QImage from HBITMAP

Question

In my windows-only program, I use a third-party library, which returns a HBITMAP.

Is there a way to initialize a QImage from its contents, i.e. to convert it to a QImage?

Sphacelus

Answer 1

This is the way to do it for Qt 4 (QtGui):

QImage image(QPixmap::fromWinHBITMAP(hBitmap).toImage());

This is the way to do it for Qt 5 (QtWinExtras):

QPixmap pixmap = QtWin::fromHBITMAP(hBitmap);
QImage image = pixmap.toImage();

// or

QtWin::imageFromHBITMAP(hdc, hBitmap, width, height)

Cryptography

For Qt 6 fromWinHBITMAP is now part of QImage natively, so you can just call QImage.fromHBITMAP. – Bataan

Answer 2

OK, this seems to work for me:

QImage image(QPixmap::fromWinHBITMAP(hBitmap).toImage());

Sphacelus

This is not available after Qt 4.8 – Lippi

Answer 3

Qt5 without Extras: Put before your code

#include <QPixmap>
Q_GUI_EXPORT QPixmap qt_pixmapFromWinHBITMAP(HBITMAP bitmap, int hbitmapFormat=0);

and in your function, for example

QPixmap pixmap = qt_pixmapFromWinHBITMAP(LoadBitmap(uiID));

Cheers

Splendent

This is not a public API. – Novara

Answer 4

As of Qt 6.0, you could use the static QImage::fromHBITMAP(HBITMAP hbitmap):

Returns a QImage that is equivalent to the given hbitmap.

HBITMAP does not store information about the alpha channel.

In the standard case, the alpha channel is ignored and a fully opaque image is created (typically of >format QImage::Format_RGB32).

There are cases where the alpha channel is used, though, for example for application icon or systray icons. In that case, reinterpretAsFormat(QImage::Format_ARGB32) should be called on the returned image to ensure the format is correct.

This function was introduced in Qt 6.0.

Cozy