gecko/gfx/thebes/cairo-gdk-utils.h

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#ifndef CAIROGDKUTILS_H_
#define CAIROGDKUTILS_H_

#include "cairo.h"
#include <gdk/gdk.h>

CAIRO_BEGIN_DECLS

/**
 * This callback encapsulates GDK-based rendering. We assume that the
 * execution of the callback is equivalent to compositing some RGBA image of
 * size (bounds_width, bounds_height) onto the drawable at offset (offset_x,
 * offset_y), clipped to the union of the clip_rects if num_rects is greater
 * than zero. This includes the assumption that the same RGBA image
 * is composited if you call the callback multiple times with the same closure,
 * display and visual during a single cairo_draw_with_gdk call.
 * 
 * @return True when able to draw, False otherwise
 */
typedef cairo_bool_t (* cairo_gdk_drawing_callback)
    (void *closure,
     cairo_surface_t *surface,
     short offset_x, short offset_y,
     GdkRectangle * clip_rects, unsigned int num_rects);

/**
 * This type specifies whether the native drawing callback draws all pixels
 * in its bounds opaquely, independent of the contents of the target drawable,
 * or whether it leaves pixels transparent/translucent or depends on the
 * existing contents of the target drawable in some way.
 */
typedef enum _cairo_gdk_drawing_opacity {
    CAIRO_GDK_DRAWING_OPAQUE,
    CAIRO_GDK_DRAWING_TRANSPARENT
} cairo_gdk_drawing_opacity_t;

/**
 * This type encodes the capabilities of the native drawing callback.
 * 
 * If CAIRO_GDK_DRAWING_SUPPORTS_CLIP_RECT is set, then 'num_rects' can be
 * zero or one in the call to the callback. Otherwise 'num_rects' will be
 * zero.
 */
typedef enum {
    CAIRO_GDK_DRAWING_SUPPORTS_CLIP_RECT = 0x02,
} cairo_gdk_drawing_support_t;

/**
 * Draw GDK output into any cairo context. All cairo transforms and effects
 * are honored, including the current operator. This is equivalent to a
 * cairo_set_source_surface and then cairo_paint.
 * @param cr the context to draw into
 * @param drawable a GDK Drawable that we're targetting
 * @param callback the code to perform GDK rendering
 * @param closure associated data
 * @param width the width of the putative image drawn by the callback
 * @param height the height of the putative image drawn by the callback
 * @param is_opaque set to CAIRO_GDK_DRAWING_IS_OPAQUE to indicate
 * that all alpha values of the putative image will be 1.0; the pixels drawn into
 * the Drawable must not depend on the prior contents of the Drawable
 * in any way
 * @param capabilities the capabilities of the callback as described above.
 * @param result if non-NULL, we *may* fill in the struct with information about
 * the rendered image. 'surface' may be filled in with a surface representing
 * the image, similar to the target of 'cr'. If 'uniform_alpha' is True then
 * every pixel of the image has the same alpha value 'alpha'. If
 * 'uniform_color' is True then every pixel of the image has the same RGB
 * color (r, g, b). If the image has uniform color and alpha (or alpha is zero,
 * in which case the color is always uniform) then we won't bother returning
 * a surface for it.
 */
void cairo_draw_with_gdk (cairo_t *cr,
                          cairo_gdk_drawing_callback callback,
                          void * closure,
                          unsigned int width, unsigned int height,
                          cairo_gdk_drawing_opacity_t is_opaque,
                          cairo_gdk_drawing_support_t capabilities,
                          cairo_gdk_drawing_result_t *result);

CAIRO_END_DECLS

#endif /*CAIROGDKUTILS_H_*/