| // Copyright 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| package org.chromium.android_webview; |
| |
| import android.view.View; |
| import android.view.View.MeasureSpec; |
| |
| /** |
| * Helper methods used to manage the layout of the View that contains AwContents. |
| */ |
| public class AwLayoutSizer { |
| // These are used to prevent a re-layout if the content size changes within a dimension that is |
| // fixed by the view system. |
| private boolean mWidthMeasurementIsFixed; |
| private boolean mHeightMeasurementIsFixed; |
| |
| // Size of the rendered content, as reported by native. |
| private int mContentHeightCss; |
| private int mContentWidthCss; |
| |
| // Page scale factor. |
| private float mPageScaleFactor = 1.0f; |
| |
| // Whether to postpone layout requests. |
| private boolean mFreezeLayoutRequests; |
| // Did we try to request a layout since the last time mPostponeLayoutRequests was set to true. |
| private boolean mFrozenLayoutRequestPending; |
| |
| private double mDIPScale; |
| |
| // Was our height larger than the AT_MOST constraint the last time onMeasure was called? |
| private boolean mHeightMeasurementLimited; |
| // If mHeightMeasurementLimited is true then this contains the height limit. |
| private int mHeightMeasurementLimit; |
| |
| // Callback object for interacting with the View. |
| private Delegate mDelegate; |
| |
| /** |
| * Delegate interface through which the AwLayoutSizer communicates with the view it's sizing. |
| */ |
| public interface Delegate { |
| void requestLayout(); |
| void setMeasuredDimension(int measuredWidth, int measuredHeight); |
| boolean isLayoutParamsHeightWrapContent(); |
| void setForceZeroLayoutHeight(boolean forceZeroHeight); |
| } |
| |
| /** |
| * Default constructor. Note: both setDelegate and setDIPScale must be called before the class |
| * is ready for use. |
| */ |
| public AwLayoutSizer() { |
| } |
| |
| public void setDelegate(Delegate delegate) { |
| mDelegate = delegate; |
| } |
| |
| public void setDIPScale(double dipScale) { |
| mDIPScale = dipScale; |
| } |
| |
| /** |
| * Postpone requesting layouts till unfreezeLayoutRequests is called. |
| */ |
| public void freezeLayoutRequests() { |
| mFreezeLayoutRequests = true; |
| mFrozenLayoutRequestPending = false; |
| } |
| |
| /** |
| * Stop postponing layout requests and request layout if such a request would have been made |
| * had the freezeLayoutRequests method not been called before. |
| */ |
| public void unfreezeLayoutRequests() { |
| mFreezeLayoutRequests = false; |
| if (mFrozenLayoutRequestPending) { |
| mFrozenLayoutRequestPending = false; |
| mDelegate.requestLayout(); |
| } |
| } |
| |
| /** |
| * Update the contents size. |
| * This should be called whenever the content size changes (due to DOM manipulation or page |
| * load, for example). |
| */ |
| public void onContentSizeChanged(int widthCss, int heightCss) { |
| doUpdate(widthCss, heightCss, mPageScaleFactor); |
| } |
| |
| /** |
| * Update the contents page scale. |
| * This should be called whenever the content page scale factor changes (due to pinch zoom, for |
| * example). |
| */ |
| public void onPageScaleChanged(float pageScaleFactor) { |
| doUpdate(mContentWidthCss, mContentHeightCss, pageScaleFactor); |
| } |
| |
| private void doUpdate(int widthCss, int heightCss, float pageScaleFactor) { |
| // We want to request layout only if the size or scale change, however if any of the |
| // measurements are 'fixed', then changing the underlying size won't have any effect, so we |
| // ignore changes to dimensions that are 'fixed'. |
| final int heightPix = (int) (heightCss * mPageScaleFactor * mDIPScale); |
| boolean pageScaleChanged = mPageScaleFactor != pageScaleFactor; |
| boolean contentHeightChangeMeaningful = !mHeightMeasurementIsFixed |
| && (!mHeightMeasurementLimited || heightPix < mHeightMeasurementLimit); |
| boolean pageScaleChangeMeaningful = |
| !mWidthMeasurementIsFixed || contentHeightChangeMeaningful; |
| boolean layoutNeeded = (mContentWidthCss != widthCss && !mWidthMeasurementIsFixed) |
| || (mContentHeightCss != heightCss && contentHeightChangeMeaningful) |
| || (pageScaleChanged && pageScaleChangeMeaningful); |
| |
| mContentWidthCss = widthCss; |
| mContentHeightCss = heightCss; |
| mPageScaleFactor = pageScaleFactor; |
| |
| if (layoutNeeded) { |
| if (mFreezeLayoutRequests) { |
| mFrozenLayoutRequestPending = true; |
| } else { |
| mDelegate.requestLayout(); |
| } |
| } |
| } |
| |
| /** |
| * Calculate the size of the view. |
| * This is designed to be used to implement the android.view.View#onMeasure() method. |
| */ |
| public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { |
| int heightMode = MeasureSpec.getMode(heightMeasureSpec); |
| int heightSize = MeasureSpec.getSize(heightMeasureSpec); |
| int widthMode = MeasureSpec.getMode(widthMeasureSpec); |
| int widthSize = MeasureSpec.getSize(widthMeasureSpec); |
| |
| int contentHeightPix = (int) (mContentHeightCss * mPageScaleFactor * mDIPScale); |
| int contentWidthPix = (int) (mContentWidthCss * mPageScaleFactor * mDIPScale); |
| |
| int measuredHeight = contentHeightPix; |
| int measuredWidth = contentWidthPix; |
| |
| // Always use the given size unless unspecified. This matches WebViewClassic behavior. |
| mWidthMeasurementIsFixed = (widthMode != MeasureSpec.UNSPECIFIED); |
| mHeightMeasurementIsFixed = (heightMode == MeasureSpec.EXACTLY); |
| mHeightMeasurementLimited = |
| (heightMode == MeasureSpec.AT_MOST) && (contentHeightPix > heightSize); |
| mHeightMeasurementLimit = heightSize; |
| |
| if (mHeightMeasurementIsFixed || mHeightMeasurementLimited) { |
| measuredHeight = heightSize; |
| } |
| |
| if (mWidthMeasurementIsFixed) { |
| measuredWidth = widthSize; |
| } |
| |
| if (measuredHeight < contentHeightPix) { |
| measuredHeight |= View.MEASURED_STATE_TOO_SMALL; |
| } |
| |
| if (measuredWidth < contentWidthPix) { |
| measuredWidth |= View.MEASURED_STATE_TOO_SMALL; |
| } |
| |
| mDelegate.setMeasuredDimension(measuredWidth, measuredHeight); |
| } |
| |
| /** |
| * Notify the AwLayoutSizer that the size of the view has changed. |
| * This should be called by the Android view system after onMeasure if the view's size has |
| * changed. |
| */ |
| public void onSizeChanged(int w, int h, int ow, int oh) { |
| updateLayoutSettings(); |
| } |
| |
| /** |
| * Notify the AwLayoutSizer that the layout pass requested via Delegate.requestLayout has |
| * completed. |
| * This should be called after onSizeChanged regardless of whether the size has changed or not. |
| */ |
| public void onLayoutParamsChange() { |
| updateLayoutSettings(); |
| } |
| |
| // This needs to be called every time either the physical size of the view is changed or layout |
| // params are updated. |
| private void updateLayoutSettings() { |
| mDelegate.setForceZeroLayoutHeight(mDelegate.isLayoutParamsHeightWrapContent()); |
| } |
| } |