[DUG]: Canvas and cliprect....

[Sabu Hariharan]

Hi Chris,

Your code is right but it will work with valid bitmaps only.
If you try the same with Jpeg images, it will not work.

Regards,
Sabu
iSOFT, India.



Original message :
Message: 3

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Date: Wed, 29 Jun 2005 09:00:51 +1200
From: "Chris Veale" <CVeale at hortresearch.co.nz>
Subject: [DUG]: Canvas and cliprect....
To: <delphi at delphi.org.nz>
Message-ID: <s2c263cd.064 at hra2.marc.hort.cri.nz>
Content-Type: text/plain;	charset=US-ASCII


Hi,

I have an image that I want to display the colour of the pixel under the
cursor when the left mouse button is clicked.

I have the following section of code that does it (doesnt sound
difficult does it.)...

====================
procedure TForm1.imageMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var
  colour:TColor;
begin
  colour := Form1.image.Canvas.Pixels[X,Y]; ====================

However I always get -1 returned as the cliprect for the image canvas is
always [0,0],[1,1]

Looking at the help and trial and error I cannot set the cliprect
parameters, so my question is how do these values get set at runtime,
and also how can I actually get the colour being recognised?

Cheers

Chris

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