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|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>
Drawing
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<font color="#000000" size="2">GTK+ / Gnome Application
Development</font>
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<div class="SECT1">
<h1 class="SECT1">
<a name="Z132">Drawing</a>
</h1>
<p>
Once you understand drawables, colors, visuals, graphics
contexts, and fonts, actually drawing is very simple. This
section is a quick summary of the GDK drawing routines.
Remember that drawing is a server-side operation; for
example, if you ask to draw a line, Xlib will send the
line's endpoints to the server, and the server will do the
actual drawing using the specified GC (the GC is also a
server-side resource). Often this is an important
performance consideration.
</p>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z133">Points</a>
</h2>
<p>
You can draw a single point with <tt class="FUNCTION">
gdk_draw_point()</tt>, or multiple points with <tt class=
"FUNCTION">gdk_draw_points()</tt> (<a href=
"z132.html#FL-GDKPOINTS">Figure 17</a>). The point is
drawn in the current foreground color. Multiple points
are given as an array. A <span class="STRUCTNAME">
GdkPoint</span> looks like this:
</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
typedef struct _GdkPoint GdkPoint;
struct _GdkPoint
{
gint16 x;
gint16 y;
};
</pre>
</td>
</tr>
</table>
<p>
Remember that X coordinates start in the top left corner,
are relative to the drawable, and may not overflow a
signed sixteen-bit integer.
</p>
<div class="FIGURE">
<a name="FL-GDKPOINTS"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKPOINTS.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_point</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkGC*
<tt class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>x</i></tt>, gint <tt class=
"PARAMETER"><i>y</i></tt>);</code>
</p>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_points</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkGC*
<tt class="PARAMETER"><i>gc</i></tt>, GdkPoint* <tt
class="PARAMETER"><i>points</i></tt>, gint <tt class=
"PARAMETER"><i>npoints</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 17. Drawing Points</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z134">Lines</a>
</h2>
<p>
To draw a single line, pass its endpoints as arguments to
<tt class="FUNCTION">gdk_draw_line()</tt> (<a href=
"z132.html#FL-GDKLINES">Figure 18</a>). To draw connected
lines, you pass a list of points to <tt class="FUNCTION">
gdk_draw_lines()</tt>; GDK will "connect the dots." To
draw multiple lines that aren't necessarily connected,
pass a list of segments to <tt class="FUNCTION">
gdk_draw_segments()</tt>; a <span class="STRUCTNAME">
GdkSegment</span> is:
</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
typedef struct _GdkSegment GdkSegment;
struct _GdkSegment
{
gint16 x1;
gint16 y1;
gint16 x2;
gint16 y2;
};
</pre>
</td>
</tr>
</table>
<p>
If lines or segments drawn in the same request meet at
their endpoints, they are joined with the join style from
the GC.
</p>
<div class="FIGURE">
<a name="FL-GDKLINES"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKLINES.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_line</tt></code>(GdkDrawable* <tt
class="PARAMETER"><i>drawable</i></tt>, GdkGC* <tt
class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>x1</i></tt>, gint <tt class=
"PARAMETER"><i>y1</i></tt>, gint <tt class=
"PARAMETER"><i>x2</i></tt>, gint <tt class=
"PARAMETER"><i>y2</i></tt>);</code>
</p>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_lines</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkGC*
<tt class="PARAMETER"><i>gc</i></tt>, GdkPoint* <tt
class="PARAMETER"><i>points</i></tt>, gint <tt class=
"PARAMETER"><i>npoints</i></tt>);</code>
</p>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_segments</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkGC*
<tt class="PARAMETER"><i>gc</i></tt>, GdkSegment* <tt
class="PARAMETER"><i>segments</i></tt>, gint <tt
class="PARAMETER"><i>nsegments</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 18. Drawing Lines</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z135">Rectangles</a>
</h2>
<p>
Rectangles are drawn with <tt class="FUNCTION">
gdk_draw_rectangle()</tt> (<a href=
"z132.html#FL-GDKRECT">Figure 19</a>). The <span class=
"STRUCTNAME">filled</span> argument indicates whether to
fill the rectangle; <span class="STRUCTNAME">TRUE</span>
means to fill it.
</p>
<div class="FIGURE">
<a name="FL-GDKRECT"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKRECT.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">
gdk_draw_rectangle</tt></code>(GdkDrawable* <tt
class="PARAMETER"><i>drawable</i></tt>, GdkGC* <tt
class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>filled</i></tt>, gint <tt class=
"PARAMETER"><i>x</i></tt>, gint <tt class=
"PARAMETER"><i>y</i></tt>, gint <tt class=
"PARAMETER"><i>width</i></tt>, gint <tt class=
"PARAMETER"><i>height</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 19. Drawing Rectangles</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z136">Arcs</a>
</h2>
<p>
<tt class="FUNCTION">gdk_draw_arc()</tt> draws an ellipse
or a portion of one. (<a href=
"z132.html#FL-GDKARC">Figure 20</a>). The arc can be
filled or unfilled; the third argument to the function
toggles fill. The fourth through seventh arguments
describe a rectangle; the ellipse is inscribed in this
rectangle. <span class="STRUCTNAME">angle1</span> is the
angle at which to start drawing; it is relative to the 3
o'clock position (that is, 0 radians). <span class=
"STRUCTNAME">angle2</span> is the distance to travel
around the arc; if positive, travel is counterclockwise,
otherwise travel is clockwise. Both <span class=
"STRUCTNAME">angle1</span> and <span class="STRUCTNAME">
angle2</span> are specified in sixty-fourths of a degree;
so, 360 degrees is given as <span class="STRUCTNAME">
360*64</span>. This allows more precise specification of
the arc's size and shape, without using floating point
numbers. <span class="STRUCTNAME">angle2</span> should
not exceed 360 degrees, since it is nonsensical to move
more than 360 degrees around the ellipse.
</p>
<p>
To draw a circle, draw from 0 to 360*64 inside a square:
</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
gdk_draw_arc(drawable, gc, TRUE,
0, 0,
50, 50,
0, 360*64);
</pre>
</td>
</tr>
</table>
<p>
To draw half an ellipse, change the aspect ratio and
halve the span of the arc:
</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
gdk_draw_arc(drawable, gc, TRUE,
0, 0,
100, 50,
0, 180*64);
</pre>
</td>
</tr>
</table>
<p>
Many X servers draw the edges of filled arcs in an
aesthetically unpleasing way; in particular, very small
circles may not look very circular. You can work around
this by also drawing the circle's outline.
</p>
<div class="FIGURE">
<a name="FL-GDKARC"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKARC.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_arc</tt></code>(GdkDrawable* <tt
class="PARAMETER"><i>drawable</i></tt>, GdkGC* <tt
class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>filled</i></tt>, gint <tt class=
"PARAMETER"><i>x</i></tt>, gint <tt class=
"PARAMETER"><i>y</i></tt>, gint <tt class=
"PARAMETER"><i>width</i></tt>, gint <tt class=
"PARAMETER"><i>height</i></tt>, gint <tt class=
"PARAMETER"><i>angle1</i></tt>, gint <tt class=
"PARAMETER"><i>angle2</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 20. Drawing Arcs</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z137">Polygons</a>
</h2>
<p>
<tt class="FUNCTION">gdk_draw_polygon()</tt> draws a
filled or unfilled polygon (<a href=
"z132.html#FL-GDKPOLY">Figure 21</a>). Notice that <tt
class="FUNCTION">gdk_draw_lines()</tt> can also be used
to draw an unfilled polygon (there is no reason to prefer
one or the other). The arguments to <tt class="FUNCTION">
gdk_draw_polygon()</tt> are the same as those to <tt
class="FUNCTION">gdk_draw_lines()</tt>. The polygon does
not have to be convex. It may also be self-intersecting.
Self-intersecting polygons are filled with an "Even-Odd
Rule," which means regions with an odd number of polygon
areas overlapping them are not filled. That is, if the
polygon does not overlap itself, it is entirely filled;
if a region is overlapped once, it is not filled; if it's
overlapped twice, it is filled; and so on.
</p>
<div class="FIGURE">
<a name="FL-GDKPOLY"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKPOLY.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_polygon</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkGC*
<tt class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>filled</i></tt>, GdkPoint* <tt class=
"PARAMETER"><i>points</i></tt>, gint <tt class=
"PARAMETER"><i>npoints</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 21. Drawing Polygons</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z138">Text</a>
</h2>
<p>
There are two functions to draw strings; as an
optimization, <tt class="FUNCTION">gdk_draw_text()</tt>
takes the length of the string to draw as an argument.
<tt class="FUNCTION">gdk_draw_string()</tt> uses <tt
class="FUNCTION">strlen()</tt> to compute the string
length for you. Otherwise the two are identical. The
<span class="STRUCTNAME">x</span> and <span class=
"STRUCTNAME">y</span> coordinates specify the location of
the left side of the text's baseline. See <a href=
"sec-gdkfont.html">the section called <i>Fonts</i></a>
for more information on fonts and font metrics. Text is
drawn in the foreground color.
</p>
<p>
There is no way to draw scaled or rotated text with GDK.
<span class="STRUCTNAME">GnomeCanvasText</span> offers a
slow and low-quality way to render scaled and rotated
text (see <a href=
"sec-itemreference.html#SEC-GNOMECANVASTEXT">the section
called <i>Text Item</i> in the chapter called <i><tt
class="CLASSNAME">GnomeCanvas</tt></i></a>). If you need
high-quality scaling and rotating, you will need to use
additional libraries, such as <tt class="APPLICATION">
t1lib</tt> for Type 1 fonts or FreeType for True Type
fonts. Another possibility is the Display Postscript
extension to X (XDPS); the GNU Project is working on a
free implementation of XDPS. The Gnome project also has a
text solution in development, as part of the <tt class=
"APPLICATION">gnome-print</tt> library.
</p>
<div class="FIGURE">
<a name="FL-GDKTEXT"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKTEXT.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_string</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkFont*
<tt class="PARAMETER"><i>font</i></tt>, GdkGC* <tt
class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>x</i></tt>, gint <tt class=
"PARAMETER"><i>y</i></tt>, const gchar* <tt class=
"PARAMETER"><i>text</i></tt>);</code>
</p>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_text</tt></code>(GdkDrawable* <tt
class="PARAMETER"><i>drawable</i></tt>, GdkFont* <tt
class="PARAMETER"><i>font</i></tt>, GdkGC* <tt class=
"PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>x</i></tt>, gint <tt class=
"PARAMETER"><i>y</i></tt>, const gchar* <tt class=
"PARAMETER"><i>text</i></tt>, gint <tt class=
"PARAMETER"><i>text_length</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 22. Drawing Text</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="Z139">Pixmaps</a>
</h2>
<p>
<tt class="FUNCTION">gdk_draw_pixmap()</tt> copies a
region from a pixmap to another drawable (pixmap or
window). The source and destination drawables must have
the same depth and visual. If you pass <span class=
"STRUCTNAME">-1</span> for the width or height, the full
size of the source pixmap is substituted. The source can
actually be any drawable, including a window, but <tt
class="FUNCTION">gdk_window_copy_area()</tt> will make
your code clearer if the source is a window. <a href=
"z132.html#FL-GDKDRAWPIXMAP">Figure 23</a> shows <tt
class="FUNCTION">gdk_draw_pixmap()</tt>.
</p>
<div class="FIGURE">
<a name="FL-GDKDRAWPIXMAP"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKDRAWPIXMAP.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdk.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_draw_pixmap</tt></code>(GdkDrawable*
<tt class="PARAMETER"><i>drawable</i></tt>, GdkGC*
<tt class="PARAMETER"><i>gc</i></tt>, GdkDrawable*
<tt class="PARAMETER"><i>src</i></tt>, gint <tt
class="PARAMETER"><i>xsrc</i></tt>, gint <tt class=
"PARAMETER"><i>ysrc</i></tt>, gint <tt class=
"PARAMETER"><i>xdest</i></tt>, gint <tt class=
"PARAMETER"><i>ydest</i></tt>, gint <tt class=
"PARAMETER"><i>width</i></tt>, gint <tt class=
"PARAMETER"><i>height</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 23. Drawing Pixmaps</b>
</p>
</div>
</div>
<div class="SECT2">
<h2 class="SECT2">
<a name="SEC-GDKRGB">RGB Buffers</a>
</h2>
<p>
GDK's GdkRGB module allows you to copy a client-side
buffer of image data to a drawable. If you need to
manipulate images extensively, or copy image data to the
server, this is the correct way to do it. You can't
directly manipulate a <span class="STRUCTNAME">
GdkPixmap</span> because a pixmap is a server-side
object. Copying image data to the server with <tt class=
"FUNCTION">gdk_draw_point()</tt> would be unbelievably
slow, since each point would require a server request
(probably more than one, since you will need to change
the GC for each point).
</p>
<p>
Internally, GdkRGB uses an object called <span class=
"STRUCTNAME">GdkImage</span> to rapidly copy image data
to the server in a single request. This is still somewhat
slow---sizeable data does have to be copied---but GdkRGB
is highly tuned and uses shared memory if the client and
server happen to be on the same machine. So it's the
fastest way to perform this task, given the X
architecture. It will also handle some tricky issues for
you (such as adapting to the colormaps and visuals
available on a given X server).
</p>
<p>
The GdkRGB functions are in a separate header, <tt class=
"FILENAME">gdk/gdkrgb.h</tt>. Before using any GdkRGB
functions, you must initialize the module with <tt class=
"FUNCTION">gdk_rgb_init()</tt> (<a href=
"z132.html#FL-GDKRGB">Figure 24</a>); this sets up the
visual and colormap GdkRGB will use, and some internal
data structures.
</p>
<p>
The drawable you intend to copy the RGB buffer to must
use GdkRGB's visual and colormap. If the drawable is a
part of a widget, the easiest way to ensure this is to
push the GdkRGB visual and colormap when you create the
widget:
</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
GtkWidget* widget;
gtk_widget_push_visual(gdk_rgb_get_visual());
gtk_widget_push_colormap(gdk_rgb_get_cmap());
widget = gtk_whatever_new();
gtk_widget_pop_visual();
gtk_widget_pop_colormap();
</pre>
</td>
</tr>
</table>
<p>
The current version of GTK+ will be better-behaved if you
do this when creating the toplevel window containing the
drawable, instead of when creating the drawable itself.
However, in principle you can do it for only the
drawable.
</p>
<p>
GdkRGB understands several kinds of image data, including
24- and 32-bit RGB data, 8-bit grayscale, and 8-bit
indexes into an array of RGB values (a client-side <span
class="STRUCTNAME">GdkRgbCmap</span>). This section
describes only the simplest, 24-bit RGB data; this kind
of buffer is rendered with <tt class="FUNCTION">
gdk_draw_rgb_image()</tt>. There are separate functions
to render the other buffer types, but all of them work in
essentially the same way.
</p>
<p>
A 24-bit RGB buffer is a one-dimensional array of bytes;
every byte triplet makes up a pixel (byte 0 is red, byte
1 is green, byte 2 is blue). Three numbers describe the
size of the array and the location of bytes within it:
</p>
<ul>
<li>
<p>
The <i class="FIRSTTERM">width</i> is the number of
pixels (byte triplets) per row of the image.
</p>
</li>
<li>
<p>
The <i class="FIRSTTERM">height</i> is the number of
rows in the image.
</p>
</li>
<li>
<p>
The <i class="FIRSTTERM">rowstride</i> is the number
of bytes between rows. That is, for a buffer with
rowstride <i class="EMPHASIS">r</i>, if row <i class=
"EMPHASIS">n</i> starts at array index <i class=
"EMPHASIS">i</i> row <i class="EMPHASIS">n+1</i>
starts at array index <i class="EMPHASIS">i+r</i>.
The rowstride is not necessarily three times the
buffer's width; GdkRGB is faster if both the source
pointer and the rowstride are aligned to a 4-byte
boundary. Specifying a rowstride allows you to use
padding to achieve this.
</p>
</li>
</ul>
<p>
The <span class="STRUCTNAME">x</span>, <span class=
"STRUCTNAME">y</span>, <span class="STRUCTNAME">
width</span>, and <span class="STRUCTNAME">height</span>
arguments to <tt class="FUNCTION">
gdk_rgb_draw_image()</tt> define a region of the target
drawable to copy the RGB buffer to. The RGB buffer must
have at least <span class="STRUCTNAME">width</span>
columns and <span class="STRUCTNAME">height</span> rows.
Row 0, column 0 of the RGB buffer will be copied to point
(<span class="STRUCTNAME">x</span>, <span class=
"STRUCTNAME">y</span>) on the drawable.
</p>
<p>
Dithering simulates a larger number of colors on displays
with a limited palette. Dithering only matters on 8- and
16-bit displays; 24-bit displays do not have a limited
palette. The <span class="STRUCTNAME">dither</span>
argument is an enumerated type; it has three possible
values:
</p>
<ul>
<li>
<p>
<span class="STRUCTNAME">GDK_RGB_DITHER_NONE</span>
specifies that no dithering will be done. It's
appropriate for text or line drawings with few
colors, but inappropriate for photographic images.
</p>
</li>
<li>
<p>
<span class="STRUCTNAME">GDK_RGB_DITHER_NORMAL</span>
specifies dithering on 8-bit displays, but not 16-bit
displays. This is usually the best
quality/performance tradeoff.
</p>
</li>
<li>
<p>
<span class="STRUCTNAME">GDK_RGB_DITHER_MAX</span>
specifies that dithering will always be done on 8-
and 16-bit displays. The quality gain on 16-bit
displays is probably not worth the speed
penalty.
</p>
</li>
</ul>
<p>
The <span class="STRUCTNAME">gc</span> argument to <tt
class="FUNCTION">gdk_draw_rgb_image()</tt> is simply
passed through to <tt class="FUNCTION">
gdk_draw_image()</tt> (recall that GdkRGB uses <span
class="STRUCTNAME">GdkImage</span> internally). The <span
class="STRUCTNAME">gc</span> components that make sense
are used (such as the clip mask, drawing function, and
subwindow mode).
</p>
<div class="FIGURE">
<a name="FL-GDKRGB"></a>
<div class="FUNCSYNOPSIS">
<a name="FL-GDKRGB.SYNOPSIS"></a>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="FUNCSYNOPSISINFO">
#include <gdk/gdkrgb.h>
</pre>
</td>
</tr>
</table>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">gdk_rgb_init</tt></code>(void);</code>
</p>
<p>
<code><code class="FUNCDEF">GdkColormap* <tt class=
"FUNCTION">gdk_rgb_get_cmap</tt></code>(void);</code>
</p>
<p>
<code><code class="FUNCDEF">GdkVisual* <tt class=
"FUNCTION">
gdk_rgb_get_visual</tt></code>(void);</code>
</p>
<p>
<code><code class="FUNCDEF">void <tt class=
"FUNCTION">
gdk_draw_rgb_image</tt></code>(GdkDrawable* <tt
class="PARAMETER"><i>drawable</i></tt>, GdkGC* <tt
class="PARAMETER"><i>gc</i></tt>, gint <tt class=
"PARAMETER"><i>x</i></tt>, gint <tt class=
"PARAMETER"><i>y</i></tt>, gint <tt class=
"PARAMETER"><i>width</i></tt>, gint <tt class=
"PARAMETER"><i>height</i></tt>, GdkRGBDither <tt
class="PARAMETER"><i>dither</i></tt>, guchar* <tt
class="PARAMETER"><i>rgb_buf</i></tt>, gint <tt
class="PARAMETER"><i>rowstride</i></tt>);</code>
</p>
</div>
<p>
<b>Figure 24. GdkRGB</b>
</p>
</div>
</div>
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