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canvas: Better coordinate rounding in scaling

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When scaling in pixman you give the source coordinates in transformed
space rather than in the source coordinates. This is a bit problematic
when both source and destination coordinates are at integer positions, but
the scaling factor is not an exact 16.16 fixed point value. We used
to calculate the transformed source based on the floating point
transformation, which gave the wrong answer sometimes. Now we do the
calculations based on the fixed point transform that we give pixman.

However, even with this patch I can still sometimes see issues related
to this, although they are less bad.
This commit is contained in:
Alexander Larsson 2010-08-27 16:33:35 +02:00 committed by Marc-André Lureau
parent 6264783c53
commit b0fe22b6ff
1 changed files with 36 additions and 28 deletions
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64
common/sw_canvas.c
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@ -453,16 +453,15 @@ static void __scale_image(SpiceCanvas *spice_canvas,
{
SwCanvas *canvas = (SwCanvas *)spice_canvas;
pixman_transform_t transform;
double sx, sy;
pixman_fixed_t fsx, fsy;
int scaled_src_x, scaled_src_y;
sx = (double)(src_width) / (dest_width);
sy = (double)(src_height) / (dest_height);
fsx = ((pixman_fixed_48_16_t) src_width * 65536) / dest_width;
fsy = ((pixman_fixed_48_16_t) src_height * 65536) / dest_height;
pixman_image_set_clip_region32(canvas->image, region);
pixman_transform_init_scale(&transform,
pixman_double_to_fixed(sx),
pixman_double_to_fixed(sy));
pixman_transform_init_scale(&transform, fsx, fsy);
pixman_image_set_transform(src, &transform);
pixman_image_set_repeat(src, PIXMAN_REPEAT_NONE);
@ -473,9 +472,12 @@ static void __scale_image(SpiceCanvas *spice_canvas,
PIXMAN_FILTER_NEAREST : PIXMAN_FILTER_GOOD,
NULL, 0);
scaled_src_x = ((pixman_fixed_48_16_t)src_x * 65536 + fsx/2 ) / fsx;
scaled_src_y = ((pixman_fixed_48_16_t)src_y * 65536 + fsy/2 ) / fsy;
pixman_image_composite32(PIXMAN_OP_SRC,
src, NULL, canvas->image,
ROUND(src_x / sx), ROUND(src_y / sy), /* src */
scaled_src_x, scaled_src_y, /* src */
0, 0, /* mask */
dest_x, dest_y, /* dst */
dest_width, dest_height);
@ -527,10 +529,11 @@ static void __scale_image_rop(SpiceCanvas *spice_canvas,
pixman_image_t *scaled;
pixman_box32_t *rects;
int n_rects, i;
double sx, sy;
pixman_fixed_t fsx, fsy;
int scaled_src_x, scaled_src_y;
sx = (double)(src_width) / (dest_width);
sy = (double)(src_height) / (dest_height);
fsx = ((pixman_fixed_48_16_t) src_width * 65536) / dest_width;
fsy = ((pixman_fixed_48_16_t) src_height * 65536) / dest_height;
scaled = pixman_image_create_bits(spice_pixman_image_get_format(src),
dest_width,
@ -540,9 +543,7 @@ static void __scale_image_rop(SpiceCanvas *spice_canvas,
pixman_region32_translate(region, -dest_x, -dest_y);
pixman_image_set_clip_region32(scaled, region);
pixman_transform_init_scale(&transform,
pixman_double_to_fixed(sx),
pixman_double_to_fixed(sy));
pixman_transform_init_scale(&transform, fsx, fsy);
pixman_image_set_transform(src, &transform);
pixman_image_set_repeat(src, PIXMAN_REPEAT_NONE);
@ -553,9 +554,12 @@ static void __scale_image_rop(SpiceCanvas *spice_canvas,
PIXMAN_FILTER_NEAREST : PIXMAN_FILTER_GOOD,
NULL, 0);
scaled_src_x = ((pixman_fixed_48_16_t)src_x * 65536 + fsx/2 ) / fsx;
scaled_src_y = ((pixman_fixed_48_16_t)src_y * 65536 + fsy/2 ) / fsy;
pixman_image_composite32(PIXMAN_OP_SRC,
src, NULL, scaled,
ROUND(src_x / sx), ROUND(src_y / sy), /* src */
scaled_src_x, scaled_src_y, /* src */
0, 0, /* mask */
0, 0, /* dst */
dest_width,
@ -724,18 +728,17 @@ static void __blend_scale_image(SpiceCanvas *spice_canvas,
SwCanvas *canvas = (SwCanvas *)spice_canvas;
pixman_transform_t transform;
pixman_image_t *mask, *dest;
double sx, sy;
pixman_fixed_t fsx, fsy;
int scaled_src_x, scaled_src_y;
sx = (double)(src_width) / (dest_width);
sy = (double)(src_height) / (dest_height);
fsx = ((pixman_fixed_48_16_t) src_width * 65536) / dest_width;
fsy = ((pixman_fixed_48_16_t) src_height * 65536) / dest_height;
dest = canvas_get_as_surface(canvas, dest_has_alpha);
pixman_image_set_clip_region32(dest, region);
pixman_transform_init_scale(&transform,
pixman_double_to_fixed(sx),
pixman_double_to_fixed(sy));
pixman_transform_init_scale(&transform, fsx, fsy);
mask = NULL;
if (overall_alpha != 0xff) {
@ -753,9 +756,12 @@ static void __blend_scale_image(SpiceCanvas *spice_canvas,
PIXMAN_FILTER_NEAREST : PIXMAN_FILTER_GOOD,
NULL, 0);
scaled_src_x = ((pixman_fixed_48_16_t)src_x * 65536 + fsx/2 ) / fsx;
scaled_src_y = ((pixman_fixed_48_16_t)src_y * 65536 + fsy/2 ) / fsy;
pixman_image_composite32(PIXMAN_OP_OVER,
src, mask, dest,
ROUND(src_x / sx), ROUND(src_y / sy), /* src */
scaled_src_x, scaled_src_y, /* src */
0, 0, /* mask */
dest_x, dest_y, /* dst */
dest_width, dest_height);
@ -881,10 +887,11 @@ static void __colorkey_scale_image(SpiceCanvas *spice_canvas,
pixman_image_t *scaled;
pixman_box32_t *rects;
int n_rects, i;
double sx, sy;
pixman_fixed_t fsx, fsy;
int scaled_src_x, scaled_src_y;
sx = (double)(src_width) / (dest_width);
sy = (double)(src_height) / (dest_height);
fsx = ((pixman_fixed_48_16_t) src_width * 65536) / dest_width;
fsy = ((pixman_fixed_48_16_t) src_height * 65536) / dest_height;
scaled = pixman_image_create_bits(spice_pixman_image_get_format (src),
dest_width,
@ -894,9 +901,7 @@ static void __colorkey_scale_image(SpiceCanvas *spice_canvas,
pixman_region32_translate(region, -dest_x, -dest_y);
pixman_image_set_clip_region32(scaled, region);
pixman_transform_init_scale(&transform,
pixman_double_to_fixed(sx),
pixman_double_to_fixed(sy));
pixman_transform_init_scale(&transform, fsx, fsy);
pixman_image_set_transform(src, &transform);
pixman_image_set_repeat(src, PIXMAN_REPEAT_NONE);
@ -904,9 +909,12 @@ static void __colorkey_scale_image(SpiceCanvas *spice_canvas,
PIXMAN_FILTER_NEAREST,
NULL, 0);
scaled_src_x = ((pixman_fixed_48_16_t)src_x * 65536 + fsx/2 ) / fsx;
scaled_src_y = ((pixman_fixed_48_16_t)src_y * 65536 + fsy/2 ) / fsy;
pixman_image_composite32(PIXMAN_OP_SRC,
src, NULL, scaled,
ROUND(src_x / sx), ROUND(src_y / sy), /* src */
scaled_src_x, scaled_src_y, /* src */
0, 0, /* mask */
0, 0, /* dst */
dest_width,