Unify Android Webview and Chrome's fling

android_webview/java/src/org/chromium/android_webview/AwContents.java

 // 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.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.ComponentCallbacks2;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.Picture;
 import android.graphics.Rect;
 import android.net.Uri;
 import android.net.http.SslCertificate;
 import android.os.AsyncTask;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
+import android.os.SystemClock;
 import android.text.TextUtils;
 import android.util.Base64;
+import android.util.FloatMath;
 import android.util.Log;
 import android.util.Pair;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityNodeInfo;
 import android.view.accessibility.AccessibilityNodeProvider;
+import android.view.animation.AnimationUtils;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
 import android.webkit.GeolocationPermissions;
 import android.webkit.JavascriptInterface;
 import android.webkit.ValueCallback;
 import android.widget.OverScroller;
 
 import org.chromium.android_webview.permission.AwPermissionRequest;
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
@@ skipping 521 matching lines @@
         public void onPinchEnded() {
             mLayoutSizer.unfreezeLayoutRequests();
         }
 
         @Override
         public void onFlingCancelGesture() {
             mScrollOffsetManager.onFlingCancelGesture();
         }
 
         @Override
-        public void onUnhandledFlingStartEvent(int velocityX, int velocityY) {
-            mScrollOffsetManager.onUnhandledFlingStartEvent(velocityX, velocityY);
-        }
-
-        @Override
         public void onScrollUpdateGestureConsumed() {
             mScrollAccessibilityHelper.postViewScrolledAccessibilityEventCallback();
         }
     }
 
     //--------------------------------------------------------------------------------------------
     private class AwComponentCallbacks implements ComponentCallbacks2 {
         @Override
         public void onTrimMemory(final int level) {
             if (isDestroyed()) return;
@@ skipping 1280 matching lines @@
      */
     public float getScale() {
         return (float) (mPageScaleFactor * mDIPScale);
     }
 
     /**
      * @see android.webkit.WebView#flingScroll(int, int)
      */
     public void flingScroll(int velocityX, int velocityY) {
         if (TRACE) Log.d(TAG, "flingScroll");
-        mScrollOffsetManager.flingScroll(velocityX, velocityY);
+        mContentViewCore.fling(SystemClock.uptimeMillis(), 0, 0, -velocityX, -velocityY);
     }
 
     /**
      * @see android.webkit.WebView#pageUp(boolean)
      */
     public boolean pageUp(boolean top) {
         if (TRACE) Log.d(TAG, "pageUp");
         return mScrollOffsetManager.pageUp(top);
     }
 
@@ skipping 590 matching lines @@
         // This change notification comes from the renderer thread, not from the cc/ impl thread.
         mLayoutSizer.onContentSizeChanged(widthCss, heightCss);
     }
 
     @CalledByNative
     private void scrollContainerViewTo(int x, int y) {
         mScrollOffsetManager.scrollContainerViewTo(x, y);
     }
 
     @CalledByNative
-    public boolean isFlingActive() {
-        return mScrollOffsetManager.isFlingActive();
+    public boolean isSmoothScrollingActive() {
+        return mScrollOffsetManager.isSmoothScrollingActive();
     }
 
     @CalledByNative
     private void updateScrollState(int maxContainerViewScrollOffsetX,
             int maxContainerViewScrollOffsetY, int contentWidthDip, int contentHeightDip,
             float pageScaleFactor, float minPageScaleFactor, float maxPageScaleFactor) {
         mContentWidthDip = contentWidthDip;
         mContentHeightDip = contentHeightDip;
         mScrollOffsetManager.setMaxScrollOffset(maxContainerViewScrollOffsetX,
                 maxContainerViewScrollOffsetY);
         setPageScaleFactorAndLimits(pageScaleFactor, minPageScaleFactor, maxPageScaleFactor);
     }
 
     @CalledByNative
     private void setAwAutofillClient(AwAutofillClient client) {
         mAwAutofillClient = client;
         client.init(mContentViewCore);
     }
 
     @CalledByNative
-    private void didOverscroll(int deltaX, int deltaY) {
-        if (mOverScrollGlow != null) {
-            mOverScrollGlow.setOverScrollDeltas(deltaX, deltaY);
+    private void didOverscroll(int deltaX, int deltaY, float velocityX, float velocityY,
+            boolean firstOverscrollX, boolean firstOverscrollY) {
+        if (mOverScrollGlow == null) return;
+
+        mOverScrollGlow.setOverScrollDeltas(deltaX, deltaY);
+
+        // TODO(jdduke): Skip this for components with non-zero velocity?

[jdduke (slow), 2015/05/12 20:46:06]

It's quite possible we don't even need these checks for
|firstOverscrollX|/|firstOverscrollY|. It looks like OverscrollGlow.java may
already have the necessary data to make the call on whether to process the glow,
so maybe try removing this guard and see if it works OK?

If so, we can probably get rid of the |firstOverscrollX|/|firstOverscrollY|
computation altogether. I think I may have introduced that b/c we have to do
something with Chrome's version of the overscroll glow, but again, looking at
OverscrollGlow.java I think it may already have the data it needs to know when
an overscroll actually starts.

[hush (inactive), 2015/05/13 23:26:20]

OverScrollGlow class has all the information it needs. I will remove
firstOverScrollX/Y.

+        if ((velocityX != 0 && firstOverscrollX) || (velocityY != 0 && firstOverscrollY)) {

[aelias_OOO_until_Jul13, 2015/05/09 03:32:04]

Could you explain why the first overscroll needs to be special?

[hush (inactive), 2015/05/12 19:08:45]

I guess the original idea to absorb the glow if it is the first overscroll.
However, I just found WebView's overScroll glow is not working properly,
including version m39:
The overscroll glow does not *always* show when you fling the webview towards
the corners. You have to be very close to the corner when you start the fling
for the overscroll glow to appear. This is different from Chrome on Android,
where you always have the edge glow effects when the velocity is non-zero at the
corner.


I am thinking of fixing this by removing WebView's own "OverScrollGlow" if
possible and just Chrome's overscroll glow edge effect. Like what Marcin said in

https://code.google.com/p/chromium/issues/detail?id=378984#c2

[jdduke (slow), 2015/05/12 19:34:11]

I would love for this to be the case, but Chrome's effect uses the browser
compositor so it won't be as simple as a drop-in replacement for what WebView
has.

In theory we could abstract the rendering so that it uses the same logic as
Chrome, but does its rendering differently (similar to selection handles,
CompositedTouchHandleDrawable vs PopupTouchHandleDrawable), but that's probably
best carved out as a separate project (if at all).

[hush (inactive), 2015/05/13 23:26:20]

Okay.. I will just continue using WebView's custom overscroll glow class.

+            final int oldX = mContainerView.getScrollX();
+            final int oldY = mContainerView.getScrollY();
+            final int x = oldX + deltaX;
+            final int y = oldX + deltaY;

[hush (inactive), 2015/05/13 23:26:20]

It should have been oldY + deltaY.

+            final int scrollRangeX = mScrollOffsetManager.computeMaximumHorizontalScrollOffset();
+            final int scrollRangeY = mScrollOffsetManager.computeMaximumVerticalScrollOffset();
+            mOverScrollGlow.absorbGlow(x, y, oldX, oldY, scrollRangeX, scrollRangeY,
+                    FloatMath.hypot(velocityX, velocityY));
+        } else {
+            mScrollOffsetManager.overScrollBy(deltaX, deltaY);
         }
 
-        mScrollOffsetManager.overScrollBy(deltaX, deltaY);
-
-        if (mOverScrollGlow != null && mOverScrollGlow.isAnimating()) {
+        if (mOverScrollGlow.isAnimating()) {
             postInvalidateOnAnimation();
         }
     }
 
     // -------------------------------------------------------------------------------------------
     // Helper methods
     // -------------------------------------------------------------------------------------------
 
     private void setPageScaleFactorAndLimits(
             float pageScaleFactor, float minPageScaleFactor, float maxPageScaleFactor) {
@@ skipping 383 matching lines @@
             return mScrollOffsetManager.computeVerticalScrollOffset();
         }
 
         @Override
         public int computeVerticalScrollExtent() {
             return mScrollOffsetManager.computeVerticalScrollExtent();
         }
 
         @Override
         public void computeScroll() {
-            mScrollOffsetManager.computeScrollAndAbsorbGlow(mOverScrollGlow);
+            if (mScrollOffsetManager.willComputeScroll()) {
+                mScrollOffsetManager.computeScrollAndAbsorbGlow(mOverScrollGlow);
+            } else {
+                if (isDestroyed()) return;
+                nativeOnComputeScroll(
+                        mNativeAwContents, AnimationUtils.currentAnimationTimeMillis());
+            }
         }
     }
 
     // Return true if the GeolocationPermissionAPI should be used.
     @CalledByNative
     private boolean useLegacyGeolocationPermissionAPI() {
         // Always return true since we are not ready to swap the geolocation yet.
         // TODO: If we decide not to migrate the geolocation, there are some unreachable
         // code need to remove. http://crbug.com/396184.
         return true;
@@ skipping 16 matching lines @@
             AwContentsClientBridge contentsClientBridge,
             AwContentsIoThreadClient ioThreadClient,
             InterceptNavigationDelegate navigationInterceptionDelegate);
     private native WebContents nativeGetWebContents(long nativeAwContents);
 
     private native void nativeDocumentHasImages(long nativeAwContents, Message message);
     private native void nativeGenerateMHTML(
             long nativeAwContents, String path, ValueCallback<String> callback);
 
     private native void nativeAddVisitedLinks(long nativeAwContents, String[] visitedLinks);
+    private native void nativeOnComputeScroll(
+            long nativeAwContents, long currentAnimationTimeMillis);
     private native boolean nativeOnDraw(long nativeAwContents, Canvas canvas,
             boolean isHardwareAccelerated, int scrollX, int scrollY,
             int visibleLeft, int visibleTop, int visibleRight, int visibleBottom);
     private native void nativeFindAllAsync(long nativeAwContents, String searchString);
     private native void nativeFindNext(long nativeAwContents, boolean forward);
     private native void nativeClearMatches(long nativeAwContents);
     private native void nativeClearCache(long nativeAwContents, boolean includeDiskFiles);
     private native byte[] nativeGetCertificate(long nativeAwContents);
 
     // Coordinates in desity independent pixels.
@@ skipping 39 matching lines @@
     private native void nativeCreatePdfExporter(long nativeAwContents, AwPdfExporter awPdfExporter);
 
     private native void nativePreauthorizePermission(long nativeAwContents, String origin,
             long resources);
 
     private native void nativePostMessageToFrame(long nativeAwContents, String frameId,
             String message, String targetOrigin, int[] msgPorts);
 
     private native void nativeCreateMessageChannel(long nativeAwContents, AwMessagePort[] ports);
 }