Problem in QPainter

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R.M

Beginner

Posts: 11

Wednesday, April 16th 2008, 8:50pm

Problem in QPainter

Hello everyone ,,

I'm using qt3 under linux (Debian). I have a large project , but I have a problem in the interface ,, in my project I need a frame for writing on it ,, and and a button for erasing all what was written , and another button that acts as an eraser and of course a button for re-writing on the frame.

The problem was once I write on the frame and erase it ( using QWidget::erase())
and another window come over my window ,, all what was erased before is draw on the frame

This is the constructor of my class

Source code

TextFrame::TextFrame(QWidget *parent)  : QFrame(parent)
{
    QPixmap  a ( QPixmap("Text.png") )  ; 
    
    _buffer =   a  ;    // _buffer is private variable of tyep QPixmap
    
    CounterOfPoint = 0 ; 
    
    _currentSize=0;
   
}

paintEvent Function

	Source code
1 2 3 4 5	void TextFrame :: paintEvent(QPaintEvent*) { bitBlt(this , 0 , 0 , &_buffer) ; }

mousePressEvent and mouseMoveEvent approximately the same

Source code

void TextFrame::mousePressEvent( QMouseEvent * e )
{
    
    //  I want to write on frame : 
    if ( erase == false ) 
    {
        _last = e->pos(); 
	
         // Add point to array of points
         Points [CounterOfPoint].x = _last.x() ; 
         Points [CounterOfPoint].y = _last.y() ;
	 
         CounterOfPoint++;
	
         pen.setWidth ( _currentSize) ; 
         pen.setColor (_currentColor);
   
         windowpainter.begin (this) ; 
	 
         bufferpainter.begin(& _buffer) ;
    
         windowpainter.setPen (pen);
         bufferpainter.setPen (pen);
	 
         windowpainter.drawPoint(_last);
        
         windowpainter.end() ; 
       
         bufferpainter.end () ; 
    }
    
    // erase from frame :
    else 
	CheckEraseSize(e);
    
} //end if

Source code

and the is the resizeEvent function ,,

void TextFrame :: resizeEvent ( QResizeEvent * event) 
{	
    QPixmap save ( _buffer ) ; 
    
    _buffer.resize ( event -> size () ) ; 
    
    bitBlt ( &_buffer , 0, 0 , &save ) ; 
}

EraseCheckSize(e) is jsut a function that checks the size choosed by the user and then use:
QWidget::erase(Region);

for erasing all the frame I could use this code and the prblem disappears , but I don't know how to do if I would only earase some of my drawing not every thing:

	Source code
1 2 3 4 5 6 7 8 9 10 11 12 13	void TextFrame :: EraseAll() { CounterOfPoint = 0 ; _buffer = *(QWidget::erasePixmap ()); QWidget::setErasePixmap (_buffer) ; }

Any help is greatly appreciated..

This post has been edited 1 times, last edit by "R.M" (Apr 16th 2008, 9:10pm)

R.M

Beginner

Posts: 11

Friday, April 18th 2008, 12:59pm

R.M

Beginner

Posts: 11

Monday, April 28th 2008, 6:18pm

up ..

Am I write my problem in a wrong place ?

This post has been edited 1 times, last edit by "R.M" (May 4th 2008, 6:30pm)