CanvasRenderingContext2D should update font on demand

CanvasRenderingContext2D stores a font to draw text, but doesn't always update it when the document's font cache is invalidated. In particular, it's not notified when @font-face rules are added or removed. This patch makes CanvasRenderingContext2D to ensure font validity when using the font, by updating the font if it's invalid. Bug: 1051715 Change-Id: I29d89a897b9ccaf14848dab0f33b115f4b3eee0c Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2053508Reviewed-by: Fernando Serboncini <fserb@chromium.org> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org> Cr-Commit-Position: refs/heads/master@{#744363}

CanvasRenderingContext2D should update font on demand
CanvasRenderingContext2D stores a font to draw text, but doesn't always update it when the document's font cache is invalidated. In particular, it's not notified when @font-face rules are added or removed. This patch makes CanvasRenderingContext2D to ensure font validity when using the font, by updating the font if it's invalid. Bug: 1051715 Change-Id: I29d89a897b9ccaf14848dab0f33b115f4b3eee0c Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2053508Reviewed-by: Fernando Serboncini <fserb@chromium.org> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org> Cr-Commit-Position: refs/heads/master@{#744363}
8eafe392 · Xiaocheng Hu · Commit Bot · ee16e6cf · 8eafe392 · 8eafe392
Commit 8eafe392 authored Feb 25, 2020 by Xiaocheng Hu Committed by Commit Bot Feb 25, 2020
5 changed files
--- a/third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d.cc
+++ b/third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d.cc
@@ -459,8 +459,7 @@ String CanvasRenderingContext2D::font() const {

  canvas()->GetDocument().GetCanvasFontCache()->WillUseCurrentFont();
  StringBuilder serialized_font;
-  const FontDescription& font_description =
-      GetState().GetFont().GetFontDescription();
+  const FontDescription& font_description = GetState().GetFontDescription();

  if (font_description.Style() == ItalicSlopeValue())
    serialized_font.Append("italic ");
@@ -933,7 +932,7 @@ const Font& CanvasRenderingContext2D::AccessFont() {
  if (!GetState().HasRealizedFont())
    setFont(GetState().UnparsedFont());
  canvas()->GetDocument().GetCanvasFontCache()->WillUseCurrentFont();
-  return GetState().GetFont();
+  return ModifiableState().GetFont();
 }

 void CanvasRenderingContext2D::SetIsInHiddenPage(bool hidden) {

--- a/third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d_state.cc
+++ b/third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d_state.cc
@@ -262,11 +262,19 @@ void CanvasRenderingContext2DState::SetFont(const Font& font,
    selector->RegisterForInvalidationCallbacks(this);
 }

-const Font& CanvasRenderingContext2DState::GetFont() const {
+const Font& CanvasRenderingContext2DState::GetFont() {
  DCHECK(realized_font_);
+  if (!font_.IsFallbackValid())
+    FontsNeedUpdate(font_.GetFontSelector());
  return font_;
 }

+const FontDescription& CanvasRenderingContext2DState::GetFontDescription()
+    const {
+  DCHECK(realized_font_);
+  return font_.GetFontDescription();
+}
+
 void CanvasRenderingContext2DState::SetTransform(
    const AffineTransform& transform) {
  is_transform_invertible_ = transform.IsInvertible();

--- a/third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d_state.h
+++ b/third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d_state.h
@@ -79,7 +79,8 @@ class CanvasRenderingContext2DState final
  }

  void SetFont(const Font&, FontSelector*);
-  const Font& GetFont() const;
+  const Font& GetFont();
+  const FontDescription& GetFontDescription() const;
  bool HasRealizedFont() const { return realized_font_; }
  void SetUnparsedFont(const String& font) { unparsed_font_ = font; }
  const String& UnparsedFont() const { return unparsed_font_; }

--- a/third_party/blink/renderer/modules/canvas/offscreencanvas2d/offscreen_canvas_rendering_context_2d.cc
+++ b/third_party/blink/renderer/modules/canvas/offscreencanvas2d/offscreen_canvas_rendering_context_2d.cc
@@ -355,8 +355,7 @@ String OffscreenCanvasRenderingContext2D::font() const {
    return kDefaultFont;

  StringBuilder serialized_font;
-  const FontDescription& font_description =
-      GetState().GetFont().GetFontDescription();
+  const FontDescription& font_description = GetState().GetFontDescription();

  if (font_description.Style() == ItalicSlopeValue())
    serialized_font.Append("italic ");
@@ -606,7 +605,7 @@ TextMetrics* OffscreenCanvasRenderingContext2D::measureText(
 const Font& OffscreenCanvasRenderingContext2D::AccessFont() {
  if (!GetState().HasRealizedFont())
    setFont(GetState().UnparsedFont());
-  return GetState().GetFont();
+  return ModifiableState().GetFont();
 }

 bool OffscreenCanvasRenderingContext2D::IsCanvas2DBufferValid() const {

--- a/third_party/blink/web_tests/fast/canvas/canvas-fillText-font-change-crash.html
+++ b/third_party/blink/web_tests/fast/canvas/canvas-fillText-font-change-crash.html
+<!DOCTYPE html>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<canvas id="target"></canvas>
+<script>
+// https://crbug.com/1051715
+test(() => {
+  const ctx = document.getElementById('target').getContext('2d');
+  ctx.font = '25px custom-font';
+
+  const style = document.createElement('style');
+  style.textContent = '@font-face { font-family: custom-font; src: url(fake-font.woff); }';
+  document.body.appendChild(style);
+
+  ctx.fillText('foo', 0, 0);
+
+  // This is a crash test. Nothing to assert.
+}, '@font-face rule changes should not lead to canvas crash');
+</script>