Bug 1778910 - Hook up rendering support for canvas2d fontVariantCaps,…

… and add WPT reftests. r=gfx-reviewers,lsalzman

The behavior in some of these cases is open to debate, as the spec is quite unclear;
see whatwg/html#8103. What I've implemented here gives the
same rendering result as Chrome for these tests, so hopefully we can get this clarified
in the spec as well.

Differential Revision: https://phabricator.services.mozilla.com/D182567

dom/canvas/CanvasRenderingContext2D.cpp

@@ -3693,6 +3693,10 @@ void CanvasRenderingContext2D::SetFont(const nsACString& aFont,
     return;
   }
 
+  // Setting the font attribute magically resets fontVariantCaps to normal.
+  // (spec unclear, cf. https://github.com/whatwg/html/issues/8103)
+  SetFontVariantCaps(CanvasFontVariantCaps::Normal);
+
   // If letterSpacing or wordSpacing is present, recompute to account for
   // changes to font-relative dimensions.
   UpdateSpacing();
@@ -3752,6 +3756,38 @@ bool CanvasRenderingContext2D::SetFontInternal(const nsACString& aFont,
 
   resizedFont.kerning = CanvasToGfx(CurrentState().fontKerning);
 
+  // fontVariantCaps handling: if fontVariantCaps is not 'normal', apply it;
+  // if it is, then use the smallCaps boolean from the shorthand.
+  // XXX(jfkthame) The interaction between the shorthand and the separate attr
+  // here is not clearly spec'd, and we may want to reconsider it (or revise
+  // the available values); see https://github.com/whatwg/html/issues/8103.
+  switch (CurrentState().fontVariantCaps) {
+    case CanvasFontVariantCaps::Normal:
+      // Leave whatever the shorthand set.
+      break;
+    case CanvasFontVariantCaps::Small_caps:
+      resizedFont.variantCaps = NS_FONT_VARIANT_CAPS_SMALLCAPS;
+      break;
+    case CanvasFontVariantCaps::All_small_caps:
+      resizedFont.variantCaps = NS_FONT_VARIANT_CAPS_ALLSMALL;
+      break;
+    case CanvasFontVariantCaps::Petite_caps:
+      resizedFont.variantCaps = NS_FONT_VARIANT_CAPS_PETITECAPS;
+      break;
+    case CanvasFontVariantCaps::All_petite_caps:
+      resizedFont.variantCaps = NS_FONT_VARIANT_CAPS_ALLPETITE;
+      break;
+    case CanvasFontVariantCaps::Unicase:
+      resizedFont.variantCaps = NS_FONT_VARIANT_CAPS_UNICASE;
+      break;
+    case CanvasFontVariantCaps::Titling_caps:
+      resizedFont.variantCaps = NS_FONT_VARIANT_CAPS_TITLING;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("unknown caps value");
+      break;
+  }
+
   c->Document()->FlushUserFontSet();
 
   nsFontMetrics::Params params;
@@ -3857,8 +3893,42 @@ bool CanvasRenderingContext2D::SetFontInternalDisconnected(
   }
 
   fontStyle.size = QuantizeFontSize(size);
-  fontStyle.variantCaps =
-      smallCaps ? NS_FONT_VARIANT_CAPS_SMALLCAPS : NS_FONT_VARIANT_CAPS_NORMAL;
+
+  // fontVariantCaps handling: if fontVariantCaps is not 'normal', apply it;
+  // if it is, then use the smallCaps boolean from the shorthand.
+  // XXX(jfkthame) The interaction between the shorthand and the separate attr
+  // here is not clearly spec'd, and we may want to reconsider it (or revise
+  // the available values); see https://github.com/whatwg/html/issues/8103.
+  switch (CurrentState().fontVariantCaps) {
+    case CanvasFontVariantCaps::Normal:
+      fontStyle.variantCaps = smallCaps ? NS_FONT_VARIANT_CAPS_SMALLCAPS
+                                        : NS_FONT_VARIANT_CAPS_NORMAL;
+      break;
+    case CanvasFontVariantCaps::Small_caps:
+      fontStyle.variantCaps = NS_FONT_VARIANT_CAPS_SMALLCAPS;
+      break;
+    case CanvasFontVariantCaps::All_small_caps:
+      fontStyle.variantCaps = NS_FONT_VARIANT_CAPS_ALLSMALL;
+      break;
+    case CanvasFontVariantCaps::Petite_caps:
+      fontStyle.variantCaps = NS_FONT_VARIANT_CAPS_PETITECAPS;
+      break;
+    case CanvasFontVariantCaps::All_petite_caps:
+      fontStyle.variantCaps = NS_FONT_VARIANT_CAPS_ALLPETITE;
+      break;
+    case CanvasFontVariantCaps::Unicase:
+      fontStyle.variantCaps = NS_FONT_VARIANT_CAPS_UNICASE;
+      break;
+    case CanvasFontVariantCaps::Titling_caps:
+      fontStyle.variantCaps = NS_FONT_VARIANT_CAPS_TITLING;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("unknown caps value");
+      break;
+  }
+  // If variantCaps is set, we need to disable a gfxFont fast-path.
+  fontStyle.noFallbackVariantFeatures =
+      (fontStyle.variantCaps == NS_FONT_VARIANT_CAPS_NORMAL);
 
   // Set the kerning feature, if required by the fontKerning attribute.
   gfxFontFeature setting{TRUETYPE_TAG('k', 'e', 'r', 'n'), 0};
@@ -3907,6 +3977,7 @@ bool CanvasRenderingContext2D::SetFontInternalDisconnected(
   SerializeFontForCanvas(list, fontStyle, CurrentState().font);
   CurrentState().fontFont = nsFont(StyleFontFamily{list, false, false},
                                    StyleCSSPixelLength::FromPixels(size));
+  CurrentState().fontFont.variantCaps = fontStyle.variantCaps;
   CurrentState().fontLanguage = nullptr;
   CurrentState().fontExplicitLanguage = false;
   return true;

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/fontVariantCaps-1.html

@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas Test: the 'fontVariantCaps' property</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-fontvariantcaps">
+<link rel="match" href="reference/fontVariantCaps-1-ref.html">
+<meta name="assert" content="text rendering respects the fontVariantCaps property">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "32px serif";
+ctx.fontVariantCaps = "small-caps";
+// This should render the same as font = "small-caps 32px serif".
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/fontVariantCaps-2.html

@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas Test: the 'fontVariantCaps' property</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-fontvariantcaps">
+<link rel="mismatch" href="reference/fontVariantCaps-2-ref.html">
+<meta name="assert" content="text rendering respects the fontVariantCaps property">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "small-caps 32px serif";
+// "mismatch" test, to verify that small-caps does change the rendering.
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/fontVariantCaps-3.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas Test: the 'fontVariantCaps' property</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-fontvariantcaps">
+<link rel="match" href="reference/fontVariantCaps-3-ref.html">
+<meta name="assert" content="text rendering respects the fontVariantCaps property">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "32px serif";
+ctx.fontVariantCaps = "all-small-caps";
+// This should render the same as using font = "small-caps 32px serif"
+// with all the underlying text in lowercase.
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/fontVariantCaps-4.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas Test: the 'fontVariantCaps' property</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-fontvariantcaps">
+<link rel="match" href="reference/fontVariantCaps-3-ref.html">
+<meta name="assert" content="text rendering respects the fontVariantCaps property">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "small-caps 32px serif";
+// fontVariantCaps overrides the small-caps setting from the font attribute
+// (spec unclear, cf. https://github.com/whatwg/html/issues/8103)
+ctx.fontVariantCaps = "all-small-caps";
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/fontVariantCaps-5.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas Test: the 'fontVariantCaps' property</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-fontvariantcaps">
+<link rel="match" href="reference/fontVariantCaps-1-ref.html">
+<meta name="assert" content="text rendering respects the fontVariantCaps property">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "small-caps 32px serif";
+// fontVariantCaps 'normal' does not override the setting from the font attribute.
+// (spec unclear, cf. https://github.com/whatwg/html/issues/8103)
+ctx.fontVariantCaps = "normal";
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/fontVariantCaps-6.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas Test: the 'fontVariantCaps' property</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-fontvariantcaps">
+<link rel="match" href="reference/fontVariantCaps-2-ref.html">
+<meta name="assert" content="text rendering respects the fontVariantCaps property">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+// fontVariantCaps is reset when the font attribute is set.
+// (spec unclear, cf. https://github.com/whatwg/html/issues/8103)
+ctx.fontVariantCaps = "all-small-caps";
+ctx.font = "32px serif";
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/reference/fontVariantCaps-1-ref.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas reference</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "small-caps 32px serif";
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/reference/fontVariantCaps-2-ref.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas reference</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "32px serif";
+ctx.fillText("Hello World", 20, 100);
+</script>

testing/web-platform/tests/html/canvas/element/drawing-text-to-the-canvas/reference/fontVariantCaps-3-ref.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Canvas reference</title>
+<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
+
+<canvas id="c"></canvas>
+
+<script>
+let ctx = c.getContext("2d");
+ctx.font = "small-caps 32px serif";
+ctx.fillText("hello world", 20, 100);
+</script>