1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
<!doctype HTML PUBLIC "-//IETF//DTD HTML//EN">
<html>
<head>
<title>Clipping</title>
<meta http-equiv="Content-Language" content="en-us">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<link rel="stylesheet" type="text/css" href="../../style.css">
</head>
<body>
<h2 align="center">Clipping</h2>
<p>The clipping area is an area that limits the available drawing area inside the
canvas. Any primitive is drawn only inside the clipping area. It affects all
primitives.</p>
<p>You can set the clipping area by using the function <b>cdClipArea</b>, and
retrieve it using <b>cdGetClipArea</b>. The clipping area is a rectangle by
default, but it can has other shapes. In some drivers a polygon area can be
defined, and in display based drivers a complex region can be defined. The
complex region can be a combination of boxes, polygons, sectors, chords and
texts.</p>
<p>The <b>cdClip</b> function activates and deactivaes the clipping.</p>
<hr>
<pre class="function"><span class="mainFunction">int cdCanvasClip(cdCanvas* canvas, int mode); [in C]</span>
canvas:Clip(mode: number) -> (old_mode: number) [in Lua]</pre>
<p>Activates or deactivates clipping. Returns the previous status. Values: <b>CD_CLIPAREA,
CD_CLIPPOLYGON, CD_CLIPREGION</b> or <b>CD_CLIPOFF</b>. The value <b>CD_QUERY</b>
simply returns the current status. Default value: <b>CD_CLIPOFF</b>.</p>
<p>The value <b>CD_CLIPAREA</b> activates a rectangular area as the clipping
region.
</p>
<p>The value <b>CD_CLIPPOLYGON</b> activates a polygon as a clipping region, but
works only in some drivers (please refer to the notes of each driver). The
clipping polygon must be defined before activating the polygon clipping; if it
is not defined, the current clipping state remains unchanged. See the
documentation of <a href="polygon.html">cdBegin/cdVertex/cdEnd</a> to create a
polygon.</p>
<p>The value <b>CD_CLIPREGION</b> activates a complex clipping region. See the
documentation of <a href="region.html">Regions</a>.</p>
<pre class="function"><span class="mainFunction">void cdCanvasClipArea(cdCanvas* canvas, int xmin, int xmax, int ymin, int ymax); [in C]</span>
void cdfCanvasClipArea(cdCanvas* canvas, double xmin, double xmax, double ymin, double ymax); [in C]
void wdCanvasClipArea(cdCanvas* canvas, double xmin, double xmax, double ymin, double ymax); (WC) [in C]
canvas:ClipArea(xmin, xmax, ymin, ymax: number) [in Lua]
canvas:wClipArea(xmin, xmax, ymin, ymax: number) (WC) [in Lua]</pre>
<p>Defines a rectangle for clipping. Only the points in the interval <i><b>xmin<=
x <= xmax</b></i> and<b> </b><i><b>ymin <= y <= ymax</b></i> will
be printed. Default region: (0, w-1, 0, h-1).
</p>
<pre class="function"><span class="mainFunction">int cdCanvasGetClipArea(cdCanvas* canvas, int *xmin, int *xmax, int *ymin, int *ymax); [in C]</span>
int cdfCanvasGetClipArea(cdCanvas* canvas, double *xmin, double *xmax, double *ymin, double *ymax); [in C]
int wdCanvasGetClipArea(cdCanvas* canvas, double *xmin, double *xmax, double *ymin, double *ymax); (WC) [in C]
canvas:GetClipArea() -> (xmin, xmax, ymin, ymax, status: number) [in Lua]
canvas:wGetClipArea() -> (xmin, xmax, ymin, ymax, status: number) (WC) [in Lua]</pre>
<p>Returns the rectangle and the clipping status. It is not necessary to provide
all return pointers, you can provide only the desired values and <i><b>NULL</b></i>
for the others.</p>
<h4><a name="Polygons">Polygons</a></h4>
<p>A polygon for clipping can be created using <font face="Courier"><strong>cdBegin(</strong>CD_CLIP<strong>)/cdVertex(x,y)/.../cdEnd()</strong></font>.</p>
<p>See the documentation of <a href="polygon.html">cdBegin/cdVertex/cdEnd</a>.</p>
</body>
</html>
|
