Qt-interest Archive, January 2008
QPainter - Cannot paint on null pixmap
Message 1 in thread
Hi,
I've got a problem and I cannot figure out where it comes from. So,
here's what I have:
A QMainWindow including a QTableWidget and a customized QWidget.
This QWidget is included for some really simple painting activities.
The QTableWidget has 8 columns. The content of the first column
will be extracted and drawn into the QWidget. The content is a text
string and shall be displayed as large as possible but at a max of
21 pixels. If the string is too long to fit into the QWidget, the
font size of 21 pixels is decreased by 1 pixel as long as either
the string fits into the QWidget properly or the font size reaches
a minimum value of 8 pixels. If so, the string is shortened and the
procedure is repeated again by a font size of 21 pixels. Additionally
the QTableWidget has implemented the QWidget::resizeEvent to resize
the colums and rows to their contents by using QTableView::resizeColumnsToContents
and QTableView::resizeRowsToContents. (This seems to be the bad part
in my opinion.)
This all works very fine (!) until the string to be drawn gets about
5300 characters. Then I got the errors:
QPainter::begin: Cannot paint on a null pixmap
QPainter::end: Painter not active, aborted
X Error: BadAlloc (insufficient resources for operation) 11
Major opcode: 53 (X_CreatePixmap)
Resource id: 0x4010028
X Error: BadDrawable (invalid Pixmap or Window parameter) 9
Extension: 153 (RENDER)
Minor opcode: 4 (RenderCreatePicture)
Resource id: 0x4010028
X Error: RenderBadPicture (invalid Picture parameter) 177
Extension: 153 (RENDER)
Minor opcode: 7 (RenderFreePicture)
Resource id: 0x4010029
X Error: BadPixmap (invalid Pixmap parameter) 4
Major opcode: 54 (X_FreePixmap)
Resource id: 0x4010028
If I resize the QMainWindow's nothing happens but if I resize the
QTableWidget's first column (Will the resizeEvent be called?) those
errors appear. A bit curios about this: Sometimes only the first
to lines appear, sometimes all the erros come accross.
Hope anyone could help.
Thanks in advance,
Marcel
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