1QCanvasView(3qt) QCanvasView(3qt)
2
6 QCanvasView - On-screen view of a QCanvas
7
9 #include <qcanvas.h>
10 Inherits QScrollView.
12 Public Members
14 QCanvasView ( QWidget * parent = 0, const char * name = 0, WFlags f = 0
15 )
16 QCanvasView ( QCanvas * canvas, QWidget * parent = 0, const char * name
17 = 0, WFlags f = 0 )
18 ~QCanvasView ()
19 QCanvas * canvas () const
20 void setCanvas ( QCanvas * canvas )
21 const QWMatrix & worldMatrix () const
22 const QWMatrix & inverseWorldMatrix () const
23 bool setWorldMatrix ( const QWMatrix & wm )
24 Protected Members
26 virtual void drawContents ( QPainter * p, int cx, int cy, int cw, int
27 ch )
28 virtual QSize sizeHint () const
29
31 The QCanvasView class provides an on-screen view of a QCanvas.
32 A QCanvasView is widget which provides a view of a QCanvas.
34 If you want users to be able to interact with a canvas view, subclass
36 QCanvasView. You might then reimplement
37 QScrollView::contentsMousePressEvent(). For example, assuming no
38 transformation matrix is set:
39 void MyCanvasView::contentsMousePressEvent( QMouseEvent* e )
41 {
42 QCanvasItemList l = canvas()->collisions(e->pos());
43 for (QCanvasItemList::Iterator it=l.begin(); it!=l.end(); ++it) {
44 if ( (*it)->rtti() == QCanvasRectangle::RTTI )
45 qDebug("A QCanvasRectangle lies somewhere at this point");
46 }
47 }
48 The canvas view shows canvas canvas(); this can be changed using
50 setCanvas().
51 A transformation matrix can be used to transform the view of the canvas
53 in various ways, for example, zooming in or out or rotating. For
54 example:
55 QWMatrix wm;
57 wm.scale( 2, 2 ); // Zooms in by 2 times
58 wm.rotate( 90 ); // Rotates 90 degrees counter clockwise
59 // around the origin.
60 wm.translate( 0, -canvas->height() );
61 // moves the canvas down so what was visible
62 // before is still visible.
63 myCanvasView->setWorldMatrix( wm );
64 Use setWorldMatrix() to set the canvas view's world matrix: you must
66 ensure that the world matrix is invertible. The current world matrix is
67 retrievable with worldMatrix(), and its inversion is retrievable with
68 inverseWorldMatrix().
69 Example:
71 The following code finds the part of the canvas that is visible in this
73 view, i.e. the bounding rectangle of the view in canvas coordinates.
74 QRect rc = QRect( myCanvasView->contentsX(), myCanvasView->contentsY(),
76 myCanvasView->visibleWidth(), myCanvasView->visibleHeight() );
77 QRect canvasRect = myCanvasView->inverseWorldMatrix().mapRect(rc);
78 See also QWMatrix, QPainter::setWorldMatrix(), Graphics Classes, and
80 Image Processing Classes.
81
84 f = 0 )
85 Constructs a QCanvasView with parent parent, and name name, using the
86 widget flags f. The canvas view is not associated with a canvas, so you
87 must to call setCanvas() to view a canvas.
88
90 * name = 0, WFlags f = 0 )
91 This is an overloaded member function, provided for convenience. It
92 behaves essentially like the above function.
93 Constructs a QCanvasView which views canvas canvas, with parent parent,
95 and name name, using the widget flags f.
96
98 Destroys the canvas view. The associated canvas is not deleted.
99
101 Returns a pointer to the canvas which the QCanvasView is currently
102 showing.
103
105 ) [virtual protected]
106 Repaints part of the QCanvas that the canvas view is showing starting
107 at cx by cy, with a width of cw and a height of ch using the painter p.
108 Warning: When double buffering is enabled, drawContents() will not
110 respect the current settings of the painter when setting up the painter
111 for the double buffer (e.g., viewport() and window()). Also, be aware
112 that QCanvas::update() bypasses drawContents(), which means any
113 reimplementation of drawContents() is not called.
114 See also QCanvas::setDoubleBuffering().
116 Reimplemented from QScrollView.
118
120 Returns a reference to the inverse of the canvas view's current
121 transformation matrix.
122 See also setWorldMatrix() and worldMatrix().
124
126 Sets the canvas that the QCanvasView is showing to the canvas canvas.
127
129 Sets the transformation matrix of the QCanvasView to wm. The matrix
130 must be invertible (i.e. if you create a world matrix that zooms out by
131 2 times, then the inverse of this matrix is one that will zoom in by 2
132 times).
133 When you use this, you should note that the performance of the
135 QCanvasView will decrease considerably.
136 Returns FALSE if wm is not invertable; otherwise returns TRUE.
138 See also worldMatrix(), inverseWorldMatrix(), and
140 QWMatrix::isInvertible().
141 Example: canvas/canvas.cpp.
143
145 Suggests a size sufficient to view the entire canvas.
146
148 Returns a reference to the canvas view's current transformation matrix.
149 See also setWorldMatrix() and inverseWorldMatrix().
151 Example: canvas/canvas.cpp.
153
156 http://doc.trolltech.com/qcanvasview.html
157 http://www.trolltech.com/faq/tech.html
158
160 Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
161 license file included in the distribution for a complete license
162 statement.
163
165 Generated automatically from the source code.
166
168 If you find a bug in Qt, please report it as described in
169 http://doc.trolltech.com/bughowto.html. Good bug reports help us to
170 help you. Thank you.
171 The definitive Qt documentation is provided in HTML format; it is
173 located at $QTDIR/doc/html and can be read using Qt Assistant or with a
174 web browser. This man page is provided as a convenience for those users
175 who prefer man pages, although this format is not officially supported
176 by Trolltech.
177 If you find errors in this manual page, please report them to qt-
179 bugs@trolltech.com. Please include the name of the manual page
180 (qcanvasview.3qt) and the Qt version (3.3.8).
181Trolltech AS 2 February 2007 QCanvasView(3qt)