Bug 1283932 - support COLR table layers with unset color, r=jfkthame

gfx/thebes/gfxFont.cpp

@@ -1786,7 +1786,7 @@ gfxFont::DrawOneGlyph(uint32_t aGlyphID, double aAdvance, gfxPoint *aPt,
     }
 
     if (fontParams.haveColorGlyphs &&
-        RenderColorGlyph(runParams.dt,
+        RenderColorGlyph(runParams.dt, runParams.context,
                          fontParams.scaledFont, fontParams.renderingOptions,
                          fontParams.drawOptions,
                          fontParams.matInv * gfx::Point(devPt.x, devPt.y),
@@ -2170,6 +2170,7 @@ gfxFont::RenderSVGGlyph(gfxContext *aContext, gfxPoint aPoint,
 
 bool
 gfxFont::RenderColorGlyph(DrawTarget* aDrawTarget,
+                          gfxContext* aContext,
                           mozilla::gfx::ScaledFont* scaledFont,
                           GlyphRenderingOptions* aRenderingOptions,
                           mozilla::gfx::DrawOptions aDrawOptions,
@@ -2179,7 +2180,12 @@ gfxFont::RenderColorGlyph(DrawTarget* aDrawTarget,
     AutoTArray<uint16_t, 8> layerGlyphs;
     AutoTArray<mozilla::gfx::Color, 8> layerColors;
 
-    if (!GetFontEntry()->GetColorLayersInfo(aGlyphId, layerGlyphs, layerColors)) {
+    mozilla::gfx::Color defaultColor;
+    if (!aContext->GetDeviceColor(defaultColor)) {
+        defaultColor = mozilla::gfx::Color(0, 0, 0);
+    }
+    if (!GetFontEntry()->GetColorLayersInfo(aGlyphId, defaultColor,
+                                            layerGlyphs, layerColors)) {
         return false;
     }
 

gfx/thebes/gfxFont.h

@@ -2155,6 +2155,7 @@ protected:
                         bool& aEmittedGlyphs) const;
 
     bool RenderColorGlyph(DrawTarget* aDrawTarget,
+                          gfxContext* aContext,
                           mozilla::gfx::ScaledFont* scaledFont,
                           mozilla::gfx::GlyphRenderingOptions* renderingOptions,
                           mozilla::gfx::DrawOptions drawOptions,

gfx/thebes/gfxFontEntry.cpp

@@ -1062,12 +1062,14 @@ gfxFontEntry::SupportsGraphiteFeature(uint32_t aFeatureTag)
 
 bool
 gfxFontEntry::GetColorLayersInfo(uint32_t aGlyphId,
+                            const mozilla::gfx::Color& aDefaultColor,
                             nsTArray<uint16_t>& aLayerGlyphs,
                             nsTArray<mozilla::gfx::Color>& aLayerColors)
 {
     return gfxFontUtils::GetColorGlyphLayers(mCOLR,
                                              mCPAL,
                                              aGlyphId,
+                                             aDefaultColor,
                                              aLayerGlyphs,
                                              aLayerColors);
 }

gfx/thebes/gfxFontEntry.h

@@ -265,6 +265,7 @@ public:
 
     bool     TryGetColorGlyphs();
     bool     GetColorLayersInfo(uint32_t aGlyphId,
+                                const mozilla::gfx::Color& aDefaultColor,
                                 nsTArray<uint16_t>& layerGlyphs,
                                 nsTArray<mozilla::gfx::Color>& layerColors);
 

gfx/thebes/gfxFontUtils.cpp

@@ -1669,7 +1669,8 @@ gfxFontUtils::ValidateColorGlyphs(hb_blob_t* aCOLR, hb_blob_t* aCPAL)
             reinterpret_cast<const uint8_t*>(colr) + offsetLayerRecord);
 
     for (uint16_t i = 0; i < numLayerRecords; i++, layer++) {
-        if (uint16_t(layer->paletteEntryIndex) >= numPaletteEntries) {
+        if (uint16_t(layer->paletteEntryIndex) >= numPaletteEntries &&
+            uint16_t(layer->paletteEntryIndex) != 0xFFFF) {
             // CPAL palette entry record is overflow
             return false;
         }
@@ -1713,6 +1714,7 @@ bool
 gfxFontUtils::GetColorGlyphLayers(hb_blob_t* aCOLR,
                                   hb_blob_t* aCPAL,
                                   uint32_t aGlyphId,
+                                  const mozilla::gfx::Color& aDefaultColor,
                                   nsTArray<uint16_t>& aGlyphs,
                                   nsTArray<mozilla::gfx::Color>& aColors)
 {
@@ -1744,15 +1746,19 @@ gfxFontUtils::GetColorGlyphLayers(hb_blob_t* aCOLR,
 
     for (uint16_t layerIndex = 0; layerIndex < numLayers; layerIndex++) {
         aGlyphs.AppendElement(uint16_t(layer->glyphId));
-        const CPALColorRecord* color =
-            reinterpret_cast<const CPALColorRecord*>(
-                reinterpret_cast<const uint8_t*>(cpal) +
-                offsetFirstColorRecord +
-                sizeof(CPALColorRecord) * uint16_t(layer->paletteEntryIndex));
-        aColors.AppendElement(mozilla::gfx::Color(color->red / 255.0,
-                                                  color->green / 255.0,
-                                                  color->blue / 255.0,
-                                                  color->alpha / 255.0));
+        if (uint16_t(layer->paletteEntryIndex) == 0xFFFF) {
+            aColors.AppendElement(aDefaultColor);
+        } else {
+            const CPALColorRecord* color =
+                reinterpret_cast<const CPALColorRecord*>(
+                    reinterpret_cast<const uint8_t*>(cpal) +
+                    offsetFirstColorRecord +
+                    sizeof(CPALColorRecord) * uint16_t(layer->paletteEntryIndex));
+            aColors.AppendElement(mozilla::gfx::Color(color->red / 255.0,
+                                                      color->green / 255.0,
+                                                      color->blue / 255.0,
+                                                      color->alpha / 255.0));
+        }
         layer++;
     }
     return true;

gfx/thebes/gfxFontUtils.h

@@ -979,6 +979,7 @@ public:
     static bool GetColorGlyphLayers(hb_blob_t* aCOLR,
                                     hb_blob_t* aCPAL,
                                     uint32_t aGlyphId,
+                                    const mozilla::gfx::Color& aDefaultColor,
                                     nsTArray<uint16_t> &aGlyphs,
                                     nsTArray<mozilla::gfx::Color> &aColors);