commit 76d84aec28a1d00fe8807803e842bf17282814f3
author Nader Jawad <njawad@google.com> Thu May 13 20:43:18 2021 -0700
committer Nader Jawad <njawad@google.com> Thu May 13 20:43:18 2021 -0700
tree c506718f90b76ac894c528893a85de6ba20d26d4
parent 91a55b613d572497a660fb3303a6326d1844cd02

Improve Stretch shader performance more

Refactor stretch shader to always work in
skia's coordinate system instead of normalizing
the input coordinates.
Improves performance on coral by approximately 10-20% across
various use cases on top of the branching refactoring
perf improvements
~1k fps to ~1.1k fps on non-surfaceview cases
~500 fps to ~600 fps o surfaceview cases

Bug: 187718492
Test: manual
Change-Id: I0b36f48699739979948bfec160a8aa64fc80b7a7

libs/hwui/effects/StretchEffect.cpp

diff --git a/libs/hwui/effects/StretchEffect.cpp b/libs/hwui/effects/StretchEffect.cpp
index df480af..807fb75 100644
--- a/libs/hwui/effects/StretchEffect.cpp
+++ b/libs/hwui/effects/StretchEffect.cpp
@@ -94,13 +94,14 @@
         float uStretchAffectedDist,
         float uInverseStretchAffectedDist,
         float distanceStretched,
-        float interpolationStrength
+        float interpolationStrength,
+        float viewportDimension
     ) {
         float offsetPos = inPos - reverseStretchDist;
         float posBasedVariation = mix(
                 1. ,easeIn(offsetPos, uInverseStretchAffectedDist), interpolationStrength);
         float stretchIntensity = (-overscroll) * posBasedVariation;
-        return 1 - (distanceStretched - (offsetPos / (1. + stretchIntensity)));
+        return viewportDimension - (distanceStretched - (offsetPos / (1. + stretchIntensity)));
     }
 
     // Prefer usage of return values over out parameters as it enables
@@ -113,7 +114,8 @@
         float uInverseStretchAffectedDist,
         float distanceStretched,
         float distanceDiff,
-        float interpolationStrength
+        float interpolationStrength,
+        float viewportDimension
     ) {
       if (overscroll > 0) {
         if (inPos <= uStretchAffectedDist) {
@@ -129,7 +131,7 @@
             return distanceDiff + inPos;
         }
       } else if (overscroll < 0) {
-        float stretchAffectedDist = 1. - uStretchAffectedDist;
+        float stretchAffectedDist = viewportDimension - uStretchAffectedDist;
         if (inPos >= stretchAffectedDist) {
             return computeOverscrollEnd(
               inPos,
@@ -138,7 +140,8 @@
               uStretchAffectedDist,
               uInverseStretchAffectedDist,
               distanceStretched,
-              interpolationStrength
+              interpolationStrength,
+              viewportDimension
             );
         } else {
             return -distanceDiff + inPos;
@@ -149,12 +152,11 @@
     }
 
     vec4 main(vec2 coord) {
-        // Normalize SKSL pixel coordinate into a unit vector
-        float inU = coord.x / viewportWidth;
-        float inV = coord.y / viewportHeight;
+        float inU = coord.x;
+        float inV = coord.y;
         float outU;
         float outV;
-        // Add the normalized scroll position within scrolling list
+
         inU += uScrollX;
         inV += uScrollY;
         outU = computeOverscroll(
@@ -164,7 +166,8 @@
             uInverseDistanceStretchedX,
             uDistanceStretchedX,
             uDistDiffX,
-            uInterpolationStrength
+            uInterpolationStrength,
+            viewportWidth
         );
         outV = computeOverscroll(
             inV,
@@ -173,15 +176,15 @@
             uInverseDistanceStretchedY,
             uDistanceStretchedY,
             uDistDiffY,
-            uInterpolationStrength
+            uInterpolationStrength,
+            viewportHeight
         );
-        coord.x = outU * viewportWidth;
-        coord.y = outV * viewportHeight;
+        coord.x = outU;
+        coord.y = outV;
         return sample(uContentTexture, coord);
     })");
 
 static const float ZERO = 0.f;
-static const float CONTENT_DISTANCE_STRETCHED = 1.f;
 static const float INTERPOLATION_STRENGTH_VALUE = 0.7f;
 
 sk_sp<SkShader> StretchEffect::getShader(float width, float height,
@@ -192,12 +195,12 @@
 
     float normOverScrollDistX = mStretchDirection.x();
     float normOverScrollDistY = mStretchDirection.y();
-    float distanceStretchedX = CONTENT_DISTANCE_STRETCHED / (1 + abs(normOverScrollDistX));
-    float distanceStretchedY = CONTENT_DISTANCE_STRETCHED / (1 + abs(normOverScrollDistY));
-    float inverseDistanceStretchedX = 1.f / CONTENT_DISTANCE_STRETCHED;
-    float inverseDistanceStretchedY = 1.f / CONTENT_DISTANCE_STRETCHED;
-    float diffX = distanceStretchedX - CONTENT_DISTANCE_STRETCHED;
-    float diffY = distanceStretchedY - CONTENT_DISTANCE_STRETCHED;
+    float distanceStretchedX = width / (1 + abs(normOverScrollDistX));
+    float distanceStretchedY = height / (1 + abs(normOverScrollDistY));
+    float inverseDistanceStretchedX = 1.f / width;
+    float inverseDistanceStretchedY = 1.f / height;
+    float diffX = distanceStretchedX - width;
+    float diffY = distanceStretchedY - height;
 
     if (mBuilder == nullptr) {
         mBuilder = std::make_unique<SkRuntimeShaderBuilder>(getStretchEffect());
@@ -206,8 +209,8 @@
     mBuilder->child("uContentTexture") = snapshotImage->makeShader(
             SkTileMode::kClamp, SkTileMode::kClamp, SkSamplingOptions(SkFilterMode::kLinear));
     mBuilder->uniform("uInterpolationStrength").set(&INTERPOLATION_STRENGTH_VALUE, 1);
-    mBuilder->uniform("uStretchAffectedDistX").set(&CONTENT_DISTANCE_STRETCHED, 1);
-    mBuilder->uniform("uStretchAffectedDistY").set(&CONTENT_DISTANCE_STRETCHED, 1);
+    mBuilder->uniform("uStretchAffectedDistX").set(&width, 1);
+    mBuilder->uniform("uStretchAffectedDistY").set(&height, 1);
     mBuilder->uniform("uDistanceStretchedX").set(&distanceStretchedX, 1);
     mBuilder->uniform("uDistanceStretchedY").set(&distanceStretchedY, 1);
     mBuilder->uniform("uInverseDistanceStretchedX").set(&inverseDistanceStretchedX, 1);