| GDK Reference Manual | |||
|---|---|---|---|
| <<< Previous Page | Home | Up | Next Page >>> |
#include <gdk/gdk.h> struct GdkDrawable; GdkDrawable* gdk_drawable_ref (GdkDrawable *drawable); void gdk_drawable_unref (GdkDrawable *drawable); void gdk_drawable_set_data (GdkDrawable *drawable, const gchar *key, gpointer data, GDestroyNotify destroy_func); gpointer gdk_drawable_get_data (GdkDrawable *drawable, const gchar *key); GdkDisplay* gdk_drawable_get_display (GdkDrawable *drawable); GdkScreen* gdk_drawable_get_screen (GdkDrawable *drawable); GdkVisual* gdk_drawable_get_visual (GdkDrawable *drawable); void gdk_drawable_set_colormap (GdkDrawable *drawable, GdkColormap *colormap); GdkColormap* gdk_drawable_get_colormap (GdkDrawable *drawable); gint gdk_drawable_get_depth (GdkDrawable *drawable); void gdk_drawable_get_size (GdkDrawable *drawable, gint *width, gint *height); GdkRegion* gdk_drawable_get_clip_region (GdkDrawable *drawable); GdkRegion* gdk_drawable_get_visible_region (GdkDrawable *drawable); void gdk_draw_point (GdkDrawable *drawable, GdkGC *gc, gint x, gint y); void gdk_draw_points (GdkDrawable *drawable, GdkGC *gc, GdkPoint *points, gint npoints); void gdk_draw_line (GdkDrawable *drawable, GdkGC *gc, gint x1, gint y1, gint x2, gint y2); void gdk_draw_lines (GdkDrawable *drawable, GdkGC *gc, GdkPoint *points, gint npoints); void gdk_draw_segments (GdkDrawable *drawable, GdkGC *gc, GdkSegment *segs, gint nsegs); struct GdkSegment; void gdk_draw_rectangle (GdkDrawable *drawable, GdkGC *gc, gint filled, gint x, gint y, gint width, gint height); void gdk_draw_arc (GdkDrawable *drawable, GdkGC *gc, gint filled, gint x, gint y, gint width, gint height, gint angle1, gint angle2); void gdk_draw_polygon (GdkDrawable *drawable, GdkGC *gc, gint filled, GdkPoint *points, gint npoints); void gdk_draw_glyphs (GdkDrawable *drawable, GdkGC *gc, PangoFont *font, gint x, gint y, PangoGlyphString *glyphs); void gdk_draw_layout_line (GdkDrawable *drawable, GdkGC *gc, gint x, gint y, PangoLayoutLine *line); void gdk_draw_layout_line_with_colors (GdkDrawable *drawable, GdkGC *gc, gint x, gint y, PangoLayoutLine *line, GdkColor *foreground, GdkColor *background); void gdk_draw_layout (GdkDrawable *drawable, GdkGC *gc, gint x, gint y, PangoLayout *layout); void gdk_draw_layout_with_colors (GdkDrawable *drawable, GdkGC *gc, gint x, gint y, PangoLayout *layout, GdkColor *foreground, GdkColor *background); void gdk_draw_string (GdkDrawable *drawable, GdkFont *font, GdkGC *gc, gint x, gint y, const gchar *string); void gdk_draw_text (GdkDrawable *drawable, GdkFont *font, GdkGC *gc, gint x, gint y, const gchar *text, gint text_length); void gdk_draw_text_wc (GdkDrawable *drawable, GdkFont *font, GdkGC *gc, gint x, gint y, const GdkWChar *text, gint text_length); #define gdk_draw_pixmap void gdk_draw_drawable (GdkDrawable *drawable, GdkGC *gc, GdkDrawable *src, gint xsrc, gint ysrc, gint xdest, gint ydest, gint width, gint height); void gdk_draw_image (GdkDrawable *drawable, GdkGC *gc, GdkImage *image, gint xsrc, gint ysrc, gint xdest, gint ydest, gint width, gint height); GdkImage* gdk_drawable_get_image (GdkDrawable *drawable, gint x, gint y, gint width, gint height); |
These functions provide support for drawing points, lines, arcs and text onto what are called 'drawables'. Drawables, as the name suggests, are things which support drawing onto them, and are either GdkWindow or GdkPixmap objects.
Many of the drawing operations take a GdkGC argument, which represents a graphics context. This GdkGC contains a number of drawing attributes such as foreground color, background color and line width, and is used to reduce the number of arguments needed for each drawing operation. See the Graphics Contexts section for more information.
struct GdkDrawable; |
An opaque structure representing an object that can be drawn onto. This can be a GdkPixmap, a GdkBitmap, or a GdkWindow.
GdkDrawable* gdk_drawable_ref (GdkDrawable *drawable); |
| Warning |
gdk_drawable_ref is deprecated and should not be used in newly-written code. |
Deprecated equivalent of calling g_object_ref() on drawable. (Drawables were not objects in previous versions of GDK.)
void gdk_drawable_unref (GdkDrawable *drawable); |
| Warning |
gdk_drawable_unref is deprecated and should not be used in newly-written code. |
Deprecated equivalent of calling g_object_unref() on drawable.
void gdk_drawable_set_data (GdkDrawable *drawable,
const gchar *key,
gpointer data,
GDestroyNotify destroy_func); |
| Warning |
gdk_drawable_set_data is deprecated and should not be used in newly-written code. |
This function is equivalent to g_object_set_data(), the GObject variant should be used instead.
gpointer gdk_drawable_get_data (GdkDrawable *drawable, const gchar *key); |
| Warning |
gdk_drawable_get_data is deprecated and should not be used in newly-written code. |
Equivalent to g_object_get_data(); the GObject variant should be used instead.
GdkDisplay* gdk_drawable_get_display (GdkDrawable *drawable); |
Gets the GdkDisplay associated with a GdkDrawable.
| drawable : | a GdkDrawable |
| Returns : | the GdkDisplay associated with drawable |
GdkScreen* gdk_drawable_get_screen (GdkDrawable *drawable); |
Gets the GdkScreen associated with a GdkDrawable.
| drawable : | a GdkDrawable |
| Returns : | the GdkScreen associated with drawable |
GdkVisual* gdk_drawable_get_visual (GdkDrawable *drawable); |
Gets the GdkVisual describing the pixel format of drawable.
| drawable : | a GdkDrawable |
| Returns : | a GdkVisual |
void gdk_drawable_set_colormap (GdkDrawable *drawable,
GdkColormap *colormap); |
Sets the colormap associated with drawable. Normally this will happen automatically when the drawable is created; you only need to use this function if the drawable-creating function did not have a way to determine the colormap, and you then use drawable operations that require a colormap. The colormap for all drawables and graphics contexts you intend to use together should match. i.e. when using a GdkGC to draw to a drawable, or copying one drawable to another, the colormaps should match.
| drawable : | a GdkDrawable |
| colormap : | a GdkColormap |
GdkColormap* gdk_drawable_get_colormap (GdkDrawable *drawable); |
Gets the colormap for drawable, if one is set; returns NULL otherwise.
gint gdk_drawable_get_depth (GdkDrawable *drawable); |
Obtains the bit depth of the drawable, that is, the number of bits that make up a pixel in the drawable's visual. Examples are 8 bits per pixel, 24 bits per pixel, etc.
void gdk_drawable_get_size (GdkDrawable *drawable,
gint *width,
gint *height); |
Fills *width and *height with the size of drawable. width or height can be NULL if you only want the other one.
On the X11 platform, if drawable is a GdkWindow, the returned size is the size reported in the most-recently-processed configure event, rather than the current size on the X server.
GdkRegion* gdk_drawable_get_clip_region (GdkDrawable *drawable); |
Computes the region of a drawable that potentially can be written to by drawing primitives. This region will not take into account the clip region for the GC, and may also not take into account other factors such as if the window is obscured by other windows, but no area outside of this region will be affected by drawing primitives.
| drawable : | a GdkDrawable |
| Returns : | a GdkRegion. This must be freed with gdk_region_destroy() when you are done. |
GdkRegion* gdk_drawable_get_visible_region (GdkDrawable *drawable); |
Computes the region of a drawable that is potentially visible. This does not necessarily take into account if the window is obscured by other windows, but no area outside of this region is visible.
| drawable : | |
| Returns : | a GdkRegion. This must be freed with gdk_region_destroy() when you are done. |
void gdk_draw_point (GdkDrawable *drawable,
GdkGC *gc,
gint x,
gint y); |
Draws a point, using the foreground color and other attributes of the GdkGC.
void gdk_draw_points (GdkDrawable *drawable,
GdkGC *gc,
GdkPoint *points,
gint npoints); |
Draws a number of points, using the foreground color and other attributes of the GdkGC.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| gc : | a GdkGC. |
| points : | an array of GdkPoint structures. |
| npoints : | the number of points to be drawn. |
void gdk_draw_line (GdkDrawable *drawable,
GdkGC *gc,
gint x1,
gint y1,
gint x2,
gint y2); |
Draws a line, using the foreground color and other attributes of the GdkGC.
void gdk_draw_lines (GdkDrawable *drawable,
GdkGC *gc,
GdkPoint *points,
gint npoints); |
Draws a series of lines connecting the given points. The way in which joins between lines are draw is determined by the GdkCapStyle value in the GdkGC. This can be set with gdk_gc_set_line_attributes().
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| gc : | a GdkGC. |
| points : | an array of GdkPoint structures specifying the endpoints of the lines. |
| npoints : | the size of the points array. |
void gdk_draw_segments (GdkDrawable *drawable,
GdkGC *gc,
GdkSegment *segs,
gint nsegs); |
Draws a number of unconnected lines.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| gc : | a GdkGC. |
| segs : | an array of GdkSegment structures specifying the start and end points of the lines to be drawn, |
| nsegs : | the number of line segments to draw, i.e. the size of the segs array. |
struct GdkSegment
{
gint x1;
gint y1;
gint x2;
gint y2;
};
|
Specifies the start and end point of a line for use by the gdk_draw_segments() function.
void gdk_draw_rectangle (GdkDrawable *drawable,
GdkGC *gc,
gint filled,
gint x,
gint y,
gint width,
gint height); |
Draws a rectangular outline or filled rectangle, using the foreground color and other attributes of the GdkGC.
Note: A rectangle drawn filled is 1 pixel smaller in both dimensions than a rectangle outlined. Calling gdk_draw_rectangle (window, gc, TRUE, 0, 0, 20, 20) results in a filled rectangle 20 pixels wide and 20 pixels high. Calling gdk_draw_rectangle (window, gc, FALSE, 0, 0, 20, 20) results in an outlined rectangle with corners at (0, 0), (0, 20), (20, 20), and (20, 0), which makes it 21 pixels wide and 21 pixels high.
void gdk_draw_arc (GdkDrawable *drawable,
GdkGC *gc,
gint filled,
gint x,
gint y,
gint width,
gint height,
gint angle1,
gint angle2); |
Draws an arc or a filled 'pie slice'. The arc is defined by the bounding rectangle of the entire ellipse, and the start and end angles of the part of the ellipse to be drawn.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| gc : | a GdkGC. |
| filled : | TRUE if the arc should be filled, producing a 'pie slice'. |
| x : | the x coordinate of the left edge of the bounding rectangle. |
| y : | the y coordinate of the top edge of the bounding rectangle. |
| width : | the width of the bounding rectangle. |
| height : | the height of the bounding rectangle. |
| angle1 : | the start angle of the arc, relative to the 3 o'clock position, counter-clockwise, in 1/64ths of a degree. |
| angle2 : | the end angle of the arc, relative to angle1, in 1/64ths of a degree. |
void gdk_draw_polygon (GdkDrawable *drawable,
GdkGC *gc,
gint filled,
GdkPoint *points,
gint npoints); |
Draws an outlined or filled polygon.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| gc : | a GdkGC. |
| filled : | TRUE if the polygon should be filled. The polygon is closed automatically, connecting the last point to the first point if necessary. |
| points : | an array of GdkPoint structures specifying the points making up the polygon. |
| npoints : | the number of points. |
void gdk_draw_glyphs (GdkDrawable *drawable,
GdkGC *gc,
PangoFont *font,
gint x,
gint y,
PangoGlyphString *glyphs); |
This is a low-level function; 99% of text rendering should be done using gdk_draw_layout() instead.
A glyph is a character in a font. This function draws a sequence of glyphs. To obtain a sequence of glyphs you have to understand a lot about internationalized text handling, which you don't want to understand; thus, use gdk_draw_layout() instead of this function, gdk_draw_layout() handles the details.
void gdk_draw_layout_line (GdkDrawable *drawable,
GdkGC *gc,
gint x,
gint y,
PangoLayoutLine *line); |
Render a PangoLayoutLine onto an GDK drawable
| drawable : | the drawable on which to draw the line |
| gc : | base graphics to use |
| x : | the x position of start of string (in pixels) |
| y : | the y position of baseline (in pixels) |
| line : | a PangoLayoutLine |
void gdk_draw_layout_line_with_colors
(GdkDrawable *drawable,
GdkGC *gc,
gint x,
gint y,
PangoLayoutLine *line,
GdkColor *foreground,
GdkColor *background); |
Render a PangoLayoutLine onto a GdkDrawable, overriding the layout's normal colors with foreground and/or background. foreground and background need not be allocated.
| drawable : | the drawable on which to draw the line |
| gc : | base graphics to use |
| x : | the x position of start of string (in pixels) |
| y : | the y position of baseline (in pixels) |
| line : | a PangoLayoutLine |
| foreground : | foreground override color, or NULL for none |
| background : | background override color, or NULL for none |
void gdk_draw_layout (GdkDrawable *drawable,
GdkGC *gc,
gint x,
gint y,
PangoLayout *layout); |
Render a PangoLayout onto a GDK drawable
void gdk_draw_layout_with_colors (GdkDrawable *drawable,
GdkGC *gc,
gint x,
gint y,
PangoLayout *layout,
GdkColor *foreground,
GdkColor *background); |
Render a PangoLayout onto a GdkDrawable, overriding the layout's normal colors with foreground and/or background. foreground and background need not be allocated.
| drawable : | the drawable on which to draw string |
| gc : | base graphics context to use |
| x : | the X position of the left of the layout (in pixels) |
| y : | the Y position of the top of the layout (in pixels) |
| layout : | a PangoLayout |
| foreground : | foreground override color, or NULL for none |
| background : | background override color, or NULL for none |
void gdk_draw_string (GdkDrawable *drawable,
GdkFont *font,
GdkGC *gc,
gint x,
gint y,
const gchar *string); |
| Warning |
gdk_draw_string is deprecated and should not be used in newly-written code. |
Draws a string of characters in the given font or fontset.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| font : | a GdkFont. |
| gc : | a GdkGC. |
| x : | the x coordinate of the left edge of the text. |
| y : | the y coordinate of the baseline of the text. |
| string : | the string of characters to draw. |
void gdk_draw_text (GdkDrawable *drawable,
GdkFont *font,
GdkGC *gc,
gint x,
gint y,
const gchar *text,
gint text_length); |
| Warning |
gdk_draw_text is deprecated and should not be used in newly-written code. |
Draws a number of characters in the given font or fontset.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| font : | a GdkFont. |
| gc : | a GdkGC. |
| x : | the x coordinate of the left edge of the text. |
| y : | the y coordinate of the baseline of the text. |
| text : | the characters to draw. |
| text_length : | the number of characters of text to draw. |
void gdk_draw_text_wc (GdkDrawable *drawable,
GdkFont *font,
GdkGC *gc,
gint x,
gint y,
const GdkWChar *text,
gint text_length); |
| Warning |
gdk_draw_text_wc is deprecated and should not be used in newly-written code. |
Draws a number of wide characters using the given font of fontset. If the font is a 1-byte font, the string is converted into 1-byte characters (discarding the high bytes) before output.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| font : | a GdkFont. |
| gc : | a GdkGC. |
| x : | the x coordinate of the left edge of the text. |
| y : | the y coordinate of the baseline of the text. |
| text : | the wide characters to draw. |
| text_length : | the number of characters to draw. |
#define gdk_draw_pixmap gdk_draw_drawable |
| Warning |
gdk_draw_pixmap is deprecated and should not be used in newly-written code. |
Draws a pixmap, or a part of a pixmap, onto another drawable.
void gdk_draw_drawable (GdkDrawable *drawable,
GdkGC *gc,
GdkDrawable *src,
gint xsrc,
gint ysrc,
gint xdest,
gint ydest,
gint width,
gint height); |
Copies the width x height region of src at coordinates (xsrc, ysrc) to coordinates (xdest, ydest) in drawable. width and/or height may be given as -1, in which case the entire src drawable will be copied.
Most fields in gc are not used for this operation, but notably the clip mask or clip region will be honored.
The source and destination drawables must have the same visual and colormap, or errors will result. (On X11, failure to match visual/colormap results in a BadMatch error from the X server.) A common cause of this problem is an attempt to draw a bitmap to a color drawable. The way to draw a bitmap is to set the bitmap as a clip mask on your GdkGC, then use gdk_draw_rectangle() to draw a rectangle clipped to the bitmap.
| drawable : | a GdkDrawable |
| gc : | a GdkGC sharing the drawable's visual and colormap |
| src : | another GdkDrawable |
| xsrc : | X position in src of rectangle to draw |
| ysrc : | Y position in src of rectangle to draw |
| xdest : | X position in drawable where the rectangle should be drawn |
| ydest : | Y position in drawable where the rectangle should be drawn |
| width : | width of rectangle to draw, or -1 for entire src width |
| height : | height of rectangle to draw, or -1 for entire src height |
void gdk_draw_image (GdkDrawable *drawable,
GdkGC *gc,
GdkImage *image,
gint xsrc,
gint ysrc,
gint xdest,
gint ydest,
gint width,
gint height); |
Draws a GdkImage onto a drawable. The depth of the GdkImage must match the depth of the GdkDrawable.
| drawable : | a GdkDrawable (a GdkWindow or a GdkPixmap). |
| gc : | a GdkGC. |
| image : | the GdkImage to draw. |
| xsrc : | the left edge of the source rectangle within image. |
| ysrc : | the top of the source rectangle within image. |
| xdest : | the x coordinate of the destination within drawable. |
| ydest : | the y coordinate of the destination within drawable. |
| width : | the width of the area to be copied, or -1 to make the area extend to the right edge of image. |
| height : | the height of the area to be copied, or -1 to make the area extend to the bottom edge of image. |
GdkImage* gdk_drawable_get_image (GdkDrawable *drawable, gint x, gint y, gint width, gint height); |
A GdkImage stores client-side image data (pixels). In contrast, GdkPixmap and GdkWindow are server-side objects. gdk_drawable_get_image() obtains the pixels from a server-side drawable as a client-side GdkImage. The format of a GdkImage depends on the GdkVisual of the current display, which makes manipulating GdkImage extremely difficult; therefore, in most cases you should use gdk_pixbuf_get_from_drawable() instead of this lower-level function. A GdkPixbuf contains image data in a canonicalized RGB format, rather than a display-dependent format. Of course, there's a convenience vs. speed tradeoff here, so you'll want to think about what makes sense for your application.
x, y, width, and height define the region of drawable to obtain as an image.
You would usually copy image data to the client side if you intend to examine the values of individual pixels, for example to darken an image or add a red tint. It would be prohibitively slow to make a round-trip request to the windowing system for each pixel, so instead you get all of them at once, modify them, then copy them all back at once.
If the X server or other windowing system backend is on the local machine, this function may use shared memory to avoid copying the image data.
If the source drawable is a GdkWindow and partially offscreen or obscured, then the obscured portions of the returned image will contain undefined data.
| drawable : | a GdkDrawable |
| x : | x coordinate on drawable |
| y : | y coordinate on drawable |
| width : | width of region to get |
| height : | height or region to get |
| Returns : | a GdkImage containing the contents of drawable |