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      1 /*
      2  * Copyright (C) 2016 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.launcher3.graphics;
     18 
     19 import android.graphics.Bitmap;
     20 import android.graphics.Bitmap.Config;
     21 import android.graphics.BlurMaskFilter;
     22 import android.graphics.BlurMaskFilter.Blur;
     23 import android.graphics.Canvas;
     24 import android.graphics.Paint;
     25 import android.graphics.RectF;
     26 
     27 import com.android.launcher3.LauncherAppState;
     28 import com.android.launcher3.util.Preconditions;
     29 
     30 /**
     31  * Utility class to add shadows to bitmaps.
     32  */
     33 public class ShadowGenerator {
     34 
     35     // Percent of actual icon size
     36     private static final float HALF_DISTANCE = 0.5f;
     37     private static final float BLUR_FACTOR = 0.5f/48;
     38 
     39     // Percent of actual icon size
     40     private static final float KEY_SHADOW_DISTANCE = 1f/48;
     41     private static final int KEY_SHADOW_ALPHA = 61;
     42 
     43     private static final int AMBIENT_SHADOW_ALPHA = 30;
     44 
     45     private static final Object LOCK = new Object();
     46     // Singleton object guarded by {@link #LOCK}
     47     private static ShadowGenerator sShadowGenerator;
     48 
     49     private final int mIconSize;
     50 
     51     private final Canvas mCanvas;
     52     private final Paint mBlurPaint;
     53     private final Paint mDrawPaint;
     54 
     55     private ShadowGenerator() {
     56         mIconSize = LauncherAppState.getInstance().getInvariantDeviceProfile().iconBitmapSize;
     57         mCanvas = new Canvas();
     58         mBlurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
     59         mBlurPaint.setMaskFilter(new BlurMaskFilter(mIconSize * BLUR_FACTOR, Blur.NORMAL));
     60         mDrawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
     61     }
     62 
     63     public synchronized Bitmap recreateIcon(Bitmap icon) {
     64         int[] offset = new int[2];
     65         Bitmap shadow = icon.extractAlpha(mBlurPaint, offset);
     66         Bitmap result = Bitmap.createBitmap(mIconSize, mIconSize, Config.ARGB_8888);
     67         mCanvas.setBitmap(result);
     68 
     69         // Draw ambient shadow
     70         mDrawPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
     71         mCanvas.drawBitmap(shadow, offset[0], offset[1], mDrawPaint);
     72 
     73         // Draw key shadow
     74         mDrawPaint.setAlpha(KEY_SHADOW_ALPHA);
     75         mCanvas.drawBitmap(shadow, offset[0], offset[1] + KEY_SHADOW_DISTANCE * mIconSize, mDrawPaint);
     76 
     77         // Draw the icon
     78         mDrawPaint.setAlpha(255);
     79         mCanvas.drawBitmap(icon, 0, 0, mDrawPaint);
     80 
     81         mCanvas.setBitmap(null);
     82         return result;
     83     }
     84 
     85     public static ShadowGenerator getInstance() {
     86         Preconditions.assertNonUiThread();
     87         synchronized (LOCK) {
     88             if (sShadowGenerator == null) {
     89                 sShadowGenerator = new ShadowGenerator();
     90             }
     91         }
     92         return sShadowGenerator;
     93     }
     94 
     95     /**
     96      * Returns the minimum amount by which an icon with {@param bounds} should be scaled
     97      * so that the shadows do not get clipped.
     98      */
     99     public static float getScaleForBounds(RectF bounds) {
    100         float scale = 1;
    101 
    102         // For top, left & right, we need same space.
    103         float minSide = Math.min(Math.min(bounds.left, bounds.right), bounds.top);
    104         if (minSide < BLUR_FACTOR) {
    105             scale = (HALF_DISTANCE - BLUR_FACTOR) / (HALF_DISTANCE - minSide);
    106         }
    107 
    108         float bottomSpace = BLUR_FACTOR + KEY_SHADOW_DISTANCE;
    109         if (bounds.bottom < bottomSpace) {
    110             scale = Math.min(scale, (HALF_DISTANCE - bottomSpace) / (HALF_DISTANCE - bounds.bottom));
    111         }
    112         return scale;
    113     }
    114 }
    115