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 18 package com.android.email.view; 19 20 import android.content.Context; 21 import android.util.AttributeSet; 22 import android.util.Log; 23 import android.webkit.WebView; 24 25 import com.android.email.Clock; 26 import com.android.email.Email; 27 import com.android.email.Throttle; 28 import com.android.emailcommon.Logging; 29 import com.android.emailcommon.utility.Utility; 30 31 /** 32 * A custom WebView that is robust to rapid resize events in sequence. 33 * 34 * This is useful for a WebView which needs to have a layout of {@code WRAP_CONTENT}, since any 35 * contents with percent-based height will force the WebView to infinitely expand (or shrink). 36 */ 37 public class RigidWebView extends WebView { 38 RigidWebView(Context context)39 public RigidWebView(Context context) { 40 super(context); 41 } RigidWebView(Context context, AttributeSet attrs)42 public RigidWebView(Context context, AttributeSet attrs) { 43 super(context, attrs); 44 } RigidWebView(Context context, AttributeSet attrs, int defStyle)45 public RigidWebView(Context context, AttributeSet attrs, int defStyle) { 46 super(context, attrs, defStyle); 47 } 48 49 private static final int MIN_RESIZE_INTERVAL = 200; 50 private static final int MAX_RESIZE_INTERVAL = 300; 51 private final Clock mClock = Clock.INSTANCE; 52 53 private final Throttle mThrottle = new Throttle(getClass().getName(), 54 new Runnable() { 55 @Override public void run() { 56 performSizeChangeDelayed(); 57 } 58 }, Utility.getMainThreadHandler(), 59 MIN_RESIZE_INTERVAL, MAX_RESIZE_INTERVAL); 60 61 private int mRealWidth; 62 private int mRealHeight; 63 private boolean mIgnoreNext; 64 private long mLastSizeChangeTime = -1; 65 66 @Override onSizeChanged(int w, int h, int ow, int oh)67 protected void onSizeChanged(int w, int h, int ow, int oh) { 68 mRealWidth = w; 69 mRealHeight = h; 70 long now = mClock.getTime(); 71 boolean recentlySized = (now - mLastSizeChangeTime < MIN_RESIZE_INTERVAL); 72 73 // It's known that the previous resize event may cause a resize event immediately. If 74 // this happens sufficiently close to the last resize event, drop it on the floor. 75 if (mIgnoreNext) { 76 mIgnoreNext = false; 77 if (recentlySized) { 78 if (Email.DEBUG) { 79 Log.w(Logging.LOG_TAG, "Supressing size change in RigidWebView"); 80 } 81 return; 82 } 83 } 84 85 if (recentlySized) { 86 mThrottle.onEvent(); 87 } else { 88 // It's been a sufficiently long time - just perform the resize as normal. This should 89 // be the normal code path. 90 performSizeChange(ow, oh); 91 } 92 } 93 performSizeChange(int ow, int oh)94 private void performSizeChange(int ow, int oh) { 95 super.onSizeChanged(mRealWidth, mRealHeight, ow, oh); 96 mLastSizeChangeTime = mClock.getTime(); 97 } 98 performSizeChangeDelayed()99 private void performSizeChangeDelayed() { 100 mIgnoreNext = true; 101 performSizeChange(getWidth(), getHeight()); 102 } 103 } 104