Update to latest spec changes for ctx.font setter and getter. (Bug 508452) r=bzbarsky

content/canvas/src/nsCanvasRenderingContext2D.cpp

@@ -74,6 +74,7 @@
 
 #include "nsCSSParser.h"
 #include "nsICSSStyleRule.h"
+#include "mozilla/css/Declaration.h"
 #include "nsComputedDOMStyle.h"
 #include "nsStyleSet.h"
 
@@ -2307,6 +2308,23 @@ nsCanvasRenderingContext2D::SetFont(const nsAString& font)
     if (NS_FAILED(rv))
         return rv;
 
+    css::Declaration *declaration = rule->GetDeclaration();
+    // The easiest way to see whether we got a syntax error or whether
+    // we got 'inherit' or 'initial' is to look at font-size-adjust,
+    // which the shorthand resets to either 'none' or
+    // '-moz-system-font'.
+    // We know the declaration is not !important, so we can use
+    // GetNormalBlock().
+    const nsCSSValue *fsaVal =
+      declaration->GetNormalBlock()->
+        ValueStorageFor(eCSSProperty_font_size_adjust);
+    if (!fsaVal || (fsaVal->GetUnit() != eCSSUnit_None &&
+                    fsaVal->GetUnit() != eCSSUnit_System_Font)) {
+        // We got an all-property value or a syntax error.  The spec says
+        // this value must be ignored.
+        return NS_OK;
+    }
+
     rules.AppendObject(rule);
 
     nsStyleSet* styleSet = presShell->StyleSet();
@@ -2375,7 +2393,13 @@ nsCanvasRenderingContext2D::SetFont(const nsAString& font)
                                                     &style,
                                                     presShell->GetPresContext()->GetUserFontSet());
     NS_ASSERTION(CurrentState().fontGroup, "Could not get font group");
-    CurrentState().font = font;
+
+    // The font getter is required to be reserialized based on what we
+    // parsed (including having line-height removed).  (Older drafts of
+    // the spec required font sizes be converted to pixels, but that no
+    // longer seems to be required.)
+    declaration->GetValue(eCSSProperty_font, CurrentState().font);
+
     return NS_OK;
 }
 

content/canvas/test/test_canvas_font_setter.html

@@ -18,11 +18,51 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=
 var canvas = document.getElementById("display");
 var cx = canvas.getContext("2d");
 
+is(cx.font, "10px sans-serif", "initial font of canvas context");
+
 cx.font = "italic 16px sans-serif";
 is(cx.font, "italic 16px sans-serif", "valid font should round-trip");
 cx.font = "bold 12px serif; background: green";
 is(cx.font, "italic 16px sans-serif", "invalid font should be ignored");
 
+cx.font = "bold 12px/3.0 serif";
+is(cx.font, "bold 12px serif", "line-height should be dropped");
+cx.font = "inherit";
+is(cx.font, "bold 12px serif", "inherit should be ignored");
+cx.font = "boold 18px sans-serif";
+is(cx.font, "bold 12px serif", "syntax error should be ignored");
+cx.font = "menu";
+todo_is(cx.font, "menu", "system fonts should work");
+
+function textmeas() {
+  return cx.measureText("hello").width;
+}
+
+cx.font = "66px serif";
+var w_at_66 = textmeas();
+cx.font = "20px serif";
+var w_at_20 = textmeas();
+ok(w_at_66 > w_at_20, "text should be wider at 66px than at 20px");
+
+canvas.style.fontSize = "33px";
+cx.font = "2em serif";
+is(cx.font, "2em serif", "serialization of em");
+is(textmeas(), w_at_66, "em should be relative to canvas font size");
+canvas.style.fontSize = "16px";
+is(cx.font, "2em serif", "serialization of em");
+is(textmeas(), w_at_66,
+   "em should be relative to canvas font size at time of setting");
+document.body.removeChild(canvas);
+is(cx.font, "2em serif", "serialization of em");
+is(textmeas(), w_at_66,
+   "em should be relative to canvas font size at time of setting");
+canvas.style.fontSize = "33px";
+cx.font = "2em serif";
+is(cx.font, "2em serif", "serialization of em");
+is(textmeas(), w_at_20,
+   "em should be relative to 10px when canvas not in document");
+document.body.appendChild(canvas);
+
 </script>
 </pre>
 </body>