| 1 | // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | package org.chromium.android_webview; |
| 6 | |
| 7 | import android.util.Pair; |
| 8 | import android.view.View.MeasureSpec; |
| 9 | import android.view.View; |
| 10 | |
| 11 | import org.chromium.content.browser.ContentViewCore; |
| 12 | |
| 13 | /** |
| 14 | * Helper methods used to manage the layout of the View that contains AwContents. |
| 15 | */ |
| 16 | public class AwLayoutSizer { |
| 17 | // These are used to prevent a re-layout if the content size changes within a dimension that is |
| 18 | // fixed by the view system. |
| 19 | private boolean mWidthMeasurementIsFixed; |
| 20 | private boolean mHeightMeasurementIsFixed; |
| 21 | |
| 22 | // Size of the rendered content, as reported by native. |
| 23 | private int mContentHeightCss; |
| 24 | private int mContentWidthCss; |
| 25 | |
| 26 | // Page scale factor. This is set to zero initially so that we don't attempt to do a layout if |
| 27 | // we get the content size change notification first and a page scale change second. |
| 28 | private double mPageScaleFactor = 0.0; |
| 29 | |
| 30 | // Whether to postpone layout requests. |
| 31 | private boolean mFreezeLayoutRequests; |
| 32 | // Did we try to request a layout since the last time mPostponeLayoutRequests was set to true. |
| 33 | private boolean mFrozenLayoutRequestPending; |
| 34 | |
| 35 | private double mDIPScale; |
| 36 | |
| 37 | // Callback object for interacting with the View. |
| 38 | private Delegate mDelegate; |
| 39 | |
| 40 | public interface Delegate { |
| 41 | void requestLayout(); |
| 42 | void setMeasuredDimension(int measuredWidth, int measuredHeight); |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Default constructor. Note: both setDelegate and setDIPScale must be called before the class |
| 47 | * is ready for use. |
| 48 | */ |
| 49 | public AwLayoutSizer() { |
| 50 | } |
| 51 | |
| 52 | public void setDelegate(Delegate delegate) { |
| 53 | mDelegate = delegate; |
| 54 | } |
| 55 | |
| 56 | public void setDIPScale(double dipScale) { |
| 57 | mDIPScale = dipScale; |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * This is used to register the AwLayoutSizer to preferred content size change notifications in |
| 62 | * the AwWebContentsDelegate. |
| 63 | * NOTE: The preferred size notifications come in from the Renderer main thread and might be |
| 64 | * out of sync with the content size as seen by the InProcessViewRenderer (and Compositor). |
| 65 | */ |
| 66 | public AwWebContentsDelegateAdapter.PreferredSizeChangedListener |
| 67 | getPreferredSizeChangedListener() { |
| 68 | return new AwWebContentsDelegateAdapter.PreferredSizeChangedListener() { |
| 69 | @Override |
| 70 | public void updatePreferredSize(int widthCss, int heightCss) { |
| 71 | onContentSizeChanged(widthCss, heightCss); |
| 72 | } |
| 73 | }; |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Postpone requesting layouts till unfreezeLayoutRequests is called. |
| 78 | */ |
| 79 | public void freezeLayoutRequests() { |
| 80 | mFreezeLayoutRequests = true; |
| 81 | mFrozenLayoutRequestPending = false; |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * Stop postponing layout requests and request layout if such a request would have been made |
| 86 | * had the freezeLayoutRequests method not been called before. |
| 87 | */ |
| 88 | public void unfreezeLayoutRequests() { |
| 89 | mFreezeLayoutRequests = false; |
| 90 | if (mFrozenLayoutRequestPending) { |
| 91 | mFrozenLayoutRequestPending = false; |
| 92 | mDelegate.requestLayout(); |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Update the contents size. |
| 98 | * This should be called whenever the content size changes (due to DOM manipulation or page |
| 99 | * load, for example). |
| 100 | * The width and height should be in CSS pixels. |
| 101 | */ |
| 102 | public void onContentSizeChanged(int widthCss, int heightCss) { |
| 103 | doUpdate(widthCss, heightCss, mPageScaleFactor); |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * Update the contents page scale. |
| 108 | * This should be called whenever the content page scale factor changes (due to pinch zoom, for |
| 109 | * example). |
| 110 | */ |
| 111 | public void onPageScaleChanged(double pageScaleFactor) { |
| 112 | doUpdate(mContentWidthCss, mContentHeightCss, pageScaleFactor); |
| 113 | } |
| 114 | |
| 115 | private void doUpdate(int widthCss, int heightCss, double pageScaleFactor) { |
| 116 | // We want to request layout only if the size or scale change, however if any of the |
| 117 | // measurements are 'fixed', then changing the underlying size won't have any effect, so we |
| 118 | // ignore changes to dimensions that are 'fixed'. |
| 119 | boolean anyMeasurementNotFixed = !mWidthMeasurementIsFixed || !mHeightMeasurementIsFixed; |
| 120 | boolean layoutNeeded = (mContentWidthCss != widthCss && !mWidthMeasurementIsFixed) || |
| 121 | (mContentHeightCss != heightCss && !mHeightMeasurementIsFixed) || |
| 122 | (mPageScaleFactor != pageScaleFactor && anyMeasurementNotFixed); |
| 123 | |
| 124 | mContentWidthCss = widthCss; |
| 125 | mContentHeightCss = heightCss; |
| 126 | mPageScaleFactor = pageScaleFactor; |
| 127 | |
| 128 | if (layoutNeeded) { |
| 129 | if (mFreezeLayoutRequests) { |
| 130 | mFrozenLayoutRequestPending = true; |
| 131 | } else { |
| 132 | mDelegate.requestLayout(); |
| 133 | } |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * Calculate the size of the view. |
| 139 | * This is designed to be used to implement the android.view.View#onMeasure() method. |
| 140 | */ |
| 141 | public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { |
| 142 | int heightMode = MeasureSpec.getMode(heightMeasureSpec); |
| 143 | int heightSize = MeasureSpec.getSize(heightMeasureSpec); |
| 144 | int widthMode = MeasureSpec.getMode(widthMeasureSpec); |
| 145 | int widthSize = MeasureSpec.getSize(widthMeasureSpec); |
| 146 | |
| 147 | int measuredHeight = heightSize; |
| 148 | int measuredWidth = widthSize; |
| 149 | |
| 150 | int contentHeightPix = (int) (mContentHeightCss * mPageScaleFactor * mDIPScale); |
| 151 | int contentWidthPix = (int) (mContentWidthCss * mPageScaleFactor * mDIPScale); |
| 152 | |
| 153 | // Always use the given size unless unspecified. This matches WebViewClassic behavior. |
| 154 | mWidthMeasurementIsFixed = (widthMode != MeasureSpec.UNSPECIFIED); |
| 155 | // Freeze the height if an exact size is given by the parent or if the content size has |
| 156 | // exceeded the maximum size specified by the parent. |
| 157 | // TODO(mkosiba): Actually we'd like the reduction in content size to cause the WebView to |
| 158 | // shrink back again but only as a result of a page load. |
| 159 | mHeightMeasurementIsFixed = (heightMode == MeasureSpec.EXACTLY) || |
| 160 | (heightMode == MeasureSpec.AT_MOST && contentHeightPix > heightSize); |
| 161 | |
| 162 | if (!mHeightMeasurementIsFixed) { |
| 163 | measuredHeight = contentHeightPix; |
| 164 | } |
| 165 | |
| 166 | if (!mWidthMeasurementIsFixed) { |
| 167 | measuredWidth = contentWidthPix; |
| 168 | } |
| 169 | |
| 170 | if (measuredHeight < contentHeightPix) { |
| 171 | measuredHeight |= View.MEASURED_STATE_TOO_SMALL; |
| 172 | } |
| 173 | |
| 174 | if (measuredWidth < contentWidthPix) { |
| 175 | measuredWidth |= View.MEASURED_STATE_TOO_SMALL; |
| 176 | } |
| 177 | |
| 178 | mDelegate.setMeasuredDimension(measuredWidth, measuredHeight); |
| 179 | } |
| 180 | } |