1 /* 2 * Copyright (C) 2017 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 package com.android.wallpaper.widget; 17 18 import android.content.Context; 19 import android.graphics.Matrix; 20 import android.util.AttributeSet; 21 import android.widget.ImageView; 22 23 import androidx.annotation.Nullable; 24 25 /** 26 * Custom ImageView that mimics the home launcher screen wallpaper position by aligning start and 27 * centering vertically its drawable. Scales down the image as much as possible without 28 * letterboxing. 29 */ 30 public class WallpaperThumbnailView extends ImageView { 31 WallpaperThumbnailView(Context context)32 public WallpaperThumbnailView(Context context) { 33 super(context); 34 setScaleType(ScaleType.MATRIX); 35 } 36 WallpaperThumbnailView(Context context, @Nullable AttributeSet attrs)37 public WallpaperThumbnailView(Context context, @Nullable AttributeSet attrs) { 38 super(context, attrs); 39 setScaleType(ScaleType.MATRIX); 40 } 41 42 @Override onLayout(boolean changed, int left, int top, int right, int bottom)43 protected void onLayout(boolean changed, int left, int top, int right, int bottom) { 44 super.onLayout(changed, left, top, right, bottom); 45 recomputeImageMatrix(); 46 } 47 recomputeImageMatrix()48 private void recomputeImageMatrix() { 49 // The drawable may be null on the first layout pass. 50 if (getDrawable() == null) { 51 return; 52 } 53 54 final Matrix matrix = getImageMatrix(); 55 56 final int viewWidth = getWidth() - getPaddingLeft() - getPaddingRight(); 57 final int viewHeight = getHeight() - getPaddingTop() - getPaddingBottom(); 58 final int drawableWidth = getDrawable().getIntrinsicWidth(); 59 final int drawableHeight = getDrawable().getIntrinsicHeight(); 60 61 float scale; 62 if (drawableWidth * viewHeight > drawableHeight * viewWidth) { 63 scale = (float) viewHeight / drawableHeight; 64 } else { 65 scale = (float) viewWidth / drawableWidth; 66 } 67 68 // Set scale such that the maximum area of the drawable is shown without letterboxing. 69 matrix.setScale(scale, scale); 70 71 // Center the drawable vertically within the view. 72 if ((drawableHeight * scale) > viewHeight) { 73 float dy = -(((drawableHeight * scale) - viewHeight) / 2f); 74 matrix.postTranslate(0, dy); 75 } 76 77 // If layout direction is RTL, then matrix should align the image towards the right. 78 if (getLayoutDirection() == LAYOUT_DIRECTION_RTL) { 79 float dx = -((drawableWidth * scale) - viewWidth); 80 matrix.postTranslate(dx, 0); 81 } 82 83 setImageMatrix(matrix); 84 invalidate(); 85 } 86 } 87