TCustomCheckCombo.DrawItem procedure

Member of TCustomCheckComboprotectedIn unit ComboEx

Draws a check box item defined in the combo-box control.

Declaration

pascal

procedure DrawItem(Index: Integer; ARect: TRect; State: TOwnerDrawState)
 ; override

Arguments

`Index`	Ordinal position for the check box drawn in the method.
`ARect`	Rectangle with the coordinates for the check box drawn in the method.
`State`	Owner draw state for the check box.

Description

DrawItem is an overridden procedure used to draw a check box defined in the Items for the control.

Index contains the ordinal position for the TComboExItem instance in ItemsEx that is drawn in the method.

ARect is the rectangle with the coordinates for the check box item drawn in the method. The values in ARect are set in the calling procedure (LMDrawListItem in TCustomComboBox).

State contains the owner draw state used to render the check box item, and determines the window and font colors for the check box.

DrawItem uses ThemeServices to get theme element details applied to check box items in the combo-box. DrawItem ensures that a valid text height is available for the control Canvas, and is used to draw the text for the check box.

DrawItem configures the Canvas to use the brush style and font color needed for the value in State. Text drawing flags are derived for the item, and the text is rendered by calling the DrawText method.

DrawItem does NOT call the inherited method in TCustomComboBox or trigger its OnDrawItem event handler. The item is rendered entirely in this method.

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.