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gimp/app/core/gimpdrawable-preview.c

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/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <string.h>
#include <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "core-types.h"
#include "base/pixel-region.h"
#include "base/temp-buf.h"
#include "paint-funcs/scale-funcs.h"
#include "config/gimpcoreconfig.h"
#include "gimp.h"
#include "gimpchannel.h"
#include "gimpimage.h"
#include "gimpimage-colormap.h"
#include "gimpdrawable-preview.h"
#include "gimplayer.h"
#include "gimppreviewcache.h"
/* local function prototypes */
static TempBuf * gimp_drawable_preview_private (GimpDrawable *drawable,
gint width,
gint height);
static void gimp_drawable_preview_scale (GimpImageType type,
const guchar *cmap,
PixelRegion *srcPR,
PixelRegion *destPR,
gint subsample);
/* public functions */
TempBuf *
gimp_drawable_get_preview (GimpViewable *viewable,
GimpContext *context,
gint width,
gint height)
{
GimpDrawable *drawable;
GimpImage *image;
drawable = GIMP_DRAWABLE (viewable);
image = gimp_item_get_image (GIMP_ITEM (drawable));
if (! image->gimp->config->layer_previews)
return NULL;
/* Ok prime the cache with a large preview if the cache is invalid */
if (! drawable->preview_valid &&
width <= PREVIEW_CACHE_PRIME_WIDTH &&
height <= PREVIEW_CACHE_PRIME_HEIGHT &&
image &&
image->width > PREVIEW_CACHE_PRIME_WIDTH &&
image->height > PREVIEW_CACHE_PRIME_HEIGHT)
{
TempBuf *tb = gimp_drawable_preview_private (drawable,
PREVIEW_CACHE_PRIME_WIDTH,
PREVIEW_CACHE_PRIME_HEIGHT);
/* Save the 2nd call */
if (width == PREVIEW_CACHE_PRIME_WIDTH &&
height == PREVIEW_CACHE_PRIME_HEIGHT)
return tb;
}
/* Second call - should NOT visit the tile cache...*/
return gimp_drawable_preview_private (drawable, width, height);
}
gint
gimp_drawable_preview_bytes (GimpDrawable *drawable)
{
GimpImageBaseType base_type;
gint bytes = 0;
g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), 0);
base_type = GIMP_IMAGE_TYPE_BASE_TYPE (gimp_drawable_type (drawable));
switch (base_type)
{
case GIMP_RGB:
case GIMP_GRAY:
bytes = gimp_drawable_bytes (drawable);
break;
case GIMP_INDEXED:
bytes = gimp_drawable_has_alpha (drawable) ? 4 : 3;
break;
}
return bytes;
}
TempBuf *
gimp_drawable_get_sub_preview (GimpDrawable *drawable,
gint src_x,
gint src_y,
gint src_width,
gint src_height,
gint dest_width,
gint dest_height)
{
GimpItem *item;
GimpImage *image;
TempBuf *preview_buf;
PixelRegion srcPR;
PixelRegion destPR;
gint bytes;
gint subsample;
g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
g_return_val_if_fail (src_x >= 0, NULL);
g_return_val_if_fail (src_y >= 0, NULL);
g_return_val_if_fail (src_width > 0, NULL);
g_return_val_if_fail (src_height > 0, NULL);
g_return_val_if_fail (dest_width > 0, NULL);
g_return_val_if_fail (dest_height > 0, NULL);
item = GIMP_ITEM (drawable);
g_return_val_if_fail ((src_x + src_width) <= gimp_item_width (item), NULL);
g_return_val_if_fail ((src_y + src_height) <= gimp_item_height (item), NULL);
image = gimp_item_get_image (item);
if (! image->gimp->config->layer_previews)
return NULL;
bytes = gimp_drawable_preview_bytes (drawable);
/* calculate 'acceptable' subsample */
subsample = 1;
while ((dest_width * (subsample + 1) * 2 < src_width) &&
(dest_height * (subsample + 1) * 2 < src_width))
subsample += 1;
pixel_region_init (&srcPR, gimp_drawable_get_tiles (drawable),
src_x, src_y, src_width, src_height,
FALSE);
preview_buf = temp_buf_new (dest_width, dest_height, bytes, 0, 0, NULL);
pixel_region_init_temp_buf (&destPR, preview_buf,
0, 0, dest_width, dest_height);
if (GIMP_IS_LAYER (drawable))
{
gimp_drawable_preview_scale (gimp_drawable_type (drawable),
gimp_image_get_colormap (image),
&srcPR, &destPR,
subsample);
}
else if (GIMP_IS_CHANNEL (drawable))
{
subsample_region (&srcPR, &destPR, subsample);
}
return preview_buf;
}
/* private functions */
static TempBuf *
gimp_drawable_preview_private (GimpDrawable *drawable,
gint width,
gint height)
{
TempBuf *ret_buf;
if (! drawable->preview_valid ||
! (ret_buf = gimp_preview_cache_get (&drawable->preview_cache,
width, height)))
{
GimpItem *item = GIMP_ITEM (drawable);
ret_buf = gimp_drawable_get_sub_preview (drawable,
0, 0,
gimp_item_width (item),
gimp_item_height (item),
width,
height);
if (! drawable->preview_valid)
gimp_preview_cache_invalidate (&drawable->preview_cache);
drawable->preview_valid = TRUE;
gimp_preview_cache_add (&drawable->preview_cache, ret_buf);
}
return ret_buf;
}
static void
gimp_drawable_preview_scale (GimpImageType type,
const guchar *cmap,
PixelRegion *srcPR,
PixelRegion *destPR,
gint subsample)
{
#define EPSILON 0.000001
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;
g_return_if_fail (! GIMP_IMAGE_TYPE_IS_INDEXED (type) || 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 = GIMP_IMAGE_TYPE_HAS_ALPHA (type);
/* 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;
for (i = 0; i < width + orig_width; i++)
{
if (x_cum + x_rat <= (src_col + 1 + EPSILON))
{
x_cum += x_rat;
x_frac[i] = x_cum - x_last;
}
else
{
src_col++;
x_frac[i] = src_col - x_last;
}
x_last += x_frac[i];
}
/* counters... */
src_row = 0;
y_cum = (gdouble) src_row;
y_last = y_cum;
pixel_region_get_row (srcPR,
srcPR->x,
srcPR->y + src_row * subsample,
orig_width * subsample,
src,
subsample);
/* Scale the selected region */
for (i = 0; i < height; )
{
src_col = 0;
x_cum = (gdouble) src_col;
/* determine the fraction of the src pixel we are using for y */
if (y_cum + y_rat <= (src_row + 1 + EPSILON))
{
y_cum += y_rat;
y_frac = y_cum - y_last;
advance_dest = TRUE;
}
else
{
src_row++;
y_frac = src_row - y_last;
advance_dest = FALSE;
}
y_last += y_frac;
s = src;
r = row;
frac = 0;
j = width;
while (j)
{
tot_frac = x_frac[frac++] * y_frac;
/* If indexed, transform the color to RGB */
if (GIMP_IMAGE_TYPE_IS_INDEXED (type))
{
gint index = *s * 3;
if (has_alpha)
{
if (s[ALPHA_I_PIX] & 0x80)
{
r[RED_PIX] += cmap[index++] * tot_frac;
r[GREEN_PIX] += cmap[index++] * tot_frac;
r[BLUE_PIX] += cmap[index++] * tot_frac;
r[ALPHA_PIX] += tot_frac;
}
/* else the pixel contributes nothing and needs
* not to be added
*/
}
else
{
r[RED_PIX] += cmap[index++] * tot_frac;
r[GREEN_PIX] += cmap[index++] * tot_frac;
r[BLUE_PIX] += cmap[index++] * tot_frac;
}
}
else
{
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_cum + x_rat <= (src_col + 1 + EPSILON))
{
r += bytes;
x_cum += x_rat;
j--;
}
/* increment the source */
else
{
s += srcPR->bytes;
src_col++;
}
}
if (advance_dest)
{
tot_frac = 1.0 / (x_rat * y_rat);
/* copy "row" to "dest" */
d = dest;
r = row;
j = width;
while (j--)
{
if (has_alpha)
{
/* unpremultiply */
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;
/* clear the "row" array */
memset (row, 0, sizeof (gdouble) * destwidth);
i++;
}
else
{
pixel_region_get_row (srcPR,
srcPR->x,
srcPR->y + src_row * subsample,
orig_width * subsample,
src,
subsample);
}
}
/* free up temporary arrays */
g_free (row);
g_free (x_frac);
g_free (src);
}
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