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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.internal.view;
import static android.util.MathUtils.constrain;
import static java.lang.Math.max;
import static java.lang.Math.min;
import android.annotation.NonNull;
import android.graphics.Rect;
import android.os.CancellationSignal;
import android.webkit.WebView;
import java.util.function.Consumer;
/**
* ScrollCapture for WebView.
*/
public class WebViewCaptureHelper implements ScrollCaptureViewHelper<WebView> {
private static final String TAG = "WebViewScrollCapture";
private final Rect mRequestWebViewLocal = new Rect();
private final Rect mWebViewBounds = new Rect();
private int mOriginScrollY;
private int mOriginScrollX;
@Override
public boolean onAcceptSession(@NonNull WebView view) {
return view.isVisibleToUser()
&& (view.getContentHeight() * view.getScale()) > view.getHeight();
}
@Override
public void onPrepareForStart(@NonNull WebView view, @NonNull Rect scrollBounds) {
mOriginScrollX = view.getScrollX();
mOriginScrollY = view.getScrollY();
}
@NonNull
@Override
public void onScrollRequested(@NonNull WebView view, @NonNull Rect scrollBounds,
@NonNull Rect requestRect, CancellationSignal cancellationSignal,
Consumer<ScrollResult> resultConsumer) {
int scrollDelta = view.getScrollY() - mOriginScrollY;
ScrollResult result = new ScrollResult();
result.requestedArea = new Rect(requestRect);
result.availableArea = new Rect();
result.scrollDelta = scrollDelta;
mWebViewBounds.set(0, 0, view.getWidth(), view.getHeight());
if (!view.isVisibleToUser()) {
resultConsumer.accept(result);
}
// Map the request into local coordinates
mRequestWebViewLocal.set(requestRect);
mRequestWebViewLocal.offset(0, -scrollDelta);
// Offset to center the rect vertically, clamp to available content
int upLimit = min(0, -view.getScrollY());
int contentHeightPx = (int) (view.getContentHeight() * view.getScale());
int downLimit = max(0, (contentHeightPx - view.getHeight()) - view.getScrollY());
int scrollToCenter = mRequestWebViewLocal.centerY() - mWebViewBounds.centerY();
int scrollMovement = constrain(scrollToCenter, upLimit, downLimit);
// Scroll and update relative based on the new position
view.scrollBy(mOriginScrollX, scrollMovement);
scrollDelta = view.getScrollY() - mOriginScrollY;
mRequestWebViewLocal.offset(0, -scrollMovement);
result.scrollDelta = scrollDelta;
if (mRequestWebViewLocal.intersect(mWebViewBounds)) {
result.availableArea = new Rect(mRequestWebViewLocal);
result.availableArea.offset(0, result.scrollDelta);
}
resultConsumer.accept(result);
}
@Override
public void onPrepareForEnd(@NonNull WebView view) {
view.scrollTo(mOriginScrollX, mOriginScrollY);
}
}
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