@Pl45m4 In this function I am painting on axis->labelPix which is a QPixmap. The axis->labelPix is then put in its correct position using QPainter in the paintEvent() of PlotWidget.

thank you for the direction.

The constructors are still wrong. Should be

QSliderButton::QSliderButton(QWidget* parent) : QWidget(parent) {}

and the empty one is just redundant. You don't need it at all.

Better yet don't manually implement any constructors, just do

class QSliderButton : public QWidget { Q_OBJECT public: using QWidget::QWidget; ...

The using statement will inherit all the constructors from the base class so you don't have to implement any.

I'm afraid that doesn't help for my use case, since I need the images to appear as clear and clean as possible when being scaled down.

@timob256 said in Is stroke the text (Circle text ):

cannot align the bypass line with the inner line

Sorry, i don't understand.

If you want the background to be green, add a fillPath before stroke path:

painter.fillPath(path,Qt::green); painter.strokePath(path,pen);

Simply two QPainter::drawArc() calls with a different color.

@Vijay-R-Gawade said in Qt app freeze when remove usb drive while qpainter is drwaing:

@SGaist Timer is used to add some delay to Update Progress bar on UI by one step when each record from DB is drawn.

That's a fishy procedure to update your progress bar.

One of the issue here is that the conversion must be done each time the draw method is called. If you know that your images will not change or not much then you should do the conversion upfront so that the painting can be optimized.

@Christian-Ehrlicher Thanks for tracking that down. Hope Qt gets it fixed soon.

Thank you so much nagesh.

@TenG
Be aware that not all of Qt modules are supported in WASM. Before anything, check the list at https://doc.qt.io/qt-5/wasm.html#supported-qt-modules against what is in your app. For example, it doesn't do databases, you can't access the local file system, and so on. Also I noticed this time that it requires a Qt static build, but maybe you have to have that for iOS anyway, I don't know.

If it works for you it's a really simple solution compared to rewriting anything. Just check out the gotchas.

Thanks for the code !

You can use the Q_OS_XXX macros to ifdef your code.

so write a test program, meter the performance of canvas writes vs out-of-bounds writes, and report back.

Just let Qt do its work. If by drawing directly on QWidget you mean subclassing it and rewriting its Paint() method - don't do it unless you absolutely have to. Or, when you need to provide a delegate for a view.
So far I've not had the necessity to dive that deep.
And since you can display (and scale) images and videos using QLabel, push buttons can be readily supplied with an icon... I just had not need.
Then again, your needs might differ.

Solved it by changing my drawline to: painter.drawLine(QPointF(pX1, pY1), QPointF(pX2, pY2));

Thank you, I think this will do just perfect!

@Bonnie

Thank you, setting it before drawPixmap works. I don't need any smoothing so nearest neighbor resize is fine for me.

@mrjj Thanks, so I hit the limit. I'll try not to go over that.