html/en/drv/dbufrgb.html


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<h2>CD_DBUFFERRGB - Double Buffer Driver using a RGB image (cdirgb.h)</h2>

  <p>Implements the concept of offscreen drawing. It is based on a Image 
  RGB (the back buffer) and any other canvas (the front buffer).</p>

<h3>Use</h3>

  <p>The canvas is created by means of a call to function
  <a href="../func/init.html#cdCreateCanvas">
  <font face="Courier"><strong>cdCreateCanvas</strong></font></a><font face="Courier">(CD_DBUFFERRGB, 
  Data)</font>, after which other functions in the CD library can be called as 
  usual. This function creates a CD canvas to use with any existing canvas. The parameter <font face="Courier">Data</font> is a 
  pointer to the already created canvas.</p>
  <p>Any amount of such canvases may exist simultaneously. It is important to 
  note that a call to function
  <a href="../func/init.html#cdKillCanvas">
  <font face="Courier"><strong>cdKillCanvas</strong></font></a> is required to 
  properly <b>end</b> the driver. Call function
  <a href="../func/init.html#cdKillCanvas">
  <font face="Courier"><strong>cdKillCanvas</strong></font></a> for this driver 
  before calling <font face="Courier"><strong>cdKillCanvas</strong></font> for 
  the client canvas driver.</p>
  <p>The drawing functions will work normally as if they were drawn on 
  the image RGB driver. When function <font face="Courier"><b>
  <a href="../func/control.html#cdFlush">
  cdCanvasFlush</a></b></font> is executed, the image is drawn in the canvas 
  passed as parameter in the canvas creation.</p>
  <p>When the window's size changes, the RGB image is automatically recreated 
  using the same size as the canvas. This is done in the function
  <font face="Courier"><b>
  <a href="../func/init.html#cdActivate">
  cdCanvasActivate</a></b></font>.</p>

<h3>Behavior of Functions</h3>

  <p>This driver depends on the <a href="irgb.html">RGB Client Image Driver</a>.</p>
<h4>Control</h4>
<ul>
  <li><a href="../func/control.html#cdFlush"><font face="Courier"><strong>Flush</strong></font></a>: 
  draws the contents of the image into the window. It is affected by <strong>
  Origin</strong> and <strong>Clipping</strong>, but not by <strong>WriteMode</strong>.</li>
</ul>
<p>&nbsp;</p>


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