Move blur code from FontRenderer to utils/Blur.cpp

Change-Id: I2cebbfbcb722ed4b37e54ffbf8b53bb92ad0c964
diff --git a/libs/hwui/FontRenderer.cpp b/libs/hwui/FontRenderer.cpp
index 77b8df1..f0dcb30 100644
--- a/libs/hwui/FontRenderer.cpp
+++ b/libs/hwui/FontRenderer.cpp
@@ -23,9 +23,11 @@
 
 #include <utils/Log.h>
 
-#include "RenderScript.h"
+#include <RenderScript.h>
 
+#include "utils/Blur.h"
 #include "utils/Timing.h"
+
 #include "Caches.h"
 #include "Debug.h"
 #include "FontRenderer.h"
@@ -569,7 +571,7 @@
     }
 
     int size = paddedWidth * paddedHeight;
-    uint8_t* dataBuffer = (uint8_t*)memalign(RS_CPU_ALLOCATION_ALIGNMENT, size);
+    uint8_t* dataBuffer = (uint8_t*) memalign(RS_CPU_ALLOCATION_ALIGNMENT, size);
     memset(dataBuffer, 0, size);
 
     int penX = radius - bounds.left;
@@ -655,147 +657,21 @@
     }
 }
 
-void FontRenderer::computeGaussianWeights(float* weights, int32_t radius) {
-    // Compute gaussian weights for the blur
-    // e is the euler's number
-    float e = 2.718281828459045f;
-    float pi = 3.1415926535897932f;
-    // g(x) = ( 1 / sqrt( 2 * pi ) * sigma) * e ^ ( -x^2 / 2 * sigma^2 )
-    // x is of the form [-radius .. 0 .. radius]
-    // and sigma varies with radius.
-    // Based on some experimental radius values and sigma's
-    // we approximately fit sigma = f(radius) as
-    // sigma = radius * 0.3  + 0.6
-    // The larger the radius gets, the more our gaussian blur
-    // will resemble a box blur since with large sigma
-    // the gaussian curve begins to lose its shape
-    float sigma = 0.3f * (float) radius + 0.6f;
-
-    // Now compute the coefficints
-    // We will store some redundant values to save some math during
-    // the blur calculations
-    // precompute some values
-    float coeff1 = 1.0f / (sqrt( 2.0f * pi ) * sigma);
-    float coeff2 = - 1.0f / (2.0f * sigma * sigma);
-
-    float normalizeFactor = 0.0f;
-    for (int32_t r = -radius; r <= radius; r ++) {
-        float floatR = (float) r;
-        weights[r + radius] = coeff1 * pow(e, floatR * floatR * coeff2);
-        normalizeFactor += weights[r + radius];
-    }
-
-    //Now we need to normalize the weights because all our coefficients need to add up to one
-    normalizeFactor = 1.0f / normalizeFactor;
-    for (int32_t r = -radius; r <= radius; r ++) {
-        weights[r + radius] *= normalizeFactor;
-    }
-}
-
-void FontRenderer::horizontalBlur(float* weights, int32_t radius,
-        const uint8_t* source, uint8_t* dest, int32_t width, int32_t height) {
-    float blurredPixel = 0.0f;
-    float currentPixel = 0.0f;
-
-    for (int32_t y = 0; y < height; y ++) {
-
-        const uint8_t* input = source + y * width;
-        uint8_t* output = dest + y * width;
-
-        for (int32_t x = 0; x < width; x ++) {
-            blurredPixel = 0.0f;
-            const float* gPtr = weights;
-            // Optimization for non-border pixels
-            if (x > radius && x < (width - radius)) {
-                const uint8_t *i = input + (x - radius);
-                for (int r = -radius; r <= radius; r ++) {
-                    currentPixel = (float) (*i);
-                    blurredPixel += currentPixel * gPtr[0];
-                    gPtr++;
-                    i++;
-                }
-            } else {
-                for (int32_t r = -radius; r <= radius; r ++) {
-                    // Stepping left and right away from the pixel
-                    int validW = x + r;
-                    if (validW < 0) {
-                        validW = 0;
-                    }
-                    if (validW > width - 1) {
-                        validW = width - 1;
-                    }
-
-                    currentPixel = (float) input[validW];
-                    blurredPixel += currentPixel * gPtr[0];
-                    gPtr++;
-                }
-            }
-            *output = (uint8_t)blurredPixel;
-            output ++;
-        }
-    }
-}
-
-void FontRenderer::verticalBlur(float* weights, int32_t radius,
-        const uint8_t* source, uint8_t* dest, int32_t width, int32_t height) {
-    float blurredPixel = 0.0f;
-    float currentPixel = 0.0f;
-
-    for (int32_t y = 0; y < height; y ++) {
-        uint8_t* output = dest + y * width;
-
-        for (int32_t x = 0; x < width; x ++) {
-            blurredPixel = 0.0f;
-            const float* gPtr = weights;
-            const uint8_t* input = source + x;
-            // Optimization for non-border pixels
-            if (y > radius && y < (height - radius)) {
-                const uint8_t *i = input + ((y - radius) * width);
-                for (int32_t r = -radius; r <= radius; r ++) {
-                    currentPixel = (float)(*i);
-                    blurredPixel += currentPixel * gPtr[0];
-                    gPtr++;
-                    i += width;
-                }
-            } else {
-                for (int32_t r = -radius; r <= radius; r ++) {
-                    int validH = y + r;
-                    // Clamp to zero and width
-                    if (validH < 0) {
-                        validH = 0;
-                    }
-                    if (validH > height - 1) {
-                        validH = height - 1;
-                    }
-
-                    const uint8_t *i = input + validH * width;
-                    currentPixel = (float) (*i);
-                    blurredPixel += currentPixel * gPtr[0];
-                    gPtr++;
-                }
-            }
-            *output = (uint8_t) blurredPixel;
-            output++;
-        }
-    }
-}
-
 void FontRenderer::blurImage(uint8_t** image, int32_t width, int32_t height, int32_t radius) {
     if (width * height * radius < RS_MIN_INPUT_CUTOFF) {
         float *gaussian = new float[2 * radius + 1];
-        computeGaussianWeights(gaussian, radius);
+        Blur::generateGaussianWeights(gaussian, radius);
 
         uint8_t* scratch = new uint8_t[width * height];
-
-        horizontalBlur(gaussian, radius, *image, scratch, width, height);
-        verticalBlur(gaussian, radius, scratch, *image, width, height);
+        Blur::horizontal(gaussian, radius, *image, scratch, width, height);
+        Blur::vertical(gaussian, radius, scratch, *image, width, height);
 
         delete[] gaussian;
         delete[] scratch;
         return;
     }
 
-    uint8_t* outImage = (uint8_t*)memalign(RS_CPU_ALLOCATION_ALIGNMENT, width * height);
+    uint8_t* outImage = (uint8_t*) memalign(RS_CPU_ALLOCATION_ALIGNMENT, width * height);
 
     if (mRs.get() == 0) {
         mRs = new RSC::RS();