Using the QImageReader::setClipRect function, can not be used to load the interesting parts of a given image

[Tricoffee]

QString filename = "C:/NDev/CPPDev/XVisual/SEB2023.bmp";
QImageReader* reader = new QImageReader(filename);
int tileHeight = 512;
int tileWidth = 512;
QRect tileRect(0, 0, tileWidth, tileHeight);
reader->setClipRect(tileRect);
QImage image = reader->read();

Using the QImageReader::setClipRect function,
can not be used to load the interesting parts of a given image,
but load an entire image in memory at once!

[Christian Ehrlicher]

Looks like the bmp reader does not support this option - see https://doc.qt.io/qt-6/qimagereader.html#supportsOption

[Tricoffee]

@Christian-Ehrlicher Yes，you're right.

    if(reader->supportsOption(QImageIOHandler::ClipRect))
    {
        qDebug() << "Support QImageIOHandler::ClipRect";
    }
    else
    {
        qDebug() << "QImageIOHandler::ClipRect are not Supported";
    }

The above judgment statement outputs：
QImageIOHandler::ClipRect are not Supported

[Tricoffee]

@Christian-Ehrlicher Is there an alternative method to only load the part of interest of the given BMP image?

[Christian Ehrlicher]

@Tricoffee said in Using the QImageReader::setClipRect function, can not be used to load the interesting parts of a given image:

Is there an alternative method to only load the part of interest of the given BMP image?

No, read the complete image and then copy out the part of interest.