pixman: Branch 'master' - 2 commits

[Søren Sandmann Pedersen]

 pixman/pixman-bits-image.c |   10 +++++-----
 test/utils.c               |   13 ++++++++++---
 2 files changed, 15 insertions(+), 8 deletions(-)

New commits:
commit e24c1c849d29f43dc6e50e1f15102709059b40f8
Author: Søren Sandmann Pedersen <ssp at redhat.com>
Date:   Thu Apr 5 00:52:21 2012 -0400

    bits_image_fetch_pixel_convolution(): Make sure channels are signed
    
    In the computation:
    
        srtot += RED_8 (pixel) * f
    
    RED_8 (pixel) is an unsigned quantity, which means the signed filter
    coefficient f gets converted to an unsigned integer before the
    multiplication. We get away with this because when the 32 bit unsigned
    result is converted to int32_t, the correct sign is produced. But if
    srtot had been an int64_t, the result would have been a very large
    positive number.
    
    Fix this by explicitly casting the channels to int.

diff --git a/pixman/pixman-bits-image.c b/pixman/pixman-bits-image.c
index d105d2f..1f6897c 100644
--- a/pixman/pixman-bits-image.c
+++ b/pixman/pixman-bits-image.c
@@ -381,11 +381,11 @@ bits_image_fetch_pixel_convolution (bits_image_t   *image,
     int y_off = (params[1] - pixman_fixed_1) >> 1;
     int32_t cwidth = pixman_fixed_to_int (params[0]);
     int32_t cheight = pixman_fixed_to_int (params[1]);
-    int32_t srtot, sgtot, sbtot, satot;
     int32_t i, j, x1, x2, y1, y2;
     pixman_repeat_t repeat_mode = image->common.repeat;
     int width = image->width;
     int height = image->height;
+    int srtot, sgtot, sbtot, satot;
 
     params += 2;
 
@@ -421,10 +421,10 @@ bits_image_fetch_pixel_convolution (bits_image_t   *image,
 		    pixel = get_pixel (image, rx, ry, TRUE);
 		}
 
-		srtot += RED_8 (pixel) * f;
-		sgtot += GREEN_8 (pixel) * f;
-		sbtot += BLUE_8 (pixel) * f;
-		satot += ALPHA_8 (pixel) * f;
+		srtot += (int)RED_8 (pixel) * f;
+		sgtot += (int)GREEN_8 (pixel) * f;
+		sbtot += (int)BLUE_8 (pixel) * f;
+		satot += (int)ALPHA_8 (pixel) * f;
 	    }
 
 	    params++;
commit 4d2fee14063b960c6b81b55dd3aa94b956d23eeb
Author: Søren Sandmann Pedersen <ssp at redhat.com>
Date:   Thu Apr 5 00:42:55 2012 -0400

    test/utils.c: Clip values to the [0, 255] interval
    
    Unpremultiplying a superluminescent pixel can result in values greater
    than 255.

diff --git a/test/utils.c b/test/utils.c
index cc0365a..c1bf6dc 100644
--- a/test/utils.c
+++ b/test/utils.c
@@ -358,9 +358,16 @@ a8r8g8b8_to_rgba_np (uint32_t *dst, uint32_t *src, int n_pixels)
 
 	if (a != 0)
 	{
-	    r = (r * 255) / a;
-	    g = (g * 255) / a;
-	    b = (b * 255) / a;
+#define DIVIDE(c, a)							\
+	    do								\
+	    {								\
+		int t = ((c) * 255) / a;				\
+		(c) = t < 0? 0 : t > 255? 255 : t;			\
+	    } while (0)
+
+	    DIVIDE (r, a);
+	    DIVIDE (g, a);
+	    DIVIDE (b, a);
 	}
 
 	*dst8++ = r;