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345 lines
18 KiB
345 lines
18 KiB
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<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/opengl/qgl.cpp:733 -->
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>TQGLContext Class Reference<br><small>[<a href="opengl.html">OpenGL module</a>]</small></h1>
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<p>The TQGLContext class encapsulates an OpenGL rendering context.
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<a href="#details">More...</a>
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<p><tt>#include <<a href="qgl-h.html">ntqgl.h</a>></tt>
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<p>Inherits <a href="ntqgl.html">TQGL</a>.
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<p><a href="qglcontext-members.html">List of all member functions.</a>
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<h2>Public Members</h2>
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<ul>
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<li class=fn><a href="#TQGLContext"><b>TQGLContext</b></a> ( const TQGLFormat & format, TQPaintDevice * device )</li>
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<li class=fn>virtual <a href="#~TQGLContext"><b>~TQGLContext</b></a> ()</li>
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<li class=fn>virtual bool <a href="#create"><b>create</b></a> ( const TQGLContext * shareContext = 0 )</li>
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<li class=fn>bool <a href="#isValid"><b>isValid</b></a> () const</li>
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<li class=fn>bool <a href="#isSharing"><b>isSharing</b></a> () const</li>
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<li class=fn>virtual void <a href="#reset"><b>reset</b></a> ()</li>
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<li class=fn>TQGLFormat <a href="#format"><b>format</b></a> () const</li>
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<li class=fn>TQGLFormat <a href="#requestedFormat"><b>requestedFormat</b></a> () const</li>
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<li class=fn>virtual void <a href="#setFormat"><b>setFormat</b></a> ( const TQGLFormat & format )</li>
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<li class=fn>virtual void <a href="#makeCurrent"><b>makeCurrent</b></a> ()</li>
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<li class=fn>virtual void <a href="#swapBuffers"><b>swapBuffers</b></a> () const</li>
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<li class=fn>TQPaintDevice * <a href="#device"><b>device</b></a> () const</li>
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<li class=fn>TQColor <a href="#overlayTransparentColor"><b>overlayTransparentColor</b></a> () const</li>
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</ul>
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<h2>Static Public Members</h2>
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<ul>
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<li class=fn>const TQGLContext * <a href="#currentContext"><b>currentContext</b></a> ()</li>
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</ul>
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<h2>Protected Members</h2>
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<ul>
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<li class=fn>virtual bool <a href="#chooseContext"><b>chooseContext</b></a> ( const TQGLContext * shareContext = 0 )</li>
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<li class=fn>virtual void <a href="#doneCurrent"><b>doneCurrent</b></a> ()</li>
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<li class=fn>virtual int <a href="#choosePixelFormat"><b>choosePixelFormat</b></a> ( void * dummyPfd, HDC pdc )</li>
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<li class=fn>virtual void * <a href="#chooseVisual"><b>chooseVisual</b></a> ()</li>
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<li class=fn>virtual void * <a href="#chooseMacVisual"><b>chooseMacVisual</b></a> ( GDHandle device )</li>
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<li class=fn>bool <a href="#deviceIsPixmap"><b>deviceIsPixmap</b></a> () const</li>
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<li class=fn>bool <a href="#windowCreated"><b>windowCreated</b></a> () const</li>
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<li class=fn>void <a href="#setWindowCreated"><b>setWindowCreated</b></a> ( bool on )</li>
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<li class=fn>bool <a href="#initialized"><b>initialized</b></a> () const</li>
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<li class=fn>void <a href="#setInitialized"><b>setInitialized</b></a> ( bool on )</li>
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<li class=fn>void <a href="#generateFontDisplayLists"><b>generateFontDisplayLists</b></a> ( const TQFont & font, int listBase )</li>
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</ul>
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<hr><a name="details"></a><h2>Detailed Description</h2>
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The TQGLContext class encapsulates an OpenGL rendering context.
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<p>
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<p> An OpenGL<sup>*</sup> rendering context is a complete set of
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OpenGL state variables.
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<p> The context's <a href="ntqgl.html#FormatOption-enum">format</a> is set in the
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constructor or later with <a href="#setFormat">setFormat</a>(). The format options that are
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actually set are returned by <a href="#format">format</a>(); the options you asked for
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are returned by <a href="#requestedFormat">requestedFormat</a>(). Note that after a TQGLContext
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object has been constructed, the actual OpenGL context must be
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created by explicitly calling the <a href="#create">create()</a>
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function. The <a href="#makeCurrent">makeCurrent</a>() function makes this context the
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current rendering context. You can make <em>no</em> context current
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using <a href="#doneCurrent">doneCurrent</a>(). The <a href="#reset">reset</a>() function will reset the context
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and make it invalid.
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<p> You can examine properties of the context with, e.g. <a href="#isValid">isValid</a>(),
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<a href="#isSharing">isSharing</a>(), <a href="#initialized">initialized</a>(), <a href="#windowCreated">windowCreated</a>() and
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<a href="#overlayTransparentColor">overlayTransparentColor</a>().
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<p> If you're using double buffering you can swap the screen contents
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with the off-screen buffer using <a href="#swapBuffers">swapBuffers</a>().
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<p> Please note that TQGLContext is not thread safe.
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<p> <sup>*</sup> OpenGL is a trademark of Silicon Graphics, Inc. in the
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United States and other countries.
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<p> <p>See also <a href="graphics.html">Graphics Classes</a> and <a href="images.html">Image Processing Classes</a>.
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<hr><h2>Member Function Documentation</h2>
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<h3 class=fn><a name="TQGLContext"></a>TQGLContext::TQGLContext ( const <a href="qglformat.html">TQGLFormat</a> & format, <a href="ntqpaintdevice.html">TQPaintDevice</a> * device )
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</h3>
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Constructs an OpenGL context for the paint device <em>device</em>, which
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can be a widget or a pixmap. The <em>format</em> specifies several
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display options for the context.
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<p> If the underlying OpenGL/Window system cannot satisfy all the
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features requested in <em>format</em>, the nearest subset of features
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will be used. After creation, the <a href="#format">format</a>() method will return the
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actual format obtained.
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<p> Note that after a TQGLContext object has been constructed, <a href="#create">create()</a> must be called explicitly to create
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the actual OpenGL context. The context will be <a href="#isValid">invalid</a> if it was not possible to obtain a GL context at
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all.
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<p> <p>See also <a href="#format">format</a>() and <a href="#isValid">isValid</a>().
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<h3 class=fn><a name="~TQGLContext"></a>TQGLContext::~TQGLContext ()<tt> [virtual]</tt>
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</h3>
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Destroys the OpenGL context and frees its resources.
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<h3 class=fn>bool <a name="chooseContext"></a>TQGLContext::chooseContext ( const <a href="qglcontext.html">TQGLContext</a> * shareContext = 0 )<tt> [virtual protected]</tt>
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</h3>
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<p> This semi-internal function is called by <a href="#create">create</a>(). It creates a
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system-dependent OpenGL handle that matches the <a href="#format">format</a>() of <em>shareContext</em> as closely as possible.
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<p> On Windows, it calls the virtual function <a href="#choosePixelFormat">choosePixelFormat</a>(),
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which finds a matching pixel format identifier. On X11, it calls
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the virtual function <a href="#chooseVisual">chooseVisual</a>() which finds an appropriate X
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visual. On other platforms it may work differently.
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<h3 class=fn>void * <a name="chooseMacVisual"></a>TQGLContext::chooseMacVisual ( GDHandle device )<tt> [virtual protected]</tt>
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</h3>
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<p> <strong>Mac only</strong>: This virtual function tries to find a
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visual that matches the format using the given <em>device</em> handle,
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reducing the demands if the original request cannot be met.
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<p> The algorithm for reducing the demands of the format is quite
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simple-minded, so override this method in your subclass if your
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application has specific requirements on visual selection.
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<p> <p>See also <a href="#chooseContext">chooseContext</a>().
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<h3 class=fn>int <a name="choosePixelFormat"></a>TQGLContext::choosePixelFormat ( void * dummyPfd, HDC pdc )<tt> [virtual protected]</tt>
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</h3>
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<strong>Win32 only</strong> This virtual function chooses a pixel
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format that matches the OpenGL <a href="#setFormat">format</a>.
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Reimplement this function in a subclass if you need a custom
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context.
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<p> <b>Warning:</b> The <em>dummyPfd</em> pointer and <em>pdc</em> are used as a <tt>PIXELFORMATDESCRIPTOR*</tt>. We use <tt>void</tt> to avoid using
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Windows-specific types in our header files.
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<p> <p>See also <a href="#chooseContext">chooseContext</a>().
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<h3 class=fn>void * <a name="chooseVisual"></a>TQGLContext::chooseVisual ()<tt> [virtual protected]</tt>
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</h3>
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<strong>X11 only</strong>: This virtual function tries to find a
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visual that matches the format, reducing the demands if the original
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request cannot be met.
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<p> The algorithm for reducing the demands of the format is quite
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simple-minded, so override this method in your subclass if your
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application has spcific requirements on visual selection.
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<p> <p>See also <a href="#chooseContext">chooseContext</a>().
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<h3 class=fn>bool <a name="create"></a>TQGLContext::create ( const <a href="qglcontext.html">TQGLContext</a> * shareContext = 0 )<tt> [virtual]</tt>
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</h3>
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Creates the GL context. Returns TRUE if it was successful in
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creating a valid GL rendering context on the paint device
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specified in the constructor; otherwise returns FALSE (i.e. the
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context is invalid).
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<p> After successful creation, <a href="#format">format</a>() returns the set of features of
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the created GL rendering context.
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<p> If <em>shareContext</em> points to a valid TQGLContext, this method will
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try to establish OpenGL display list sharing between this context
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and the <em>shareContext</em>. Note that this may fail if the two
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contexts have different formats. Use <a href="#isSharing">isSharing</a>() to see if sharing
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succeeded.
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<p> <b>Warning:</b> Implementation note: initialization of C++ class
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members usually takes place in the class constructor. TQGLContext
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is an exception because it must be simple to customize. The
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virtual functions <a href="#chooseContext">chooseContext</a>() (and <a href="#chooseVisual">chooseVisual</a>() for X11) can
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be reimplemented in a subclass to select a particular context. The
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problem is that virtual functions are not properly called during
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construction (even though this is correct C++) because C++
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constructs class hierarchies from the bottom up. For this reason
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we need a <a href="#create">create</a>() function.
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<p> <p>See also <a href="#chooseContext">chooseContext</a>(), <a href="#format">format</a>(), and <a href="#isValid">isValid</a>().
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<h3 class=fn>const <a href="qglcontext.html">TQGLContext</a> * <a name="currentContext"></a>TQGLContext::currentContext ()<tt> [static]</tt>
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</h3>
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<p> Returns the current context, i.e. the context to which any OpenGL
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commands will currently be directed. Returns 0 if no context is
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current.
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<p> <p>See also <a href="#makeCurrent">makeCurrent</a>().
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<h3 class=fn><a href="ntqpaintdevice.html">TQPaintDevice</a> * <a name="device"></a>TQGLContext::device () const
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</h3>
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<p> Returns the paint device set for this context.
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<p> <p>See also <a href="#TQGLContext">TQGLContext::TQGLContext</a>().
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<h3 class=fn>bool <a name="deviceIsPixmap"></a>TQGLContext::deviceIsPixmap () const<tt> [protected]</tt>
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</h3>
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<p> Returns TRUE if the paint device of this context is a pixmap;
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otherwise returns FALSE.
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<h3 class=fn>void <a name="doneCurrent"></a>TQGLContext::doneCurrent ()<tt> [virtual protected]</tt>
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</h3>
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<p> Makes no GL context the current context. Normally, you do not need
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to call this function; TQGLContext calls it as necessary.
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<h3 class=fn><a href="qglformat.html">TQGLFormat</a> <a name="format"></a>TQGLContext::format () const
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</h3>
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<p> Returns the frame buffer format that was obtained (this may be a
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subset of what was requested).
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<p> <p>See also <a href="#requestedFormat">requestedFormat</a>().
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<h3 class=fn>void <a name="generateFontDisplayLists"></a>TQGLContext::generateFontDisplayLists ( const <a href="ntqfont.html">TQFont</a> & font, int listBase )<tt> [protected]</tt>
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</h3>
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<p> Generates a set of 256 display lists for the 256 first characters
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in the font <em>font</em>. The first list will start at index <em>listBase</em>.
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<p> <p>See also <a href="qglwidget.html#renderText">TQGLWidget::renderText</a>().
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<h3 class=fn>bool <a name="initialized"></a>TQGLContext::initialized () const<tt> [protected]</tt>
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</h3>
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<p> Returns TRUE if this context has been initialized, i.e. if
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<a href="qglwidget.html#initializeGL">TQGLWidget::initializeGL</a>() has been performed on it; otherwise
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returns FALSE.
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<p> <p>See also <a href="#setInitialized">setInitialized</a>().
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<h3 class=fn>bool <a name="isSharing"></a>TQGLContext::isSharing () const
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</h3>
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<p> Returns TRUE if display list sharing with another context was
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requested in the <a href="#create">create</a>() call and the GL system was able to
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fulfill this request; otherwise returns FALSE. Note that display
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list sharing might not be supported between contexts with
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different formats.
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<h3 class=fn>bool <a name="isValid"></a>TQGLContext::isValid () const
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</h3>
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<p> Returns TRUE if a GL rendering context has been successfully
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created; otherwise returns FALSE.
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<h3 class=fn>void <a name="makeCurrent"></a>TQGLContext::makeCurrent ()<tt> [virtual]</tt>
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</h3>
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<p> Makes this context the current OpenGL rendering context. All GL
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functions you call operate on this context until another context
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is made current.
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<p> In some very rare cases the underlying call may fail. If this
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occurs an error message is output to stderr.
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<h3 class=fn><a href="ntqcolor.html">TQColor</a> <a name="overlayTransparentColor"></a>TQGLContext::overlayTransparentColor () const
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</h3>
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<p> If this context is a valid context in an overlay plane, returns
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the plane's transparent color. Otherwise returns an <a href="ntqcolor.html#isValid">invalid</a> color.
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<p> The returned color's <a href="ntqcolor.html#pixel">pixel</a> value is
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the index of the transparent color in the colormap of the overlay
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plane. (Naturally, the color's RGB values are meaningless.)
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<p> The returned <a href="ntqcolor.html">TQColor</a> object will generally work as expected only
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when passed as the argument to <a href="qglwidget.html#qglColor">TQGLWidget::qglColor</a>() or
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<a href="qglwidget.html#qglClearColor">TQGLWidget::qglClearColor</a>(). Under certain circumstances it can
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also be used to draw transparent graphics with a <a href="ntqpainter.html">TQPainter</a>. See the
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examples/opengl/overlay_x11 example for details.
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<h3 class=fn><a href="qglformat.html">TQGLFormat</a> <a name="requestedFormat"></a>TQGLContext::requestedFormat () const
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</h3>
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<p> Returns the frame buffer format that was originally requested in
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the constructor or <a href="#setFormat">setFormat</a>().
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<p> <p>See also <a href="#format">format</a>().
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<h3 class=fn>void <a name="reset"></a>TQGLContext::reset ()<tt> [virtual]</tt>
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</h3>
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<p> Resets the context and makes it invalid.
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<p> <p>See also <a href="#create">create</a>() and <a href="#isValid">isValid</a>().
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<h3 class=fn>void <a name="setFormat"></a>TQGLContext::setFormat ( const <a href="qglformat.html">TQGLFormat</a> & format )<tt> [virtual]</tt>
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</h3>
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Sets a <em>format</em> for this context. The context is <a href="#reset">reset</a>.
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<p> Call <a href="#create">create</a>() to create a new GL context that tries to match the
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new format.
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<p> <pre>
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TQGLContext *cx;
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// ...
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<a href="qglformat.html">TQGLFormat</a> f;
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f.<a href="qglformat.html#setStereo">setStereo</a>( TRUE );
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cx-><a href="#setFormat">setFormat</a>( f );
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if ( !cx-><a href="#create">create</a>() )
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exit(); // no OpenGL support, or cannot render on the specified paintdevice
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if ( !cx-><a href="#format">format</a>().stereo() )
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exit(); // could not create stereo context
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</pre>
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<p> <p>See also <a href="#format">format</a>(), <a href="#reset">reset</a>(), and <a href="#create">create</a>().
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<h3 class=fn>void <a name="setInitialized"></a>TQGLContext::setInitialized ( bool on )<tt> [protected]</tt>
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</h3>
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<p> If <em>on</em> is TRUE the context has been initialized, i.e.
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<a href="#setInitialized">TQGLContext::setInitialized</a>() has been called on it. If <em>on</em> is
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FALSE the context has not been initialized.
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<p> <p>See also <a href="#initialized">initialized</a>().
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<h3 class=fn>void <a name="setWindowCreated"></a>TQGLContext::setWindowCreated ( bool on )<tt> [protected]</tt>
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</h3>
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<p> If <em>on</em> is TRUE the context has had a window created for it. If
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<em>on</em> is FALSE no window has been created for the context.
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<p> <p>See also <a href="#windowCreated">windowCreated</a>().
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<h3 class=fn>void <a name="swapBuffers"></a>TQGLContext::swapBuffers () const<tt> [virtual]</tt>
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</h3>
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<p> Swaps the screen contents with an off-screen buffer. Only works if
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the context is in double buffer mode.
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<p> <p>See also <a href="qglformat.html#setDoubleBuffer">TQGLFormat::setDoubleBuffer</a>().
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<h3 class=fn>bool <a name="windowCreated"></a>TQGLContext::windowCreated () const<tt> [protected]</tt>
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</h3>
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<p> Returns TRUE if a window has been created for this context;
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otherwise returns FALSE.
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<p> <p>See also <a href="#setWindowCreated">setWindowCreated</a>().
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<!-- eof -->
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<hr><p>
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This file is part of the <a href="index.html">TQt toolkit</a>.
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Copyright © 1995-2007
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<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>TQt 3.3.8</div>
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