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unified subsampling code. 

2007-07-17  Sven Neumann  <sven@gimp.org>

	* app/paint-funcs/sample-funcs.c: unified subsampling code.


svn path=/trunk/; revision=22954
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Sven Neumann 2007-07-18 15:39:19 +00:00 committed by Sven Neumann
parent 4ed227cf0e
commit b5e8ca6925
2 changed files with 84 additions and 51 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
2007-07-17 Sven Neumann <sven@gimp.org>
* app/paint-funcs/sample-funcs.c: unified subsampling code.
2007-07-17 Sven Neumann <sven@gimp.org>
* app/paint-funcs/Makefile.am

131
app/paint-funcs/sample-funcs.c
View File

@ -45,13 +45,15 @@ subsample_region (PixelRegion *srcPR,
const gdouble y_ratio = (gdouble) orig_height / (gdouble) height;
const gint bytes = destPR->bytes;
const gint destwidth = destPR->rowstride;
const gboolean has_alpha = pixel_region_has_alpha (srcPR);
guchar *src, *s;
guchar *dest, *d;
gdouble *row, *r;
gint src_row, src_col;
gdouble x_sum, y_sum;
gdouble x_last, y_last;
gdouble *x_frac, y_frac, tot_frac;
gdouble *x_frac, y_frac;
gdouble tot_frac;
gint i, j;
gint b;
gint frac;
@ -136,8 +138,22 @@ subsample_region (PixelRegion *srcPR,
{
tot_frac = x_frac[frac++] * y_frac;
for (b = 0; b < bytes; b++)
r[b] += s[b] * tot_frac;
if (has_alpha)
{
/* premultiply */
gdouble local_frac = tot_frac * (gdouble) s[bytes - 1] / 255.0;
for (b = 0; b < (bytes - 1); b++)
r[b] += s[b] * local_frac;
r[bytes - 1] += local_frac;
}
else
{
for (b = 0; b < bytes; b++)
r[b] += s[b] * tot_frac;
}
/* increment the destination */
if (x_sum + x_ratio <= (src_col + 1 + EPSILON))
@ -166,10 +182,33 @@ subsample_region (PixelRegion *srcPR,
j = width;
while (j--)
{
b = bytes;
if (has_alpha)
{
/* unpremultiply */
while (b--)
*d++ = (guchar) (*r++ * tot_frac + 0.5);
gdouble alpha = r[bytes - 1];
if (alpha > EPSILON)
{
for (b = 0; b < (bytes - 1); b++)
d[b] = (guchar) ((r[b] / alpha) + 0.5);
d[bytes - 1] = (guchar) ((alpha * tot_frac * 255.0) + 0.5);
}
else
{
for (b = 0; b < bytes; b++)
d[b] = 0;
}
}
else
{
for (b = 0; b < bytes; b++)
d[b] = (guchar) ((r[b] * tot_frac) + 0.5);
}
r += bytes;
d += bytes;
}
dest += destwidth;
@ -202,59 +241,49 @@ subsample_indexed_region (PixelRegion *srcPR,
const guchar *cmap,
gint subsample)
{
guchar *src, *s;
guchar *dest, *d;
gdouble *row, *r;
gint destwidth;
gint src_row, src_col;
gint bytes, b;
gint width, height;
gint orig_width, orig_height;
gdouble x_rat, y_rat;
gdouble x_cum, y_cum;
gdouble x_last, y_last;
gdouble *x_frac, y_frac, tot_frac;
gint i, j;
gint frac;
gboolean advance_dest;
gboolean has_alpha;
const gint width = destPR->w;
const gint height = destPR->h;
const gint orig_width = srcPR->w / subsample;
const gint orig_height = srcPR->h / subsample;
const gdouble x_ratio = (gdouble) orig_width / (gdouble) width;
const gdouble y_ratio = (gdouble) orig_height / (gdouble) height;
const gint bytes = destPR->bytes;
const gint destwidth = destPR->rowstride;
const gboolean has_alpha = pixel_region_has_alpha (srcPR);
guchar *src, *s;
guchar *dest, *d;
gdouble *row, *r;
gint src_row, src_col;
gdouble x_sum, y_sum;
gdouble x_last, y_last;
gdouble *x_frac, y_frac;
gdouble tot_frac;
gint i, j;
gint b;
gint frac;
gint advance_dest;
g_return_if_fail (cmap != NULL);
orig_width = srcPR->w / subsample;
orig_height = srcPR->h / subsample;
width = destPR->w;
height = destPR->h;
/* Some calculations... */
bytes = destPR->bytes;
destwidth = destPR->rowstride;
has_alpha = pixel_region_has_alpha (srcPR);
/* the data pointers... */
src = g_new (guchar, orig_width * bytes);
dest = destPR->data;
/* find the ratios of old x to new x and old y to new y */
x_rat = (gdouble) orig_width / (gdouble) width;
y_rat = (gdouble) orig_height / (gdouble) height;
/* allocate an array to help with the calculations */
row = g_new0 (gdouble, width * bytes);
x_frac = g_new (gdouble, width + orig_width);
/* initialize the pre-calculated pixel fraction array */
src_col = 0;
x_cum = (gdouble) src_col;
x_last = x_cum;
x_sum = (gdouble) src_col;
x_last = x_sum;
for (i = 0; i < width + orig_width; i++)
{
if (x_cum + x_rat <= (src_col + 1 + EPSILON))
if (x_sum + x_ratio <= (src_col + 1 + EPSILON))
{
x_cum += x_rat;
x_frac[i] = x_cum - x_last;
x_sum += x_ratio;
x_frac[i] = x_sum - x_last;
}
else
{
@ -267,8 +296,8 @@ subsample_indexed_region (PixelRegion *srcPR,
/* counters... */
src_row = 0;
y_cum = (gdouble) src_row;
y_last = y_cum;
y_sum = (gdouble) src_row;
y_last = y_sum;
pixel_region_get_row (srcPR,
srcPR->x,
@ -281,13 +310,13 @@ subsample_indexed_region (PixelRegion *srcPR,
for (i = 0; i < height; )
{
src_col = 0;
x_cum = (gdouble) src_col;
x_sum = (gdouble) src_col;
/* determine the fraction of the src pixel we are using for y */
if (y_cum + y_rat <= (src_row + 1 + EPSILON))
if (y_sum + y_ratio <= (src_row + 1 + EPSILON))
{
y_cum += y_rat;
y_frac = y_cum - y_last;
y_sum += y_ratio;
y_frac = y_sum - y_last;
advance_dest = TRUE;
}
else
@ -332,10 +361,10 @@ subsample_indexed_region (PixelRegion *srcPR,
}
/* increment the destination */
if (x_cum + x_rat <= (src_col + 1 + EPSILON))
if (x_sum + x_ratio <= (src_col + 1 + EPSILON))
{
r += bytes;
x_cum += x_rat;
x_sum += x_ratio;
j--;
}
/* increment the source */
@ -348,7 +377,7 @@ subsample_indexed_region (PixelRegion *srcPR,
if (advance_dest)
{
tot_frac = 1.0 / (x_rat * y_rat);
tot_frac = 1.0 / (x_ratio * y_ratio);
/* copy "row" to "dest" */
d = dest;