FMX.Graphics.TCanvas.BeginScene

• Up to Parent: TCanvas

Delphi

function BeginScene(AClipRects: PClipRects = nil; AContextHandle: THandle = 0): Boolean;

C++

bool __fastcall BeginScene(PClipRects AClipRects = (PClipRects)(0x0), NativeUInt AContextHandle = (NativeUInt)(0x0));

Properties

Type	Visibility	Source	Unit	Parent
function	public	FMX.Graphics.pas FMX.Graphics.hpp	FMX.Graphics	TCanvas

Description

Notifies the TCanvas object that the drawing can begin.

Call BeginScene before drawing on the TCanvas.

To end the drawing session, call EndScene.

If an application has called BeginScene and BeginScene returns True, then the application must call EndScene. That is, the recommended call pattern should look like this:

if Canvas.BeginScene then
  try
    Canvas.xxx   //drawing image operations
    ...
  finally
    Canvas.EndScene;
  end;

Each time the TCanvas object calls BeginScene and BeginScene returns True, the value of the BeginSceneCount property is increased by one. Each time the TCanvas object calls EndScene, the value of the BeginSceneCount property is decreased by one. BeginScene uses BeginSceneCount to guaranty that the TCanvas object has no more than one initialized drawing at any moment.

Tip: The TForm.OnPaint event handler of a form does not need to call BeginScene explicitly.

See Also

• FMX.Graphics.TCanvas.EndScene
• FMX.Graphics.TCanvas.BeginSceneCount