/** This function must be called on the UI thread. */
public void preventedTouchFinished() {
checkMainThread();
if (mState == PanZoomState.WAITING_LISTENERS) {
// if we enter here, we just finished a block of events whose default actions
// were prevented by touch listeners. Now there are no touch points left, so
// we need to reset our state and re-bounce because we might be in overscroll
bounce();
}
}
private boolean onTouchCancel(MotionEvent event) {
cancelTouch();
if (mState == PanZoomState.WAITING_LISTENERS) {
// we might get a cancel event from the TouchEventHandler while in the
// WAITING_LISTENERS state if the touch listeners prevent-default the
// block of events. at this point being in WAITING_LISTENERS is equivalent
// to being in NOTHING with the exception of possibly being in overscroll.
// so here we don't want to do anything right now; the overscroll will be
// corrected in preventedTouchFinished().
return false;
}
// ensure we snap back if we're overscrolled
bounce();
return false;
}
/**
* Zoom to a specified rect IN CSS PIXELS.
*
* <p>While we usually use device pixels, @zoomToRect must be specified in CSS pixels.
*/
private boolean animatedZoomTo(RectF zoomToRect) {
setState(PanZoomState.ANIMATED_ZOOM);
final float startZoom = getMetrics().zoomFactor;
RectF viewport = getMetrics().getViewport();
// 1. adjust the aspect ratio of zoomToRect to match that of the current viewport,
// enlarging as necessary (if it gets too big, it will get shrunk in the next step).
// while enlarging make sure we enlarge equally on both sides to keep the target rect
// centered.
float targetRatio = viewport.width() / viewport.height();
float rectRatio = zoomToRect.width() / zoomToRect.height();
if (FloatUtils.fuzzyEquals(targetRatio, rectRatio)) {
// all good, do nothing
} else if (targetRatio < rectRatio) {
// need to increase zoomToRect height
float newHeight = zoomToRect.width() / targetRatio;
zoomToRect.top -= (newHeight - zoomToRect.height()) / 2;
zoomToRect.bottom = zoomToRect.top + newHeight;
} else { // targetRatio > rectRatio) {
// need to increase zoomToRect width
float newWidth = targetRatio * zoomToRect.height();
zoomToRect.left -= (newWidth - zoomToRect.width()) / 2;
zoomToRect.right = zoomToRect.left + newWidth;
}
float finalZoom = viewport.width() / zoomToRect.width();
ImmutableViewportMetrics finalMetrics = getMetrics();
finalMetrics =
finalMetrics.setViewportOrigin(
zoomToRect.left * finalMetrics.zoomFactor, zoomToRect.top * finalMetrics.zoomFactor);
finalMetrics = finalMetrics.scaleTo(finalZoom, new PointF(0.0f, 0.0f));
// 2. now run getValidViewportMetrics on it, so that the target viewport is
// clamped down to prevent overscroll, over-zoom, and other bad conditions.
finalMetrics = getValidViewportMetrics(finalMetrics);
bounce(finalMetrics);
return true;
}
private boolean onTouchEnd(MotionEvent event) {
switch (mState) {
case FLING:
case BOUNCE:
case WAITING_LISTENERS:
// should never happen
Log.e(LOGTAG, "Received impossible touch end while in " + mState);
// fall through
case ANIMATED_ZOOM:
case NOTHING:
// may happen if user double-taps and drags without lifting after the
// second tap. ignore if this happens.
return false;
case TOUCHING:
// the switch into TOUCHING might have happened while the page was
// snapping back after overscroll. we need to finish the snap if that
// was the case
bounce();
return false;
case PANNING:
case PANNING_LOCKED:
case PANNING_HOLD:
case PANNING_HOLD_LOCKED:
setState(PanZoomState.FLING);
fling();
return true;
case PINCHING:
setState(PanZoomState.NOTHING);
return true;
}
Log.e(LOGTAG, "Unhandled case " + mState + " in onTouchEnd");
return false;
}
/* Performs a bounce-back animation to the nearest valid viewport metrics. */
private void bounce() {
setState(PanZoomState.BOUNCE);
bounce(getValidViewportMetrics());
}
/** This function must be called from the UI thread. */
public void abortPanning() {
checkMainThread();
bounce();
}