pad the top/left of the sum buffer with zeros (so we can use it correctly)
diff --git a/src/effects/SkBlurMask.cpp b/src/effects/SkBlurMask.cpp
index 4e46ab6..a6492c3 100644
--- a/src/effects/SkBlurMask.cpp
+++ b/src/effects/SkBlurMask.cpp
@@ -18,33 +18,65 @@
#include "SkBlurMask.h"
#include "SkTemplates.h"
-static void build_sum_buffer(uint32_t dst[], int w, int h, const uint8_t src[], int srcRB)
-{
- SkASSERT(srcRB >= w);
+#if 0
+static void dump_sum_buffer(const uint32_t sum[], const int w, const int h) {
+ printf("---- sum buffer\n");
+ for (int y = 0; y <= h; y++) {
+ for (int x = 0; x <= w; x++) {
+ printf(" %5d", sum[x]);
+ }
+ printf("\n");
+ sum += w+1;
+ }
+}
+#else
+#define dump_sum_buffer(sum, w, h)
+#endif
+
+/** The sum buffer is an array of u32 to hold the accumulated sum of all of the
+ src values at their position, plus all values above and to the left.
+ When we sample into this buffer, we need an initial row and column of 0s,
+ so we have an index correspondence as follows:
+
+ src[i, j] == sum[i+1, j+1]
+ sum[0, j] == sum[i, 0] == 0
+
+ We assume that the sum buffer's stride == its width
+ */
+static void build_sum_buffer(uint32_t sum[], int srcW, int srcH, const uint8_t src[], int srcRB) {
+ int sumW = srcW + 1;
+
+ SkASSERT(srcRB >= srcW);
// mod srcRB so we can apply it after each row
- srcRB -= w;
+ srcRB -= srcW;
int x, y;
+ // zero out the top row and column
+ memset(sum, 0, sumW * sizeof(sum[0]));
+ sum += sumW;
+
// special case first row
uint32_t X = 0;
- for (x = w - 1; x >= 0; --x)
+ *sum++ = 0; // initialze the first column to 0
+ for (x = srcW - 1; x >= 0; --x)
{
X = *src++ + X;
- *dst++ = X;
+ *sum++ = X;
}
src += srcRB;
// now do the rest of the rows
- for (y = h - 1; y > 0; --y)
+ for (y = srcH - 1; y > 0; --y)
{
uint32_t L = 0;
uint32_t C = 0;
- for (x = w - 1; x >= 0; --x)
+ *sum++ = 0; // initialze the first column to 0
+ for (x = srcW - 1; x >= 0; --x)
{
- uint32_t T = dst[-w];
+ uint32_t T = sum[-sumW];
X = *src++ + L + T - C;
- *dst++ = X;
+ *sum++ = X;
L = X;
C = T;
}
@@ -52,36 +84,36 @@
}
}
-static void apply_kernel(uint8_t dst[], int rx, int ry, const uint32_t src[], int sw, int sh)
-{
+/* sw and sh are the width and height of the src. Since the sum buffer
+ matches that, but has an extra row and col at the beginning (with zeros),
+ we can just use sw and sh as our "max" values for pinning coordinates
+ when sampling into sum[][]
+ */
+static void apply_kernel(uint8_t dst[], int rx, int ry, const uint32_t sum[],
+ int sw, int sh) {
uint32_t scale = (1 << 24) / ((2*rx + 1)*(2*ry + 1));
- int rowBytes = sw;
+ int sumStride = sw + 1;
int dw = sw + 2*rx;
int dh = sh + 2*ry;
- sw -= 1; // now it is max_x
- sh -= 1; // now it is max_y
+ int prev_y = -2*ry;
+ int next_y = 1;
- int prev_y = -ry - 1 -ry;
- int next_y = ry -ry;
+ for (int y = 0; y < dh; y++) {
+ int py = SkClampPos(prev_y) * sumStride;
+ int ny = SkFastMin32(next_y, sh) * sumStride;
- for (int y = 0; y < dh; y++)
- {
- int py = SkClampPos(prev_y) * rowBytes;
- int ny = SkFastMin32(next_y, sh) * rowBytes;
+ int prev_x = -2*rx;
+ int next_x = 1;
- int prev_x = -rx - 1 -rx;
- int next_x = rx -rx;
-
- for (int x = 0; x < dw; x++)
- {
+ for (int x = 0; x < dw; x++) {
int px = SkClampPos(prev_x);
int nx = SkFastMin32(next_x, sw);
- uint32_t sum = src[px+py] + src[nx+ny] - src[nx+py] - src[px+ny];
- *dst++ = SkToU8(sum * scale >> 24);
+ uint32_t tmp = sum[px+py] + sum[nx+ny] - sum[nx+py] - sum[px+ny];
+ *dst++ = SkToU8(tmp * scale >> 24);
prev_x += 1;
next_x += 1;
@@ -91,8 +123,13 @@
}
}
-static void apply_kernel_interp(uint8_t dst[], int rx, int ry, const uint32_t src[], int sw, int sh, U8CPU outer_weight)
-{
+/* sw and sh are the width and height of the src. Since the sum buffer
+ matches that, but has an extra row and col at the beginning (with zeros),
+ we can just use sw and sh as our "max" values for pinning coordinates
+ when sampling into sum[][]
+ */
+static void apply_kernel_interp(uint8_t dst[], int rx, int ry,
+ const uint32_t sum[], int sw, int sh, U8CPU outer_weight) {
SkASSERT(rx > 0 && ry > 0);
SkASSERT(outer_weight <= 255);
@@ -105,38 +142,33 @@
uint32_t outer_scale = (outer_weight << 16) / ((2*rx + 1)*(2*ry + 1));
uint32_t inner_scale = (inner_weight << 16) / ((2*rx - 1)*(2*ry - 1));
- int rowBytes = sw;
+ int sumStride = sw + 1;
int dw = sw + 2*rx;
int dh = sh + 2*ry;
- sw -= 1; // now it is max_x
- sh -= 1; // now it is max_y
+ int prev_y = -2*ry;
+ int next_y = 1;
- int prev_y = -ry - 1 -ry;
- int next_y = ry -ry;
+ for (int y = 0; y < dh; y++) {
+ int py = SkClampPos(prev_y) * sumStride;
+ int ny = SkFastMin32(next_y, sh) * sumStride;
- for (int y = 0; y < dh; y++)
- {
- int py = SkClampPos(prev_y) * rowBytes;
- int ny = SkFastMin32(next_y, sh) * rowBytes;
+ int ipy = SkClampPos(prev_y + 1) * sumStride;
+ int iny = SkClampMax(next_y - 1, sh) * sumStride;
- int ipy = SkClampPos(prev_y + 1) * rowBytes;
- int iny = SkClampMax(next_y - 1, sh) * rowBytes;
+ int prev_x = -2*rx;
+ int next_x = 1;
- int prev_x = -rx - 1 -rx;
- int next_x = rx -rx;
-
- for (int x = 0; x < dw; x++)
- {
+ for (int x = 0; x < dw; x++) {
int px = SkClampPos(prev_x);
int nx = SkFastMin32(next_x, sw);
int ipx = SkClampPos(prev_x + 1);
int inx = SkClampMax(next_x - 1, sw);
- uint32_t outer_sum = src[px+py] + src[nx+ny] - src[nx+py] - src[px+ny];
- uint32_t inner_sum = src[ipx+ipy] + src[inx+iny] - src[inx+ipy] - src[ipx+iny];
+ uint32_t outer_sum = sum[px+py] + sum[nx+ny] - sum[nx+py] - sum[px+ny];
+ uint32_t inner_sum = sum[ipx+ipy] + sum[inx+iny] - sum[inx+ipy] - sum[ipx+iny];
*dst++ = SkToU8((outer_sum * outer_scale + inner_sum * inner_scale) >> 24);
prev_x += 1;
@@ -172,8 +204,7 @@
static void clamp_with_orig(uint8_t dst[], int dstRowBytes,
const uint8_t src[], int srcRowBytes,
int sw, int sh,
- SkBlurMask::Style style)
-{
+ SkBlurMask::Style style) {
int x;
while (--sh >= 0) {
switch (style) {
@@ -252,10 +283,11 @@
// build the blurry destination
{
- SkAutoTMalloc<uint32_t> storage(sw * sh);
+ SkAutoTMalloc<uint32_t> storage((sw + 1) * (sh + 1));
uint32_t* sumBuffer = storage.get();
build_sum_buffer(sumBuffer, sw, sh, sp, src.fRowBytes);
+ dump_sum_buffer(sumBuffer, sw, sh);
if (outer_weight == 255)
apply_kernel(dp, rx, ry, sumBuffer, sw, sh);
else
