Q3CanvasView Class Reference
The Q3CanvasView class provides an on-screen view of a Q3Canvas. More...
#include <Q3CanvasView>This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.
Inherits: Q3ScrollView.
Public Functions
| Q3CanvasView ( QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0 ) | |
| Q3CanvasView ( Q3Canvas * canvas, QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0 ) | |
| ~Q3CanvasView () | |
| Q3Canvas * | canvas () const |
| const QMatrix & | inverseWorldMatrix () const |
| void | setCanvas ( Q3Canvas * canvas ) |
| bool | setWorldMatrix ( const QMatrix & wm ) |
| const QMatrix & | worldMatrix () const |
- 49 public functions inherited from Q3ScrollView
- 4 public functions inherited from Q3Frame
- 14 public functions inherited from QFrame
- 221 public functions inherited from QWidget
- 29 public functions inherited from QObject
- 13 public functions inherited from QPaintDevice
Reimplemented Protected Functions
| virtual void | drawContents ( QPainter * p, int cx, int cy, int cw, int ch ) |
| virtual QSize | sizeHint () const |
- 26 protected functions inherited from Q3ScrollView
- 5 protected functions inherited from Q3Frame
- 3 protected functions inherited from QFrame
- 37 protected functions inherited from QWidget
- 8 protected functions inherited from QObject
- 1 protected function inherited from QPaintDevice
Additional Inherited Members
- 10 properties inherited from Q3ScrollView
- 2 properties inherited from Q3Frame
- 6 properties inherited from QFrame
- 58 properties inherited from QWidget
- 1 property inherited from QObject
- 8 public slots inherited from Q3ScrollView
- 19 public slots inherited from QWidget
- 1 public slot inherited from QObject
- 5 signals inherited from Q3ScrollView
- 1 signal inherited from QWidget
- 1 signal inherited from QObject
- 4 static public members inherited from QWidget
- 7 static public members inherited from QObject
- 26 protected functions inherited from Q3ScrollView
- 5 protected functions inherited from Q3Frame
- 3 protected functions inherited from QFrame
- 37 protected functions inherited from QWidget
- 8 protected functions inherited from QObject
- 1 protected function inherited from QPaintDevice
- 1 protected slot inherited from QWidget
Detailed Description
The Q3CanvasView class provides an on-screen view of a Q3Canvas.
A Q3CanvasView is widget which provides a view of a Q3Canvas.
If you want users to be able to interact with a canvas view, subclass Q3CanvasView. You might then reimplement Q3ScrollView::contentsMousePressEvent(). For example:
void MyCanvasView::contentsMousePressEvent(QMouseEvent* e) { Q3CanvasItemList l = canvas()->collisions(e->pos()); for (Q3CanvasItemList::Iterator it=l.begin(); it!=l.end(); ++it) { if ((*it)->rtti() == Q3CanvasRectangle::RTTI) qDebug("A Q3CanvasRectangle lies somewhere at this point"); } }
The canvas view shows canvas canvas(); this can be changed using setCanvas().
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:
QMatrix 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().
Example:
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 QMatrix, QPainter::setWorldMatrix(), QtCanvas, and Porting to Graphics View.
Member Function Documentation
Q3CanvasView::Q3CanvasView ( QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0 )
Constructs a Q3CanvasView with parent parent, and name name, using the widget flags f. The canvas view is not associated with a canvas, so you must to call setCanvas() to view a canvas.
Q3CanvasView::Q3CanvasView ( Q3Canvas * canvas, QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0 )
This is an overloaded function.
Constructs a Q3CanvasView which views canvas canvas, with parent parent, and name name, using the widget flags f.
Q3CanvasView::~Q3CanvasView ()
Destroys the canvas view. The associated canvas is not deleted.
Q3Canvas * Q3CanvasView::canvas () const
Returns a pointer to the canvas which the Q3CanvasView is currently showing.
See also setCanvas().
void Q3CanvasView::drawContents ( QPainter * p, int cx, int cy, int cw, int ch ) [virtual protected]
Reimplemented from Q3ScrollView::drawContents().
Repaints part of the Q3Canvas 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.
const QMatrix & Q3CanvasView::inverseWorldMatrix () const
Returns a reference to the inverse of the canvas view's current transformation matrix.
See also setWorldMatrix() and worldMatrix().
void Q3CanvasView::setCanvas ( Q3Canvas * canvas )
Sets the canvas that the Q3CanvasView is showing to the canvas canvas.
See also canvas().
bool Q3CanvasView::setWorldMatrix ( const QMatrix & wm )
Sets the transformation matrix of the Q3CanvasView 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 Q3CanvasView will decrease considerably.
Returns false if wm is not invertable; otherwise returns true.
See also worldMatrix(), inverseWorldMatrix(), and QMatrix::isInvertible().
QSize Q3CanvasView::sizeHint () const [virtual protected]
Reimplemented from QWidget::sizeHint().
Suggests a size sufficient to view the entire canvas.
const QMatrix & Q3CanvasView::worldMatrix () const
Returns a reference to the canvas view's current transformation matrix.
See also setWorldMatrix() and inverseWorldMatrix().
No notes