How load QImage from path? - c++

Question

I captured an Image with camera in my qt quick application.I want to send the path to my c++ code and load that Image in c++ QImage.But the Path is image://camera/preview_1 and I don't know How work with that path?
Camera {
id: camera
imageCapture {
onImageCaptured: {
console.log("Preview = "+preview);
photoPreview.source = preview
console.log("CapturedImagePath => "+camera.imageCapture.capturedImagePath);
up.loadImage(preview);
}
}
c++ class
void UserProfile::loadImage(QString path)
{
QUrl imageUrl(path);
qWarning()<<"imageUrl.host()=>"<<imageUrl.host();
qWarning()<<"imageUrl.path()=>"<<imageUrl.path();
qWarning()<<"imageUrl.toLocalFile()=>"<<imageUrl.toLocalFile();
bool isOpend= m_image.load(path); //m_image is an QImage object
qWarning()<<"Image loaded=> "<<isOpend;
}
Application output
D MyApp: qml: Preview = image://camera/preview_1
D MyApp: qml: CapturedImagePath =>
W MyApp: imageUrl.host()=> "camera"
W MyApp: imageUrl.path()=> "/preview_1"
W MyApp: imageUrl.toLocalFile()=> ""
W MyApp: Image loaded=> false

Answer 1

The URL image://camera/preview_1 means that the image data is living in a QQuickImageProvider instance. Probably, it's a QQuickImageProvider instance created by Camera.
As the UserProfile instance is living in the same QQmlEngine as the camera lives, you can
void UserProfile::loadImage(const QString &path)
{
auto myQmlEngine = qmlEngine(this);
if(myQmlEngine==nullptr)
return;
QUrl imageUrl(path);
auto provider = reinterpret_cast<QQuickImageProvider*>( myQmlEngine->imageProvider(imageUrl.host()));
if (provider->imageType()==QQuickImageProvider::Image){
QImage img = provider->requestImage(imageUrl.path().remove(0,1),nullptr,QSize());
// do whatever you want with the image
}
}
Be careful with the reinterpret_cast. You also have to make sure that the QQuickImageProvider::imageType() is returning QQmlImageProviderBase::Image.
and you could also use capturedImagePath instead of the preview URL to prevent this complexity if it could be an option for your usecase.