTIVATED = 0x01;
63     private static final int STATE_IN_QUEUE = 0x02;
64     private static final int STATE_DECODING = 0x04;
65     private static final int STATE_DECODED = 0x08;
66     private static final int STATE_DECODE_FAIL = 0x10;
67     private static final int STATE_RECYCLING = 0x20;
68     private static final int STATE_RECYCLED = 0x40;
69 
70     private static Pool<Bitmap> sTilePool = new SynchronizedPool<Bitmap>(64);
71 
72     // TILE_SIZE must be 2^N
73     private int mTileSize;
74 
75     private TileSource mModel;
76     private BasicTexture mPreview;
77     protected int mLevelCount;  // cache the value of mScaledBitmaps.length
78 
79     // The mLevel variable indicates which level of bitmap we should use.
80     // Level 0 means the original full-sized bitmap, and a larger value means
81     // a smaller scaled bitmap (The width and height of each scaled bitmap is
82     // half size of the previous one). If the value is in [0, mLevelCount), we
83     // use the bitmap in mScaledBitmaps[mLevel] for display, otherwise the value
84     // is mLevelCount
85     private int mLevel = 0;
86 
87     private int mOffsetX;
88     private int mOffsetY;
89 
90     private int mUploadQuota;
91     private boolean mRenderComplete;
92 
93     private final RectF mSourceRect = new RectF();
94     private final RectF mTargetRect = new RectF();
95 
96     private final LongSparseArray<Tile> mActiveTiles = new LongSparseArray<Tile>();
97 
98     // The following three queue are guarded by mQueueLock
99     private final Object mQueueLock = new Object();
100     private final TileQueue mRecycledQueue = new TileQueue();
101     private final TileQueue mUploadQueue = new TileQueue();
102     private final TileQueue mDecodeQueue = new TileQueue();
103 
104     // The width and height of the full-sized bitmap
105     protected int mImageWidth = SIZE_UNKNOWN;
106     protected int mImageHeight = SIZE_UNKNOWN;
107 
108     protected int mCenterX;
109     protected int mCenterY;
110     protected float mScale;
111     protected int mRotation;
112 
113     private boolean mLayoutTiles;
114 
115     // Temp variables to avoid memory allocation
116     private final Rect mTileRange = new Rect();
117     private final Rect mActiveRange[] = {new Rect(), new Rect()};
118 
119     private TileDecoder mTileDecoder;
120     private boolean mBackgroundTileUploaded;
121 
122     private int mViewWidth, mViewHeight;
123     private View mParent;
124 
125     /**
126      * Interface for providing tiles to a {@link TiledImageRenderer}
127      */
128     public static interface TileSource {
129 
130         /**
131          * If the source does not care about the tile size, it should use
132          * {@link TiledImageRenderer#suggestedTileSize(Context)}
133          */
getTileSize()134         public int getTileSize();
getImageWidth()135         public int getImageWidth();
getImageHeight()136         public int getImageHeight();
getRotation()137         public int getRotation();
138 
139         /**
140          * Return a Preview image if available. This will be used as the base layer
141          * if higher res tiles are not yet available
142          */
getPreview()143         public BasicTexture getPreview();
144 
145         /**
146          * The tile returned by this method can be specified this way: Assuming
147          * the image size is (width, height), first take the intersection of (0,
148          * 0) - (width, height) and (x, y) - (x + tileSize, y + tileSize). If
149          * in extending the region, we found some part of the region is outside
150          * the image, those pixels are filled with black.
151          *
152          * If level > 0, it does the same operation on a down-scaled version of
153          * the original image (down-scaled by a factor of 2^level), but (x, y)
154          * still refers to the coordinate on the original image.
155          *
156          * The method would be called by the decoder thread.
157          */
getTile(int level, int x, int y, Bitmap reuse)158         public Bitmap getTile(int level, int x, int y, Bitmap reuse);
159     }
160 
suggestedTileSize(Context context)161     public static int suggestedTileSize(Context context) {
162         return isHighResolution(context) ? 512 : 256;
163     }
164 
isHighResolution(Context context)165     private static boolean isHighResolution(Context context) {
166         DisplayMetrics metrics = new DisplayMetrics();
167         WindowManager wm = (WindowManager)
168                 context.getSystemService(Context.WINDOW_SERVICE);
169         wm.getDefaultDisplay().getMetrics(metrics);
170         return metrics.heightPixels > 2048 ||  metrics.widthPixels > 2048;
171     }
172 
TiledImageRenderer(View parent)173     public TiledImageRenderer(View parent) {
174         mParent = parent;
175         mTileDecoder = new TileDecoder();
176         mTileDecoder.start();
177     }
178 
getViewWidth()179     public int getViewWidth() {
180         return mViewWidth;
181     }
182 
getViewHeight()183     public int getViewHeight() {
184         return mViewHeight;
185     }
186 
invalidate()187     private void invalidate() {
188         mParent.postInvalidate();
189     }
190 
setModel(TileSource model, int rotation)191     public void setModel(TileSource model, int rotation) {
192         if (mModel != model) {
193             mModel = model;
194             notifyModelInvalidated();
195         }
196         if (mRotation != rotation) {
197             mRotation = rotation;
198             mLayoutTiles = true;
199         }
200     }
201 
calculateLevelCount()202     private void calculateLevelCount() {
203         if (mPreview != null) {
204             mLevelCount = Math.max(0, Utils.ceilLog2(
205                 mImageWidth / (float) mPreview.getWidth()));
206         } else {
207             int levels = 1;
208             int maxDim = Math.max(mImageWidth, mImageHeight);
209             int t = mTileSize;
210             while (t < maxDim) {
211                 t <<= 1;
212                 levels++;
213             }
214             mLevelCount = levels;
215         }
216     }
217 
notifyModelInvalidated()218     public void notifyModelInvalidated() {
219         invalidateTiles();
220         if (mModel == null) {
221             mImageWidth = 0;
222             mImageHeight = 0;
223             mLevelCount = 0;
224             mPreview = null;
225         } else {
226             mImageWidth = mModel.getImageWidth();
227             mImageHeight = mModel.getImageHeight();
228             mPreview = mModel.getPreview();
229             mTileSize = mModel.getTileSize();
230             calculateLevelCount();
231         }
232         mLayoutTiles = true;
233     }
234 
setViewSize(int width, int height)235     public void setViewSize(int width, int height) {
236         mViewWidth = width;
237         mViewHeight = height;
238     }
239 
setPosition(int centerX, int centerY, float scale)240     public void setPosition(int centerX, int centerY, float scale) {
241         if (mCenterX == centerX && mCenterY == centerY
242                 && mScale == scale) {
243             return;
244         }
245         mCenterX = centerX;
246         mCenterY = centerY;
247         mScale = scale;
248         mLayoutTiles = true;
249     }
250 
251     // Prepare the tiles we want to use for display.
252     //
253     // 1. Decide the tile level we want to use for display.
254     // 2. Decide the tile levels we want to keep as texture (in addition to
255     //    the one we use for display).
256     // 3. Recycle unused tiles.
257     // 4. Activate the tiles we want.
layoutTiles()258     private void layoutTiles() {
259         if (mViewWidth == 0 || mViewHeight == 0 || !mLayoutTiles) {
260             return;
261         }
262         mLayoutTiles = false;
263 
264         // The tile levels we want to keep as texture is in the range
265         // [fromLevel, endLevel).
266         int fromLevel;
267         int endLevel;
268 
269         // We want to use a texture larger than or equal to the display size.
270         mLevel = Utils.clamp(Utils.floorLog2(1f / mScale), 0, mLevelCount);
271 
272         // We want to keep one more tile level as texture in addition to what
273         // we use for display. So it can be faster when the scale moves to the
274         // next level. We choose the level closest to the current scale.
275         if (mLevel != mLevelCount) {
276             Rect range = mTileRange;
277             getRange(range, mCenterX, mCenterY, mLevel, mScale, mRotation);
278             mOffsetX = Math.round(mViewWidth / 2f + (range.left - mCenterX) * mScale);
279             mOffsetY = Math.round(mViewHeight / 2f + (range.top - mCenterY) * mScale);
280             fromLevel = mScale * (1 << mLevel) > 0.75f ? mLevel - 1 : mLevel;
281         } else {
282             // Activate the tiles of the smallest two levels.
283             fromLevel = mLevel - 2;
284             mOffsetX = Math.round(mViewWidth / 2f - mCenterX * mScale);
285             mOffsetY = Math.round(mViewHeight / 2f - mCenterY * mScale);
286         }
287 
288         fromLevel = Math.max(0, Math.min(fromLevel, mLevelCount - 2));
289         endLevel = Math.min(fromLevel + 2, mLevelCount);
290 
291         Rect range[] = mActiveRange;
292         for (int i = fromLevel; i < endLevel; ++i) {
293             getRange(range[i - fromLevel], mCenterX, mCenterY, i, mRotation);
294         }
295 
296         // If rotation is transient, don't update the tile.
297         if (mRotation % 90 != 0) {
298             return;
299         }
300 
301         synchronized (mQueueLock) {
302             mDecodeQueue.clean();
303             mUploadQueue.clean();
304             mBackgroundTileUploaded = false;
305 
306             // Recycle unused tiles: if the level of the active tile is outside the
307             // range [fromLevel, endLevel) or not in the visible range.
308             int n = mActiveTiles.size();
309             for (int i = 0; i < n; i++) {
310                 Tile tile = mActiveTiles.valueAt(i);
311                 int level = tile.mTileLevel;
312                 if (level < fromLevel || level >= endLevel
313                         || !range[level - fromLevel].contains(tile.mX, tile.mY)) {
314                     mActiveTiles.removeAt(i);
315                     i--;
316                     n--;
317                     recycleTile(tile);
318                 }
319             }
320         }
321 
322         for (int i = fromLevel; i < endLevel; ++i) {
323             int size = mTileSize << i;
324             Rect r = range[i - fromLevel];
325             for (int y = r.top, bottom = r.bottom; y < bottom; y += size) {
326                 for (int x = r.left, right = r.right; x < right; x += size) {
327                     activateTile(x, y, i);
328                 }
329             }
330         }
331         invalidate();
332     }
333 
invalidateTiles()334     private void invalidateTiles() {
335         synchronized (mQueueLock) {
336             mDecodeQueue.clean();
337             mUploadQueue.clean();
338 
339             // TODO(xx): disable decoder
340             int n = mActiveTiles.size();
341             for (int i = 0; i < n; i++) {
342                 Tile tile = mActiveTiles.valueAt(i);
343                 recycleTile(tile);
344             }
345             mActiveTiles.clear();
346         }
347     }
348 
getRange(Rect out, int cX, int cY, int level, int rotation)349     private void getRange(Rect out, int cX, int cY, int level, int rotation) {
350         getRange(out, cX, cY, level, 1f / (1 << (level + 1)), rotation);
351     }
352 
353     // If the bitmap is scaled by the given factor "scale", return the
354     // rectangle containing visible range. The left-top coordinate returned is
355     // aligned to the tile boundary.
356     //
357     // (cX, cY) is the point on the original bitmap which will be put in the
358     // center of the ImageViewer.
getRange(Rect out, int cX, int cY, int level, float scale, int rotation)359     private void getRange(Rect out,
360             int cX, int cY, int level, float scale, int rotation) {
361 
362         double radians = Math.toRadians(-rotation);
363         double w = mViewWidth;
364         double h = mViewHeight;
365 
366         double cos = Math.cos(radians);
367         double sin = Math.sin(radians);
368         int width = (int) Math.ceil(Math.max(
369                 Math.abs(cos * w - sin * h), Math.abs(cos * w + sin * h)));
370         int height = (int) Math.ceil(Math.max(
371                 Math.abs(sin * w + cos * h), Math.abs(sin * w - cos * h)));
372 
373         int left = (int) Math.floor(cX - width / (2f * scale));
374         int top = (int) Math.floor(cY - height / (2f * scale));
375         int right = (int) Math.ceil(left + width / scale);
376         int bottom = (int) Math.ceil(top + height / scale);
377 
378         // align the rectangle to tile boundary
379         int size = mTileSize << level;
380         left = Math.max(0, size * (left / size));
381         top = Math.max(0, size * (top / size));
382         right = Math.min(mImageWidth, right);
383         bottom = Math.min(mImageHeight, bottom);
384 
385         out.set(left, top, right, bottom);
386     }
387 
freeTextures()388     public void freeTextures() {
389         mLayoutTiles = true;
390 
391         mTileDecoder.finishAndWait();
392         synchronized (mQueueLock) {
393             mUploadQueue.clean();
394             mDecodeQueue.clean();
395             Tile tile = mRecycledQueue.pop();
396             while (tile != null) {
397                 tile.recycle();
398                 tile = mRecycledQueue.pop();
399             }
400         }
401 
402         int n = mActiveTiles.size();
403         for (int i = 0; i < n; i++) {
404             Tile texture = mActiveTiles.valueAt(i);
405             texture.recycle();
406         }
407         mActiveTiles.clear();
408         mTileRange.set(0, 0, 0, 0);
409 
410         while (sTilePool.acquire() != null) {}
411     }
412 
draw(GLCanvas canvas)413     public boolean draw(GLCanvas canvas) {
414         layoutTiles();
415         uploadTiles(canvas);
416 
417         mUploadQuota = UPLOAD_LIMIT;
418         mRenderComplete = true;
419 
420         int level = mLevel;
421         int rotation = mRotation;
422         int flags = 0;
423         if (rotation != 0) {
424             flags |= GLCanvas.SAVE_FLAG_MATRIX;
425         }
426 
427         if (flags != 0) {
428             canvas.save(flags);
429             if (rotation != 0) {
430                 int centerX = mViewWidth / 2, centerY = mViewHeight / 2;
431                 canvas.translate(centerX, centerY);
432                 canvas.rotate(rotation, 0, 0, 1);
433                 canvas.translate(-centerX, -centerY);
434             }
435         }
436         try {
437             if (level != mLevelCount) {
438                 int size = (mTileSize << level);
439                 float length = size * mScale;
440                 Rect r = mTileRange;
441 
442                 for (int ty = r.top, i = 0; ty < r.bottom; ty += size, i++) {
443                     float y = mOffsetY + i * length;
444                     for (int tx = r.left, j = 0; tx < r.right; tx += size, j++) {
445                         float x = mOffsetX + j * length;
446                         drawTile(canvas, tx, ty, level, x, y, length);
447                     }
448                 }
449             } else if (mPreview != null) {
450                 mPreview.draw(canvas, mOffsetX, mOffsetY,
451                         Math.round(mImageWidth * mScale),
452                         Math.round(mImageHeight * mScale));
453             }
454         } finally {
455             if (flags != 0) {
456                 canvas.restore();
457             }
458         }
459 
460         if (mRenderComplete) {
461             if (!mBackgroundTileUploaded) {
462                 uploadBackgroundTiles(canvas);
463             }
464         } else {
465             invalidate();
466         }
467         return mRenderComplete || mPreview != null;
468     }
469 
uploadBackgroundTiles(GLCanvas canvas)470     private void uploadBackgroundTiles(GLCanvas canvas) {
471         mBackgroundTileUploaded = true;
472         int n = mActiveTiles.size();
473         for (int i = 0; i < n; i++) {
474             Tile tile = mActiveTiles.valueAt(i);
475             if (!tile.isContentValid()) {
476                 queueForDecode(tile);
477             }
478         }
479     }
480 
queueForDecode(Tile tile)481    private void queueForDecode(Tile tile) {
482        synchronized (mQueueLock) {
483            if (tile.mTileState == STATE_ACTIVATED) {
484                tile.mTileState = STATE_IN_QUEUE;
485                if (mDecodeQueue.push(tile)) {
486                    mQueueLock.notifyAll();
487                }
488            }
489        }
490     }
491 
decodeTile(Tile tile)492     private void decodeTile(Tile tile) {
493         synchronized (mQueueLock) {
494             if (tile.mTileState != STATE_IN_QUEUE) {
495                 return;
496             }
497             tile.mTileState = STATE_DECODING;
498         }
499         boolean decodeComplete = tile.decode();
500         synchronized (mQueueLock) {
501             if (tile.mTileState == STATE_RECYCLING) {
502                 tile.mTileState = STATE_RECYCLED;
503                 if (tile.mDecodedTile != null) {
504                     sTilePool.release(tile.mDecodedTile);
505                     tile.mDecodedTile = null;
506                 }
507                 mRecycledQueue.push(tile);
508                 return;
509             }
510             tile.mTileState = decodeComplete ? STATE_DECODED : STATE_DECODE_FAIL;
511             if (!decodeComplete) {
512                 return;
513             }
514             mUploadQueue.push(tile);
515         }
516         invalidate();
517     }
518 
obtainTile(int x, int y, int level)519     private Tile obtainTile(int x, int y, int level) {
520         synchronized (mQueueLock) {
521             Tile tile = mRecycledQueue.pop();
522             if (tile != null) {
523                 tile.mTileState = STATE_ACTIVATED;
524                 tile.update(x, y, level);
525                 return tile;
526             }
527             return new Tile(x, y, level);
528         }
529     }
530 
recycleTile(Tile tile)531     private void recycleTile(Tile tile) {
532         synchronized (mQueueLock) {
533             if (tile.mTileState == STATE_DECODING) {
534                 tile.mTileState = STATE_RECYCLING;
535                 return;
536             }
537             tile.mTileState = STATE_RECYCLED;
538             if (tile.mDecodedTile != null) {
539                 sTilePool.release(tile.mDecodedTile);
540                 tile.mDecodedTile = null;
541             }
542             mRecycledQueue.push(tile);
543         }
544     }
545 
activateTile(int x, int y, int level)546     private void activateTile(int x, int y, int level) {
547         long key = makeTileKey(x, y, level);
548         Tile tile = mActiveTiles.get(key);
549         if (tile != null) {
550             if (tile.mTileState == STATE_IN_QUEUE) {
551                 tile.mTileState = STATE_ACTIVATED;
552             }
553             return;
554         }
555         tile = obtainTile(x, y, level);
556         mActiveTiles.put(key, tile);
557     }
558 
getTile(int x, int y, int level)559     private Tile getTile(int x, int y, int level) {
560         return mActiveTiles.get(makeTileKey(x, y, level));
561     }
562 
makeTileKey(int x, int y, int level)563     private static long makeTileKey(int x, int y, int level) {
564         long result = x;
565         result = (result << 16) | y;
566         result = (result << 16) | level;
567         return result;
568     }
569 
uploadTiles(GLCanvas canvas)570     private void uploadTiles(GLCanvas canvas) {
571         int quota = UPLOAD_LIMIT;
572         Tile tile = null;
573         while (quota > 0) {
574             synchronized (mQueueLock) {
575                 tile = mUploadQueue.pop();
576             }
577             if (tile == null) {
578                 break;
579             }
580             if (!tile.isContentValid()) {
581                 if (tile.mTileState == STATE_DECODED) {
582                     tile.updateContent(canvas);
583                     --quota;
584                 } else {
585                     Log.w(TAG, "Tile in upload queue has invalid state: " + tile.mTileState);
586                 }
587             }
588         }
589         if (tile != null) {
590             invalidate();
591         }
592     }
593 
594     // Draw the tile to a square at canvas that locates at (x, y) and
595     // has a side length of length.
drawTile(GLCanvas canvas, int tx, int ty, int level, float x, float y, float length)596     private void drawTile(GLCanvas canvas,
597             int tx, int ty, int level, float x, float y, float length) {
598         RectF source = mSourceRect;
599         RectF target = mTargetRect;
600         target.set(x, y, x + length, y + length);
601         source.set(0, 0, mTileSize, mTileSize);
602 
603         Tile tile = getTile(tx, ty, level);
604         if (tile != null) {
605             if (!tile.isContentValid()) {
606                 if (tile.mTileState == STATE_DECODED) {
607                     if (mUploadQuota > 0) {
608                         --mUploadQuota;
609                         tile.updateContent(canvas);
610                     } else {
611                         mRenderComplete = false;
612                     }
613                 } else if (tile.mTileState != STATE_DECODE_FAIL){
614                     mRenderComplete = false;
615                     queueForDecode(tile);
616                 }
617             }
618             if (drawTile(tile, canvas, source, target)) {
619                 return;
620             }
621         }
622         if (mPreview != null) {
623             int size = mTileSize << level;
624             float scaleX = (float) mPreview.getWidth() / mImageWidth;
625             float scaleY = (float) mPreview.getHeight() / mImageHeight;
626             source.set(tx * scaleX, ty * scaleY, (tx + size) * scaleX,
627                     (ty + size) * scaleY);
628             canvas.drawTexture(mPreview, source, target);
629         }
630     }
631 
drawTile( Tile tile, GLCanvas canvas, RectF source, RectF target)632     private boolean drawTile(
633             Tile tile, GLCanvas canvas, RectF source, RectF target) {
634         while (true) {
635             if (tile.isContentValid()) {
636                 canvas.drawTexture(tile, source, target);
637                 return true;
638             }
639 
640             // Parent can be divided to four quads and tile is one of the four.
641             Tile parent = tile.getParentTile();
642             if (parent == null) {
643                 return false;
644             }
645             if (tile.mX == parent.mX) {
646                 source.left /= 2f;
647                 source.right /= 2f;
648             } else {
649                 source.left = (mTileSize + source.left) / 2f;
650                 source.right = (mTileSize + source.right) / 2f;
651             }
652             if (tile.mY == parent.mY) {
653                 source.top /= 2f;
654                 source.bottom /= 2f;
655             } else {
656                 source.top = (mTileSize + source.top) / 2f;
657                 source.bottom = (mTileSize + source.bottom) / 2f;
658             }
659             tile = parent;
660         }
661     }
662 
663     private class Tile extends UploadedTexture {
664         public int mX;
665         public int mY;
666         public int mTileLevel;
667         public Tile mNext;
668         public Bitmap mDecodedTile;
669         public volatile int mTileState = STATE_ACTIVATED;
670 
Tile(int x, int y, int level)671         public Tile(int x, int y, int level) {
672             mX = x;
673             mY = y;
674             mTileLevel = level;
675         }
676 
677         @Override
onFreeBitmap(Bitmap bitmap)678         protected void onFreeBitmap(Bitmap bitmap) {
679             sTilePool.release(bitmap);
680         }
681 
decode()682         boolean decode() {
683             // Get a tile from the original image. The tile is down-scaled
684             // by (1 << mTilelevel) from a region in the original image.
685             try {
686                 Bitmap reuse = sTilePool.acquire();
687                 if (reuse != null && reuse.getWidth() != mTileSize) {
688                     reuse = null;
689                 }
690                 mDecodedTile = mModel.getTile(mTileLevel, mX, mY, reuse);
691             } catch (Throwable t) {
692                 Log.w(TAG, "fail to decode tile", t);
693             }
694             return mDecodedTile != null;
695         }
696 
697         @Override
onGetBitmap()698         protected Bitmap onGetBitmap() {
699             Utils.assertTrue(mTileState == STATE_DECODED);
700 
701             // We need to override the width and height, so that we won't
702             // draw beyond the boundaries.
703             int rightEdge = ((mImageWidth - mX) >> mTileLevel);
704             int bottomEdge = ((mImageHeight - mY) >> mTileLevel);
705             setSize(Math.min(mTileSize, rightEdge), Math.min(mTileSize, bottomEdge));
706 
707             Bitmap bitmap = mDecodedTile;
708             mDecodedTile = null;
709             mTileState = STATE_ACTIVATED;
710             return bitmap;
711         }
712 
713         // We override getTextureWidth() and getTextureHeight() here, so the
714         // texture can be re-used for different tiles regardless of the actual
715         // size of the tile (which may be small because it is a tile at the
716         // boundary).
717         @Override
getTextureWidth()718         public int getTextureWidth() {
719             return mTileSize;
720         }
721 
722         @Override
getTextureHeight()723         public int getTextureHeight() {
724             return mTileSize;
725         }
726 
update(int x, int y, int level)727         public void update(int x, int y, int level) {
728             mX = x;
729             mY = y;
730             mTileLevel = level;
731             invalidateContent();
732         }
733 
getParentTile()734         public Tile getParentTile() {
735             if (mTileLevel + 1 == mLevelCount) {
736                 return null;
737             }
738             int size = mTileSize << (mTileLevel + 1);
739             int x = size * (mX / size);
740             int y = size * (mY / size);
741             return getTile(x, y, mTileLevel + 1);
742         }
743 
744         @Override
toString()745         public String toString() {
746             return String.format("tile(%s, %s, %s / %s)",
747                     mX / mTileSize, mY / mTileSize, mLevel, mLevelCount);
748         }
749     }
750 
751     private static class TileQueue {
752         private Tile mHead;
753 
pop()754         public Tile pop() {
755             Tile tile = mHead;
756             if (tile != null) {
757                 mHead = tile.mNext;
758             }
759             return tile;
760         }
761 
push(Tile tile)762         public boolean push(Tile tile) {
763             if (contains(tile)) {
764                 Log.w(TAG, "Attempting to add a tile already in the queue!");
765                 return false;
766             }
767             boolean wasEmpty = mHead == null;
768             tile.mNext = mHead;
769             mHead = tile;
770             return wasEmpty;
771         }
772 
contains(Tile tile)773         private boolean contains(Tile tile) {
774             Tile other = mHead;
775             while (other != null) {
776                 if (other == tile) {
777                     return true;
778                 }
779                 other = other.mNext;
780             }
781             return false;
782         }
783 
clean()784         public void clean() {
785             mHead = null;
786         }
787     }
788 
789     private class TileDecoder extends Thread {
790 
finishAndWait()791         public void finishAndWait() {
792             interrupt();
793             try {
794                 join();
795             } catch (InterruptedException e) {
796                 Log.w(TAG, "Interrupted while waiting for TileDecoder thread to finish!");
797             }
798         }
799 
waitForTile()800         private Tile waitForTile() throws InterruptedException {
801             synchronized (mQueueLock) {
802                 while (true) {
803                     Tile tile = mDecodeQueue.pop();
804                     if (tile != null) {
805                         return tile;
806                     }
807                     mQueueLock.wait();
808                 }
809             }
810         }
811 
812         @Override
run()813         public void run() {
814             try {
815                 while (!isInterrupted()) {
816                     Tile tile = waitForTile();
817                     decodeTile(tile);
818                 }
819             } catch (InterruptedException ex) {
820                 // We were finished
821             }
822         }
823 
824     }
825 }
826