[android_webview] Add onMeasure support.

This change makes it possible for the AwContents embeddder
to implement the android.view.View#onMeasure method.

A content size change listener is added to ContentViewCore
to support the wrap_content layout mode. The layout
logic is encapsulated in AwLayoutSizer class.

BUG=None
TEST=AndroidWebViewTests
Java-only change, passes on the trybots.
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/11529016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@176370 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 122 insertions, 3 deletions

diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index 93a78d4..3d51cb7 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -82,6 +82,10 @@ public class AwContents {
      * dispatching of view methods through the containing view.
      */
     public interface InternalAccessDelegate extends ContentViewCore.InternalAccessDelegate {
+        /**
+         * @see View#setMeasuredDimension(int, int)
+         */
+        void setMeasuredDimension(int measuredWidth, int measuredHeight);
     }
 
     private int mNativeAwContents;
@@ -90,7 +94,8 @@ public class AwContents {
     private AwContentsClient mContentsClient;
     private AwContentsIoThreadClient mIoThreadClient;
     private InterceptNavigationDelegateImpl mInterceptNavigationDelegate;
-    private ContentViewCore.InternalAccessDelegate mInternalAccessAdapter;
+    private InternalAccessDelegate mInternalAccessAdapter;
+    private final AwLayoutSizer mLayoutSizer;
     // This can be accessed on any thread after construction. See AwContentsIoThreadClient.
     private final AwSettings mSettings;
     private final ClientCallbackHandler mClientCallbackHandler;
@@ -271,9 +276,21 @@ public class AwContents {
         }
     }
 
+    private class AwLayoutSizerDelegate implements AwLayoutSizer.Delegate {
+        @Override
+        public void requestLayout() {
+            mContainerView.requestLayout();
+        }
+
+        @Override
+        public void setMeasuredDimension(int measuredWidth, int measuredHeight) {
+            mInternalAccessAdapter.setMeasuredDimension(measuredWidth, measuredHeight);
+        }
+    }
+
     // TODO(kristianm): Delete this when privateBrowsing parameter is removed in Android
     public AwContents(ViewGroup containerView,
-            ContentViewCore.InternalAccessDelegate internalAccessAdapter,
+            InternalAccessDelegate internalAccessAdapter,
             AwContentsClient contentsClient,
             NativeWindow nativeWindow, boolean privateBrowsing,
             boolean isAccessFromFileURLsGrantedByDefault) {
@@ -289,7 +306,7 @@ public class AwContents {
      * TODO(benm): Remove the nativeWindow parameter.
      */
     public AwContents(ViewGroup containerView,
-            ContentViewCore.InternalAccessDelegate internalAccessAdapter,
+            InternalAccessDelegate internalAccessAdapter,
             AwContentsClient contentsClient,
             NativeWindow nativeWindow,
             boolean isAccessFromFileURLsGrantedByDefault) {
@@ -309,6 +326,8 @@ public class AwContents {
                 new AwNativeWindow(mContainerView.getContext()),
                 isAccessFromFileURLsGrantedByDefault);
         mContentViewCore.setContentViewClient(mContentsClient);
+        mLayoutSizer = new AwLayoutSizer(new AwLayoutSizerDelegate());
+        mContentViewCore.setContentSizeChangeListener(mLayoutSizer);
         mContentsClient.installWebContentsObserver(mContentViewCore);
 
         mSettings = new AwSettings(mContentViewCore.getContext());
@@ -379,6 +398,10 @@ public class AwContents {
         }
     }
 
+    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        mLayoutSizer.onMeasure(widthMeasureSpec, heightMeasureSpec);
+    }
+
     public int findAllSync(String searchString) {
         if (mNativeAwContents == 0) return 0;
         return nativeFindAllSync(mNativeAwContents, searchString);
diff --git a/android_webview/java/src/org/chromium/android_webview/AwLayoutSizer.java b/android_webview/java/src/org/chromium/android_webview/AwLayoutSizer.java
new file mode 100644
index 0000000..c698ade
--- /dev/null
+++ b/android_webview/java/src/org/chromium/android_webview/AwLayoutSizer.java
@@ -0,0 +1,96 @@
+// Copyright (c) 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.util.Pair;
+import android.view.View.MeasureSpec;
+import android.view.View;
+
+import org.chromium.content.browser.ContentViewCore;
+
+/**
+ * Helper methods used to manage the layout of the View that contains AwContents.
+ */
+public class AwLayoutSizer implements ContentViewCore.ContentSizeChangeListener {
+    // 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 mContentHeight;
+    private int mContentWidth;
+
+    // Callback object for interacting with the View.
+    Delegate mDelegate;
+
+    public interface Delegate {
+        void requestLayout();
+        void setMeasuredDimension(int measuredWidth, int measuredHeight);
+    }
+
+    public AwLayoutSizer(Delegate delegate) {
+        mDelegate = delegate;
+    }
+
+    /**
+     * Update the contents size.
+     * This should be called whenever the content size changes (due to DOM manipulation or page
+     * load, for example).
+     */
+    @Override
+    public void onContentSizeChanged(int width, int height) {
+        boolean layoutNeeded = (mContentWidth != width && !mWidthMeasurementIsFixed) ||
+            (mContentHeight != height && !mHeightMeasurementIsFixed);
+
+        mContentWidth = width;
+        mContentHeight = height;
+
+        if (layoutNeeded) {
+            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 measuredHeight = heightSize;
+        int measuredWidth = widthSize;
+
+        // Always use the given size unless unspecified. This matches WebViewClassic behavior.
+        mWidthMeasurementIsFixed = (widthMode != MeasureSpec.UNSPECIFIED);
+        // Freeze the height if an exact size is given by the parent or if the content size has
+        // exceeded the maximum size specified by the parent.
+        // TODO(mkosiba): Actually we'd like the reduction in content size to cause the WebView to
+        // shrink back again but only as a result of a page load.
+        mHeightMeasurementIsFixed = (heightMode == MeasureSpec.EXACTLY) ||
+            (heightMode == MeasureSpec.AT_MOST && mContentHeight > heightSize);
+
+        if (!mHeightMeasurementIsFixed) {
+            measuredHeight = mContentHeight;
+        }
+
+        if (!mWidthMeasurementIsFixed) {
+            measuredWidth = mContentWidth;
+        }
+
+        if (measuredHeight < mContentHeight) {
+            measuredHeight |= View.MEASURED_STATE_TOO_SMALL;
+        }
+
+        if (measuredWidth < mContentWidth) {
+            measuredWidth |= View.MEASURED_STATE_TOO_SMALL;
+        }
+
+        mDelegate.setMeasuredDimension(measuredWidth, measuredHeight);
+    }
+}