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.

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.

If the source rectangle overlaps the destination rectangle on the same pixbuf, it will be overwritten during the copy operation. Therefore, you can not use this function to scroll a 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.

gdk_pixbuf_apply_embedded_orientation ()

GdkPixbuf*          gdk_pixbuf_apply_embedded_orientation
                                                        (GdkPixbuf *src);

Takes an existing pixbuf and checks for the presence of an associated "orientation" option, which may be provided by the jpeg loader (which reads the exif orientation tag) or the tiff loader (which reads the tiff orientation tag, and compensates it for the partial transforms performed by libtiff). If an orientation option/tag is present, the appropriate transform will be performed so that the pixbuf is oriented correctly.

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.