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RedHat 9 (Linux i386) - man page for qcanvasview (redhat section 3qt)

QCanvasView(3qt)								 QCanvasView(3qt)

       QCanvasView - On-screen view of a QCanvas

       #include <qcanvas.h>

       Inherits QScrollView.

   Public Members
       QCanvasView ( QWidget * parent = 0, const char * name = 0, WFlags f = 0 )
       QCanvasView ( QCanvas * canvas, QWidget * parent = 0, const char * name = 0, WFlags f = 0
       ~QCanvasView ()
       QCanvas * canvas () const
       void setCanvas ( QCanvas * canvas )
       const QWMatrix & worldMatrix () const
       const QWMatrix & inverseWorldMatrix () const
       bool setWorldMatrix ( const QWMatrix & wm )

   Protected Members
       virtual void drawContents ( QPainter * p, int cx, int cy, int cw, int ch )
       virtual QSize sizeHint () const

       The QCanvasView class provides an on-screen view of a QCanvas.

       A QCanvasView is widget which provides a view of a QCanvas.

       If you want users to be able to interact with a canvas view, subclass QCanvasView. You
       might then reimplement QScrollView::contentsMousePressEvent() for example:

	   void MyCanvasView::contentsMousePressEvent( QMouseEvent* e )
	       QCanvasItemList l = canvas()->collisions(e->pos());
	       for (QCanvasItemList::Iterator it=l.begin(); it!=l.end(); ++it) {
		   if ( (*it)->rtti() == QCanvasRectangle::RTTI )
		       qDebug("A QCanvasRectangle lies somewhere at this point");

       Set the canvas that the view shows with setCanvas() and retrieve the canvas which the view
       is showing with canvas().

       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:

	   QWMatrix wm;
	   wm.scale( 2, 2 );   // Zooms in by 2 times
	   wm.rotate( 90 );    // Rotates 90 degrees counter clockwise
			       // around the origin.
	   wm.translate( 0, -canvas->height() );
			       // moves the canvas down so what was visible
			       // before is still visible.
	   myCanvasView->setWorldMatrix( wm );

       Use setWorldMatrix() to set the canvas view's world matrix: you must ensure that the world
       matrix is invertible. The current world matrix is retrievable with worldMatrix(), and its
       inversion is retrievable with inverseWorldMatrix().


       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.

	   QRect rc = QRect( myCanvasView->contentsX(), myCanvasView->contentsY(),
			     myCanvasView->visibleWidth(), myCanvasView->visibleHeight() );
	   QRect canvasRect = myCanvasView->inverseWorldMatrix().mapRect(rc);

       See also QWMatrix, QPainter::setWorldMatrix(), Graphics Classes, and Image Processing

QCanvasView::QCanvasView ( QWidget * parent = 0, const char * name = 0, WFlags f = 0 )
       Constructs a QCanvasView with parent parent, and name name, using the widget flags f. The
       canvas view is not associated with a canvas, so you will need to call setCanvas() to
       display a canvas.

QCanvasView::QCanvasView ( QCanvas * canvas, QWidget * parent = 0, const char * name = 0, WFlags
       f = 0 )
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Constructs a QCanvasView which views canvas canvas, with parent parent, and name name,
       using the widget flags f.

QCanvasView::~QCanvasView ()
       Destroys the canvas view. The associated canvas is not deleted.

QCanvas * QCanvasView::canvas () const
       Returns a pointer to the canvas which the QCanvasView is currently showing.

void QCanvasView::drawContents ( QPainter * p, int cx, int cy, int cw, int ch ) [virtual
       Repaints part of the QCanvas that the canvas view is showing starting at cx by cy, with a
       width of cw and a height of ch using the painter p.

       Reimplemented from QScrollView.

const QWMatrix &; QCanvasView::inverseWorldMatrix () const
       Returns a reference to the inverse of the canvas view's current transformation matrix.

       See also setWorldMatrix() and worldMatrix().

void QCanvasView::setCanvas ( QCanvas * canvas )
       Sets the canvas that the QCanvasView is showing to the canvas canvas.

bool QCanvasView::setWorldMatrix ( const QWMatrix & wm )
       Sets the transformation matrix of the QCanvasView to wm. 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).

       When you use this, you should note that the performance of the QCanvasView will decrease

       Returns FALSE if wm is not invertable; otherwise returns TRUE.

       See also worldMatrix(), inverseWorldMatrix(), and QWMatrix::isInvertible().

       Example: canvas/canvas.cpp.

QSize QCanvasView::sizeHint () const [virtual protected]
       Suggests a size sufficient to view the entire canvas.

const QWMatrix &; QCanvasView::worldMatrix () const
       Returns a reference to the canvas view's current transformation matrix.

       See also setWorldMatrix() and inverseWorldMatrix().

       Example: canvas/canvas.cpp.

       http://doc.trolltech.com/qcanvasview.html http://www.trolltech.com/faq/tech.html

       Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the license file included
       in the distribution for a complete license statement.

       Generated automatically from the source code.

       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is located at
       $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. This man page is
       provided as a convenience for those users who prefer man pages, although this format is
       not officially supported by Trolltech.

       If you find errors in this manual page, please report them to qt-bugs@trolltech.com.
       Please include the name of the manual page (qcanvasview.3qt) and the Qt version (3.1.1).

Trolltech AS				 9 December 2002			 QCanvasView(3qt)

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