gtk/gdk/gdkpixbuf-render.c
Havoc Pennington fcaa719b7d Clip the rectangle to be rendered to the drawable, since
2000-11-01  Havoc Pennington  <hp@redhat.com>

	* gdk/gdkpixbuf-render.c (gdk_pixbuf_render_to_drawable_alpha):
	Clip the rectangle to be rendered to the drawable, since
	get_from_drawable() requires a region within the drawable
2000-11-01 16:34:23 +00:00

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/* GdkPixbuf library - Rendering functions
*
* Copyright (C) 1999 The Free Software Foundation
*
* Author: Federico Mena-Quintero <federico@gimp.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <config.h>
#include <gdk/gdk.h>
#include "gdk-pixbuf-private.h"
#include "gdkpixbuf.h"
/**
* gdk_pixbuf_render_threshold_alpha:
* @pixbuf: A pixbuf.
* @bitmap: Bitmap where the bilevel mask will be painted to.
* @src_x: Source X coordinate.
* @src_y: source Y coordinate.
* @dest_x: Destination X coordinate.
* @dest_y: Destination Y coordinate.
* @width: Width of region to threshold.
* @height: Height of region to threshold.
* @alpha_threshold: Opacity values below this will be painted as zero; all
* other values will be painted as one.
*
* Takes the opacity values in a rectangular portion of a pixbuf and thresholds
* them to produce a bi-level alpha mask that can be used as a clipping mask for
* a drawable.
*
**/
void
gdk_pixbuf_render_threshold_alpha (GdkPixbuf *pixbuf,
GdkBitmap *bitmap,
int src_x, int src_y,
int dest_x, int dest_y,
int width, int height,
int alpha_threshold)
{
GdkGC *gc;
GdkColor color;
int x, y;
guchar *p;
int start, start_status;
int status;
g_return_if_fail (pixbuf != NULL);
g_return_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB);
g_return_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4);
g_return_if_fail (pixbuf->bits_per_sample == 8);
g_return_if_fail (bitmap != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= pixbuf->width);
g_return_if_fail (src_y >= 0 && src_y + height <= pixbuf->height);
g_return_if_fail (alpha_threshold >= 0 && alpha_threshold <= 255);
if (width == 0 || height == 0)
return;
gc = gdk_gc_new (bitmap);
if (!pixbuf->has_alpha)
{
color.pixel = (alpha_threshold == 255) ? 0 : 1;
gdk_gc_set_foreground (gc, &color);
gdk_draw_rectangle (bitmap, gc, TRUE, dest_x, dest_y, width, height);
gdk_gc_unref (gc);
return;
}
color.pixel = 0;
gdk_gc_set_foreground (gc, &color);
gdk_draw_rectangle (bitmap, gc, TRUE, dest_x, dest_y, width, height);
color.pixel = 1;
gdk_gc_set_foreground (gc, &color);
for (y = 0; y < height; y++)
{
p = (pixbuf->pixels + (y + src_y) * pixbuf->rowstride + src_x * pixbuf->n_channels
+ pixbuf->n_channels - 1);
start = 0;
start_status = *p < alpha_threshold;
for (x = 0; x < width; x++)
{
status = *p < alpha_threshold;
if (status != start_status)
{
if (!start_status)
gdk_draw_line (bitmap, gc,
start + dest_x, y + dest_y,
x - 1 + dest_x, y + dest_y);
start = x;
start_status = status;
}
p += pixbuf->n_channels;
}
if (!start_status)
gdk_draw_line (bitmap, gc,
start + dest_x, y + dest_y,
x - 1 + dest_x, y + dest_y);
}
gdk_gc_unref (gc);
}
/**
* gdk_pixbuf_render_to_drawable:
* @pixbuf: A pixbuf.
* @drawable: Destination drawable.
* @gc: GC used for rendering.
* @src_x: Source X coordinate within pixbuf.
* @src_y: Source Y coordinate within pixbuf.
* @dest_x: Destination X coordinate within drawable.
* @dest_y: Destination Y coordinate within drawable.
* @width: Width of region to render, in pixels.
* @height: Height of region to render, in pixels.
* @dither: Dithering mode for GdkRGB.
* @x_dither: X offset for dither.
* @y_dither: Y offset for dither.
*
* Renders a rectangular portion of a pixbuf to a drawable while using the
* specified GC. This is done using GdkRGB, so the specified drawable must have
* the GdkRGB visual and colormap. Note that this function will ignore the
* opacity information for images with an alpha channel; the GC must already
* have the clipping mask set if you want transparent regions to show through.
*
* For an explanation of dither offsets, see the GdkRGB documentation. In
* brief, the dither offset is important when re-rendering partial regions of an
* image to a rendered version of the full image, or for when the offsets to a
* base position change, as in scrolling. The dither matrix has to be shifted
* for consistent visual results. If you do not have any of these cases, the
* dither offsets can be both zero.
**/
void
gdk_pixbuf_render_to_drawable (GdkPixbuf *pixbuf,
GdkDrawable *drawable,
GdkGC *gc,
int src_x, int src_y,
int dest_x, int dest_y,
int width, int height,
GdkRgbDither dither,
int x_dither, int y_dither)
{
int rowstride;
guchar *buf;
g_return_if_fail (pixbuf != NULL);
g_return_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB);
g_return_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4);
g_return_if_fail (pixbuf->bits_per_sample == 8);
g_return_if_fail (drawable != NULL);
g_return_if_fail (gc != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= pixbuf->width);
g_return_if_fail (src_y >= 0 && src_y + height <= pixbuf->height);
if (width == 0 || height == 0)
return;
/* This will have to be modified once we support other image types.
*/
if (pixbuf->n_channels == 4)
{
buf = pixbuf->pixels + src_y * pixbuf->rowstride + src_x * 4;
rowstride = pixbuf->rowstride;
gdk_draw_rgb_32_image_dithalign (drawable, gc,
dest_x, dest_y,
width, height,
dither,
buf, rowstride,
x_dither, y_dither);
}
else /* n_channels == 3 */
{
buf = pixbuf->pixels + src_y * pixbuf->rowstride + src_x * 3;
rowstride = pixbuf->rowstride;
gdk_draw_rgb_image_dithalign (drawable, gc,
dest_x, dest_y,
width, height,
dither,
buf, rowstride,
x_dither, y_dither);
}
}
/**
* gdk_pixbuf_render_to_drawable_alpha:
* @pixbuf: A pixbuf.
* @drawable: Destination drawable.
* @src_x: Source X coordinate within pixbuf.
* @src_y: Source Y coordinates within pixbuf.
* @dest_x: Destination X coordinate within drawable.
* @dest_y: Destination Y coordinate within drawable.
* @width: Width of region to render, in pixels.
* @height: Height of region to render, in pixels.
* @alpha_mode: If the image does not have opacity information, this is ignored.
* Otherwise, specifies how to handle transparency when rendering.
* @alpha_threshold: If the image does have opacity information and @alpha_mode
* is GDK_PIXBUF_ALPHA_BILEVEL, specifies the threshold value for opacity
* values.
* @dither: Dithering mode for GdkRGB.
* @x_dither: X offset for dither.
* @y_dither: Y offset for dither.
*
* Renders a rectangular portion of a pixbuf to a drawable. This is done using
* GdkRGB, so the specified drawable must have the GdkRGB visual and colormap.
*
* When used with #GDK_PIXBUF_ALPHA_BILEVEL, this function has to create a bitmap
* out of the thresholded alpha channel of the image and, it has to set this
* bitmap as the clipping mask for the GC used for drawing. This can be a
* significant performance penalty depending on the size and the complexity of
* the alpha channel of the image. If performance is crucial, consider handling
* the alpha channel yourself (possibly by caching it in your application) and
* using gdk_pixbuf_render_to_drawable() or GdkRGB directly instead.
*
* The #GDK_PIXBUF_ALPHA_FULL mode involves round trips to the X
* server, and may also be somewhat slow in its current implementation
* (though in the future it could be made significantly faster, in
* principle).
**/
void
gdk_pixbuf_render_to_drawable_alpha (GdkPixbuf *pixbuf,
GdkDrawable *drawable,
int src_x, int src_y,
int dest_x, int dest_y,
int width, int height,
GdkPixbufAlphaMode alpha_mode,
int alpha_threshold,
GdkRgbDither dither,
int x_dither, int y_dither)
{
GdkBitmap *bitmap = NULL;
GdkGC *gc;
GdkPixbuf *composited = NULL;
gint dwidth, dheight;
g_return_if_fail (pixbuf != NULL);
g_return_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB);
g_return_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4);
g_return_if_fail (pixbuf->bits_per_sample == 8);
g_return_if_fail (drawable != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= pixbuf->width);
g_return_if_fail (src_y >= 0 && src_y + height <= pixbuf->height);
/* Clip to the drawable; this is required for get_from_drawable() so
* can't be done implicitly
*/
if (dest_x < 0)
{
src_x -= dest_x;
width += dest_x;
dest_x = 0;
}
if (dest_y < 0)
{
src_y -= dest_y;
height += dest_y;
dest_y = 0;
}
gdk_drawable_get_size (drawable, &dwidth, &dheight);
if ((dest_x + width) > dwidth)
width = dwidth - dest_x;
if ((dest_y + height) > dheight)
height = dheight - dest_y;
if (width <= 0 || height <= 0)
return;
/* Actually draw */
gc = gdk_gc_new (drawable);
if (pixbuf->has_alpha)
{
if (alpha_mode == GDK_PIXBUF_ALPHA_BILEVEL)
{
bitmap = gdk_pixmap_new (NULL, width, height, 1);
gdk_pixbuf_render_threshold_alpha (pixbuf, bitmap,
src_x, src_y,
0, 0,
width, height,
alpha_threshold);
gdk_gc_set_clip_mask (gc, bitmap);
gdk_gc_set_clip_origin (gc, dest_x, dest_y);
}
else if (alpha_mode == GDK_PIXBUF_ALPHA_FULL)
{
GdkPixbuf *sub = NULL;
composited = gdk_pixbuf_get_from_drawable (NULL,
drawable,
NULL,
dest_x, dest_y,
0, 0,
width, height);
if (src_x != 0 || src_y != 0)
{
sub = gdk_pixbuf_new_subpixbuf (pixbuf, src_x, src_y,
width, height);
}
gdk_pixbuf_composite (sub ? sub : pixbuf,
composited,
0, 0,
width, height,
0, 0,
1.0, 1.0,
GDK_INTERP_BILINEAR,
255);
if (sub)
g_object_unref (G_OBJECT (sub));
}
}
if (composited)
{
gdk_pixbuf_render_to_drawable (composited,
drawable, gc,
0, 0,
dest_x, dest_y,
width, height,
dither,
x_dither, y_dither);
}
else
{
gdk_pixbuf_render_to_drawable (pixbuf,
drawable, gc,
src_x, src_y,
dest_x, dest_y,
width, height,
dither,
x_dither, y_dither);
}
if (bitmap)
gdk_bitmap_unref (bitmap);
if (composited)
g_object_unref (G_OBJECT (composited));
gdk_gc_unref (gc);
}
/**
* gdk_pixbuf_render_pixmap_and_mask:
* @pixbuf: A pixbuf.
* @pixmap_return: Return value for the created pixmap.
* @mask_return: Return value for the created mask.
* @alpha_threshold: Threshold value for opacity values.
*
* Creates a pixmap and a mask bitmap which are returned in the @pixmap_return
* and @mask_return arguments, respectively, and renders a pixbuf and its
* corresponding tresholded alpha mask to them. This is merely a convenience
* function; applications that need to render pixbufs with dither offsets or to
* given drawables should use gdk_pixbuf_render_to_drawable_alpha() or
* gdk_pixbuf_render_to_drawable(), and gdk_pixbuf_render_threshold_alpha().
*
* If the pixbuf does not have an alpha channel, then *@mask_return will be set
* to NULL.
**/
void
gdk_pixbuf_render_pixmap_and_mask (GdkPixbuf *pixbuf,
GdkPixmap **pixmap_return,
GdkBitmap **mask_return,
int alpha_threshold)
{
g_return_if_fail (pixbuf != NULL);
if (pixmap_return)
{
GdkGC *gc;
*pixmap_return = gdk_pixmap_new (NULL, pixbuf->width, pixbuf->height,
gdk_rgb_get_visual ()->depth);
gc = gdk_gc_new (*pixmap_return);
gdk_pixbuf_render_to_drawable (pixbuf, *pixmap_return, gc,
0, 0, 0, 0,
pixbuf->width, pixbuf->height,
GDK_RGB_DITHER_NORMAL,
0, 0);
gdk_gc_unref (gc);
}
if (mask_return)
{
if (pixbuf->has_alpha)
{
*mask_return = gdk_pixmap_new (NULL, pixbuf->width, pixbuf->height, 1);
gdk_pixbuf_render_threshold_alpha (pixbuf, *mask_return,
0, 0, 0, 0,
pixbuf->width, pixbuf->height,
alpha_threshold);
}
else
*mask_return = NULL;
}
}