Bug 1477366 - Handle color space conversion for drop shadow filters with WebRender. r=mstange

Differential Revision: https://phabricator.services.mozilla.com/D17089

--HG--
extra : moz-landing-system : lando

gfx/src/FilterSupport.cpp

@@ -54,7 +54,7 @@ static const float glinearRGBTosRGBMap[256] = {
 
 // c = n / 255
 // c <= 0.04045f ? c / 12.92f : powf((c + 0.055f) / 1.055f, 2.4f)
-static const float gsRGBToLinearRGBMap[256] = {
+extern const float gsRGBToLinearRGBMap[256] = {
     0.000f, 0.000f, 0.001f, 0.001f, 0.001f, 0.002f, 0.002f, 0.002f, 0.002f,
     0.003f, 0.003f, 0.003f, 0.004f, 0.004f, 0.004f, 0.005f, 0.005f, 0.006f,
     0.006f, 0.007f, 0.007f, 0.007f, 0.008f, 0.009f, 0.009f, 0.010f, 0.010f,

gfx/src/FilterSupport.h

@@ -24,6 +24,8 @@ class FilterPrimitiveDescription;
 
 DECLARE_USE_COPY_CONSTRUCTORS(mozilla::gfx::FilterPrimitiveDescription)
 
+extern const float gsRGBToLinearRGBMap[256];
+
 namespace mozilla {
 namespace gfx {
 

layout/svg/nsFilterInstance.cpp

@@ -150,14 +150,14 @@ bool nsFilterInstance::BuildWebRenderFilters(nsIFrame* aFilteredFrame,
       return false;
     }
 
-    bool primIsSrgb = primitive.OutputColorSpace() == gfx::ColorSpace::SRGB;
-    if (srgb && !primIsSrgb) {
+    bool previousSrgb = srgb;
+    bool primNeedsSrgb = primitive.InputColorSpace(0) == gfx::ColorSpace::SRGB;
+    if (srgb && !primNeedsSrgb) {
       aWrFilters.AppendElement(wr::FilterOp::SrgbToLinear());
-      srgb = false;
-    } else if (!srgb && primIsSrgb) {
+    } else if (!srgb && primNeedsSrgb) {
       aWrFilters.AppendElement(wr::FilterOp::LinearToSrgb());
-      srgb = true;
     }
+    srgb = primitive.OutputColorSpace() == gfx::ColorSpace::SRGB;
 
     const PrimitiveAttributes& attr = primitive.Attributes();
 
@@ -237,8 +237,14 @@ bool nsFilterInstance::BuildWebRenderFilters(nsIFrame* aFilteredFrame,
       wr::LayoutVector2D offset = {(float)shadow.mOffset.x,
                                    (float)shadow.mOffset.y};
       float radius = stdDev.width;
-      wr::FilterOp filterOp =
-          wr::FilterOp::DropShadow(offset, radius, wr::ToColorF(shadow.mColor));
+      Color color = shadow.mColor;
+      if (!primNeedsSrgb) {
+        color = Color(gsRGBToLinearRGBMap[uint8_t(color.r * 255)],
+                      gsRGBToLinearRGBMap[uint8_t(color.g * 255)],
+                      gsRGBToLinearRGBMap[uint8_t(color.b * 255)], color.a);
+      }
+      wr::FilterOp filterOp = wr::FilterOp::DropShadow(
+          offset, radius, wr::ToColorF(ToDeviceColor(color)));
 
       aWrFilters.AppendElement(filterOp);
     } else {
@@ -256,7 +262,7 @@ bool nsFilterInstance::BuildWebRenderFilters(nsIFrame* aFilteredFrame,
       // sRGB->linear->no-op->sRGB roundtrip introduces a slight error and we
       // cannot add fuzziness to the test.
       Unused << aWrFilters.PopLastElement();
-      srgb = !srgb;
+      srgb = previousSrgb;
     }
 
     if (!filterIsNoop) {