Backed out changeset d55b7b5e620c (bug 1852513) for causing gradient-eval-* failures. CLOSED TREE

layout/painting/nsCSSRenderingGradients.cpp

@@ -37,8 +37,6 @@
 #include "mozilla/webrender/WebRenderAPI.h"
 #include "Units.h"
 
-#include "mozilla/StaticPrefs_layout.h"
-
 using namespace mozilla;
 using namespace mozilla::gfx;
 
@@ -1197,73 +1195,11 @@ void nsCSSGradientRenderer::BuildWebRenderParameters(
   aMode =
       mGradient->Repeating() ? wr::ExtendMode::Repeat : wr::ExtendMode::Clamp;
 
-  // If the interpolation space is not sRGB, or if color management is active,
-  // we need to add additional stops so that the sRGB interpolation in WebRender
-  // still closely approximates the correct curves.  We prefer avoiding this if
-  // the gradient is simple because WebRender has fast rendering of linear
-  // gradients with 2 stops (which represent >99% of all gradients on the web).
-  //
-  // WebRender doesn't have easy access to StyleAbsoluteColor and CMS display
-  // color correction, so we just expand the gradient stop table significantly
-  // so that gamma and hue interpolation errors become imperceptible.
-  //
-  // This always turns into 128 stops inside WebRender as an implementation
-  // detail, so the number of stops we generate here should have very little
-  // impact on performance as the texture upload is always the same, except for
-  // the special linear gradient 2-stop case.
-  //
-  // Color management bugs that this addresses:
-  // * https://bugzilla.mozilla.org/show_bug.cgi?id=939387
-  // * https://bugzilla.mozilla.org/show_bug.cgi?id=1248178
-  StyleColorInterpolationMethod styleColorInterpolationMethod =
-      mGradient->ColorInterpolationMethod();
-  if (mStops.Length() >= 2 &&
-      (styleColorInterpolationMethod.space != StyleColorSpace::Srgb ||
-       gfxPlatform::GetCMSMode() == CMSMode::All)) {
-    aStops.SetLengthAndRetainStorage(0);
-    // this could be made tunable, but at 1/32nd the error is very very small.
-    //
-    // note that we don't attempt to place the positions of these stops
-    // precisely at intervals, we just add this many extra stops across the
-    // range where it is convenient.
-    const int fullRangeExtraStops = 32;
-    // we always emit at least two stops (start and end) for each input stop,
-    // which avoids ambiguity with incomplete oklch/lch/hsv/hsb color stops for
-    // the last stop pair, where the last color stop can't be interpreted on its
-    // own because it actually depends on the previous stop.
-    aStops.SetLength(mStops.Length() * 2 + fullRangeExtraStops);
-    uint32_t outputStop = 0;
-    for (uint32_t i = 0; i < mStops.Length() - 1; i++) {
-      auto& start = mStops[i];
-      auto& end = i + 1 < mStops.Length() ? mStops[i + 1] : mStops[i];
-      StyleAbsoluteColor startColor = start.mColor;
-      StyleAbsoluteColor endColor = end.mColor;
-      int extraStops = (int)(floor(end.mPosition * fullRangeExtraStops) -
-                             floor(start.mPosition * fullRangeExtraStops));
-      extraStops = clamped(extraStops, 1, fullRangeExtraStops);
-      float step = 1.0f / (float)extraStops;
-      for (int extraStop = 0;
-           extraStop <= extraStops && outputStop < aStops.Capacity();
-           extraStop++) {
-        auto lerp = (float)extraStop * step;
-        auto position =
-            start.mPosition + lerp * (end.mPosition - start.mPosition);
-        StyleAbsoluteColor color = Servo_InterpolateColor(
-            styleColorInterpolationMethod, &endColor, &startColor, lerp);
-        aStops[outputStop].color = wr::ToColorF(ToDeviceColor(color));
-        aStops[outputStop].color.a *= aOpacity;
-        aStops[outputStop].offset = (float)position;
-        outputStop++;
-      }
-    }
-    aStops.SetLength(outputStop);
-  } else {
-    aStops.SetLength(mStops.Length());
-    for (uint32_t i = 0; i < mStops.Length(); i++) {
-      aStops[i].color = wr::ToColorF(ToDeviceColor(mStops[i].mColor));
-      aStops[i].color.a *= aOpacity;
-      aStops[i].offset = (float)mStops[i].mPosition;
-    }
+  aStops.SetLength(mStops.Length());
+  for (uint32_t i = 0; i < mStops.Length(); i++) {
+    aStops[i].color = wr::ToColorF(ToDeviceColor(mStops[i].mColor));
+    aStops[i].color.a *= aOpacity;
+    aStops[i].offset = mStops[i].mPosition;
   }
 
   aLineStart = LayoutDevicePoint(mLineStart.x, mLineStart.y);