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📐 Calculate WebView screen coverage in onDraw.
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Instead of registering a PreDrawListener which causes some Android
overhead, we manually check for WebView screen coverage updates in the
WebView's onDraw method.

Change-Id: Ic35fd0987dbf2e7fb610fd47c7a4a97045932b9b
Bug: 1138032
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2825689
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Peter Conn <peconn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#875076}
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Peter E Conn authored and Chromium LUCI CQ committed Apr 22, 2021
1 parent b018eca commit 4afe929
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Showing 2 changed files with 95 additions and 34 deletions.
124 changes: 90 additions & 34 deletions android_webview/java/src/org/chromium/android_webview/AwContents.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,6 @@
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewStructure;
import android.view.ViewTreeObserver;
import android.view.accessibility.AccessibilityNodeProvider;
import android.view.animation.AnimationUtils;
import android.view.autofill.AutofillValue;
Expand Down Expand Up @@ -177,7 +176,7 @@ public class AwContents implements SmartClipProvider {
private static final Pattern sDataURLWithSelectorPattern =
Pattern.compile("^[^#]*(#[A-Za-z][A-Za-z0-9\\-_:.]*)$");

private static final HashMap<View, AwContents.AwOnPreDrawListener> sRootViewPreDrawListeners =
private static final HashMap<View, AwWindowCoverageTracker> sWindowCoverageTrackers =
new HashMap<>();

private static class ForceAuxiliaryBitmapRendering {
Expand Down Expand Up @@ -481,6 +480,10 @@ public abstract static class VisualStateCallback {
private final AwDisplayModeController mDisplayModeController;
private final Rect mCachedSafeAreaRect = new Rect();

// The current AwWindowCoverageTracker, if any. This will be non-null when the AwContents is
// attached to the Window and size tracking is enabled. It will be null otherwise.
private AwWindowCoverageTracker mAwWindowCoverageTracker;

private static class WebContentsInternalsHolder implements WebContents.InternalsHolder {
private final WeakReference<AwContents> mAwContentsRef;

Expand Down Expand Up @@ -850,35 +853,72 @@ public void onDIPScaleChanged(float dipScale) {
}
};

private static class AwOnPreDrawListener implements ViewTreeObserver.OnPreDrawListener {
private View mRootView;
private List<AwContents> mAwContentsList = new ArrayList<AwContents>();
private static class AwWindowCoverageTracker {
private static final long RECALCULATION_DELAY_MS = 200;

private final View mRootView;
private List<AwContents> mAwContentsList = new ArrayList<>();
private long mRecalculationTime;
private boolean mPendingRecalculation;

public AwOnPreDrawListener(View rootView) {
private AwWindowCoverageTracker(View rootView) {
mRootView = rootView;
}

public boolean trackContents(AwContents contents) {
contents.mAwWindowCoverageTracker = this;
return mAwContentsList.add(contents);
}

public boolean unTrackContents(AwContents contents) {
public boolean untrackContents(AwContents contents) {
contents.mAwWindowCoverageTracker = null;
return mAwContentsList.remove(contents);
}

public boolean isTracking() {
return mAwContentsList.size() > 0;
}

@Override
public boolean onPreDraw() {
if (TRACE) Log.i(TAG, "%s onPreDraw", this);
/**
* Notifies this object that a recalculation of the window coverage is necessary.
*
* This should be called every time any of the tracked AwContents changes its size or
* whether it is displaying open web contents (the result of a call to
* {@link AwContentsJni#isDisplayingOpenWebContent}).
*
* Recalculation won't happen immediately, and will be rate limited.
*/
public void onInputsUpdated() {
long time = SystemClock.uptimeMillis();

if (mPendingRecalculation) return;
mPendingRecalculation = true;

if (time > mRecalculationTime + RECALCULATION_DELAY_MS) {
// Enough time has elapsed since the last recalculation, run it now.
mRecalculationTime = time;
} else {
// Not enough time has elapsed, run it once enough time has elapsed.
mRecalculationTime += RECALCULATION_DELAY_MS;
}

PostTask.postDelayedTask(UiThreadTaskTraits.DEFAULT, () -> {
recalculate();
mPendingRecalculation = false;
}, mRecalculationTime - time);
}

private void recalculate() {
if (TRACE) Log.i(TAG, "%s onVisibilityRectUpdated", this);

List<Rect> openWebContentRects = new ArrayList<Rect>();
for (AwContents content : mAwContentsList) {
assert !content.isDestroyed(NO_WARN);
if (AwContentsJni.get().isDisplayingOpenWebContent(
content.mNativeAwContents, content)) {
openWebContentRects.add(content.getGlobalVisibleRect());
// The result of getGlobalVisibleRect can change underneath us, so take a
// protective copy.
openWebContentRects.add(RectUtils.copyRect(content.getGlobalVisibleRect()));
}
}

Expand All @@ -893,7 +933,6 @@ public boolean onPreDraw() {

AwContentsJni.get().updateOpenWebScreenArea(
openWebPixelCoverage, (int) openWebVisiblePercentage);
return true;
}
}

Expand Down Expand Up @@ -3005,41 +3044,40 @@ public void onAttachedToWindow() {
mWindowAndroid.getWindowAndroid().getDisplay().addObserver(mDisplayObserver);

if (AwFeatureList.isEnabled(AwFeatures.WEBVIEW_MEASURE_SCREEN_COVERAGE)) {
AwOnPreDrawListener listener = getOrCreateOnPreDrawListener(mContainerView);
listener.trackContents(this);
AwWindowCoverageTracker tracker = getOrCreateWindowCoverageTracker(mContainerView);
tracker.trackContents(this);
}

if (mDisplayCutoutController != null) mDisplayCutoutController.onAttachedToWindow();
}

private AwOnPreDrawListener getOrCreateOnPreDrawListener(ViewGroup viewGroup) {
AwOnPreDrawListener listener = null;
private AwWindowCoverageTracker getOrCreateWindowCoverageTracker(ViewGroup viewGroup) {
View rootView = viewGroup.getRootView();
if (!sRootViewPreDrawListeners.containsKey(rootView)) {
if (TRACE) Log.i(TAG, "%s installing OnPreDraw Listener for %s", this, rootView);
AwWindowCoverageTracker tracker = sWindowCoverageTrackers.get(rootView);

ViewTreeObserver viewTreeObserver = rootView.getViewTreeObserver();
listener = new AwOnPreDrawListener(rootView);
viewTreeObserver.addOnPreDrawListener(listener);
sRootViewPreDrawListeners.put(rootView, listener);
} else {
listener = sRootViewPreDrawListeners.get(rootView);
if (tracker == null) {
if (TRACE) Log.i(TAG, "%s creating WindowCoverageTracker for %s", this, rootView);

tracker = new AwWindowCoverageTracker(rootView);
sWindowCoverageTrackers.put(rootView, tracker);
}
return listener;

return tracker;
}

private void detachPreDrawListener() {
// Don't use getOrCreateOnPreDrawListener, if we have to create
private void detachWindowCoverageTracker() {
View rootView = mContainerView.getRootView();
// Don't use getOrCreateWindowCoverageTracker, if we have to create
// the listener at this point then something has gone wrong and
// we should fail rather than create a new one.
AwOnPreDrawListener listener = sRootViewPreDrawListeners.get(mContainerView.getRootView());
if (listener == null) return;
AwWindowCoverageTracker tracker = sWindowCoverageTrackers.get(rootView);
if (tracker == null) return;

listener.unTrackContents(this);
if (listener.isTracking()) return;
tracker.untrackContents(this);
if (tracker.isTracking()) return;

if (TRACE) Log.i(TAG, "%s removing " + listener, this);
sRootViewPreDrawListeners.remove(mContainerView.getRootView());
if (TRACE) Log.i(TAG, "%s removing " + tracker, this);
sWindowCoverageTrackers.remove(rootView);
}

/**
Expand All @@ -3050,7 +3088,7 @@ public void onDetachedFromWindow() {
if (TRACE) Log.i(TAG, "%s onDetachedFromWindow", this);

if (AwFeatureList.isEnabled(AwFeatures.WEBVIEW_MEASURE_SCREEN_COVERAGE)) {
detachPreDrawListener();
detachWindowCoverageTracker();
}
mWindowAndroid.getWindowAndroid().getDisplay().removeObserver(mDisplayObserver);
mAwViewMethods.onDetachedFromWindow();
Expand Down Expand Up @@ -3783,6 +3821,10 @@ private class AwViewMethodsImpl implements AwViewMethods {
// Only valid within software onDraw().
private final Rect mClipBoundsTemporary = new Rect();

// Variables that track the state as of the previous onDraw call.
private Rect mPreviousGlobalVisibleRect = new Rect();
private boolean mPreviouslyDisplayingWebContent;

@SuppressLint("DrawAllocation") // For new AwFunctor.
@Override
public void onDraw(Canvas canvas) {
Expand Down Expand Up @@ -3815,6 +3857,20 @@ public void onDraw(Canvas canvas) {
int scrollX = mContainerView.getScrollX();
int scrollY = mContainerView.getScrollY();
Rect globalVisibleRect = getGlobalVisibleRect();

if (mAwWindowCoverageTracker != null) {
boolean displayingWebContent = AwContentsJni.get().isDisplayingOpenWebContent(
mNativeAwContents, AwContents.this);

if (!globalVisibleRect.equals(mPreviousGlobalVisibleRect)
|| mPreviouslyDisplayingWebContent != displayingWebContent) {
mPreviousGlobalVisibleRect.set(globalVisibleRect);
mPreviouslyDisplayingWebContent = displayingWebContent;

mAwWindowCoverageTracker.onInputsUpdated();
}
}

// Workaround for bug in libhwui on N that does not swap if inserting functor is the
// only operation in a canvas. See crbug.com/704212.
if (Build.VERSION.SDK_INT == Build.VERSION_CODES.N
Expand Down
5 changes: 5 additions & 0 deletions android_webview/java/src/org/chromium/android_webview/gfx/RectUtils.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,11 @@ public static int getRectArea(Rect rect) {
return rect.width() * rect.height();
}

/** Creates a new {@link Rect} with the same bounds as the given {@link Rect}. */
public static Rect copyRect(Rect rect) {
return new Rect(rect.left, rect.top, rect.right, rect.bottom);
}

/**
* Segment Type Constants
*/
Expand Down

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