From bd0d2a899ed32035ba2bf659e4390ffecc16cbaf Mon Sep 17 00:00:00 2001
From: Ben Komalo <benkomalo@google.com>
Date: Thu, 11 Aug 2011 16:45:49 -0700
Subject: [PATCH] Prevent infinite resizes in webview

Bug: 2349275
Change-Id: Iea502beafcc232105486dfdd5a2d93229313bc45
---
 res/layout-sw600dp/message_view_fragment.xml |   2 +-
 res/layout/message_view_fragment.xml         |   7 +-
 src/com/android/email/view/RigidWebView.java | 103 +++++++++++++++++++
 3 files changed, 106 insertions(+), 6 deletions(-)
 create mode 100644 src/com/android/email/view/RigidWebView.java

diff --git a/res/layout-sw600dp/message_view_fragment.xml b/res/layout-sw600dp/message_view_fragment.xml
index 790ecaab5..ea337f97e 100644
--- a/res/layout-sw600dp/message_view_fragment.xml
+++ b/res/layout-sw600dp/message_view_fragment.xml
@@ -218,7 +218,7 @@
                 android:layout_weight="1"
                 android:layout_marginLeft="14dip"
                 android:layout_marginRight="14dip"
-                android:background="#ffffffff"
+                android:background="@android:color/white"
                 android:visibility="gone"
                 />
 
diff --git a/res/layout/message_view_fragment.xml b/res/layout/message_view_fragment.xml
index 09b4772c7..38014fcc0 100644
--- a/res/layout/message_view_fragment.xml
+++ b/res/layout/message_view_fragment.xml
@@ -150,17 +150,14 @@
             <!-- end of tab area -->
             <!--
                 content area - only one of them is visible at a time.
-
-                TODO Decide what to do with the scrollview+webview issue, and remove the scrollviews
-                     below if we go with the outer scrollview.
             -->
-            <WebView
+            <com.android.email.view.RigidWebView
                 android:id="@+id/message_content"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:layout_marginLeft="16dip"
                 android:layout_marginRight="16dip"
-                android:background="#ffffff"
+                android:background="@android:color/white"
                 android:visibility="gone"
                 />
             <!--
diff --git a/src/com/android/email/view/RigidWebView.java b/src/com/android/email/view/RigidWebView.java
new file mode 100644
index 000000000..1b31c08f2
--- /dev/null
+++ b/src/com/android/email/view/RigidWebView.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package com.android.email.view;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.util.Log;
+import android.webkit.WebView;
+
+import com.android.email.Clock;
+import com.android.email.Email;
+import com.android.email.Throttle;
+import com.android.emailcommon.Logging;
+import com.android.emailcommon.utility.Utility;
+
+/**
+ * A custom WebView that is robust to rapid resize events in sequence.
+ *
+ * This is useful for a WebView which needs to have a layout of {@code WRAP_CONTENT}, since any
+ * contents with percent-based height will force the WebView to infinitely expand (or shrink).
+ */
+public class RigidWebView extends WebView {
+
+    public RigidWebView(Context context) {
+        super(context);
+    }
+    public RigidWebView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+    public RigidWebView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    private static final int MIN_RESIZE_INTERVAL = 200;
+    private static final int MAX_RESIZE_INTERVAL = 300;
+    private final Clock mClock = Clock.INSTANCE;
+
+    private final Throttle mThrottle = new Throttle(getClass().getName(),
+            new Runnable() {
+                @Override public void run() {
+                    performSizeChangeDelayed();
+                }
+            }, Utility.getMainThreadHandler(),
+            MIN_RESIZE_INTERVAL, MAX_RESIZE_INTERVAL);
+
+    private int mRealWidth;
+    private int mRealHeight;
+    private boolean mIgnoreNext;
+    private long mLastSizeChangeTime = -1;
+
+    @Override
+    protected void onSizeChanged(int w, int h, int ow, int oh) {
+        mRealWidth = w;
+        mRealHeight = h;
+        long now = mClock.getTime();
+        boolean recentlySized = (now - mLastSizeChangeTime < MIN_RESIZE_INTERVAL);
+
+        // It's known that the previous resize event may cause a resize event immediately. If
+        // this happens sufficiently close to the last resize event, drop it on the floor.
+        if (mIgnoreNext) {
+            mIgnoreNext = false;
+            if (recentlySized) {
+                if (Email.DEBUG) {
+                    Log.w(Logging.LOG_TAG, "Supressing size change in RigidWebView");
+                }
+                return;
+            }
+        }
+
+        if (recentlySized) {
+            mThrottle.onEvent();
+        } else {
+            // It's been a sufficiently long time - just perform the resize as normal. This should
+            // be the normal code path.
+            performSizeChange(ow, oh);
+        }
+    }
+
+    private void performSizeChange(int ow, int oh) {
+        super.onSizeChanged(mRealWidth, mRealHeight, ow, oh);
+        mLastSizeChangeTime = mClock.getTime();
+    }
+
+    private void performSizeChangeDelayed() {
+        mIgnoreNext = true;
+        performSizeChange(getWidth(), getHeight());
+    }
+}