## Utilities

Utilities — Utility and miscellaneous convenience functions.

## Synopsis

    #include <gdk-pixbuf/gdk-pixbuf.h>

    GdkPixbuf*  gdk_pixbuf_add_alpha            (const GdkPixbuf *pixbuf,
                                                 gboolean substitute_color,
                                                 guchar r,
                                                 guchar g,
                                                 guchar b);
    void        gdk_pixbuf_copy_area            (const GdkPixbuf *src_pixbuf,
                                                 int src_x,
                                                 int src_y,
                                                 int width,
                                                 int height,
                                                 GdkPixbuf *dest_pixbuf,
                                                 int dest_x,
                                                 int dest_y);
    void        gdk_pixbuf_saturate_and_pixelate
                                                (const GdkPixbuf *src,
                                                 GdkPixbuf *dest,
                                                 gfloat saturation,
                                                 gboolean pixelate);
    void        gdk_pixbuf_fill                 (GdkPixbuf *pixbuf,
                                                 guint32 pixel);

## Description

These functions provide miscellaneous utilities for manipulating pixbufs. The pixel data in pixbufs may of course be manipulated directly by applications, but several common operations can be performed by these functions instead.

## Details

### gdk_pixbuf_add_alpha ()

    GdkPixbuf*  gdk_pixbuf_add_alpha            (const GdkPixbuf *pixbuf,
                                                 gboolean substitute_color,
                                                 guchar r,
                                                 guchar g,
                                                 guchar b);

Takes an existing pixbuf and adds an alpha channel to it. If the existing pixbuf already had an alpha channel, the channel values are copied from the original; otherwise, the alpha channel is initialized to 255 (full opacity).

If `substitute_color` is `TRUE`, then the color specified by (`r`, `g`, `b`) will be assigned zero opacity. That is, if you pass (255, 255, 255) for the substitute color, all white pixels will become fully transparent.

`pixbuf` : | A GdkPixbuf.
`substitute_color` : | Whether to set a color to zero opacity. If this is `FALSE`, then the (`r`, `g`, `b`) arguments will be ignored.
`r` : | Red value to substitute.
`g` : | Green value to substitute.
`b` : | Blue value to substitute.
Returns : | A newly-created pixbuf with a reference count of 1.

### gdk_pixbuf_copy_area ()

    void        gdk_pixbuf_copy_area            (const GdkPixbuf *src_pixbuf,
                                                 int src_x,
                                                 int src_y,
                                                 int width,
                                                 int height,
                                                 GdkPixbuf *dest_pixbuf,
                                                 int dest_x,
                                                 int dest_y);

Copies a rectangular area from `src_pixbuf` to `dest_pixbuf`. Conversion of pixbuf formats is done automatically.

`src_pixbuf` : | Source pixbuf.
`src_x` : | Source X coordinate within `src_pixbuf`.
`src_y` : | Source Y coordinate within `src_pixbuf`.
`width` : | Width of the area to copy.
`height` : | Height of the area to copy.
`dest_pixbuf` : | Destination pixbuf.
`dest_x` : | X coordinate within `dest_pixbuf`.
`dest_y` : | Y coordinate within `dest_pixbuf`.

### gdk_pixbuf_saturate_and_pixelate ()

    void        gdk_pixbuf_saturate_and_pixelate
                                                (const GdkPixbuf *src,
                                                 GdkPixbuf *dest,
                                                 gfloat saturation,
                                                 gboolean pixelate);

Modifies saturation and optionally pixelates `src`, placing the result in `dest`. `src` and `dest` may be the same pixbuf with no ill effects. If `saturation` is 1.0 then saturation is not changed. If it's less than 1.0, saturation is reduced (the image turns toward grayscale); if greater than 1.0, saturation is increased (the image gets more vivid colors). If `pixelate` is `TRUE`, then pixels are faded in a checkerboard pattern to create a pixelated image. `src` and `dest` must have the same image format, size, and rowstride.

`src` : | source image
`dest` : | place to write modified version of `src`
`saturation` : | saturation factor
`pixelate` : | whether to pixelate

### gdk_pixbuf_fill ()

    void        gdk_pixbuf_fill                 (GdkPixbuf *pixbuf,
                                                 guint32 pixel);

Clears a pixbuf to the given RGBA value, converting the RGBA value into the pixbuf's pixel format. The alpha will be ignored if the pixbuf doesn't have an alpha channel.

`pixbuf` : | a GdkPixbuf
`pixel` : | RGBA pixel to clear to (0xffffffff is opaque white, 0x00000000 transparent black)

## See Also

GdkPixbuf