Bug 1701749. When computing the double tap rect if there is a overflow rect that contains the bounding client rect use that. r=emilio

I'm not sure if this is better overall or not, it's better for the testcase in this bug (a div with a large amount of visible overflow). This code is a direct port of javascript code, so it only had the option of using getBoundingClientRect. Differential Revision: https://phabricator.services.mozilla.com/D110534
2021-04-12 07:45:08 +00:00 · 2021-04-12 07:45:08 +00:00 · ddd6cffdc0
--- a/gfx/layers/apz/test/mochitest/helper_doubletap_zoom_large_overflow.html
+++ b/gfx/layers/apz/test/mochitest/helper_doubletap_zoom_large_overflow.html
@ -0,0 +1,317 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=2100"/>
+  <title>Check that double tapping on overflow centers the zoom where we double tap</title>
+  <script type="application/javascript" src="apz_test_native_event_utils.js"></script>
+  <script type="application/javascript" src="apz_test_utils.js"></script>
+  <script src="/tests/SimpleTest/paint_listener.js"></script>
+  <script type="application/javascript">
+
+async function doubleTapOn(element, x, y) {
+  let useTouchpad = (location.search == "?touchpad");
+
+  let transformEndPromise = promiseTransformEnd();
+
+  if (useTouchpad) {
+    synthesizeNativeTouchpadDoubleTap(element, x, y);
+  } else {
+    synthesizeNativeTap(element, x, y);
+    synthesizeNativeTap(element, x, y);
+  }
+
+  // Wait for the APZ:TransformEnd to fire
+  await transformEndPromise;
+
+  // Flush state so we can query an accurate resolution
+  await promiseApzFlushedRepaints();
+}
+
+async function test() {
+  var resolution = getResolution();
+  ok(resolution > 0,
+     "The initial_resolution is " + resolution + ", which is some sane value");
+
+  // instant scroll to the bottom of the page
+  window.scrollTo({
+    top: 10000,
+    left: 0,
+    behavior: 'auto'
+  });
+
+  await promiseApzFlushedRepaints();
+
+  let scrollPos = window.scrollY;
+  ok(scrollPos > 1500, "window scrolled down");
+
+  info("window.scrollY " + window.scrollY);
+
+  info("window.innerHeight " + window.innerHeight);
+
+  info("document.documentElement.scrollHeight " + document.documentElement.scrollHeight);
+
+  let target = document.getElementById("target");
+
+  let x = 10;
+  let y = document.documentElement.scrollHeight - 60;
+
+  // Check that double-tapping once zooms in
+  await doubleTapOn(target, x, y);
+  var prev_resolution = resolution;
+  resolution = getResolution();
+  ok(resolution > prev_resolution, "The first double-tap has increased the resolution to " + resolution);
+
+  ok(window.scrollY > 1500, "window is still scrolled down");
+  ok(window.scrollY >= scrollPos-2, "window is still scrolled down");
+  info("window.scrollY " + window.scrollY);
+}
+
+waitUntilApzStable()
+.then(test)
+.then(subtestDone, subtestFailed);
+
+  </script>
+  <style>
+    .container {
+      background-color: #eee;
+      width: 200px;
+      height: 50px;
+      border: 1px dotted black;
+      overflow: visible;
+    }
+</style>
+</head>
+<body>
+
+<div id="target" class="container">
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+
+</div>
+
+</body>
+</html>
--- a/gfx/layers/apz/test/mochitest/test_group_double_tap_zoom.html
+++ b/gfx/layers/apz/test/mochitest/test_group_double_tap_zoom.html
@ -28,6 +28,7 @@ var subtests = [
  {"file": "helper_doubletap_zoom_textarea.html", "prefs": doubletap_prefs},
  {"file": "helper_doubletap_zoom_horizontal_center.html", "prefs": visualviewport_and_doubletap_prefs},
  {"file": "helper_doubletap_zoom_bug1702464.html", "prefs": visualviewport_and_doubletap_prefs},
+  {"file": "helper_doubletap_zoom_large_overflow.html", "prefs": doubletap_prefs},
 ];

 if (getPlatform() == "mac") {
@ -41,6 +42,7 @@ if (getPlatform() == "mac") {
    {"file": "helper_doubletap_zoom_bug1702464.html?touchpad", "prefs": visualviewport_and_doubletap_prefs},
    {"file": "helper_doubletap_zoom_htmlelement.html", "prefs": doubletap_prefs}, // scrollbars don't receive events or take space on android
    {"file": "helper_doubletap_zoom_htmlelement.html?touchpad", "prefs": doubletap_prefs},
+    {"file": "helper_doubletap_zoom_large_overflow.html?touchpad", "prefs": doubletap_prefs}
  );
 }

--- a/gfx/layers/apz/util/DoubleTapToZoom.cpp
+++ b/gfx/layers/apz/util/DoubleTapToZoom.cpp
@ -145,12 +145,37 @@ CSSRect CalculateRectToZoomTo(const RefPtr<dom::Document>& aRootContentDocument,
  CSSRect compositedArea(visualScrollOffset,
                         metrics.CalculateCompositedSizeInCssPixels());
  const CSSCoord margin = 15;
-  CSSRect rect =
-      nsLayoutUtils::GetBoundingContentRect(element, rootScrollFrame);
+  Maybe<CSSRect> nearestScrollClip;
+  CSSRect rect = nsLayoutUtils::GetBoundingContentRect(element, rootScrollFrame,
+                                                       &nearestScrollClip);

  CSSPoint point = CSSPoint::FromAppUnits(
      ViewportUtils::VisualToLayout(CSSPoint::ToAppUnits(aPoint), presShell));

+  CSSPoint documentRelativePoint =
+      point + CSSPoint::FromAppUnits(rootScrollFrame->GetScrollPosition());
+
+  // In some cases, like overflow: visible and overflowing content, the bounding
+  // client rect of the targeted element won't contain the point the user double
+  // tapped on. In that case we use the scrollable overflow rect if it contains
+  // the user point.
+  if (!rect.Contains(documentRelativePoint)) {
+    if (nsIFrame* scrolledFrame = rootScrollFrame->GetScrolledFrame()) {
+      if (nsIFrame* f = element->GetPrimaryFrame()) {
+        CSSRect overflowRect =
+            CSSRect::FromAppUnits(nsLayoutUtils::TransformFrameRectToAncestor(
+                f, f->ScrollableOverflowRect(),
+                RelativeTo{scrolledFrame, ViewportType::Layout}));
+        if (nearestScrollClip.isSome()) {
+          overflowRect = nearestScrollClip->Intersect(overflowRect);
+        }
+        if (overflowRect.Contains(documentRelativePoint)) {
+          rect = overflowRect;
+        }
+      }
+    }
+  }
+
  // If the element is taller than the visible area of the page scale
  // the height of the |rect| so that it has the same aspect ratio as
  // the root frame.  The clipped |rect| is centered on the y value of
@ -159,9 +184,7 @@ CSSRect CalculateRectToZoomTo(const RefPtr<dom::Document>& aRootContentDocument,
    const float widthRatio = rect.Width() / compositedArea.Width();
    float targetHeight = compositedArea.Height() * widthRatio;
    if (widthRatio < 0.9 && targetHeight < rect.Height()) {
-      const CSSPoint scrollPoint =
-          CSSPoint::FromAppUnits(rootScrollFrame->GetScrollPosition());
-      float newY = point.y + scrollPoint.y - (targetHeight * 0.5f);
+      float newY = documentRelativePoint.y - (targetHeight * 0.5f);
      if ((newY + targetHeight) > rect.YMost()) {
        rect.MoveByY(rect.Height() - targetHeight);
      } else if (newY > rect.Y()) {
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@ -8992,16 +8992,18 @@ nsBlockFrame* nsLayoutUtils::GetFloatContainingBlock(nsIFrame* aFrame) {
 // Element::GetBoundingClientRect().
 /* static */
 CSSRect nsLayoutUtils::GetBoundingContentRect(
-    const nsIContent* aContent, const nsIScrollableFrame* aRootScrollFrame) {
+    const nsIContent* aContent, const nsIScrollableFrame* aRootScrollFrame,
+    Maybe<CSSRect>* aOutNearestScrollClip) {
  if (nsIFrame* frame = aContent->GetPrimaryFrame()) {
-    return GetBoundingFrameRect(frame, aRootScrollFrame);
+    return GetBoundingFrameRect(frame, aRootScrollFrame, aOutNearestScrollClip);
  }
  return CSSRect();
 }

 /* static */
 CSSRect nsLayoutUtils::GetBoundingFrameRect(
-    nsIFrame* aFrame, const nsIScrollableFrame* aRootScrollFrame) {
+    nsIFrame* aFrame, const nsIScrollableFrame* aRootScrollFrame,
+    Maybe<CSSRect>* aOutNearestScrollClip) {
  CSSRect result;
  nsIFrame* relativeTo = aRootScrollFrame->GetScrolledFrame();
  result = CSSRect::FromAppUnits(nsLayoutUtils::GetAllInFlowRectsUnion(
@ -9021,6 +9023,10 @@ CSSRect nsLayoutUtils::GetBoundingFrameRect(
        CSSRect::FromAppUnits(nsLayoutUtils::TransformFrameRectToAncestor(
            subFrame, subFrame->GetRectRelativeToSelf(), relativeTo));

+    if (aOutNearestScrollClip) {
+      *aOutNearestScrollClip = Some(subFrameRect);
+    }
+
    result = subFrameRect.Intersect(result);
  }
  return result;
--- a/layout/base/nsLayoutUtils.h
+++ b/layout/base/nsLayoutUtils.h
@ -2802,15 +2802,21 @@ class nsLayoutUtils {
   * of the scrolled content of |aRootScrollFrame|.
   * Where the element is contained inside a scrollable subframe, the
   * bounding rect is clipped to the bounds of the subframe.
+   * If non-null aOutNearestScrollClip will be filled in with the rect of the
+   * nearest scroll frame (excluding aRootScrollFrame) that is an ancestor of
+   * the frame of aContent, if such exists, in the same coords are the returned
+   * rect. This rect is used to clip the result.
   */
  static CSSRect GetBoundingContentRect(
-      const nsIContent* aContent, const nsIScrollableFrame* aRootScrollFrame);
+      const nsIContent* aContent, const nsIScrollableFrame* aRootScrollFrame,
+      mozilla::Maybe<CSSRect>* aOutNearestScrollClip = nullptr);

  /**
   * Similar to GetBoundingContentRect for nsIFrame.
   */
  static CSSRect GetBoundingFrameRect(
-      nsIFrame* aFrame, const nsIScrollableFrame* aRootScrollFrame);
+      nsIFrame* aFrame, const nsIScrollableFrame* aRootScrollFrame,
+      mozilla::Maybe<CSSRect>* aOutNearestScrollClip = nullptr);

  /**
   * Returns the first ancestor who is a float containing block.