Use a dst size threshold for multitexturing images.

TODO: Set thresholds based on GPU in use.

Change-Id: I0aeac596d11ab63922f2df0d76c668b4f8be5353
Reviewed-on: https://skia-review.googlesource.com/77900
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

2 files changed, 10 insertions, 5 deletions

diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index b19281b00d..86b27b066a 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -225,9 +225,6 @@ protected:
     // Vulkan doesn't support this (yet) and some drivers have issues, too
     bool fCrossContextTextureSupport                 : 1;
 
-    // Disables using multiple texture units to batch multiple SkImages at once.
-    bool fDisableImageMultitexturingSupport          : 1;
-
     InstancedSupport fInstancedSupport;
 
     BlendEquationSupport fBlendEquationSupport;
diff --git a/include/gpu/GrShaderCaps.h b/include/gpu/GrShaderCaps.h
index 4c847ac8b0..15377ff0b1 100644
--- a/include/gpu/GrShaderCaps.h
+++ b/include/gpu/GrShaderCaps.h
@@ -196,7 +196,14 @@ public:
 
     int maxCombinedSamplers() const { return fMaxCombinedSamplers; }
 
-    bool disableImageMultitexturingSupport() const { return fDisableImageMultitexturing; }
+    /**
+     * In general using multiple texture units for image rendering seems to be a win at smaller
+     * sizes of dst rects and a loss at larger sizes. Dst rects above this pixel area threshold will
+     * not use multitexturing.
+     */
+    size_t disableImageMultitexturingDstRectAreaThreshold() const {
+        return fDisableImageMultitexturingDstRectAreaThreshold;
+    }
 
     /**
      * Given a texture's config, this determines what swizzle must be appended to accesses to the
@@ -245,7 +252,6 @@ private:
     bool fVertexIDSupport : 1;
     bool fFloatIs32Bits : 1;
     bool fHalfIs32Bits : 1;
-    bool fDisableImageMultitexturing : 1;
 
     // Used for specific driver bug work arounds
     bool fCanUseMinAndAbsTogether : 1;
@@ -277,6 +283,8 @@ private:
     int fMaxFragmentSamplers;
     int fMaxCombinedSamplers;
 
+    size_t fDisableImageMultitexturingDstRectAreaThreshold;
+
     AdvBlendEqInteraction fAdvBlendEqInteraction;
 
     GrSwizzle fConfigTextureSwizzle[kGrPixelConfigCnt];