Bug 1663475 - Paint caret geometry from the containing block. r=mats

This matches other browsers and shouldn't be too terrible, though I'm
not quite a fan of it.

Differential Revision: https://phabricator.services.mozilla.com/D89483

layout/base/nsCaret.cpp

@@ -19,6 +19,7 @@
 #include "nsIFrame.h"
 #include "nsIScrollableFrame.h"
 #include "nsIContent.h"
+#include "nsIFrameInlines.h"
 #include "nsLayoutUtils.h"
 #include "nsPresContext.h"
 #include "nsBlockFrame.h"
@@ -448,7 +449,27 @@ void nsCaret::CheckSelectionLanguageChange() {
   }
 }
 
-nsIFrame* nsCaret::GetPaintGeometry(nsRect* aRect) {
+// This ensures that the caret is not affected by clips on inlines and so forth.
+[[nodiscard]] static nsIFrame* MapToContainingBlock(nsIFrame* aFrame,
+                                                    nsRect* aCaretRect,
+                                                    nsRect* aHookRect) {
+  if (aFrame->IsBlockOutside() || aFrame->IsBlockFrameOrSubclass()) {
+    return aFrame;
+  }
+  nsIFrame* containingBlock = aFrame->GetContainingBlock();
+  if (!containingBlock) {
+    return aFrame;
+  }
+
+  *aCaretRect = nsLayoutUtils::TransformFrameRectToAncestor(aFrame, *aCaretRect,
+                                                            containingBlock);
+  *aHookRect = nsLayoutUtils::TransformFrameRectToAncestor(aFrame, *aHookRect,
+                                                           containingBlock);
+  return containingBlock;
+}
+
+nsIFrame* nsCaret::GetPaintGeometry(nsRect* aCaretRect, nsRect* aHookRect,
+                                    nscolor* aCaretColor) {
   // Return null if we should not be visible.
   if (!IsVisible() || !mIsBlinkOn) {
     return nullptr;
@@ -491,43 +512,44 @@ nsIFrame* nsCaret::GetPaintGeometry(nsRect* aRect) {
     return nullptr;
   }
 
+  if (aCaretColor) {
+    *aCaretColor = frame->GetCaretColorAt(frameOffset);
+  }
+
+  ComputeCaretRects(frame, frameOffset, aCaretRect, aHookRect);
+  return MapToContainingBlock(frame, aCaretRect, aHookRect);
+}
+
+nsIFrame* nsCaret::GetPaintGeometry(nsRect* aRect) {
   nsRect caretRect;
   nsRect hookRect;
-  ComputeCaretRects(frame, frameOffset, &caretRect, &hookRect);
-
+  nsIFrame* frame = GetPaintGeometry(&caretRect, &hookRect);
   aRect->UnionRect(caretRect, hookRect);
   return frame;
 }
 
-nsIFrame* nsCaret::GetFrame(int32_t* aContentOffset) {
-  return GetFrameAndOffset(GetSelection(), mOverrideContent, mOverrideOffset,
-                           aContentOffset);
-}
-
 void nsCaret::PaintCaret(DrawTarget& aDrawTarget, nsIFrame* aForFrame,
                          const nsPoint& aOffset) {
-  int32_t contentOffset;
-  nsIFrame* frame = GetFrame(&contentOffset);
+  nsRect caretRect;
+  nsRect hookRect;
+  nscolor color;
+  nsIFrame* frame = GetPaintGeometry(&caretRect, &hookRect, &color);
+  MOZ_ASSERT(frame == aForFrame, "We're referring different frame");
+
   if (!frame) {
     return;
   }
-  NS_ASSERTION(frame == aForFrame, "We're referring different frame");
 
   int32_t appUnitsPerDevPixel = frame->PresContext()->AppUnitsPerDevPixel();
-
-  nsRect caretRect;
-  nsRect hookRect;
-  ComputeCaretRects(frame, contentOffset, &caretRect, &hookRect);
-
   Rect devPxCaretRect = NSRectToSnappedRect(caretRect + aOffset,
                                             appUnitsPerDevPixel, aDrawTarget);
   Rect devPxHookRect =
       NSRectToSnappedRect(hookRect + aOffset, appUnitsPerDevPixel, aDrawTarget);
-  ColorPattern color(ToDeviceColor(frame->GetCaretColorAt(contentOffset)));
 
-  aDrawTarget.FillRect(devPxCaretRect, color);
+  ColorPattern pattern(ToDeviceColor(color));
+  aDrawTarget.FillRect(devPxCaretRect, pattern);
   if (!hookRect.IsEmpty()) {
-    aDrawTarget.FillRect(devPxHookRect, color);
+    aDrawTarget.FillRect(devPxHookRect, pattern);
   }
 }
 

layout/base/nsCaret.h

@@ -143,6 +143,12 @@ class nsCaret final : public nsISelectionListener {
    * off).
    */
   nsIFrame* GetPaintGeometry(nsRect* aRect);
+  /**
+   * Same as the overload above, but returns the caret and hook rects
+   * separately, and also computes the color if requested.
+   */
+  nsIFrame* GetPaintGeometry(nsRect* aCaretRect, nsRect* aHookRect,
+                             nscolor* aCaretColor = nullptr);
   /**
    * A simple wrapper around GetGeometry. Does not take any caret state into
    * account other than the current selection.
@@ -194,10 +200,6 @@ class nsCaret final : public nsISelectionListener {
 
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 
-  nsIFrame* GetFrame(int32_t* aContentOffset);
-  void ComputeCaretRects(nsIFrame* aFrame, int32_t aFrameOffset,
-                         nsRect* aCaretRect, nsRect* aHookRect);
-
  protected:
   static void CaretBlinkCallback(nsITimer* aTimer, void* aClosure);
 
@@ -212,6 +214,8 @@ class nsCaret final : public nsISelectionListener {
   };
   static Metrics ComputeMetrics(nsIFrame* aFrame, int32_t aOffset,
                                 nscoord aCaretHeight);
+  void ComputeCaretRects(nsIFrame* aFrame, int32_t aFrameOffset,
+                         nsRect* aCaretRect, nsRect* aHookRect);
 
   // Returns true if we should not draw the caret because of XUL menu popups.
   // The caret should be hidden if:

layout/base/tests/bug1663475-1-ref.html

@@ -0,0 +1,28 @@
+<!doctype html>
+<html class="reftest-wait">
+<title>Caret is correctly painted over inline with clip</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<style>
+  div {
+    font: 16px/1 monospace;
+    outline: 2px solid blue;
+    caret-color: black;
+  }
+  span {
+    color: transparent;
+  }
+</style>
+<div contenteditable spellcheck="no">
+  <span>ab</span>c<span>de</span>
+</div>
+<script>
+SimpleTest.waitForFocus(function() {
+  document.querySelector('[contenteditable]').focus();
+  requestAnimationFrame(function() {
+    // Position the caret between "a" and "b".
+    synthesizeKey("KEY_ArrowRight");
+    document.documentElement.removeAttribute("class");
+  });
+});
+</script>

layout/base/tests/bug1663475-1.html

@@ -0,0 +1,32 @@
+<!doctype html>
+<html class="reftest-wait">
+<title>Caret is correctly painted over inline with clip</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<style>
+  div {
+    font: 16px/1 monospace;
+    caret-color: black;
+  }
+  div:focus {
+    outline: 2px solid blue;
+  }
+  span {
+    /* This should only leave the "c" letter visible, but the caret should
+       still be visible when between "a" and "b" */
+    clip-path: inset(0 2ch);
+  }
+</style>
+<div contenteditable spellcheck="no">
+  <span>abcde</span>
+</div>
+<script>
+SimpleTest.waitForFocus(function() {
+  document.querySelector('[contenteditable]').focus();
+  requestAnimationFrame(function() {
+    // Position the caret between "a" and "b".
+    synthesizeKey("KEY_ArrowRight");
+    document.documentElement.removeAttribute("class");
+  });
+});
+</script>

layout/base/tests/bug1663475-2-ref.html

@@ -0,0 +1,29 @@
+<!doctype html>
+<html class="reftest-wait">
+<title>Caret is correctly painted over inline with clip</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<style>
+  span[contenteditable] {
+    font: 16px/1 monospace;
+    caret-color: black;
+    display: inline-block;
+    outline: 2px solid blue;
+  }
+  span > span {
+    color: transparent;
+  }
+</style>
+<span contenteditable spellcheck="no">
+  <span>ab</span>c<span>de</span>
+</span>
+<script>
+SimpleTest.waitForFocus(function() {
+  document.querySelector('[contenteditable]').focus();
+  requestAnimationFrame(function() {
+    // Position the caret between "a" and "b".
+    synthesizeKey("KEY_ArrowRight");
+    document.documentElement.removeAttribute("class");
+  });
+});
+</script>

layout/base/tests/bug1663475-2.html

@@ -0,0 +1,33 @@
+<!doctype html>
+<html class="reftest-wait">
+<title>Caret is correctly painted over inline with clip</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<style>
+  span[contenteditable] {
+    font: 16px/1 monospace;
+    caret-color: black;
+    display: inline-block;
+  }
+  span[contenteditable]:focus {
+    outline: 2px solid blue;
+  }
+  span > span {
+    /* This should only leave the "c" letter visible, but the caret should
+       still be visible when between "a" and "b" */
+    clip-path: inset(0 2ch);
+  }
+</style>
+<span contenteditable spellcheck="no">
+  <span>abcde</span>
+</span>
+<script>
+SimpleTest.waitForFocus(function() {
+  document.querySelector('[contenteditable]').focus();
+  requestAnimationFrame(function() {
+    // Position the caret between "a" and "b".
+    synthesizeKey("KEY_ArrowRight");
+    document.documentElement.removeAttribute("class");
+  });
+});
+</script>

layout/base/tests/mochitest.ini

@@ -375,6 +375,10 @@ support-files =
   bug1637476-2-ref.html
   bug1637476-3.html
   bug1637476-3-ref.html
+  bug1663475-1.html
+  bug1663475-1-ref.html
+  bug1663475-2.html
+  bug1663475-2-ref.html
   image_rgrg-256x256.png
   input-invalid-ref.html
   input-maxlength-invalid-change.html

layout/base/tests/test_reftests_with_caret.html

@@ -274,6 +274,8 @@ var tests = [
     [ 'bug1637476-1.html' , 'bug1637476-1-ref.html' ] ,
     [ 'bug1637476-2.html' , 'bug1637476-2-ref.html' ] ,
     [ 'bug1637476-3.html' , 'bug1637476-3-ref.html' ] ,
+    [ 'bug1663475-1.html' , 'bug1663475-1-ref.html' ] ,
+    [ 'bug1663475-2.html' , 'bug1663475-2-ref.html' ] ,
     function() {SpecialPowers.pushPrefEnv({'clear': [['layout.accessiblecaret.enabled_on_touch']]}, nextTest);} ,
     function() {SpecialPowers.pushPrefEnv({'set': [['accessibility.browsewithcaret', true]]}, nextTest);} ,
     [ 'bug1529492-1.html' , 'bug1529492-1-ref.html' ] ,

layout/painting/nsDisplayList.cpp

@@ -4935,20 +4935,18 @@ bool nsDisplayCaret::CreateWebRenderCommands(
     mozilla::layers::RenderRootStateManager* aManager,
     nsDisplayListBuilder* aDisplayListBuilder) {
   using namespace mozilla::layers;
-  int32_t contentOffset;
-  nsIFrame* frame = mCaret->GetFrame(&contentOffset);
+  nsRect caretRect;
+  nsRect hookRect;
+  nscolor caretColor;
+  nsIFrame* frame =
+      mCaret->GetPaintGeometry(&caretRect, &hookRect, &caretColor);
+  MOZ_ASSERT(frame == mFrame, "We're referring different frame");
   if (!frame) {
     return true;
   }
-  NS_ASSERTION(frame == mFrame, "We're referring different frame");
 
   int32_t appUnitsPerDevPixel = frame->PresContext()->AppUnitsPerDevPixel();
-
-  nsRect caretRect;
-  nsRect hookRect;
-  mCaret->ComputeCaretRects(frame, contentOffset, &caretRect, &hookRect);
-
-  gfx::DeviceColor color = ToDeviceColor(frame->GetCaretColorAt(contentOffset));
+  gfx::DeviceColor color = ToDeviceColor(caretColor);
   LayoutDeviceRect devCaretRect = LayoutDeviceRect::FromAppUnits(
       caretRect + ToReferenceFrame(), appUnitsPerDevPixel);
   LayoutDeviceRect devHookRect = LayoutDeviceRect::FromAppUnits(