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Thread: Drawing a QPixmap mit rounded corners

  1. #1
    Join Date
    Apr 2020
    Qt products

    Default Drawing a QPixmap mit rounded corners


    I design a DAB app. Stations can be selected via pushbutton and if the right png file exists, the station logo is shown in the button(stretched to fill the button). It works but doesn't look that nice.


    The code for each button looks like this (I'm sure it can be done better, but still learning ab Qt and C++...)

    Qt Code:
    1. if(dab_found_favs.size() >= 2){
    2. ui->btn_dab_st02->setEnabled(true);
    3. QString btn_sid = dab_vec_vec[][2];
    4. bool dab_logo_exist {MainWindow::dab_logo_exists(btn_sid)};
    6. if(dab_logo_exist == true){
    7. ui->btn_dab_st02->setText("");
    8. QString dab_logo = path_dab_icons + btn_sid + ".png";
    9. QPixmap pixmap(dab_logo);
    10. QIcon ButtonIcon(pixmap);
    11. ui->btn_dab_st02->setIcon(ButtonIcon);
    12. ui->btn_dab_st02->setIconSize(pixmap.rect().size());
    13. } else {
    14. ui->btn_dab_st02->setText(dab_vec_vec[][0]);
    15. }
    16. } else if(dab_found_favs.size() < 2){
    17. ui->btn_dab_st02->setIcon(QIcon());
    18. ui->btn_dab_st02->setEnabled(false);
    19. ui->btn_dab_st02->setText("no favorite\navailable");
    20. }
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    How can i make the corners rounded? Already tried with QPainter, but it only drew a border with rounded corners on top of the picture.

  2. #2
    Join Date
    Jan 2008
    Alameda, CA, USA
    Thanked 721 Times in 711 Posts
    Qt products
    Windows Android

    Default Re: Drawing a QPixmap mit rounded corners

    Create a QBitmap mask using your rounded rectangle. The parts that you want to mask off should be set to a 0 value; everything else should be set to 1. Then use QPixmap::setMask(). Use the QBitmap as a paint device, use QPainter to fill it with white (0), then use QPainter to draw your rounded rect with a black (1) brush and pen. That's your mask.
    <=== The Great Pumpkin says ===>
    Please use CODE tags when posting source code so it is more readable. Click "Go Advanced" and then the "#" icon to insert the tags. Paste your code between them.

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