setWindowIcon() with ICO format

[ChrisW67]

There is an ICO format image format plugin in Qt 4.8.4. I don't know exactly when it was added, but it has been around for quite a while. The code in that plugin is quite capable of loading the multiple images in ICO file but defaults to the first for non-animated formats. You can use the QImageReader directly to find the image you want. So, for this icon:

$ identify qtcreator.ico 
qtcreator.ico[0] ICO 256x256 256x256+0+0 32-bit DirectClass 288KB 0.000u 0:00.009
qtcreator.ico[1] ICO 48x48 48x48+0+0 32-bit DirectClass 288KB 0.000u 0:00.000
qtcreator.ico[2] ICO 32x32 32x32+0+0 32-bit DirectClass 288KB 0.000u 0:00.000
qtcreator.ico[3] ICO 24x24 24x24+0+0 32-bit DirectClass 288KB 0.000u 0:00.000
qtcreator.ico[4] ICO 16x16 16x16+0+0 32-bit DirectClass 288KB 0.000u 0:00.000

$ identify qtcreator.ico 
qtcreator.ico[0] ICO 256x256 256x256+0+0 32-bit DirectClass 288KB 0.000u 0:00.009
qtcreator.ico[1] ICO 48x48 48x48+0+0 32-bit DirectClass 288KB 0.000u 0:00.000
qtcreator.ico[2] ICO 32x32 32x32+0+0 32-bit DirectClass 288KB 0.000u 0:00.000
qtcreator.ico[3] ICO 24x24 24x24+0+0 32-bit DirectClass 288KB 0.000u 0:00.000
qtcreator.ico[4] ICO 16x16 16x16+0+0 32-bit DirectClass 288KB 0.000u 0:00.000

To copy to clipboard, switch view to plain text mode 

This selects the 16x16 icon (and the first image if 16x16 is not matched):

#include <QtGui>
#include <QDebug>
 
int main(int argc, char **argv)
{
    QApplication app(argc, argv);
 
    QImageReader reader("qtcreator.ico");
    QImage result = reader.read();  // this acts as a default if the size is not matched
    for (int i = 0; i < reader.imageCount(); ++i) {
        reader.jumpToImage(i);
        QImage image = reader.read();
        if (image.size() == QSize(16, 16)) {
            result = image;
            break;
        }
    }
 
    QWidget w;
    w.setWindowIcon(QPixmap::fromImage(result));
    w.show();
 
    return app.exec();
}

#include <QtGui>
#include <QDebug>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QImageReader reader("qtcreator.ico");
    QImage result = reader.read();  // this acts as a default if the size is not matched
    for (int i = 0; i < reader.imageCount(); ++i) {
        reader.jumpToImage(i);
        QImage image = reader.read();
        if (image.size() == QSize(16, 16)) {
            result = image;
            break;
        }
    }

    QWidget w;
    w.setWindowIcon(QPixmap::fromImage(result));
    w.show();

    return app.exec();
}

To copy to clipboard, switch view to plain text mode