[Overview][Types][Classes][Procedures and functions][Index] | Reference for unit 'ExtCtrls' (#lcl)

# TCustomImage.Invalidate

Causes the control to be repainted.

## Declaration

Source position: extctrls.pp line 576

`public procedure TCustomImage.Invalidate; override;`

## Description

Invalidate is an overridden procedure which causes the control to be repainted. Invalidate is called when the content or dimensions for the image have been changed.

Invalidate extends the ancestor method to include logic that reduces the number of calls to the Paint method, and avoids flicker caused by the redundant calls. It uses an internal flag in the class to determine if the Paint method has already been called, but has not yet been completed. If the flag has not been set, the inherited Invalidate method is called to refresh the control using its visibility and control style settings.

Remark: | No actions are performed in the method when Paint is already active.

## See also

TCustomImage.Paint |  | Draws the image to the control canvas.
TControl.IsVisible |  | Gets the effective visibility for the control and all of its Parent controls.
TControl.ControlStyle |  | Contains style flags which control the features or behaviors enabled for the control.
TControl.Invalidate |  | Causes a delayed Repaint of the control by marking its visible area of the control as invalid.