CODEWITHSUNDEEP
qtqmlqt-quick
grefab
grefab

Reputation: 2045

Does an Item emit a signal when its position/size is changed in QML?

I have a canvas that contains a few MouseAreas that can be dragged. The canvas draws some decoration between these items that cannot be expressed as native QML elements.

How can I initiate a redraw of the canvas when an Item changes size or position? I know that I need to call canvas.requestPaint(), but on which event? The only solution I found so far was calling requestPaint() within a timer, but I want to avoid that due to performance reasons.

Upvotes: 4

Views: 7469

Answers (1)

koopajah
koopajah

Reputation: 25552

According to the QML documentation, each property of a QML component has an implicit signal associated with a change of value in the property:

Signal handlers for property change signal take the syntax form on<Property>Changed where <Property> is the name of the property, with the first letter capitalized. For example, although the TextInput type documentation does not document a textChanged signal, this signal is implicitly available through the fact that TextInput has a text property and so it is possible to write an onTextChanged signal handler to be called whenever this property changes

Upvotes: 6

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