gtk2/docs/tools/shadow.c

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#include "shadow.h"
#include <math.h>
#define BLUR_RADIUS 5
#define SHADOW_OFFSET (BLUR_RADIUS * 4 / 5)
#define SHADOW_OPACITY 0.75
typedef struct {
int size;
double *data;
} ConvFilter;
static double
gaussian (double x, double y, double r)
{
return ((1 / (2 * M_PI * r)) *
exp ((- (x * x + y * y)) / (2 * r * r)));
}
static ConvFilter *
create_blur_filter (int radius)
{
ConvFilter *filter;
int x, y;
double sum;
filter = g_new0 (ConvFilter, 1);
filter->size = radius * 2 + 1;
filter->data = g_new (double, filter->size * filter->size);
sum = 0.0;
for (y = 0 ; y < filter->size; y++)
{
for (x = 0 ; x < filter->size; x++)
{
sum += filter->data[y * filter->size + x] = gaussian (x - (filter->size >> 1),
y - (filter->size >> 1),
radius);
}
}
for (y = 0; y < filter->size; y++)
{
for (x = 0; x < filter->size; x++)
{
filter->data[y * filter->size + x] /= sum;
}
}
return filter;
}
static GdkPixbuf *
create_shadow (GdkPixbuf *src)
{
int x, y, i, j;
int width, height;
GdkPixbuf *dest;
static ConvFilter *filter = NULL;
int src_rowstride, dest_rowstride;
int src_bpp, dest_bpp;
guchar *src_pixels, *dest_pixels;
if (!filter)
filter = create_blur_filter (BLUR_RADIUS);
width = gdk_pixbuf_get_width (src) + BLUR_RADIUS * 2 + SHADOW_OFFSET;
height = gdk_pixbuf_get_height (src) + BLUR_RADIUS * 2 + SHADOW_OFFSET;
dest = gdk_pixbuf_new (gdk_pixbuf_get_colorspace (src),
gdk_pixbuf_get_has_alpha (src),
gdk_pixbuf_get_bits_per_sample (src),
width, height);
gdk_pixbuf_fill (dest, 0);
src_pixels = gdk_pixbuf_get_pixels (src);
src_rowstride = gdk_pixbuf_get_rowstride (src);
src_bpp = gdk_pixbuf_get_has_alpha (src) ? 4 : 3;
dest_pixels = gdk_pixbuf_get_pixels (dest);
dest_rowstride = gdk_pixbuf_get_rowstride (dest);
dest_bpp = gdk_pixbuf_get_has_alpha (dest) ? 4 : 3;
for (y = 0; y < height; y++)
{
for (x = 0; x < width; x++)
{
int sumr = 0, sumg = 0, sumb = 0, suma = 0;
for (i = 0; i < filter->size; i++)
{
for (j = 0; j < filter->size; j++)
{
int src_x, src_y;
src_y = -(BLUR_RADIUS + SHADOW_OFFSET) + y - (filter->size >> 1) + i;
src_x = -(BLUR_RADIUS + SHADOW_OFFSET) + x - (filter->size >> 1) + j;
if (src_y < 0 || src_y > gdk_pixbuf_get_height (src) ||
src_x < 0 || src_x > gdk_pixbuf_get_width (src))
continue;
sumr += src_pixels [src_y * src_rowstride +
src_x * src_bpp + 0] *
filter->data [i * filter->size + j];
sumg += src_pixels [src_y * src_rowstride +
src_x * src_bpp + 1] *
filter->data [i * filter->size + j];
sumb += src_pixels [src_y * src_rowstride +
src_x * src_bpp + 2] *
filter->data [i * filter->size + j];
if (src_bpp == 4)
suma += src_pixels [src_y * src_rowstride +
src_x * src_bpp + 3] *
filter->data [i * filter->size + j];
}
}
if (dest_bpp == 4)
dest_pixels [y * dest_rowstride +
x * dest_bpp + 3] = suma * SHADOW_OPACITY;
}
}
return dest;
}
GdkPixbuf *
create_shadowed_pixbuf (GdkPixbuf *src)
{
GdkPixbuf *dest;
dest = create_shadow (src);
gdk_pixbuf_composite (src, dest,
BLUR_RADIUS, BLUR_RADIUS,
gdk_pixbuf_get_width (src),
gdk_pixbuf_get_height (src),
BLUR_RADIUS, BLUR_RADIUS, 1.0, 1.0,
GDK_INTERP_NEAREST, 255);
return dest;
}