<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/canvas/qcanvas.cpp:3456 --> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>TQCanvasView Class</title> <style type="text/css"><!-- fn { margin-left: 1cm; text-indent: -1cm; } a:link { color: #004faf; text-decoration: none } a:visited { color: #672967; text-decoration: none } body { background: #ffffff; color: black; } --></style> </head> <body> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr bgcolor="#E5E5E5"> <td valign=center> <a href="index.html"> <font color="#004faf">Home</font></a> | <a href="classes.html"> <font color="#004faf">All Classes</font></a> | <a href="mainclasses.html"> <font color="#004faf">Main Classes</font></a> | <a href="annotated.html"> <font color="#004faf">Annotated</font></a> | <a href="groups.html"> <font color="#004faf">Grouped Classes</font></a> | <a href="functions.html"> <font color="#004faf">Functions</font></a> </td> <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>TQCanvasView Class Reference<br><small>[<a href="canvas.html">canvas module</a>]</small></h1> <p>The TQCanvasView class provides an on-screen view of a TQCanvas. <a href="#details">More...</a> <p><tt>#include <<a href="qcanvas-h.html">ntqcanvas.h</a>></tt> <p>Inherits <a href="ntqscrollview.html">TQScrollView</a>. <p><a href="qcanvasview-members.html">List of all member functions.</a> <h2>Public Members</h2> <ul> <li class=fn><a href="#TQCanvasView"><b>TQCanvasView</b></a> ( TQWidget * parent = 0, const char * name = 0, WFlags f = 0 )</li> <li class=fn><a href="#TQCanvasView-2"><b>TQCanvasView</b></a> ( TQCanvas * canvas, TQWidget * parent = 0, const char * name = 0, WFlags f = 0 )</li> <li class=fn><a href="#~TQCanvasView"><b>~TQCanvasView</b></a> ()</li> <li class=fn>TQCanvas * <a href="#canvas"><b>canvas</b></a> () const</li> <li class=fn>void <a href="#setCanvas"><b>setCanvas</b></a> ( TQCanvas * canvas )</li> <li class=fn>const TQWMatrix & <a href="#worldMatrix"><b>worldMatrix</b></a> () const</li> <li class=fn>const TQWMatrix & <a href="#inverseWorldMatrix"><b>inverseWorldMatrix</b></a> () const</li> <li class=fn>bool <a href="#setWorldMatrix"><b>setWorldMatrix</b></a> ( const TQWMatrix & wm )</li> </ul> <h2>Protected Members</h2> <ul> <li class=fn>virtual void <a href="#drawContents"><b>drawContents</b></a> ( TQPainter * p, int cx, int cy, int cw, int ch )</li> <li class=fn>virtual TQSize <a href="#sizeHint"><b>sizeHint</b></a> () const</li> </ul> <hr><a name="details"></a><h2>Detailed Description</h2> The TQCanvasView class provides an on-screen view of a <a href="ntqcanvas.html">TQCanvas</a>. <p> <p> A TQCanvasView is widget which provides a view of a TQCanvas. <p> If you want users to be able to interact with a canvas view, subclass TQCanvasView. You might then reimplement <a href="ntqscrollview.html#contentsMousePressEvent">TQScrollView::contentsMousePressEvent</a>(). For example, assuming no <a href="ntqwmatrix.html#TransformationMode">transformation matrix</a> is set: <p> <pre> void MyCanvasView::contentsMousePressEvent( <a href="qmouseevent.html">TQMouseEvent</a>* e ) { <a href="qcanvasitemlist.html">TQCanvasItemList</a> l = <a href="#canvas">canvas</a>()->collisions(e-><a href="qmouseevent.html#pos">pos</a>()); for (TQCanvasItemList::Iterator it=l.<a href="ntqvaluelist.html#begin">begin</a>(); it!=l.<a href="ntqvaluelist.html#end">end</a>(); ++it) { if ( (*it)->rtti() == TQCanvasRectangle::RTTI ) <a href="ntqapplication.html#qDebug">tqDebug</a>("A TQCanvasRectangle lies somewhere at this point"); } } </pre> <p> The canvas view shows canvas <a href="#canvas">canvas</a>(); this can be changed using <a href="#setCanvas">setCanvas</a>(). <p> A transformation matrix can be used to transform the view of the canvas in various ways, for example, zooming in or out or rotating. For example: <p> <pre> <a href="ntqwmatrix.html">TQWMatrix</a> wm; wm.<a href="ntqwmatrix.html#scale">scale</a>( 2, 2 ); // Zooms in by 2 times wm.<a href="ntqwmatrix.html#rotate">rotate</a>( 90 ); // Rotates 90 degrees counter clockwise // around the origin. wm.<a href="ntqwmatrix.html#translate">translate</a>( 0, -canvas->height() ); // moves the canvas down so what was visible // before is still visible. myCanvasView->setWorldMatrix( wm ); </pre> <p> Use <a href="#setWorldMatrix">setWorldMatrix</a>() to set the canvas view's world matrix: you must ensure that the world matrix is invertible. The current world matrix is retrievable with <a href="#worldMatrix">worldMatrix</a>(), and its inversion is retrievable with <a href="#inverseWorldMatrix">inverseWorldMatrix</a>(). <p> Example: <p> The following code finds the part of the canvas that is visible in this view, i.e. the bounding rectangle of the view in canvas coordinates. <p> <pre> <a href="ntqrect.html">TQRect</a> rc = TQRect( myCanvasView->contentsX(), myCanvasView->contentsY(), myCanvasView->visibleWidth(), myCanvasView->visibleHeight() ); <a href="ntqrect.html">TQRect</a> canvasRect = myCanvasView->inverseWorldMatrix().mapRect(rc); </pre> <p> <p>See also <a href="ntqwmatrix.html">TQWMatrix</a>, <a href="ntqpainter.html#setWorldMatrix">TQPainter::setWorldMatrix</a>(), <a href="graphics.html">Graphics Classes</a>, and <a href="images.html">Image Processing Classes</a>. <p> <hr><h2>Member Function Documentation</h2> <h3 class=fn><a name="TQCanvasView"></a>TQCanvasView::TQCanvasView ( <a href="ntqwidget.html">TQWidget</a> * parent = 0, const char * name = 0, WFlags f = 0 ) </h3> Constructs a TQCanvasView with parent <em>parent</em>, and name <em>name</em>, using the widget flags <em>f</em>. The canvas view is not associated with a canvas, so you must to call <a href="#setCanvas">setCanvas</a>() to view a canvas. <h3 class=fn><a name="TQCanvasView-2"></a>TQCanvasView::TQCanvasView ( <a href="ntqcanvas.html">TQCanvas</a> * canvas, <a href="ntqwidget.html">TQWidget</a> * parent = 0, const char * name = 0, WFlags f = 0 ) </h3> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. <p> Constructs a TQCanvasView which views canvas <em>canvas</em>, with parent <em>parent</em>, and name <em>name</em>, using the widget flags <em>f</em>. <h3 class=fn><a name="~TQCanvasView"></a>TQCanvasView::~TQCanvasView () </h3> Destroys the canvas view. The associated canvas is <em>not</em> deleted. <h3 class=fn><a href="ntqcanvas.html">TQCanvas</a> * <a name="canvas"></a>TQCanvasView::canvas () const </h3> <p> Returns a pointer to the canvas which the TQCanvasView is currently showing. <h3 class=fn>void <a name="drawContents"></a>TQCanvasView::drawContents ( <a href="ntqpainter.html">TQPainter</a> * p, int cx, int cy, int cw, int ch )<tt> [virtual protected]</tt> </h3> Repaints part of the <a href="ntqcanvas.html">TQCanvas</a> that the canvas view is showing starting at <em>cx</em> by <em>cy</em>, with a width of <em>cw</em> and a height of <em>ch</em> using the painter <em>p</em>. <p> <b>Warning:</b> When double buffering is enabled, <a href="#drawContents">drawContents</a>() will not respect the current settings of the painter when setting up the painter for the double buffer (e.g., <a href="ntqscrollview.html#viewport">viewport</a>() and window()). Also, be aware that <a href="ntqcanvas.html#update">TQCanvas::update</a>() bypasses drawContents(), which means any reimplementation of drawContents() is not called. <p> <p>See also <a href="ntqcanvas.html#setDoubleBuffering">TQCanvas::setDoubleBuffering</a>(). <p>Reimplemented from <a href="ntqscrollview.html#drawContents">TQScrollView</a>. <h3 class=fn>const <a href="ntqwmatrix.html">TQWMatrix</a> & <a name="inverseWorldMatrix"></a>TQCanvasView::inverseWorldMatrix () const </h3> Returns a reference to the inverse of the canvas view's current <a href="ntqwmatrix.html#TransformationMode">transformation matrix</a>. <p> <p>See also <a href="#setWorldMatrix">setWorldMatrix</a>() and <a href="#worldMatrix">worldMatrix</a>(). <h3 class=fn>void <a name="setCanvas"></a>TQCanvasView::setCanvas ( <a href="ntqcanvas.html">TQCanvas</a> * canvas ) </h3> Sets the canvas that the TQCanvasView is showing to the canvas <em>canvas</em>. <h3 class=fn>bool <a name="setWorldMatrix"></a>TQCanvasView::setWorldMatrix ( const <a href="ntqwmatrix.html">TQWMatrix</a> & wm ) </h3> Sets the <a href="ntqwmatrix.html#TransformationMode">transformation matrix</a> of the TQCanvasView to <em>wm</em>. The matrix must be invertible (i.e. if you create a world matrix that zooms out by 2 times, then the inverse of this matrix is one that will zoom in by 2 times). <p> When you use this, you should note that the performance of the TQCanvasView will decrease considerably. <p> Returns FALSE if <em>wm</em> is not invertable; otherwise returns TRUE. <p> <p>See also <a href="#worldMatrix">worldMatrix</a>(), <a href="#inverseWorldMatrix">inverseWorldMatrix</a>(), and <a href="ntqwmatrix.html#isInvertible">TQWMatrix::isInvertible</a>(). <p>Example: <a href="canvas-example.html#x2930">canvas/canvas.cpp</a>. <h3 class=fn><a href="ntqsize.html">TQSize</a> <a name="sizeHint"></a>TQCanvasView::sizeHint () const<tt> [virtual protected]</tt> </h3> Suggests a size sufficient to view the entire canvas. <h3 class=fn>const <a href="ntqwmatrix.html">TQWMatrix</a> & <a name="worldMatrix"></a>TQCanvasView::worldMatrix () const </h3> Returns a reference to the canvas view's current <a href="ntqwmatrix.html#TransformationMode">transformation matrix</a>. <p> <p>See also <a href="#setWorldMatrix">setWorldMatrix</a>() and <a href="#inverseWorldMatrix">inverseWorldMatrix</a>(). <p>Example: <a href="canvas-example.html#x2931">canvas/canvas.cpp</a>. <!-- eof --> <hr><p> This file is part of the <a href="index.html">TQt toolkit</a>. 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