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 How to draw a TIEBitmap to the canvas of TPaintbox		  New Topic  Reply to Topic
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casual1001

2 Posts
Posted - Feb 19 2019 :  12:15:14  Show Profile  Reply
Hi, Anybody can help me the below question?

I assigned a bitmap to a TIEBitmap. And then process the TIEBitmap with chroma key effect. How to draw the result TIEBitmap to the canvas of TPaintBox with the chroma key effect?

Thanks

xequte

38180 Posts
Posted - Feb 19 2019 :  14:46:56  Show Profile  Reply
Hi

In the OnPaint event of the PaintBox, you just need to render the TIEBitmap to the canvas:

https://www.imageen.com/help/TIEBitmap.DrawToCanvas.html

Something like:

// trigger OnPaint event
PaintBox1.Paint();

procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
  MyChromaBitmap.DrawToCanvas( TPaintBox(Sender).Canvas, 0, 0 );
end;


Of course, that isn't scrollable, so you need to include a TScrollBox to allow scrolling (or just use a TImageEnView, of course )

Nigel
Xequte Software
www.imageen.com
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casual1001

2 Posts
Posted - Feb 19 2019 :  20:58:04  Show Profile  Reply
Hi Nigel,

Thanks!

I did the same as your code. But there were two issues.

1. the alphachannel of TIEBitmap didn't work.

2. System raise an "Access Violation" Error.

By the way, I put the chroma key process in a thread circulation. After process a bitmap then make the paintbox invalidate to trigger the paint event every circulation.
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xequte

38180 Posts
Posted - Feb 19 2019 :  22:22:45  Show Profile  Reply
Hi

1. If you want Alpha use:

https://www.imageen.com/help/TIEBitmap.DrawToCanvasWithAlpha.html

2. You'd have to show me your code. If you are using threads, ensure you are synchronizing before communicating with the UI (i.e. TPaintBox).



Nigel
Xequte Software
www.imageen.com
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