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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.launcher3.graphics;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BlurMaskFilter;
import android.graphics.BlurMaskFilter.Blur;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import com.android.launcher3.LauncherAppState;
import com.android.launcher3.util.Preconditions;
/**
* Utility class to add shadows to bitmaps.
*/
public class ShadowGenerator {
// Percent of actual icon size
private static final float HALF_DISTANCE = 0.5f;
private static final float BLUR_FACTOR = 0.5f/48;
// Percent of actual icon size
private static final float KEY_SHADOW_DISTANCE = 1f/48;
private static final int KEY_SHADOW_ALPHA = 61;
private static final int AMBIENT_SHADOW_ALPHA = 30;
private static final Object LOCK = new Object();
// Singleton object guarded by {@link #LOCK}
private static ShadowGenerator sShadowGenerator;
private final int mIconSize;
private final Canvas mCanvas;
private final Paint mBlurPaint;
private final Paint mDrawPaint;
private ShadowGenerator() {
mIconSize = LauncherAppState.getInstance().getInvariantDeviceProfile().iconBitmapSize;
mCanvas = new Canvas();
mBlurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
mBlurPaint.setMaskFilter(new BlurMaskFilter(mIconSize * BLUR_FACTOR, Blur.NORMAL));
mDrawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
}
public synchronized Bitmap recreateIcon(Bitmap icon) {
int[] offset = new int[2];
Bitmap shadow = icon.extractAlpha(mBlurPaint, offset);
Bitmap result = Bitmap.createBitmap(mIconSize, mIconSize, Config.ARGB_8888);
mCanvas.setBitmap(result);
// Draw ambient shadow
mDrawPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
mCanvas.drawBitmap(shadow, offset[0], offset[1], mDrawPaint);
// Draw key shadow
mDrawPaint.setAlpha(KEY_SHADOW_ALPHA);
mCanvas.drawBitmap(shadow, offset[0], offset[1] + KEY_SHADOW_DISTANCE * mIconSize, mDrawPaint);
// Draw the icon
mDrawPaint.setAlpha(255);
mCanvas.drawBitmap(icon, 0, 0, mDrawPaint);
mCanvas.setBitmap(null);
return result;
}
public static ShadowGenerator getInstance() {
Preconditions.assertNonUiThread();
synchronized (LOCK) {
if (sShadowGenerator == null) {
sShadowGenerator = new ShadowGenerator();
}
}
return sShadowGenerator;
}
/**
* Returns the minimum amount by which an icon with {@param bounds} should be scaled
* so that the shadows do not get clipped.
*/
public static float getScaleForBounds(RectF bounds) {
float scale = 1;
// For top, left & right, we need same space.
float minSide = Math.min(Math.min(bounds.left, bounds.right), bounds.top);
if (minSide < BLUR_FACTOR) {
scale = (HALF_DISTANCE - BLUR_FACTOR) / (HALF_DISTANCE - minSide);
}
float bottomSpace = BLUR_FACTOR + KEY_SHADOW_DISTANCE;
if (bounds.bottom < bottomSpace) {
scale = Math.min(scale, (HALF_DISTANCE - bottomSpace) / (HALF_DISTANCE - bounds.bottom));
}
return scale;
}
}
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