gfx/thebes/cairo-gdk-utils.h

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  15  * The Original Code is Novell code.
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  22  *   rocallahan@novell.com
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  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef CAIROGDKUTILS_H_
  39 #define CAIROGDKUTILS_H_
  40
  41 #include "cairo.h"
  42 #include <gdk/gdk.h>
  43
  44 CAIRO_BEGIN_DECLS
  45
  46 /**
  47  * This callback encapsulates GDK-based rendering. We assume that the
  48  * execution of the callback is equivalent to compositing some RGBA image of
  49  * size (bounds_width, bounds_height) onto the drawable at offset (offset_x,
  50  * offset_y), clipped to the union of the clip_rects if num_rects is greater
  51  * than zero. This includes the assumption that the same RGBA image
  52  * is composited if you call the callback multiple times with the same closure,
  53  * display and visual during a single cairo_draw_with_gdk call.
  54  *
  55  * @return True when able to draw, False otherwise
  56  */
  57 typedef cairo_bool_t (* cairo_gdk_drawing_callback)
  58     (void *closure,
  59      cairo_surface_t *surface,
  60      short offset_x, short offset_y,
  61      GdkRectangle * clip_rects, unsigned int num_rects);
  62
  63 /**
  64  * This type specifies whether the native drawing callback draws all pixels
  65  * in its bounds opaquely, independent of the contents of the target drawable,
  66  * or whether it leaves pixels transparent/translucent or depends on the
  67  * existing contents of the target drawable in some way.
  68  */
  69 typedef enum _cairo_gdk_drawing_opacity {
  70     CAIRO_GDK_DRAWING_OPAQUE,
  71     CAIRO_GDK_DRAWING_TRANSPARENT
  72 } cairo_gdk_drawing_opacity_t;
  73
  74 /**
  75  * This type encodes the capabilities of the native drawing callback.
  76  *
  77  * If CAIRO_GDK_DRAWING_SUPPORTS_CLIP_RECT is set, then 'num_rects' can be
  78  * zero or one in the call to the callback. Otherwise 'num_rects' will be
  79  * zero.
  80  */
  81 typedef enum {
  82     CAIRO_GDK_DRAWING_SUPPORTS_CLIP_RECT = 0x02,
  83 } cairo_gdk_drawing_support_t;
  84
  85 /**
  86  * Draw GDK output into any cairo context. All cairo transforms and effects
  87  * are honored, including the current operator. This is equivalent to a
  88  * cairo_set_source_surface and then cairo_paint.
  89  * @param cr the context to draw into
  90  * @param drawable a GDK Drawable that we're targetting
  91  * @param callback the code to perform GDK rendering
  92  * @param closure associated data
  93  * @param width the width of the putative image drawn by the callback
  94  * @param height the height of the putative image drawn by the callback
  95  * @param is_opaque set to CAIRO_GDK_DRAWING_IS_OPAQUE to indicate
  96  * that all alpha values of the putative image will be 1.0; the pixels drawn into
  97  * the Drawable must not depend on the prior contents of the Drawable
  98  * in any way
  99  * @param capabilities the capabilities of the callback as described above.
 100  * @param result if non-NULL, we *may* fill in the struct with information about
 101  * the rendered image. 'surface' may be filled in with a surface representing
 102  * the image, similar to the target of 'cr'. If 'uniform_alpha' is True then
 103  * every pixel of the image has the same alpha value 'alpha'. If
 104  * 'uniform_color' is True then every pixel of the image has the same RGB
 105  * color (r, g, b). If the image has uniform color and alpha (or alpha is zero,
 106  * in which case the color is always uniform) then we won't bother returning
 107  * a surface for it.
 108  */
 109 void cairo_draw_with_gdk (cairo_t *cr,
 110                           cairo_gdk_drawing_callback callback,
 111                           void * closure,
 112                           unsigned int width, unsigned int height,
 113                           cairo_gdk_drawing_opacity_t is_opaque,
 114                           cairo_gdk_drawing_support_t capabilities,
 115                           cairo_gdk_drawing_result_t *result);
 116
 117 CAIRO_END_DECLS
 118
 119 #endif /*CAIROGDKUTILS_H_*/