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<title>World Coordinates</title>
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<h2 align="center">World Coordinates</h2>
<p>Allows the use of a World Coordinate System. In this system you can attribute
coordinates to any unit you want. After you define a window (rectangular
region) in your world, each given coordinate is then mapped to canvas
coordinates to draw the primitives. You can define a viewport in your canvas to
change the coordinate mapping from world to canvas. The image below shows the
relation between Window and Viewport.</p>
<p align="center"><font size="4">Window x Viewport</font><br>
<img src="../../img/wc-dc.gif" border="2" width="330" height="182"></p>
<p>If you want to map coordinates from one system to another, use the <font>wdWorld2Canvas</font>
e <font>wdCanvas2World</font> functions.
</p>
<p>The quality of the picture depends on the conversion from World to Canvas, so
if the canvas has a small size the picture quality will be poor. To increase
picture quality create a canvas with a larger size, if possible.</p>
<p>All World Coordinate drawing in all drivers are simulated using other CD
primitives.</p>
<hr>
<pre class="function"><span class="mainFunction">void <a name="wdWindow">wdCanvasWindow</a>(cdCanvas* canvas, double xmin, double xmax, double ymin, double ymax); [in C]</span>
canvas:wWindow(xmin, xmax, ymin, ymax: number) [in Lua]</pre>
<p>Configures a window in the world coordinate system to be used to convert world
coordinates (with values in real numbers) into canvas coordinates (with values
in integers). The default window is the size in millimeters of the whole
canvas.</p>
<pre class="function"><span class="mainFunction">void <a name="wdGetWindow">wdCanvasGetWindow</a>(cdCanvas* canvas, double *xmin, double *xmax, double *ymin, double *ymax); [in C]</span>
canvas:wGetWindow() -> (xmin, xmax, ymin, ymax: number) [in Lua]</pre>
<p>Queries the current window in the world coordinate system being used to
convert world coordinates into canvas coordinates (and the other way round). It
is not necessary to provide all return pointers, you can provide only the
desired values.</p>
<pre class="function"><span class="mainFunction">void <a name="wdViewport">wdCanvasViewport</a>(cdCanvas* canvas, int xmin, int xmax, int ymin, int ymax); [in C]</span>
canvas:wViewport(xmin, xmax, ymin, ymax: number) [in Lua]</pre>
<p>Configures a viewport in the canvas coordinate system to be used to convert
world coordinates (with values in real numbers) into canvas coordinates (with
values in integers). The default viewport is the whole canvas <font>(0,w-1,0,h-1)</font>.
If the canvas size is changed, the viewport will not be automatically updated.
</p>
<pre class="function"><span class="mainFunction">void <a name="wdGetViewport">wdCanvasGetViewport</a>(cdCanvas* canvas, int *xmin, int *xmax, int *ymin, int *ymax); [in C]</span>
canvas:wGetViewport() -> (xmin, xmax, ymin, ymax: number) [in Lua]</pre>
<p>Queries the current viewport in the world coordinate system being used to
convert world coordinates into canvas coordinates (and the other way round). It
is not necessary to provide all return pointers, you can provide only the
desired values and <font>NULL</font> for the others.</p>
<pre class="function"><span class="mainFunction">void <a name="wdWorld2Canvas">wdCanvasWorld2Canvas</a>(cdCanvas* canvas, double xw, double yw, int *xv, int *yv); [in C]</span>
canvas:wWorld2Canvas(xw, yw: number) -> (xv, yv: number) [in Lua]</pre>
<p>Converts world coordinates into canvas coordinates. It is not necessary to
provide all return pointers, you can provide only the desired values and <font>NULL</font>
for the others.</p>
<pre class="function"><span class="mainFunction">void <a name="wdCanvas2World">wdCanvasCanvas2World</a>(cdCanvas* canvas, int xv, int yv, double *xw, double *yw); [in C]</span>
canvas:wCanvas2World(xv, yv: number) -> (xw, yw: number) [in Lua]</pre>
<p>Converts canvas coordinates into world coordinates. It is not necessary to
provide all return pointers, you can provide only the desired values and <font>NULL</font>
for the others.</p>
<h3>Extra</h3>
<pre class="function"><span class="mainFunction">void <a name="wdHardcopy">wdCanvasHardcopy</a>(cdCanvas *canvas, cdContext* ctx, void *data, void(*draw_func)(cdCanvas *canvas_copy)); [in C]</span>
canvas:wCanvasHardcopy(ctx: number, data: string or userdata, draw_func: function) [in Lua]</pre>
<p>Creates a new canvas, prepares Window and Viewport according to
the provided canvas, maintaining the aspect ratio and making the drawing occupy
the largest possible area of the new canvas, calls the drawing function (which
must use routines in WC) and, finally, removes the new canvas.</p>
<p>It is usually used for "hard copies" of drawings (print equivalent copy). The
most common used contexts are Printer, PS and PDF.</p>
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