How can I copy image from anohter image

[ChrisW67]

Line 2 has an error and should be checking the height not width.

[chong_kimkeang]

Hello everyone, for doing with polygon, I can't because it always can't be close. So could you tell me how to cut the image by using mask?

[ChrisW67]

If you don't have a closed polygon then what defines the region you want to copy?

Here is an example of a faster way to do it:

#include <QtGui>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QImage source("Lenna.png");
 
    // An arbitrary region to cut out
    QPolygon region;
    region << QPoint(10, 10) << QPoint(100, 200) << QPoint(500, 50);
 
    // Let's do it
    QPainterPath path;
    path.addPolygon(region);
 
    QImage cutout(source.size(), QImage::Format_ARGB32_Premultiplied);
    cutout.fill(Qt::transparent);
    QPainter p(&cutout);
    p.setClipPath(path);
    p.drawImage(0, 0, source);
    p.end();
 
    QLabel l;
    l.setPixmap(QPixmap::fromImage(cutout));
    l.show();
 
    return a.exec();
}

#include <QtGui>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QImage source("Lenna.png");

    // An arbitrary region to cut out
    QPolygon region;
    region << QPoint(10, 10) << QPoint(100, 200) << QPoint(500, 50);

    // Let's do it
    QPainterPath path;
    path.addPolygon(region);

    QImage cutout(source.size(), QImage::Format_ARGB32_Premultiplied);
    cutout.fill(Qt::transparent);
    QPainter p(&cutout);
    p.setClipPath(path);
    p.drawImage(0, 0, source);
    p.end();

    QLabel l;
    l.setPixmap(QPixmap::fromImage(cutout));
    l.show();
    
    return a.exec();
}

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[chong_kimkeang]

Hello everyone, I am very happy because now I can cut that image. Greatly thank everyone particularly the Expert ChrisW67 who give me the sample code which help me create this success.