summaryrefslogtreecommitdiffstats
path: root/src/com/android/launcher3/WidgetPreviewLoader.java
blob: 7e1ad6d7614009a1ce3ccd0aa7d7a9d0cb23256a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
package com.android.launcher3;

import android.appwidget.AppWidgetProviderInfo;
import android.content.ComponentName;
import android.content.ContentValues;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.res.Resources;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.Rect;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.util.Log;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;

abstract class SoftReferenceThreadLocal<T> {
    private ThreadLocal<SoftReference<T>> mThreadLocal;
    public SoftReferenceThreadLocal() {
        mThreadLocal = new ThreadLocal<SoftReference<T>>();
    }

    abstract T initialValue();

    public void set(T t) {
        mThreadLocal.set(new SoftReference<T>(t));
    }

    public T get() {
        SoftReference<T> reference = mThreadLocal.get();
        T obj;
        if (reference == null) {
            obj = initialValue();
            mThreadLocal.set(new SoftReference<T>(obj));
            return obj;
        } else {
            obj = reference.get();
            if (obj == null) {
                obj = initialValue();
                mThreadLocal.set(new SoftReference<T>(obj));
            }
            return obj;
        }
    }
}

class CanvasCache extends SoftReferenceThreadLocal<Canvas> {
    @Override
    protected Canvas initialValue() {
        return new Canvas();
    }
}

class PaintCache extends SoftReferenceThreadLocal<Paint> {
    @Override
    protected Paint initialValue() {
        return null;
    }
}

class BitmapCache extends SoftReferenceThreadLocal<Bitmap> {
    @Override
    protected Bitmap initialValue() {
        return null;
    }
}

class RectCache extends SoftReferenceThreadLocal<Rect> {
    @Override
    protected Rect initialValue() {
        return new Rect();
    }
}

class BitmapFactoryOptionsCache extends SoftReferenceThreadLocal<BitmapFactory.Options> {
    @Override
    protected BitmapFactory.Options initialValue() {
        return new BitmapFactory.Options();
    }
}

public class WidgetPreviewLoader {
    static final String TAG = "WidgetPreviewLoader";
    static final String ANDROID_INCREMENTAL_VERSION_NAME_KEY = "android.incremental.version";

    private int mPreviewBitmapWidth;
    private int mPreviewBitmapHeight;
    private String mSize;
    private Context mContext;
    private PackageManager mPackageManager;
    private PagedViewCellLayout mWidgetSpacingLayout;

    // Used for drawing shortcut previews
    private BitmapCache mCachedShortcutPreviewBitmap = new BitmapCache();
    private PaintCache mCachedShortcutPreviewPaint = new PaintCache();
    private CanvasCache mCachedShortcutPreviewCanvas = new CanvasCache();

    // Used for drawing widget previews
    private CanvasCache mCachedAppWidgetPreviewCanvas = new CanvasCache();
    private RectCache mCachedAppWidgetPreviewSrcRect = new RectCache();
    private RectCache mCachedAppWidgetPreviewDestRect = new RectCache();
    private PaintCache mCachedAppWidgetPreviewPaint = new PaintCache();
    private String mCachedSelectQuery;
    private BitmapFactoryOptionsCache mCachedBitmapFactoryOptions = new BitmapFactoryOptionsCache();

    private int mAppIconSize;
    private IconCache mIconCache;

    private final float sWidgetPreviewIconPaddingPercentage = 0.25f;

    private CacheDb mDb;

    private HashMap<String, WeakReference<Bitmap>> mLoadedPreviews;
    private ArrayList<SoftReference<Bitmap>> mUnusedBitmaps;
    private static HashSet<String> sInvalidPackages;

    static {
        sInvalidPackages = new HashSet<String>();
    }

    public WidgetPreviewLoader(Context context) {
        LauncherAppState app = LauncherAppState.getInstance();
        DeviceProfile grid = app.getDynamicGrid().getDeviceProfile();

        mContext = context;
        mPackageManager = mContext.getPackageManager();
        mAppIconSize = grid.iconSizePx;
        mIconCache = app.getIconCache();
        mDb = app.getWidgetPreviewCacheDb();
        mLoadedPreviews = new HashMap<String, WeakReference<Bitmap>>();
        mUnusedBitmaps = new ArrayList<SoftReference<Bitmap>>();

        SharedPreferences sp = context.getSharedPreferences(
                LauncherAppState.getSharedPreferencesKey(), Context.MODE_PRIVATE);
        final String lastVersionName = sp.getString(ANDROID_INCREMENTAL_VERSION_NAME_KEY, null);
        final String versionName = android.os.Build.VERSION.INCREMENTAL;
        if (!versionName.equals(lastVersionName)) {
            // clear all the previews whenever the system version changes, to ensure that previews
            // are up-to-date for any apps that might have been updated with the system
            clearDb();

            SharedPreferences.Editor editor = sp.edit();
            editor.putString(ANDROID_INCREMENTAL_VERSION_NAME_KEY, versionName);
            editor.commit();
        }
    }

    public void setPreviewSize(int previewWidth, int previewHeight,
            PagedViewCellLayout widgetSpacingLayout) {
        mPreviewBitmapWidth = previewWidth;
        mPreviewBitmapHeight = previewHeight;
        mSize = previewWidth + "x" + previewHeight;
        mWidgetSpacingLayout = widgetSpacingLayout;
    }

    public Bitmap getPreview(final Object o) {
        final String name = getObjectName(o);
        final String packageName = getObjectPackage(o);
        // check if the package is valid
        boolean packageValid = true;
        synchronized(sInvalidPackages) {
            packageValid = !sInvalidPackages.contains(packageName);
        }
        if (!packageValid) {
            return null;
        }
        if (packageValid) {
            synchronized(mLoadedPreviews) {
                // check if it exists in our existing cache
                if (mLoadedPreviews.containsKey(name) && mLoadedPreviews.get(name).get() != null) {
                    return mLoadedPreviews.get(name).get();
                }
            }
        }

        Bitmap unusedBitmap = null;
        synchronized(mUnusedBitmaps) {
            // not in cache; we need to load it from the db
            while ((unusedBitmap == null || !unusedBitmap.isMutable() ||
                    unusedBitmap.getWidth() != mPreviewBitmapWidth ||
                    unusedBitmap.getHeight() != mPreviewBitmapHeight)
                    && mUnusedBitmaps.size() > 0) {
                unusedBitmap = mUnusedBitmaps.remove(0).get();
            }
            if (unusedBitmap != null) {
                final Canvas c = mCachedAppWidgetPreviewCanvas.get();
                c.setBitmap(unusedBitmap);
                c.drawColor(0, PorterDuff.Mode.CLEAR);
                c.setBitmap(null);
            }
        }

        if (unusedBitmap == null) {
            unusedBitmap = Bitmap.createBitmap(mPreviewBitmapWidth, mPreviewBitmapHeight,
                    Bitmap.Config.ARGB_8888);
        }

        Bitmap preview = null;

        if (packageValid) {
            preview = readFromDb(name, unusedBitmap);
        }

        if (preview != null) {
            synchronized(mLoadedPreviews) {
                mLoadedPreviews.put(name, new WeakReference<Bitmap>(preview));
            }
            return preview;
        } else {
            // it's not in the db... we need to generate it
            final Bitmap generatedPreview = generatePreview(o, unusedBitmap);
            preview = generatedPreview;
            if (preview != unusedBitmap) {
                throw new RuntimeException("generatePreview is not recycling the bitmap " + o);
            }

            synchronized(mLoadedPreviews) {
                mLoadedPreviews.put(name, new WeakReference<Bitmap>(preview));
            }

            // write to db on a thread pool... this can be done lazily and improves the performance
            // of the first time widget previews are loaded
            new AsyncTask<Void, Void, Void>() {
                public Void doInBackground(Void ... args) {
                    writeToDb(o, generatedPreview);
                    return null;
                }
            }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void) null);

            return preview;
        }
    }

    public void recycleBitmap(Object o, Bitmap bitmapToRecycle) {
        String name = getObjectName(o);
        synchronized (mLoadedPreviews) {
            if (mLoadedPreviews.containsKey(name)) {
                Bitmap b = mLoadedPreviews.get(name).get();
                if (b == bitmapToRecycle) {
                    mLoadedPreviews.remove(name);
                    if (bitmapToRecycle.isMutable()) {
                        synchronized (mUnusedBitmaps) {
                            mUnusedBitmaps.add(new SoftReference<Bitmap>(b));
                        }
                    }
                } else {
                    throw new RuntimeException("Bitmap passed in doesn't match up");
                }
            }
        }
    }

    static class CacheDb extends SQLiteOpenHelper {
        final static int DB_VERSION = 2;
        final static String DB_NAME = "widgetpreviews.db";
        final static String TABLE_NAME = "shortcut_and_widget_previews";
        final static String COLUMN_NAME = "name";
        final static String COLUMN_SIZE = "size";
        final static String COLUMN_PREVIEW_BITMAP = "preview_bitmap";
        Context mContext;

        public CacheDb(Context context) {
            super(context, new File(context.getCacheDir(), DB_NAME).getPath(), null, DB_VERSION);
            // Store the context for later use
            mContext = context;
        }

        @Override
        public void onCreate(SQLiteDatabase database) {
            database.execSQL("CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " (" +
                    COLUMN_NAME + " TEXT NOT NULL, " +
                    COLUMN_SIZE + " TEXT NOT NULL, " +
                    COLUMN_PREVIEW_BITMAP + " BLOB NOT NULL, " +
                    "PRIMARY KEY (" + COLUMN_NAME + ", " + COLUMN_SIZE + ") " +
                    ");");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            if (oldVersion != newVersion) {
                // Delete all the records; they'll be repopulated as this is a cache
                db.execSQL("DELETE FROM " + TABLE_NAME);
            }
        }
    }

    private static final String WIDGET_PREFIX = "Widget:";
    private static final String SHORTCUT_PREFIX = "Shortcut:";

    private static String getObjectName(Object o) {
        // should cache the string builder
        StringBuilder sb = new StringBuilder();
        String output;
        if (o instanceof AppWidgetProviderInfo) {
            sb.append(WIDGET_PREFIX);
            sb.append(((AppWidgetProviderInfo) o).provider.flattenToString());
            output = sb.toString();
            sb.setLength(0);
        } else {
            sb.append(SHORTCUT_PREFIX);

            ResolveInfo info = (ResolveInfo) o;
            sb.append(new ComponentName(info.activityInfo.packageName,
                    info.activityInfo.name).flattenToString());
            output = sb.toString();
            sb.setLength(0);
        }
        return output;
    }

    private String getObjectPackage(Object o) {
        if (o instanceof AppWidgetProviderInfo) {
            return ((AppWidgetProviderInfo) o).provider.getPackageName();
        } else {
            ResolveInfo info = (ResolveInfo) o;
            return info.activityInfo.packageName;
        }
    }

    private void writeToDb(Object o, Bitmap preview) {
        String name = getObjectName(o);
        SQLiteDatabase db = mDb.getWritableDatabase();
        ContentValues values = new ContentValues();

        values.put(CacheDb.COLUMN_NAME, name);
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        preview.compress(Bitmap.CompressFormat.PNG, 100, stream);
        values.put(CacheDb.COLUMN_PREVIEW_BITMAP, stream.toByteArray());
        values.put(CacheDb.COLUMN_SIZE, mSize);
        db.insert(CacheDb.TABLE_NAME, null, values);
    }

    private void clearDb() {
        SQLiteDatabase db = mDb.getWritableDatabase();
        // Delete everything
        db.delete(CacheDb.TABLE_NAME, null, null);
    }

    public static void removePackageFromDb(final CacheDb cacheDb, final String packageName) {
        synchronized(sInvalidPackages) {
            sInvalidPackages.add(packageName);
        }
        new AsyncTask<Void, Void, Void>() {
            public Void doInBackground(Void ... args) {
                SQLiteDatabase db = cacheDb.getWritableDatabase();
                db.delete(CacheDb.TABLE_NAME,
                        CacheDb.COLUMN_NAME + " LIKE ? OR " +
                        CacheDb.COLUMN_NAME + " LIKE ?", // SELECT query
                        new String[] {
                            WIDGET_PREFIX + packageName + "/%",
                            SHORTCUT_PREFIX + packageName + "/%"} // args to SELECT query
                            );
                synchronized(sInvalidPackages) {
                    sInvalidPackages.remove(packageName);
                }
                return null;
            }
        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void) null);
    }

    public static void removeItemFromDb(final CacheDb cacheDb, final String objectName) {
        new AsyncTask<Void, Void, Void>() {
            public Void doInBackground(Void ... args) {
                SQLiteDatabase db = cacheDb.getWritableDatabase();
                db.delete(CacheDb.TABLE_NAME,
                        CacheDb.COLUMN_NAME + " = ? ", // SELECT query
                        new String[] { objectName }); // args to SELECT query
                return null;
            }
        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void) null);
    }

    private Bitmap readFromDb(String name, Bitmap b) {
        if (mCachedSelectQuery == null) {
            mCachedSelectQuery = CacheDb.COLUMN_NAME + " = ? AND " +
                    CacheDb.COLUMN_SIZE + " = ?";
        }
        SQLiteDatabase db = mDb.getReadableDatabase();
        Cursor result = db.query(CacheDb.TABLE_NAME,
                new String[] { CacheDb.COLUMN_PREVIEW_BITMAP }, // cols to return
                mCachedSelectQuery, // select query
                new String[] { name, mSize }, // args to select query
                null,
                null,
                null,
                null);
        if (result.getCount() > 0) {
            result.moveToFirst();
            byte[] blob = result.getBlob(0);
            result.close();
            final BitmapFactory.Options opts = mCachedBitmapFactoryOptions.get();
            opts.inBitmap = b;
            opts.inSampleSize = 1;
            try {
                return BitmapFactory.decodeByteArray(blob, 0, blob.length, opts);
            } catch (IllegalArgumentException e) {
                removeItemFromDb(mDb, name);
                return null;
            }
        } else {
            result.close();
            return null;
        }
    }

    public Bitmap generatePreview(Object info, Bitmap preview) {
        if (preview != null &&
                (preview.getWidth() != mPreviewBitmapWidth ||
                preview.getHeight() != mPreviewBitmapHeight)) {
            throw new RuntimeException("Improperly sized bitmap passed as argument");
        }
        if (info instanceof AppWidgetProviderInfo) {
            return generateWidgetPreview((AppWidgetProviderInfo) info, preview);
        } else {
            return generateShortcutPreview(
                    (ResolveInfo) info, mPreviewBitmapWidth, mPreviewBitmapHeight, preview);
        }
    }

    public Bitmap generateWidgetPreview(AppWidgetProviderInfo info, Bitmap preview) {
        int[] cellSpans = Launcher.getSpanForWidget(mContext, info);
        int maxWidth = maxWidthForWidgetPreview(cellSpans[0]);
        int maxHeight = maxHeightForWidgetPreview(cellSpans[1]);
        return generateWidgetPreview(info.provider, info.previewImage, info.icon,
                cellSpans[0], cellSpans[1], maxWidth, maxHeight, preview, null);
    }

    public int maxWidthForWidgetPreview(int spanX) {
        return Math.min(mPreviewBitmapWidth,
                mWidgetSpacingLayout.estimateCellWidth(spanX));
    }

    public int maxHeightForWidgetPreview(int spanY) {
        return Math.min(mPreviewBitmapHeight,
                mWidgetSpacingLayout.estimateCellHeight(spanY));
    }

    public Bitmap generateWidgetPreview(ComponentName provider, int previewImage,
            int iconId, int cellHSpan, int cellVSpan, int maxPreviewWidth, int maxPreviewHeight,
            Bitmap preview, int[] preScaledWidthOut) {
        // Load the preview image if possible
        String packageName = provider.getPackageName();
        if (maxPreviewWidth < 0) maxPreviewWidth = Integer.MAX_VALUE;
        if (maxPreviewHeight < 0) maxPreviewHeight = Integer.MAX_VALUE;

        Drawable drawable = null;
        if (previewImage != 0) {
            drawable = mPackageManager.getDrawable(packageName, previewImage, null);
            if (drawable == null) {
                Log.w(TAG, "Can't load widget preview drawable 0x" +
                        Integer.toHexString(previewImage) + " for provider: " + provider);
            }
        }

        int previewWidth;
        int previewHeight;
        Bitmap defaultPreview = null;
        boolean widgetPreviewExists = (drawable != null);
        if (widgetPreviewExists) {
            previewWidth = drawable.getIntrinsicWidth();
            previewHeight = drawable.getIntrinsicHeight();
        } else {
            // Generate a preview image if we couldn't load one
            if (cellHSpan < 1) cellHSpan = 1;
            if (cellVSpan < 1) cellVSpan = 1;

            BitmapDrawable previewDrawable = (BitmapDrawable) mContext.getResources()
                    .getDrawable(R.drawable.widget_tile);
            final int previewDrawableWidth = previewDrawable
                    .getIntrinsicWidth();
            final int previewDrawableHeight = previewDrawable
                    .getIntrinsicHeight();
            previewWidth = previewDrawableWidth * cellHSpan;
            previewHeight = previewDrawableHeight * cellVSpan;

            defaultPreview = Bitmap.createBitmap(previewWidth, previewHeight,
                    Config.ARGB_8888);
            final Canvas c = mCachedAppWidgetPreviewCanvas.get();
            c.setBitmap(defaultPreview);
            previewDrawable.setBounds(0, 0, previewWidth, previewHeight);
            previewDrawable.setTileModeXY(Shader.TileMode.REPEAT,
                    Shader.TileMode.REPEAT);
            previewDrawable.draw(c);
            c.setBitmap(null);

            // Draw the icon in the top left corner
            int minOffset = (int) (mAppIconSize * sWidgetPreviewIconPaddingPercentage);
            int smallestSide = Math.min(previewWidth, previewHeight);
            float iconScale = Math.min((float) smallestSide
                    / (mAppIconSize + 2 * minOffset), 1f);

            try {
                Drawable icon = null;
                int hoffset =
                        (int) ((previewDrawableWidth - mAppIconSize * iconScale) / 2);
                int yoffset =
                        (int) ((previewDrawableHeight - mAppIconSize * iconScale) / 2);
                if (iconId > 0)
                    icon = mIconCache.getFullResIcon(packageName, iconId);
                if (icon != null) {
                    renderDrawableToBitmap(icon, defaultPreview, hoffset,
                            yoffset, (int) (mAppIconSize * iconScale),
                            (int) (mAppIconSize * iconScale));
                }
            } catch (Resources.NotFoundException e) {
            }
        }

        // Scale to fit width only - let the widget preview be clipped in the
        // vertical dimension
        float scale = 1f;
        if (preScaledWidthOut != null) {
            preScaledWidthOut[0] = previewWidth;
        }
        if (previewWidth > maxPreviewWidth) {
            scale = maxPreviewWidth / (float) previewWidth;
        }
        if (scale != 1f) {
            previewWidth = (int) (scale * previewWidth);
            previewHeight = (int) (scale * previewHeight);
        }

        // If a bitmap is passed in, we use it; otherwise, we create a bitmap of the right size
        if (preview == null) {
            preview = Bitmap.createBitmap(previewWidth, previewHeight, Config.ARGB_8888);
        }

        // Draw the scaled preview into the final bitmap
        int x = (preview.getWidth() - previewWidth) / 2;
        if (widgetPreviewExists) {
            renderDrawableToBitmap(drawable, preview, x, 0, previewWidth,
                    previewHeight);
        } else {
            final Canvas c = mCachedAppWidgetPreviewCanvas.get();
            final Rect src = mCachedAppWidgetPreviewSrcRect.get();
            final Rect dest = mCachedAppWidgetPreviewDestRect.get();
            c.setBitmap(preview);
            src.set(0, 0, defaultPreview.getWidth(), defaultPreview.getHeight());
            dest.set(x, 0, x + previewWidth, previewHeight);

            Paint p = mCachedAppWidgetPreviewPaint.get();
            if (p == null) {
                p = new Paint();
                p.setFilterBitmap(true);
                mCachedAppWidgetPreviewPaint.set(p);
            }
            c.drawBitmap(defaultPreview, src, dest, p);
            c.setBitmap(null);
        }
        return preview;
    }

    private Bitmap generateShortcutPreview(
            ResolveInfo info, int maxWidth, int maxHeight, Bitmap preview) {
        Bitmap tempBitmap = mCachedShortcutPreviewBitmap.get();
        final Canvas c = mCachedShortcutPreviewCanvas.get();
        if (tempBitmap == null ||
                tempBitmap.getWidth() != maxWidth ||
                tempBitmap.getHeight() != maxHeight) {
            tempBitmap = Bitmap.createBitmap(maxWidth, maxHeight, Config.ARGB_8888);
            mCachedShortcutPreviewBitmap.set(tempBitmap);
        } else {
            c.setBitmap(tempBitmap);
            c.drawColor(0, PorterDuff.Mode.CLEAR);
            c.setBitmap(null);
        }
        // Render the icon
        Drawable icon = mIconCache.getFullResIcon(info);

        int paddingTop = mContext.
                getResources().getDimensionPixelOffset(R.dimen.shortcut_preview_padding_top);
        int paddingLeft = mContext.
                getResources().getDimensionPixelOffset(R.dimen.shortcut_preview_padding_left);
        int paddingRight = mContext.
                getResources().getDimensionPixelOffset(R.dimen.shortcut_preview_padding_right);

        int scaledIconWidth = (maxWidth - paddingLeft - paddingRight);

        renderDrawableToBitmap(
                icon, tempBitmap, paddingLeft, paddingTop, scaledIconWidth, scaledIconWidth);

        if (preview != null &&
                (preview.getWidth() != maxWidth || preview.getHeight() != maxHeight)) {
            throw new RuntimeException("Improperly sized bitmap passed as argument");
        } else if (preview == null) {
            preview = Bitmap.createBitmap(maxWidth, maxHeight, Config.ARGB_8888);
        }

        c.setBitmap(preview);
        // Draw a desaturated/scaled version of the icon in the background as a watermark
        Paint p = mCachedShortcutPreviewPaint.get();
        if (p == null) {
            p = new Paint();
            ColorMatrix colorMatrix = new ColorMatrix();
            colorMatrix.setSaturation(0);
            p.setColorFilter(new ColorMatrixColorFilter(colorMatrix));
            p.setAlpha((int) (255 * 0.06f));
            mCachedShortcutPreviewPaint.set(p);
        }
        c.drawBitmap(tempBitmap, 0, 0, p);
        c.setBitmap(null);

        renderDrawableToBitmap(icon, preview, 0, 0, mAppIconSize, mAppIconSize);

        return preview;
    }


    public static void renderDrawableToBitmap(
            Drawable d, Bitmap bitmap, int x, int y, int w, int h) {
        renderDrawableToBitmap(d, bitmap, x, y, w, h, 1f);
    }

    private static void renderDrawableToBitmap(
            Drawable d, Bitmap bitmap, int x, int y, int w, int h,
            float scale) {
        if (bitmap != null) {
            Canvas c = new Canvas(bitmap);
            c.scale(scale, scale);
            Rect oldBounds = d.copyBounds();
            d.setBounds(x, y, x + w, y + h);
            d.draw(c);
            d.setBounds(oldBounds); // Restore the bounds
            c.setBitmap(null);
        }
    }

}