// Starts the fling animation. Called both as a response to a fling gesture and as via the
// public WebView#flingScroll(int, int) API.
public void flingScroll(int velocityX, int velocityY) {
final int scrollX = mDelegate.getContainerViewScrollX();
final int scrollY = mDelegate.getContainerViewScrollY();
final int rangeX = computeMaximumHorizontalScrollOffset();
final int rangeY = computeMaximumVerticalScrollOffset();
mScroller.fling(scrollX, scrollY, velocityX, velocityY, 0, rangeX, 0, rangeY);
mDelegate.invalidate();
}
// Called by the View system as a response to the mDelegate.overScrollContainerViewBy call.
public void onContainerViewOverScrolled(
int scrollX, int scrollY, boolean clampedX, boolean clampedY) {
// Clamp the scroll offset at (0, max).
scrollX = clampHorizontalScroll(scrollX);
scrollY = clampVerticalScroll(scrollY);
mDelegate.scrollContainerViewTo(scrollX, scrollY);
// This is only necessary if the containerView scroll offset ends up being different
// than the one set from native in which case we want the value stored on the native side
// to reflect the value stored in the containerView (and not the other way around).
scrollNativeTo(mDelegate.getContainerViewScrollX(), mDelegate.getContainerViewScrollY());
}
private void scrollBy(int deltaX, int deltaY) {
if (deltaX == 0 && deltaY == 0) return;
final int scrollX = mDelegate.getContainerViewScrollX();
final int scrollY = mDelegate.getContainerViewScrollY();
final int scrollRangeX = computeMaximumHorizontalScrollOffset();
final int scrollRangeY = computeMaximumVerticalScrollOffset();
// The android.view.View.overScrollBy method is used for both scrolling and over-scrolling
// which is why we use it here.
mDelegate.overScrollContainerViewBy(
deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, mProcessingTouchEvent);
}
// Called by the native side to attempt to scroll the container view.
public void scrollContainerViewTo(int x, int y) {
mNativeScrollX = x;
mNativeScrollY = y;
final int scrollX = mDelegate.getContainerViewScrollX();
final int scrollY = mDelegate.getContainerViewScrollY();
final int deltaX = x - scrollX;
final int deltaY = y - scrollY;
final int scrollRangeX = computeMaximumHorizontalScrollOffset();
final int scrollRangeY = computeMaximumVerticalScrollOffset();
// We use overScrollContainerViewBy to be compatible with WebViewClassic which used this
// method for handling both over-scroll as well as in-bounds scroll.
mDelegate.overScrollContainerViewBy(
deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, mProcessingTouchEvent);
}
// Called immediately before the draw to update the scroll offset.
public void computeScrollAndAbsorbGlow(OverScrollGlow overScrollGlow) {
final boolean stillAnimating = mScroller.computeScrollOffset();
if (!stillAnimating) return;
final int oldX = mDelegate.getContainerViewScrollX();
final int oldY = mDelegate.getContainerViewScrollY();
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
int rangeX = computeMaximumHorizontalScrollOffset();
int rangeY = computeMaximumVerticalScrollOffset();
if (overScrollGlow != null) {
overScrollGlow.absorbGlow(x, y, oldX, oldY, rangeX, rangeY, mScroller.getCurrVelocity());
}
// The mScroller is configured not to go outside of the scrollable range, so this call
// should never result in attempting to scroll outside of the scrollable region.
scrollBy(x - oldX, y - oldY);
mDelegate.invalidate();
}
public int computeHorizontalScrollOffset() {
return mDelegate.getContainerViewScrollX();
}
public void syncScrollOffsetFromOnDraw() {
// Unfortunately apps override onScrollChanged without calling super which is why we need
// to sync the scroll offset on every onDraw.
onContainerViewScrollChanged(
mDelegate.getContainerViewScrollX(), mDelegate.getContainerViewScrollY());
}
