static void
_boxblur (guchar *buffer,
int width,
int height,
int radius,
GskBlurFlags flags)
{
guchar *flipped_buffer;
int d = get_box_filter_size (radius);
flipped_buffer = g_malloc (width * height);
if (flags & GSK_BLUR_Y)
{
/* Step 1: swap rows and columns */
flip_buffer (flipped_buffer, buffer, width, height);
/* Step 2: blur rows (really columns) */
blur_rows (flipped_buffer, buffer, height, width, d);
/* Step 3: swap rows and columns */
flip_buffer (buffer, flipped_buffer, height, width);
}
if (flags & GSK_BLUR_X)
{
/* Step 4: blur rows */
blur_rows (buffer, flipped_buffer, width, height, d);
}
g_free (flipped_buffer);
}
/* The "spread" of the filter is the number of pixels from an original
* pixel that it's blurred image extends. (A no-op blur that doesn't
* blur would have a spread of 0.) See comment in blur_rows() for why the
* odd and even cases are different
*/
static int
get_shadow_spread (int radius)
{
int d = get_box_filter_size (radius);
if (d % 2 == 1)
return 3 * (d / 2);
else
return 3 * (d / 2) - 1;
}
static void
make_shadow (MetaShadow *shadow,
cairo_region_t *region)
{
int d = get_box_filter_size (shadow->key.radius);
int spread = get_shadow_spread (shadow->key.radius);
cairo_rectangle_int_t extents;
cairo_region_t *row_convolve_region;
cairo_region_t *column_convolve_region;
guchar *buffer;
int buffer_width;
int buffer_height;
int x_offset;
int y_offset;
int n_rectangles, j, k;
cairo_region_get_extents (region, &extents);
/* In the case where top_fade >= 0 and the portion above the top
* edge of the shape will be cropped, it seems like we could create
* a smaller buffer and omit the top portion, but actually, in our
* multi-pass blur algorithm, the blur into the area above the window
* in the first pass will contribute back to the final pixel values
* for the top pixels, so we create a buffer as if we weren't cropping
* and only crop when creating the CoglTexture.
*/
buffer_width = extents.width + 2 * spread;
buffer_height = extents.height + 2 * spread;
/* Round up so we have aligned rows/columns */
buffer_width = (buffer_width + 3) & ~3;
buffer_height = (buffer_height + 3) & ~3;
/* Square buffer allows in-place swaps, which are roughly 70% faster, but we
* don't want to over-allocate too much memory.
*/
if (buffer_height < buffer_width && buffer_height > (3 * buffer_width) / 4)
buffer_height = buffer_width;
if (buffer_width < buffer_height && buffer_width > (3 * buffer_height) / 4)
buffer_width = buffer_height;
buffer = g_malloc0 (buffer_width * buffer_height);
/* Blurring with multiple box-blur passes is fast, but (especially for
* large shadow sizes) we can improve efficiency by restricting the blur
* to the region that actually needs to be blurred.
*/
row_convolve_region = meta_make_border_region (region, spread, spread, FALSE);
column_convolve_region = meta_make_border_region (region, 0, spread, TRUE);
/* Offsets between coordinates of the regions and coordinates in the buffer */
x_offset = spread;
y_offset = spread;
/* Step 1: unblurred image */
n_rectangles = cairo_region_num_rectangles (region);
for (k = 0; k < n_rectangles; k++)
{
cairo_rectangle_int_t rect;
cairo_region_get_rectangle (region, k, &rect);
for (j = y_offset + rect.y; j < y_offset + rect.y + rect.height; j++)
memset (buffer + buffer_width * j + x_offset + rect.x, 255, rect.width);
}
/* Step 2: swap rows and columns */
buffer = flip_buffer (buffer, buffer_width, buffer_height);
/* Step 3: blur rows (really columns) */
blur_rows (column_convolve_region, y_offset, x_offset,
buffer, buffer_height, buffer_width,
d);
/* Step 4: swap rows and columns */
buffer = flip_buffer (buffer, buffer_height, buffer_width);
/* Step 5: blur rows */
blur_rows (row_convolve_region, x_offset, y_offset,
buffer, buffer_width, buffer_height,
d);
/* Step 6: fade out the top, if applicable */
if (shadow->key.top_fade >= 0)
{
for (j = y_offset; j < y_offset + MIN (shadow->key.top_fade, extents.height + shadow->outer_border_bottom); j++)
fade_bytes(buffer + j * buffer_width, buffer_width, j - y_offset, shadow->key.top_fade);
}
/* We offset the passed in pixels to crop off the extra area we allocated at the top
* in the case of top_fade >= 0. We also account for padding at the left for symmetry
* though that doesn't currently occur.
*/
shadow->texture = cogl_texture_new_from_data (shadow->outer_border_left + extents.width + shadow->outer_border_right,
shadow->outer_border_top + extents.height + shadow->outer_border_bottom,
COGL_TEXTURE_NONE,
COGL_PIXEL_FORMAT_A_8,
COGL_PIXEL_FORMAT_ANY,
buffer_width,
(buffer +
(y_offset - shadow->outer_border_top) * buffer_width +
(x_offset - shadow->outer_border_left)));
cairo_region_destroy (row_convolve_region);
cairo_region_destroy (column_convolve_region);
g_free (buffer);
shadow->material = meta_create_texture_material (shadow->texture);
}
