/* GdkPixbuf library - Scaling and compositing functions
*
* Copyright (C) 1999 The Free Software Foundation
*
* Author: Owen Taylor <otaylor@redhat.com>
*
* 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, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <math.h>
#include <string.h>
#include "gdk-pixbuf-transform.h"
#include "gdk-pixbuf-private.h"
#include "pixops/pixops.h"
/**
* SECTION:scaling
* @Short_description: Scaling pixbufs and scaling and alpha blending pixbufs
* @Title: Scaling
* @See_also: <link linkend="gdk-GdkRGB">GdkRGB</link>.
*
* The GdkPixBuf contains functions to scale pixbufs, to scale
* pixbufs and alpha blend against an existing image, and to scale
* pixbufs and alpha blend against a solid color or checkerboard.
* Alpha blending a checkerboard is a common way to show an image with
* an alpha channel in image-viewing and editing software.
*
* Note that in these functions, the terms ‘alpha blending’ and ‘compositing’
* are used synonymously.
*
* Since the full-featured functions (gdk_pixbuf_scale(),
* gdk_pixbuf_composite(), and gdk_pixbuf_composite_color()) are
* rather complex to use and have many arguments, two simple
* convenience functions are provided, gdk_pixbuf_scale_simple() and
* gdk_pixbuf_composite_color_simple() which create a new pixbuf of a
* given size, scale an original image to fit, and then return the
* new pixbuf.
*
* If the destination pixbuf was created from a readonly source, these
* operations will force a copy into a mutable buffer.
*
* Scaling and alpha blending functions take advantage of MMX hardware
* acceleration on systems where MMX is supported. If gdk-pixbuf is built
* with the Sun mediaLib library, these functions are instead accelerated
* using mediaLib, which provides hardware acceleration on Intel, AMD,
* and Sparc chipsets. If desired, mediaLib support can be turned off by
* setting the `GDK_DISABLE_MEDIALIB` environment variable.
*
* The alpha blending function used is:
* |[
* Cd = Cs·As + Cd(1-As)
* ]|
* where `Cd` is the destination pixel color, `Cs` is the source pixel color,
* and `As` is the source pixel alpha.
*
* The following example demonstrates handling an expose event by
* rendering the appropriate area of a source image (which is scaled
* to fit the widget) onto the widget's window. The source image is
* rendered against a checkerboard, which provides a visual
* representation of the alpha channel if the image has one. If the
* image doesn't have an alpha channel, calling
* gdk_pixbuf_composite_color() function has exactly the same effect
* as calling gdk_pixbuf_scale().
*
* ## Handling an expose event
*
* |[
* gboolean
* expose_cb (GtkWidget *widget, GdkEventExpose *event, gpointer data)
* {
* GdkPixbuf *dest;
*
* dest = gdk_pixbuf_new (GDK_COLORSPACE_RGB, FALSE, 8, event->area.width, event->area.height);
*
* gdk_pixbuf_composite_color (pixbuf, dest,
* 0, 0, event->area.width, event->area.height,
* -event->area.x, -event->area.y,
* (double) widget->allocation.width / gdk_pixbuf_get_width (pixbuf),
* (double) widget->allocation.height / gdk_pixbuf_get_height (pixbuf),
* GDK_INTERP_BILINEAR, 255,
* event->area.x, event->area.y, 16, 0xaaaaaa, 0x555555);
*
* gdk_draw_pixbuf (widget->window, widget->style->fg_gc[GTK_STATE_NORMAL], dest,
* 0, 0, event->area.x, event->area.y,
* event->area.width, event->area.height,
* GDK_RGB_DITHER_NORMAL, event->area.x, event->area.y);
*
* gdk_pixbuf_unref (dest);
*
* return TRUE;
* }
* ]|
*/
/**
* gdk_pixbuf_scale:
* @src: a #GdkPixbuf
* @dest: the #GdkPixbuf into which to render the results
* @dest_x: the left coordinate for region to render
* @dest_y: the top coordinate for region to render
* @dest_width: the width of the region to render
* @dest_height: the height of the region to render
* @offset_x: the offset in the X direction (currently rounded to an integer)
* @offset_y: the offset in the Y direction (currently rounded to an integer)
* @scale_x: the scale factor in the X direction
* @scale_y: the scale factor in the Y direction
* @interp_type: the interpolation type for the transformation.
*
* Creates a transformation of the source image @src by scaling by
* @scale_x and @scale_y then translating by @offset_x and @offset_y,
* then renders the rectangle (@dest_x, @dest_y, @dest_width,
* @dest_height) of the resulting image onto the destination image
* replacing the previous contents.
*
* Try to use gdk_pixbuf_scale_simple() first, this function is
* the industrial-strength power tool you can fall back to if
* gdk_pixbuf_scale_simple() isn't powerful enough.
*
* If the source rectangle overlaps the destination rectangle on the
* same pixbuf, it will be overwritten during the scaling which
* results in rendering artifacts.
**/
void
gdk_pixbuf_scale (const GdkPixbuf *src,
GdkPixbuf *dest,
int dest_x,
int dest_y,
int dest_width,
int dest_height,
double offset_x,
double offset_y,
double scale_x,
double scale_y,
GdkInterpType interp_type)
{
const guint8 *src_pixels;
guint8 *dest_pixels;
g_return_if_fail (GDK_IS_PIXBUF (src));
g_return_if_fail (GDK_IS_PIXBUF (dest));
g_return_if_fail (dest_x >= 0 && dest_x + dest_width <= dest->width);
g_return_if_fail (dest_y >= 0 && dest_y + dest_height <= dest->height);
offset_x = floor (offset_x + 0.5);
offset_y = floor (offset_y + 0.5);
/* Force an implicit copy */
dest_pixels = gdk_pixbuf_get_pixels (dest);
src_pixels = gdk_pixbuf_read_pixels (src);
_pixops_scale (dest_pixels, dest->width, dest->height, dest->rowstride,
dest->n_channels, dest->has_alpha, src_pixels, src->width,
src->height, src->rowstride, src->n_channels, src->has_alpha,
dest_x, dest_y, dest_width, dest_height, offset_x, offset_y,
scale_x, scale_y, (PixopsInterpType)interp_type);
}
/**
* gdk_pixbuf_composite:
* @src: a #GdkPixbuf
* @dest: the #GdkPixbuf into which to render the results
* @dest_x: the left coordinate for region to render
* @dest_y: the top coordinate for region to render
* @dest_width: the width of the region to render
* @dest_height: the height of the region to render
* @offset_x: the offset in the X direction (currently rounded to an integer)
* @offset_y: the offset in the Y direction (currently rounded to an integer)
* @scale_x: the scale factor in the X direction
* @scale_y: the scale factor in the Y direction
* @interp_type: the interpolation type for the transformation.
* @overall_alpha: overall alpha for source image (0..255)
*
* Creates a transformation of the source image @src by scaling by
* @scale_x and @scale_y then translating by @offset_x and @offset_y.
* This gives an image in the coordinates of the destination pixbuf.
* The rectangle (@dest_x, @dest_y, @dest_width, @dest_height)
* is then alpha blended onto the corresponding rectangle of the
* original destination image.
*
* When the destination rectangle contains parts not in the source
* image, the data at the edges of the source image is replicated
* to infinity.
*
* 
*/
void
gdk_pixbuf_composite (const GdkPixbuf *src,
GdkPixbuf *dest,
int dest_x,
int dest_y,
int dest_width,
int dest_height,
double offset_x,
double offset_y,
double scale_x,
double scale_y,
GdkInterpType interp_type,
int overall_alpha)
{
const guint8 *src_pixels;
guint8 *dest_pixels;
g_return_if_fail (GDK_IS_PIXBUF (src));
g_return_if_fail (GDK_IS_PIXBUF (dest));
g_return_if_fail (dest_x >= 0 && dest_x + dest_width <= dest->width);
g_return_if_fail (dest_y >= 0 && dest_y + dest_height <= dest->height);
g_return_if_fail (overall_alpha >= 0 && overall_alpha <= 255);
offset_x = floor (offset_x + 0.5);
offset_y = floor (offset_y + 0.5);
/* Force an implicit copy */
dest_pixels = gdk_pixbuf_get_pixels (dest);
src_pixels = gdk_pixbuf_read_pixels (src);
_pixops_composite (dest_pixels, dest->width, dest->height, dest->rowstride,
dest->n_channels, dest->has_alpha, src_pixels,
src->width, src->height, src->rowstride, src->n_channels,
src->has_alpha, dest_x, dest_y, dest_width, dest_height,
offset_x, offset_y, scale_x, scale_y,
(PixopsInterpType)interp_type, overall_alpha);
}
/**
* gdk_pixbuf_composite_color:
* @src: a #GdkPixbuf
* @dest: the #GdkPixbuf into which to render the results
* @dest_x: the left coordinate for region to render
* @dest_y: the top coordinate for region to render
* @dest_width: the width of the region to render
* @dest_height: the height of the region to render
* @offset_x: the offset in the X direction (currently rounded to an integer)
* @offset_y: the offset in the Y direction (currently rounded to an integer)
* @scale_x: the scale factor in the X direction
* @scale_y: the scale factor in the Y direction
* @interp_type: the interpolation type for the transformation.
* @overall_alpha: overall alpha for source image (0..255)
* @check_x: the X offset for the checkboard (origin of checkboard is at -@check_x, -@check_y)
* @check_y: the Y offset for the checkboard
* @check_size: the size of checks in the checkboard (must be a power of two)
* @color1: the color of check at upper left
* @color2: the color of the other check
*
* Creates a transformation of the source image @src by scaling by
* @scale_x and @scale_y then translating by @offset_x and @offset_y,
* then alpha blends the rectangle (@dest_x ,@dest_y, @dest_width,
* @dest_height) of the resulting image with a checkboard of the
* colors @color1 and @color2 and renders it onto the destination
* image.
*
* If the source image has no alpha channel, and @overall_alpha is 255, a fast
* path is used which omits the alpha blending and just performs the scaling.
*
* See gdk_pixbuf_composite_color_simple() for a simpler variant of this
* function suitable for many tasks.
*
**/
void
gdk_pixbuf_composite_color (const GdkPixbuf *src,
GdkPixbuf *dest,
int dest_x,
int dest_y,
int dest_width,
int dest_height,
double offset_x,
double offset_y,
double scale_x,
double scale_y,
GdkInterpType interp_type,
int overall_alpha,
int check_x,
int check_y,
int check_size,
guint32 color1,
guint32 color2)
{
const guint8 *src_pixels;
guint8 *dest_pixels;
g_return_if_fail (GDK_IS_PIXBUF (src));
g_return_if_fail (GDK_IS_PIXBUF (dest));
g_return_if_fail (dest_x >= 0 && dest_x + dest_width <= dest->width);
g_return_if_fail (dest_y >= 0 && dest_y + dest_height <= dest->height);
g_return_if_fail (overall_alpha >= 0 && overall_alpha <= 255);
offset_x = floor (offset_x + 0.5);
offset_y = floor (offset_y + 0.5);
/* Force an implicit copy */
dest_pixels = gdk_pixbuf_get_pixels (dest);
src_pixels = gdk_pixbuf_read_pixels (src);
_pixops_composite_color (dest_pixels, dest_width, dest_height,
dest->rowstride, dest->n_channels, dest->has_alpha,
src_pixels, src->width, src->height,
src->rowstride, src->n_channels, src->has_alpha,
dest_x, dest_y, dest_width, dest_height, offset_x,
offset_y, scale_x, scale_y,
(PixopsInterpType)interp_type, overall_alpha,
check_x, check_y, check_size, color1, color2);
}
/**
* gdk_pixbuf_scale_simple:
* @src: a #GdkPixbuf
* @dest_width: the width of destination image
* @dest_height: the height of destination image
* @interp_type: the interpolation type for the transformation.
*
* Create a new #GdkPixbuf containing a copy of @src scaled to
* @dest_width x @dest_height. Leaves @src unaffected. @interp_type
* should be #GDK_INTERP_NEAREST if you want maximum speed (but when
* scaling down #GDK_INTERP_NEAREST is usually unusably ugly). The
* default @interp_type should be #GDK_INTERP_BILINEAR which offers
* reasonable quality and speed.
*
* You can scale a sub-portion of @src by creating a sub-pixbuf
* pointing into @src; see gdk_pixbuf_new_subpixbuf().
*
* If @dest_width and @dest_height are equal to the @src width and height, a
* copy of @src is returned, avoiding any scaling.
*
* For more complicated scaling/alpha blending see gdk_pixbuf_scale()
* and gdk_pixbuf_composite().
*
* Return value: (transfer full): the new #GdkPixbuf, or %NULL if not enough memory could be
* allocated for it.
**/
GdkPixbuf *
gdk_pixbuf_scale_simple (const GdkPixbuf *src,
int dest_width,
int dest_height,
GdkInterpType interp_type)
{
GdkPixbuf *dest;
g_return_val_if_fail (GDK_IS_PIXBUF (src), NULL);
g_return_val_if_fail (dest_width > 0, NULL);
g_return_val_if_fail (dest_height > 0, NULL);
/* Fast path. */
if (dest_width == src->width && dest_height == src->height)
return gdk_pixbuf_copy (src);
dest = gdk_pixbuf_new (GDK_COLORSPACE_RGB, src->has_alpha, 8, dest_width, dest_height);
if (!dest)
return NULL;
gdk_pixbuf_scale (src, dest, 0, 0, dest_width, dest_height, 0, 0,
(double) dest_width / src->width,
(double) dest_height / src->height,
interp_type);
return dest;
}
/**
* gdk_pixbuf_composite_color_simple:
* @src: a #GdkPixbuf
* @dest_width: the width of destination image
* @dest_height: the height of destination image
* @interp_type: the interpolation type for the transformation.
* @overall_alpha: overall alpha for source image (0..255)
* @check_size: the size of checks in the checkboard (must be a power of two)
* @color1: the color of check at upper left
* @color2: the color of the other check
*
* Creates a new #GdkPixbuf by scaling @src to @dest_width x
* @dest_height and alpha blending the result with a checkboard of colors
* @color1 and @color2.
*
* Return value: (transfer full): the new #GdkPixbuf, or %NULL if not enough memory could be
* allocated for it.
**/
GdkPixbuf *
gdk_pixbuf_composite_color_simple (const GdkPixbuf *src,
int dest_width,
int dest_height,
GdkInterpType interp_type,
int overall_alpha,
int check_size,
guint32 color1,
guint32 color2)
{
GdkPixbuf *dest;
g_return_val_if_fail (GDK_IS_PIXBUF (src), NULL);
g_return_val_if_fail (dest_width > 0, NULL);
g_return_val_if_fail (dest_height > 0, NULL);
g_return_val_if_fail (overall_alpha >= 0 && overall_alpha <= 255, NULL);
dest = gdk_pixbuf_new (GDK_COLORSPACE_RGB, src->has_alpha, 8, dest_width, dest_height);
if (!dest)
return NULL;
gdk_pixbuf_composite_color (src, dest, 0, 0, dest_width, dest_height, 0, 0,
(double) dest_width / src->width,
(double) dest_height / src->height,
interp_type, overall_alpha, 0, 0, check_size, color1, color2);
return dest;
}
#define OFFSET(pb, x, y) ((x) * (pb)->n_channels + (gsize)(y) * (pb)->rowstride)
/**
* gdk_pixbuf_rotate_simple:
* @src: a #GdkPixbuf
* @angle: the angle to rotate by
*
* Rotates a pixbuf by a multiple of 90 degrees, and returns the
* result in a new pixbuf.
*
* If @angle is 0, a copy of @src is returned, avoiding any rotation.
*
* Returns: (nullable) (transfer full): the new #GdkPixbuf, or %NULL
* if not enough memory could be allocated for it.
*
* Since: 2.6
*/
GdkPixbuf *
gdk_pixbuf_rotate_simple (const GdkPixbuf *src,
GdkPixbufRotation angle)
{
const guint8 *src_pixels;
guint8 *dest_pixels;
GdkPixbuf *dest;
const guchar *p;
guchar *q;
gint x, y;
g_return_val_if_fail (GDK_IS_PIXBUF (src), NULL);
src_pixels = gdk_pixbuf_read_pixels (src);
switch (angle % 360)
{
case 0:
dest = gdk_pixbuf_copy (src);
break;
case 90:
dest = gdk_pixbuf_new (src->colorspace,
src->has_alpha,
src->bits_per_sample,
src->height,
src->width);
if (!dest)
return NULL;
dest_pixels = gdk_pixbuf_get_pixels (dest);
for (y = 0; y < src->height; y++)
{
for (x = 0; x < src->width; x++)
{
p = src_pixels + OFFSET (src, x, y);
q = dest_pixels + OFFSET (dest, y, src->width - x - 1);
memcpy (q, p, dest->n_channels);
}
}
break;
case 180:
dest = gdk_pixbuf_new (src->colorspace,
src->has_alpha,
src->bits_per_sample,
src->width,
src->height);
if (!dest)
return NULL;
dest_pixels = gdk_pixbuf_get_pixels (dest);
for (y = 0; y < src->height; y++)
{
for (x = 0; x < src->width; x++)
{
p = src_pixels + OFFSET (src, x, y);
q = dest_pixels + OFFSET (dest, src->width - x - 1, src->height - y - 1);
memcpy (q, p, dest->n_channels);
}
}
break;
case 270:
dest = gdk_pixbuf_new (src->colorspace,
src->has_alpha,
src->bits_per_sample,
src->height,
src->width);
if (!dest)
return NULL;
dest_pixels = gdk_pixbuf_get_pixels (dest);
for (y = 0; y < src->height; y++)
{
for (x = 0; x < src->width; x++)
{
p = src_pixels + OFFSET (src, x, y);
q = dest_pixels + OFFSET (dest, src->height - y - 1, x);
memcpy (q, p, dest->n_channels);
}
}
break;
default:
dest = NULL;
g_warning ("gdk_pixbuf_rotate_simple() can only rotate "
"by multiples of 90 degrees");
g_assert_not_reached ();
}
return dest;
}
/**
* gdk_pixbuf_flip:
* @src: a #GdkPixbuf
* @horizontal: %TRUE to flip horizontally, %FALSE to flip vertically
*
* Flips a pixbuf horizontally or vertically and returns the
* result in a new pixbuf.
*
* Returns: (nullable) (transfer full): the new #GdkPixbuf, or %NULL
* if not enough memory could be allocated for it.
*
* Since: 2.6
*/
GdkPixbuf *
gdk_pixbuf_flip (const GdkPixbuf *src,
gboolean horizontal)
{
const guint8 *src_pixels;
guint8 *dest_pixels;
GdkPixbuf *dest;
const guchar *p;
guchar *q;
gint x, y;
g_return_val_if_fail (GDK_IS_PIXBUF (src), NULL);
dest = gdk_pixbuf_new (src->colorspace,
src->has_alpha,
src->bits_per_sample,
src->width,
src->height);
if (!dest)
return NULL;
dest_pixels = gdk_pixbuf_get_pixels (dest);
src_pixels = gdk_pixbuf_read_pixels (src);
if (!horizontal) /* flip vertical */
{
for (y = 0; y < dest->height; y++)
{
p = src_pixels + OFFSET (src, 0, y);
q = dest_pixels + OFFSET (dest, 0, dest->height - y - 1);
memcpy (q, p, dest->rowstride);
}
}
else /* flip horizontal */
{
for (y = 0; y < dest->height; y++)
{
for (x = 0; x < dest->width; x++)
{
p = src_pixels + OFFSET (src, x, y);
q = dest_pixels + OFFSET (dest, dest->width - x - 1, y);
memcpy (q, p, dest->n_channels);
}
}
}
return dest;
}