TCanvas.RequiredState procedure

Member of TCanvasprotectedIn unit Graphics

Ensures that all handles needed for the canvas are valid.

Declaration

pascal

procedure RequiredState(ReqState: TCanvasState); virtual

Arguments

ReqState

Required state flags.

Description

RequiredState is a procedure used to ensure that the canvas state flags include the values specified in the ReqState parameter. The TCanvasStates values represent handles that must be allocated for the canvas.

When a state value is not present in the flags, the corresponding routine used to create the required handle is called.

csHandleValid: Calls CreateHandle, and raises an EInvalidOperation if the handle could not be allocated. Sets the AntialiasingMode for the canvas. Includes csHandleValid in the canvas state flags on success.
csFontValid: Calls CreateFont, and includes csFontValid in the canvas state flags on success.
csPenValid: Calls CreatePen. Includes csBrushValid in the canvas state flags when the Pen style is a Brush pattern (psDash, psDot, psDashDot, psDashDotDot). Includes csPenValid in the canvas state flags on success.
csBrushValid: Calls CreateBrush. Includes csBrushValid in the canvas state flags on success.

RequiredState is called from method implementations prior to performing an operation which requires a specific canvas state (or handles).

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