The Q3CanvasView class provides an on-screen view of a Q3Canvas . 更多...
| 头： | #include <Q3CanvasView> |
| 继承： | Q3ScrollView |
| 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 |
| virtual void | drawContents (QPainter * p , int cx , int cy , int cw , int ch ) |
| virtual QSize | sizeHint () const |
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 ()。例如：
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);
使用 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 ().
范例：
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);
另请参阅 QMatrix , QPainter::setWorldMatrix (), QtCanvas ，和 Porting to Graphics View .
构造 Q3CanvasView 采用父级 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.
这是重载函数。
构造 Q3CanvasView which views canvas canvas ，采用父级 parent , and name name , using the widget flags f .
Destroys the canvas view. The associated canvas is not deleted.
Returns a pointer to the canvas which the Q3CanvasView is currently showing.
另请参阅 setCanvas ().
[virtual protected]
void
Q3CanvasView::
drawContents
(
QPainter
*
p
,
int
cx
,
int
cy
,
int
cw
,
int
ch
)
重实现自 Q3ScrollView::drawContents ().
Repaints part of the Q3Canvas that the canvas view is showing starting at cx by cy , with a width of cw 和高度 ch using the painter p .
Returns a reference to the inverse of the canvas view's current transformation matrix.
另请参阅 setWorldMatrix () 和 worldMatrix ().
Sets the canvas that the Q3CanvasView is showing to the canvas canvas .
另请参阅 canvas ().
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.
另请参阅 worldMatrix (), inverseWorldMatrix ()，和 QMatrix::isInvertible ().
[virtual protected]
QSize
Q3CanvasView::
sizeHint
() const
重实现自 QWidget::sizeHint ().
Suggests a size sufficient to view the entire canvas.
Returns a reference to the canvas view's current transformation matrix.
另请参阅 setWorldMatrix () 和 inverseWorldMatrix ().