QPropertyAnimation use of undeclared identifier rotation

The error "use of undeclared identifier 'rotation'" in QPropertyAnimation typically occurs when you are trying to animate a property that does not exist or is not recognized by the animation object.

To fix this error, make sure you are using a valid property that can be animated by QPropertyAnimation. For example, if you want to animate the rotation property of a QGraphicsItem, you need to use the "rotation" property instead of a variable named "rotation".

Here's an example that demonstrates the correct usage of QPropertyAnimation to animate the rotation property of a QGraphicsItem:

// Create a QGraphicsItem (e.g., a QGraphicsRectItem)
QGraphicsRectItem rectItem;
rectItem.setRect(0, 0, 100, 100);

// Create a QPropertyAnimation to animate the rotation property of the rectItem
QPropertyAnimation animation(&rectItem, "rotation");

// Set the target value (e.g., rotate the rectItem by 90 degrees)
animation.setEndValue(90);

// Set the duration of the animation (e.g., 1 second)
animation.setDuration(1000);

// Start the animation
animation.start();

Make sure you include the necessary headers and have the appropriate Qt modules enabled in your project file.