michael@0: var gWindowUtils;
michael@0: 
michael@0: try {
michael@0:   gWindowUtils = SpecialPowers.getDOMWindowUtils(window);
michael@0:   if (gWindowUtils && !gWindowUtils.compareCanvases)
michael@0:     gWindowUtils = null;
michael@0: } catch (e) {
michael@0:   gWindowUtils = null;
michael@0: }
michael@0: 
michael@0: function snapshotWindow(win, withCaret) {
michael@0:   return SpecialPowers.snapshotWindow(win, withCaret);
michael@0: }
michael@0: 
michael@0: // If the two snapshots don't compare as expected (true for equal, false for
michael@0: // unequal), returns their serializations as data URIs.  In all cases, returns
michael@0: // whether the comparison was as expected.
michael@0: function compareSnapshots(s1, s2, expected) {
michael@0:   var s1Str, s2Str;
michael@0:   var correct = false;
michael@0:   if (gWindowUtils) {
michael@0:     // First, check that the canvases are the same size.
michael@0:     var equal;
michael@0:     if (s1.width != s2.width || s1.height != s2.height) {
michael@0:       equal = false;
michael@0:     } else {
michael@0:       try {
michael@0:         equal = (gWindowUtils.compareCanvases(s1, s2, {}) == 0);
michael@0:       } catch (e) {
michael@0:         equal = false;
michael@0:         ok(false, "Exception thrown from compareCanvases: " + e);
michael@0:       }
michael@0:     }
michael@0:     correct = (equal == expected);
michael@0:   }
michael@0: 
michael@0:   if (!correct) {
michael@0:     s1Str = s1.toDataURL();
michael@0:     s2Str = s2.toDataURL();
michael@0: 
michael@0:     if (!gWindowUtils) {
michael@0: 	correct = ((s1Str == s2Str) == expected);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return [correct, s1Str, s2Str];
michael@0: }
michael@0: 
michael@0: function assertSnapshots(s1, s2, expected, s1name, s2name) {
michael@0:   var [correct, s1Str, s2Str] = compareSnapshots(s1, s2, expected);
michael@0:   var sym = expected ? "==" : "!=";
michael@0:   ok(correct, "reftest comparison: " + sym + " " + s1name + " " + s2name);
michael@0:   if (!correct) {
michael@0:     var report = "REFTEST TEST-UNEXPECTED-FAIL | " + s1name + " | image comparison (" + sym + ")\n";
michael@0:     if (expected) {
michael@0:       report += "REFTEST   IMAGE 1 (TEST): " + s1Str + "\n";
michael@0:       report += "REFTEST   IMAGE 2 (REFERENCE): " + s2Str + "\n";
michael@0:     } else {
michael@0:       report += "REFTEST   IMAGE: " + s1Str + "\n";
michael@0:     }
michael@0:     dump(report);
michael@0:   }
michael@0: }