1 /* 2 * Copyright (C) 2011 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.example.android.hcgallery; 18 19 import android.content.Context; 20 import android.util.AttributeSet; 21 import android.view.View; 22 import android.view.ViewGroup; 23 24 /** 25 * A simple layout that fits and centers each child view, maintaining aspect ratio. 26 */ 27 public class FitCenterFrameLayout extends ViewGroup { FitCenterFrameLayout(Context context)28 public FitCenterFrameLayout(Context context) { 29 super(context); 30 } 31 FitCenterFrameLayout(Context context, AttributeSet attrs)32 public FitCenterFrameLayout(Context context, AttributeSet attrs) { 33 super(context, attrs); 34 } 35 36 @Override onMeasure(int widthMeasureSpec, int heightMeasureSpec)37 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 38 // We purposely disregard child measurements. 39 final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec); 40 final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec); 41 setMeasuredDimension(width, height); 42 43 int childWidthSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.UNSPECIFIED); 44 int childHeightSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.UNSPECIFIED); 45 46 int childCount = getChildCount(); 47 for (int i = 0; i < childCount; i++) { 48 getChildAt(i).measure(childWidthSpec, childHeightSpec); 49 } 50 } 51 52 @Override onLayout(boolean changed, int l, int t, int r, int b)53 protected void onLayout(boolean changed, int l, int t, int r, int b) { 54 final int childCount = getChildCount(); 55 56 final int parentLeft = getPaddingLeft(); 57 final int parentTop = getPaddingTop(); 58 final int parentRight = r - l - getPaddingRight(); 59 final int parentBottom = b - t - getPaddingBottom(); 60 61 final int parentWidth = parentRight - parentLeft; 62 final int parentHeight = parentBottom - parentTop; 63 64 int unpaddedWidth, unpaddedHeight, parentUnpaddedWidth, parentUnpaddedHeight; 65 int childPaddingLeft, childPaddingTop, childPaddingRight, childPaddingBottom; 66 67 for (int i = 0; i < childCount; i++) { 68 final View child = getChildAt(i); 69 if (child.getVisibility() == GONE) { 70 continue; 71 } 72 73 // Fit and center the child within the parent. Make sure not to consider padding 74 // as part of the child's aspect ratio. 75 76 childPaddingLeft = child.getPaddingLeft(); 77 childPaddingTop = child.getPaddingTop(); 78 childPaddingRight = child.getPaddingRight(); 79 childPaddingBottom = child.getPaddingBottom(); 80 81 unpaddedWidth = child.getMeasuredWidth() - childPaddingLeft - childPaddingRight; 82 unpaddedHeight = child.getMeasuredHeight() - childPaddingTop - childPaddingBottom; 83 84 parentUnpaddedWidth = parentWidth - childPaddingLeft - childPaddingRight; 85 parentUnpaddedHeight = parentHeight - childPaddingTop - childPaddingBottom; 86 87 if (parentUnpaddedWidth * unpaddedHeight > parentUnpaddedHeight * unpaddedWidth) { 88 // The child view should be left/right letterboxed. 89 final int scaledChildWidth = unpaddedWidth * parentUnpaddedHeight 90 / unpaddedHeight + childPaddingLeft + childPaddingRight; 91 child.layout( 92 parentLeft + (parentWidth - scaledChildWidth) / 2, 93 parentTop, 94 parentRight - (parentWidth - scaledChildWidth) / 2, 95 parentBottom); 96 } else { 97 // The child view should be top/bottom letterboxed. 98 final int scaledChildHeight = unpaddedHeight * parentUnpaddedWidth 99 / unpaddedWidth + childPaddingTop + childPaddingBottom; 100 child.layout( 101 parentLeft, 102 parentTop + (parentHeight - scaledChildHeight) / 2, 103 parentRight, 104 parentTop + (parentHeight + scaledChildHeight) / 2); 105 } 106 } 107 } 108 } 109