[fpc-devel] TFPCustomCanvas Expanded Clipping

[Sven Barth]

Am 30.11.2011 13:33, schrieb Hans-Peter Diettrich:
> Felipe Monteiro de Carvalho schrieb:
>
>> I am facing a problem with clipping in TFPCustomCanvas because it has
>> these properties:
>>
>> property ClipRect : TRect read GetClipRect write SetClipRect;
>> property Clipping : boolean read GetClipping write SetClipping;
>>
>> Which obviously is not extensible for non-rectangular formats. I
>> already have written my own extensible and object oriented clipper,
>> but I'm unsure how to properly integrate it into TFPCustomCanvas.
>
> What's the purpose of your clipper?
>
> IMO the window manager uses an update region internally, from which one
> or more paint requests are generated, for rectangular ClipRects.
>
> User code can reduce the ClipRect (or region) further, when a certain
> area (control) is painted, and output outside the control's bounds
> should be suppressed.
>
> I'm not sure how far non-rectangular clipping regions are supported by
> all widgetsets, and wouldn't rely on such a capability.

You are aware that TFPCustomCanvas can be used for widgetset independant 
canvases as well? Also Felipe said that he'll need it for his 
fpvectorial project.

Regards,
Sven