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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.geckoview_example;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import androidx.core.view.NestedScrollingChild;
import androidx.core.view.NestedScrollingChildHelper;
import androidx.core.view.ViewCompat;
import org.mozilla.geckoview.GeckoView;
import org.mozilla.geckoview.PanZoomController;
/**
* GeckoView that supports nested scrolls (for using in a CoordinatorLayout).
*
* <p>This code is a simplified version of the NestedScrollView implementation which can be found in
* the support library: [android.support.v4.widget.NestedScrollView]
*
* <p>Based on: https://github.com/takahirom/webview-in-coordinatorlayout
*/
public class NestedGeckoView extends GeckoView implements NestedScrollingChild {
private int mLastY;
private final int[] mScrollOffset = new int[2];
private final int[] mScrollConsumed = new int[2];
private int mNestedOffsetY;
private NestedScrollingChildHelper mChildHelper;
/**
* Integer indicating how user's MotionEvent was handled.
*
* <p>There must be a 1-1 relation between this values and [EngineView.InputResult]'s.
*/
private int mInputResult = PanZoomController.INPUT_RESULT_UNHANDLED;
public NestedGeckoView(final Context context) {
this(context, null);
}
public NestedGeckoView(final Context context, final AttributeSet attrs) {
super(context, attrs);
mChildHelper = new NestedScrollingChildHelper(this);
setNestedScrollingEnabled(true);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
MotionEvent event = MotionEvent.obtain(ev);
final int action = event.getActionMasked();
int eventY = (int) event.getY();
switch (action) {
case MotionEvent.ACTION_MOVE:
final boolean allowScroll =
!shouldPinOnScreen() && mInputResult == PanZoomController.INPUT_RESULT_HANDLED;
int deltaY = mLastY - eventY;
if (allowScroll && dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) {
deltaY -= mScrollConsumed[1];
event.offsetLocation(0f, -mScrollOffset[1]);
mNestedOffsetY += mScrollOffset[1];
}
mLastY = eventY - mScrollOffset[1];
if (allowScroll && dispatchNestedScroll(0, mScrollOffset[1], 0, deltaY, mScrollOffset)) {
mLastY -= mScrollOffset[1];
event.offsetLocation(0f, mScrollOffset[1]);
mNestedOffsetY += mScrollOffset[1];
}
break;
case MotionEvent.ACTION_DOWN:
// A new gesture started. Reset handled status and ask GV if it can handle this.
mInputResult = PanZoomController.INPUT_RESULT_UNHANDLED;
updateInputResult(event);
mNestedOffsetY = 0;
mLastY = eventY;
// The event should be handled either by onTouchEvent,
// either by onTouchEventForResult, never by both.
// Early return if we sent it to updateInputResult(..) which calls onTouchEventForResult.
event.recycle();
return true;
// We don't care about other touch events
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
stopNestedScroll();
break;
}
// Execute event handler from parent class in all cases
final boolean eventHandled = callSuperOnTouchEvent(event);
// Recycle previously obtained event
event.recycle();
return eventHandled;
}
private boolean callSuperOnTouchEvent(MotionEvent event) {
return super.onTouchEvent(event);
}
private void updateInputResult(MotionEvent event) {
super.onTouchEventForDetailResult(event)
.accept(
inputResult -> {
mInputResult = inputResult.handledResult();
startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
});
}
public int getInputResult() {
return mInputResult;
}
@Override
public void setNestedScrollingEnabled(boolean enabled) {
mChildHelper.setNestedScrollingEnabled(enabled);
}
@Override
public boolean isNestedScrollingEnabled() {
return mChildHelper.isNestedScrollingEnabled();
}
@Override
public boolean startNestedScroll(int axes) {
return mChildHelper.startNestedScroll(axes);
}
@Override
public void stopNestedScroll() {
mChildHelper.stopNestedScroll();
}
@Override
public boolean hasNestedScrollingParent() {
return mChildHelper.hasNestedScrollingParent();
}
@Override
public boolean dispatchNestedScroll(
int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow) {
return mChildHelper.dispatchNestedScroll(
dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow);
}
@Override
public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
}
@Override
public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) {
return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed);
}
@Override
public boolean dispatchNestedPreFling(float velocityX, float velocityY) {
return mChildHelper.dispatchNestedPreFling(velocityX, velocityY);
}
}
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