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

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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  14  *
  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 structure captures the result of the native drawing, in case the
  65  * caller may wish to reapply the drawing efficiently later.
  66  */
  67 typedef struct {
  68     cairo_surface_t *surface;
  69     cairo_bool_t    uniform_alpha;
  70     cairo_bool_t    uniform_color;
  71     double          alpha; /* valid only if uniform_alpha is TRUE */
  72     double          r, g, b; /* valid only if uniform_color is TRUE */
  73 } cairo_gdk_drawing_result_t;
  74
  75 /**
  76  * This type specifies whether the native drawing callback draws all pixels
  77  * in its bounds opaquely, independent of the contents of the target drawable,
  78  * or whether it leaves pixels transparent/translucent or depends on the
  79  * existing contents of the target drawable in some way.
  80  */
  81 typedef enum _cairo_gdk_drawing_opacity {
  82     CAIRO_GDK_DRAWING_OPAQUE,
  83     CAIRO_GDK_DRAWING_TRANSPARENT
  84 } cairo_gdk_drawing_opacity_t;
  85
  86 /**
  87  * This type encodes the capabilities of the native drawing callback.
  88  *
  89  * If CAIRO_GDK_DRAWING_SUPPORTS_OFFSET is set, 'offset_x' and 'offset_y'
  90  * can be nonzero in the call to the callback; otherwise they will be zero.
  91  *
  92  * If CAIRO_GDK_DRAWING_SUPPORTS_CLIP_RECT is set, then 'num_rects' can be
  93  * zero or one in the call to the callback. If
  94  * CAIRO_GDK_DRAWING_SUPPORTS_CLIP_LIST is set, then 'num_rects' can be
  95  * anything in the call to the callback. Otherwise 'num_rects' will be zero.
  96  * Do not set both of these values.
  97  *
  98  * If CAIRO_GDK_DRAWING_SUPPORTS_ALTERNATE_DISPLAY is set, then 'dpy' can be
  99  * any display, otherwise it will be the display passed into
 100  * cairo_draw_with_gdk.
 101  *
 102  * If CAIRO_GDK_DRAWING_SUPPORTS_NONDEFAULT_VISUAL is set, then 'visual' can be
 103  * any visual, otherwise it will be equal to
 104  * DefaultVisual (dpy, DefaultScreen (dpy)).
 105  */
 106 typedef enum {
 107     CAIRO_GDK_DRAWING_SUPPORTS_OFFSET = 0x01,
 108     CAIRO_GDK_DRAWING_SUPPORTS_CLIP_RECT = 0x02,
 109     CAIRO_GDK_DRAWING_SUPPORTS_CLIP_LIST = 0x04,
 110     CAIRO_GDK_DRAWING_SUPPORTS_ALTERNATE_SCREEN = 0x08,
 111     CAIRO_GDK_DRAWING_SUPPORTS_NONDEFAULT_VISUAL = 0x10
 112 } cairo_gdk_drawing_support_t;
 113
 114 /**
 115  * Draw GDK output into any cairo context. All cairo transforms and effects
 116  * are honored, including the current operator. This is equivalent to a
 117  * cairo_set_source_surface and then cairo_paint.
 118  * @param cr the context to draw into
 119  * @param drawable a GDK Drawable that we're targetting
 120  * @param callback the code to perform GDK rendering
 121  * @param closure associated data
 122  * @param width the width of the putative image drawn by the callback
 123  * @param height the height of the putative image drawn by the callback
 124  * @param is_opaque set to CAIRO_GDK_DRAWING_IS_OPAQUE to indicate
 125  * that all alpha values of the putative image will be 1.0; the pixels drawn into
 126  * the Drawable must not depend on the prior contents of the Drawable
 127  * in any way
 128  * @param capabilities the capabilities of the callback as described above.
 129  * @param result if non-NULL, we *may* fill in the struct with information about
 130  * the rendered image. 'surface' may be filled in with a surface representing
 131  * the image, similar to the target of 'cr'. If 'uniform_alpha' is True then
 132  * every pixel of the image has the same alpha value 'alpha'. If
 133  * 'uniform_color' is True then every pixel of the image has the same RGB
 134  * color (r, g, b). If the image has uniform color and alpha (or alpha is zero,
 135  * in which case the color is always uniform) then we won't bother returning
 136  * a surface for it.
 137  */
 138 void cairo_draw_with_gdk (cairo_t *cr,
 139                           cairo_gdk_drawing_callback callback,
 140                           void * closure,
 141                           unsigned int width, unsigned int height,
 142                           cairo_gdk_drawing_opacity_t is_opaque,
 143                           cairo_gdk_drawing_support_t capabilities,
 144                           cairo_gdk_drawing_result_t *result);
 145
 146 CAIRO_END_DECLS
 147
 148 #endif /*CAIROGDKUTILS_H_*/