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      1 /*
      2  * Copyright (C) 2014 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.systemui.statusbar.policy;
     18 
     19 import android.content.Context;
     20 import android.graphics.Canvas;
     21 import android.graphics.Color;
     22 import android.graphics.ColorFilter;
     23 import android.graphics.Paint;
     24 import android.graphics.PixelFormat;
     25 import android.graphics.RadialGradient;
     26 import android.graphics.Rect;
     27 import android.graphics.Shader;
     28 import android.graphics.drawable.Drawable;
     29 import android.util.LayoutDirection;
     30 import android.view.View;
     31 
     32 import com.android.systemui.R;
     33 
     34 /**
     35  * Gradient background for the user switcher on Keyguard.
     36  */
     37 public class KeyguardUserSwitcherScrim extends Drawable
     38         implements View.OnLayoutChangeListener {
     39 
     40     private static final float OUTER_EXTENT = 2.5f;
     41     private static final float INNER_EXTENT = 0.75f;
     42 
     43     private int mDarkColor;
     44     private int mTop;
     45     private int mAlpha = 255;
     46     private Paint mRadialGradientPaint = new Paint();
     47     private int mLayoutWidth;
     48 
     49     public KeyguardUserSwitcherScrim(Context context) {
     50         mDarkColor = context.getColor(
     51                 R.color.keyguard_user_switcher_background_gradient_color);
     52     }
     53 
     54     @Override
     55     public void draw(Canvas canvas) {
     56         boolean isLtr = getLayoutDirection() == LayoutDirection.LTR;
     57         Rect bounds = getBounds();
     58         float width = bounds.width() * OUTER_EXTENT;
     59         float height = (mTop + bounds.height()) * OUTER_EXTENT;
     60         canvas.translate(0, -mTop);
     61         canvas.scale(1, height / width);
     62         canvas.drawRect(isLtr ? bounds.right - width : 0, 0,
     63                 isLtr ? bounds.right : bounds.left + width, width, mRadialGradientPaint);
     64     }
     65 
     66     @Override
     67     public void setAlpha(int alpha) {
     68         mAlpha = alpha;
     69         updatePaint();
     70         invalidateSelf();
     71     }
     72 
     73     @Override
     74     public int getAlpha() {
     75         return mAlpha;
     76     }
     77 
     78     @Override
     79     public void setColorFilter(ColorFilter colorFilter) {
     80     }
     81 
     82     @Override
     83     public int getOpacity() {
     84         return PixelFormat.TRANSLUCENT;
     85     }
     86 
     87     @Override
     88     public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft,
     89             int oldTop, int oldRight, int oldBottom) {
     90         if (left != oldLeft || top != oldTop || right != oldRight || bottom != oldBottom) {
     91             mLayoutWidth = right - left;
     92             mTop = top;
     93             updatePaint();
     94         }
     95     }
     96 
     97     private void updatePaint() {
     98         if (mLayoutWidth == 0) {
     99             return;
    100         }
    101         float radius = mLayoutWidth * OUTER_EXTENT;
    102         boolean isLtr = getLayoutDirection() == LayoutDirection.LTR;
    103         mRadialGradientPaint.setShader(
    104                 new RadialGradient(isLtr ? mLayoutWidth : 0, 0, radius,
    105                         new int[] { Color.argb(
    106                                         (int) (Color.alpha(mDarkColor) * mAlpha / 255f), 0, 0, 0),
    107                                 Color.TRANSPARENT },
    108                         new float[] { Math.max(0f, mLayoutWidth * INNER_EXTENT / radius), 1f },
    109                         Shader.TileMode.CLAMP));
    110     }
    111 }
    112