Pass the radius as a float deeper into HWUI allowing RS to generate more accurate blurs.

Also, when converting radius to an integer value snap to the appropriate integer boundaries.

bug: 10650594
Change-Id: Icca4bc17d88162bbcbc6035d4f81bd1d98a4de2d

4 files changed, 32 insertions, 14 deletions

diff --git a/libs/hwui/FontRenderer.cpp b/libs/hwui/FontRenderer.cpp
index 647c281..5244635 100644
--- a/libs/hwui/FontRenderer.cpp
+++ b/libs/hwui/FontRenderer.cpp
@@ -592,7 +592,7 @@ void FontRenderer::setFont(const SkPaint* paint, const mat4& matrix) {
 }
 
 FontRenderer::DropShadow FontRenderer::renderDropShadow(const SkPaint* paint, const char *text,
-        uint32_t startIndex, uint32_t len, int numGlyphs, uint32_t radius, const float* positions) {
+        uint32_t startIndex, uint32_t len, int numGlyphs, float radius, const float* positions) {
     checkInit();
 
     DropShadow image;
@@ -613,8 +613,9 @@ FontRenderer::DropShadow FontRenderer::renderDropShadow(const SkPaint* paint, co
     Rect bounds;
     mCurrentFont->measure(paint, text, startIndex, len, numGlyphs, &bounds, positions);
 
-    uint32_t paddedWidth = (uint32_t) (bounds.right - bounds.left) + 2 * radius;
-    uint32_t paddedHeight = (uint32_t) (bounds.top - bounds.bottom) + 2 * radius;
+    uint32_t intRadius = Blur::convertRadiusToInt(radius);
+    uint32_t paddedWidth = (uint32_t) (bounds.right - bounds.left) + 2 * intRadius;
+    uint32_t paddedHeight = (uint32_t) (bounds.top - bounds.bottom) + 2 * intRadius;
 
     uint32_t maxSize = Caches::getInstance().maxTextureSize;
     if (paddedWidth > maxSize || paddedHeight > maxSize) {
@@ -635,8 +636,8 @@ FontRenderer::DropShadow FontRenderer::renderDropShadow(const SkPaint* paint, co
 
     memset(dataBuffer, 0, size);
 
-    int penX = radius - bounds.left;
-    int penY = radius - bounds.bottom;
+    int penX = intRadius - bounds.left;
+    int penY = intRadius - bounds.bottom;
 
     if ((bounds.right > bounds.left) && (bounds.top > bounds.bottom)) {
         // text has non-whitespace, so draw and blur to create the shadow
@@ -727,9 +728,10 @@ void FontRenderer::removeFont(const Font* font) {
     }
 }
 
-void FontRenderer::blurImage(uint8_t** image, int32_t width, int32_t height, int32_t radius) {
+void FontRenderer::blurImage(uint8_t** image, int32_t width, int32_t height, float radius) {
+    uint32_t intRadius = Blur::convertRadiusToInt(radius);
 #ifdef ANDROID_ENABLE_RENDERSCRIPT
-    if (width * height * radius >= RS_MIN_INPUT_CUTOFF) {
+    if (width * height * intRadius >= RS_MIN_INPUT_CUTOFF) {
         uint8_t* outImage = (uint8_t*) memalign(RS_CPU_ALLOCATION_ALIGNMENT, width * height);
 
         if (mRs == 0) {
@@ -768,12 +770,12 @@ void FontRenderer::blurImage(uint8_t** image, int32_t width, int32_t height, int
     }
 #endif
 
-    float *gaussian = new float[2 * radius + 1];
-    Blur::generateGaussianWeights(gaussian, radius);
+    float *gaussian = new float[2 * intRadius + 1];
+    Blur::generateGaussianWeights(gaussian, intRadius);
 
     uint8_t* scratch = new uint8_t[width * height];
-    Blur::horizontal(gaussian, radius, *image, scratch, width, height);
-    Blur::vertical(gaussian, radius, scratch, *image, width, height);
+    Blur::horizontal(gaussian, intRadius, *image, scratch, width, height);
+    Blur::vertical(gaussian, intRadius, scratch, *image, width, height);
 
     delete[] gaussian;
     delete[] scratch;
diff --git a/libs/hwui/FontRenderer.h b/libs/hwui/FontRenderer.h
index 9259028..8ce22b0 100644
--- a/libs/hwui/FontRenderer.h
+++ b/libs/hwui/FontRenderer.h
@@ -129,7 +129,7 @@ public:
     // After renderDropShadow returns, the called owns the memory in DropShadow.image
     // and is responsible for releasing it when it's done with it
     DropShadow renderDropShadow(const SkPaint* paint, const char *text, uint32_t startIndex,
-            uint32_t len, int numGlyphs, uint32_t radius, const float* positions);
+            uint32_t len, int numGlyphs, float radius, const float* positions);
 
     void setTextureFiltering(bool linearFiltering) {
         mLinearFiltering = linearFiltering;
@@ -218,7 +218,7 @@ private:
             int32_t width, int32_t height);
 
     // the input image handle may have its pointer replaced (to avoid copies)
-    void blurImage(uint8_t** image, int32_t width, int32_t height, int32_t radius);
+    void blurImage(uint8_t** image, int32_t width, int32_t height, float radius);
 };
 
 }; // namespace uirenderer
diff --git a/libs/hwui/utils/Blur.cpp b/libs/hwui/utils/Blur.cpp
index c020b40..877a422 100644
--- a/libs/hwui/utils/Blur.cpp
+++ b/libs/hwui/utils/Blur.cpp
@@ -19,6 +19,7 @@
 #include <math.h>
 
 #include "Blur.h"
+#include "MathUtils.h"
 
 namespace android {
 namespace uirenderer {
@@ -35,6 +36,17 @@ float Blur::convertSigmaToRadius(float sigma) {
     return sigma > 0.5f ? (sigma - 0.5f) / BLUR_SIGMA_SCALE : 0.0f;
 }
 
+// if the original radius was on an integer boundary and the resulting radius
+// is within the conversion error tolerance then we attempt to snap to the
+// original integer boundary.
+uint32_t Blur::convertRadiusToInt(float radius) {
+    const float radiusCeil  = ceilf(radius);
+    if (MathUtils::areEqual(radiusCeil, radius)) {
+        return radiusCeil;
+    }
+    return radius;
+}
+
 /**
  * HWUI has used a slightly different equation than Skia to generate the value
  * for sigma and to preserve compatibility we have kept that logic.
diff --git a/libs/hwui/utils/Blur.h b/libs/hwui/utils/Blur.h
index 79aff65..b145333 100644
--- a/libs/hwui/utils/Blur.h
+++ b/libs/hwui/utils/Blur.h
@@ -27,8 +27,12 @@ class Blur {
 public:
     // If radius > 0, return the corresponding sigma, else return 0
     ANDROID_API static float convertRadiusToSigma(float radius);
-    // If sigma > 0.6, return the corresponding radius, else return 0
+    // If sigma > 0.5, return the corresponding radius, else return 0
     ANDROID_API static float convertSigmaToRadius(float sigma);
+    // If the original radius was on an integer boundary then after the sigma to
+    // radius conversion a small rounding error may be introduced. This function
+    // accounts for that error and snaps to the appropriate integer boundary.
+    static uint32_t convertRadiusToInt(float radius);
 
     static void generateGaussianWeights(float* weights, int32_t radius);
     static void horizontal(float* weights, int32_t radius, const uint8_t* source,