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/*
* Copyright (C) 2017 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.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RadialGradient;
import android.graphics.RectF;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.DecelerateInterpolator;
import com.android.launcher3.R;
import com.android.launcher3.Utilities;
/**
* Draws a translucent radial gradient background from an initial state with progress 0.0 to a
* final state with progress 1.0;
*/
public class RadialGradientView extends View {
public static final int DEFAULT_COLOR_1 = Color.WHITE;
public static final int DEFAULT_COLOR_2 = Color.BLACK;
private static Bitmap sFinalGradientMask;
private static Bitmap sAlphaGradientMask;
// TODO needs to be cleaned up once design finalizes
static class Config {
// dimens
final float gradientCenterX = 0.5f;
final float gradientCenterY = 1.05f;
final float gradientHeadStartFactor = 0.35f;
final float gradientAlphaMaskLengthDp = 700;
// interpolation
final boolean useGradientAlphaDecel = false;
final float decelFactorForGradientAlpha = 2f;
// colors
final float finalGradientAlpha = 0.75f;
int color1 = DEFAULT_COLOR_1;
int color2 = DEFAULT_COLOR_2;
}
private final RectF mAlphaMaskRect = new RectF();
private final RectF mFinalMaskRect = new RectF();
private final Paint mPaint = new Paint();
private final Config mConfig = new Config();
private final DecelerateInterpolator mDecelInterpolator;
private float mProgress;
private int mWidth;
private int mHeight;
private final int mMaskHeight;
private final Context mAppContext;
public RadialGradientView(Context context, AttributeSet attrs) {
super(context, attrs);
this.mAppContext = context.getApplicationContext();
this.mDecelInterpolator = new DecelerateInterpolator(mConfig.decelFactorForGradientAlpha);
this.mMaskHeight = Utilities.pxFromDp(mConfig.gradientAlphaMaskLengthDp,
mAppContext.getResources().getDisplayMetrics());
if (sFinalGradientMask == null) {
sFinalGradientMask = Utilities.convertToAlphaMask(
Utilities.createOnePixBitmap(), mConfig.finalGradientAlpha);
}
if (sAlphaGradientMask == null) {
Bitmap alphaMaskFromResource = BitmapFactory.decodeResource(context.getResources(),
R.drawable.all_apps_alpha_mask);
sAlphaGradientMask = Utilities.convertToAlphaMask(
alphaMaskFromResource, mConfig.finalGradientAlpha);
}
}
public void onExtractedColorsChanged(int color1, int color2) {
mConfig.color1 = color1;
mConfig.color2 = color2;
if (mWidth + mHeight > 0) {
createRadialShader();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
this.mWidth = getMeasuredWidth();
this.mHeight = getMeasuredHeight();
if (mWidth + mHeight > 0) {
createRadialShader();
}
}
// only being called when colors change
private void createRadialShader() {
float radius = Math.max(mHeight, mWidth) * mConfig.gradientCenterY;
float posScreenBottom = (radius - mHeight) / radius; // center lives below screen
RadialGradient shader = new RadialGradient(
mWidth * mConfig.gradientCenterX,
mHeight * mConfig.gradientCenterY,
radius,
new int[] {mConfig.color1, mConfig.color1, mConfig.color2},
new float[] {0f, posScreenBottom, 1f},
Shader.TileMode.CLAMP);
mPaint.setShader(shader);
}
public void setProgress(float progress) {
this.mProgress = progress;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
float head = mConfig.gradientHeadStartFactor;
float linearProgress = head + (mProgress * (1f - head));
float adjustProgress = mConfig.useGradientAlphaDecel
? mDecelInterpolator.getInterpolation(linearProgress)
: linearProgress;
float startMaskY = (1f - adjustProgress) * mHeight - mMaskHeight * adjustProgress;
mAlphaMaskRect.set(0, startMaskY, mWidth, startMaskY + mMaskHeight);
mFinalMaskRect.set(0, startMaskY + mMaskHeight, mWidth, mHeight);
canvas.drawBitmap(sAlphaGradientMask, null, mAlphaMaskRect, mPaint);
canvas.drawBitmap(sFinalGradientMask, null, mFinalMaskRect, mPaint);
}
}
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