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Thread: use Qpainter to draw lines + problem in my painter

  1. #1
    Join Date
    Feb 2008
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    Default use Qpainter to draw lines + problem in my painter

    Hello everyone ,,

    first of all I'm using Qt3 , and I work on Debian,,

    I try to modify drawlines.cpp code in example package of QT3 because I want my own painter program ,,

    what I want in my program is to have a white box and some other buttons ,, but I have a problem in my try , I want the drawn lines just appears in this white box but now the user can draw anywhere in the frame ,, I try to solve this problem by passing the name of the label (the white box) to the constructor of QPainter , But I have something strange mybe it is not strange for advanced programmer ,, the problem was the user could draw correctly but she has to put the mouse not on the white space BUT in a place above it with about 7 cm !
    here is the modified code

    Qt Code:
    1. #include <qpainter.h>
    2. #include <stdlib.h>
    3.  
    4.  
    5.  
    6. const int MAXPOINTS = 4000; // maximum number of points
    7.  
    8.  
    9. void mousewriting::init()
    10. {
    11.  
    12. count = 0;
    13. down = FALSE;
    14. points = new QPoint[MAXPOINTS];
    15.  
    16. }
    17.  
    18.  
    19. void mousewriting::destroy()
    20. {
    21.  
    22. delete[] points;
    23.  
    24. }
    25.  
    26.  
    27.  
    28.  
    29. void mousewriting::mousePressEvent( QMouseEvent * )
    30. {
    31.  
    32. down = TRUE;
    33. count = 0;
    34. }
    35.  
    36.  
    37. void mousewriting::mouseMoveEvent( QMouseEvent *e )
    38. {
    39.  
    40. if ( down && count < MAXPOINTS ) {
    41. QPainter paint(this); \\ I replace this by textLabel1 (the white box)
    42. // paint.setWindow ( 170, 140, 400, 500 );
    43. points[count++] = e->pos(); // add point
    44. paint.drawPoint( e->pos() ); // plot point
    45.  
    46. for ( int i=0; i<count-1; i++ ) {
    47. for ( int j=i+1; j<i+2; j++ ) {
    48.  
    49. paint.setPen( blue);
    50. paint.drawLine( points[i], points[j] ); // draw line
    51. paint.flush() ;
    52. }//end inner for
    53. }//end outer for
    54.  
    55.  
    56. }//end if
    57.  
    58. }//end funcion
    59.  
    60.  
    61. void mousewriting::cleardraw()
    62. {
    63. down= false;
    64. update();
    65. }
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    could anyone help me ,, or give me an idea to have a frame and iside it a white space for drawing in it ??

    another question , I try to draw using functions of QPainter class in the load of the program , I put it the code in the init() but it does not draw ,, is there any way to draw shapes using in the load time ?

  2. #2
    Join Date
    Feb 2008
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    Question Re: use Qpainter to draw lines + problem in my painter

    I could draw lines now in paintEvent() and the lines appeared at the run of the program ,,

    But the main problem still exists, the drawn curves are not exactly drawn with the head of the mouse , they change accouding to the white box position , I try to search fo a solution but I'm a very beginner in qt3

    any helps are greaaaaately appreciated
    Attached Files Attached Files

  3. #3
    Join Date
    Feb 2008
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    Default Re: use Qpainter to draw lines + problem in my painter

    No help

    all what i want is to draw inside a frame or label , I have read some links but all my try fails

  4. #4
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    Default Re: use Qpainter to draw lines + problem in my painter

    I don't understand posting your problem in an e-mail I received directly. I suggest you post your problem in the Qt Center Forum directly.

    I have switched from Qt 3 to Qt 4. They have made drastic changes in the "painter" . You may want to look at your problem from that prospective.

    Sorry, but I will not open any more of your e-mails sent directly to me if they contain any Qt content.

    Good luck

  5. #5
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    Default Re: use Qpainter to draw lines + problem in my painter

    Could you provide a minimal compilable example reproducing the problem?

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