Retrieving TCanvas contents into a TBitmap

Matt Olson

Delphi Developer

Fri, 10 Mar 2000 03:00:00 GMT

Retrieving TCanvas contents into a TBitmap

There doesn't seem to be functionality in the VCL to accomplish this, so
I'm wondering if anyone has a clue as to how to take whatever is drawn on a
Tcanvas and load it into a TBitmap. I'm thinking there must be a way using
the device context of the canvas and GDI functions but I'm having no luck
putting it all together.

Thanks for any help.

Matt

Derek Benne

Delphi Developer

Fri, 10 Mar 2000 03:00:00 GMT

Re:Retrieving TCanvas contents into a TBitmap

Quote

Matt Olson wrote:

> There doesn't seem to be functionality in the VCL to accomplish this, so
> I'm wondering if anyone has a clue as to how to take whatever is drawn on a
> Tcanvas and load it into a TBitmap. I'm thinking there must be a way using
> the device context of the canvas and GDI functions but I'm having no luck
> putting it all together.

> Thanks for any help.

> Matt

Are you talking like a TImage.Canvas here? It doesn't seem so and I'm
assuming that you're talking like a Form.Canvas, maybe? If so, how
about just placing a TImage on the form and copying the Form's canvas
directly to the Image's canvas and then using the Image.Picture.Bitmap?

It would help to have a little more information.

Derek

Andrew Stewar

Delphi Developer

Sat, 11 Mar 2000 03:00:00 GMT

Re:Retrieving TCanvas contents into a TBitmap

Quote

Matt Olson wrote:

> There doesn't seem to be functionality in the VCL to accomplish this,
> so
> I'm wondering if anyone has a clue as to how to take whatever is drawn
> on a
> Tcanvas and load it into a TBitmap. I'm thinking there must be a way
> using
> the device context of the canvas and GDI functions but I'm having no
> luck
> putting it all together.

> Thanks for any help.

> Matt

How about Bitmap.Canvas.CopyRect(DestRect, SourceCanvas, SourceRect)

Andrew

Matt Olso

Delphi Developer

Sat, 11 Mar 2000 03:00:00 GMT

Re:Retrieving TCanvas contents into a TBitmap

Your exact solution came to me last night as I looked this over some more.
I'm actually trying to access the canvas of a DBChart control in D3 for
reporting. I know the DBChart has print functions but they are limited as
far as formatting the entire page, adding text, etc. Thanks for your
response.

Derek Benner <dben...@pacbell.net> wrote in article
<3426F404.2F04E...@pacbell.net>...

Quote

> Matt Olson wrote:

> > There doesn't seem to be functionality in the VCL to accomplish this,
so
> > I'm wondering if anyone has a clue as to how to take whatever is drawn
on a
> > Tcanvas and load it into a TBitmap. I'm thinking there must be a way
using
> > the device context of the canvas and GDI functions but I'm having no
luck
> > putting it all together.

> > Thanks for any help.

> > Matt

> Are you talking like a TImage.Canvas here? It doesn't seem so and I'm
> assuming that you're talking like a Form.Canvas, maybe? If so, how
> about just placing a TImage on the form and copying the Form's canvas
> directly to the Image's canvas and then using the Image.Picture.Bitmap?

> It would help to have a little more information.

> Derek

sa..

Delphi Developer

Sat, 11 Mar 2000 03:00:00 GMT

Re:Retrieving TCanvas contents into a TBitmap

Hello, Matt!

Quote

> There doesn't seem to be functionality in the VCL to accomplish this, so
> I'm wondering if anyone has a clue as to how to take whatever is drawn on a
> Tcanvas and load it into a TBitmap.

I have done it, to save to a bmp file one graph image painted directly
to the canvas of a component. Try with this function or something like
it (its in spanish language, but I think you will understand it):

Procedure TGrafica.GuardarImagen(NombreFichero:String);
Var Mapa:TBitmap;
begin
Screen.Cursor:=crHourGlass;
Repaint;
Mapa:=TBitmap.Create;
Mapa.Width:=Width;
Mapa.Height:=Width;
Mapa.Canvas.CopyRect(ClientRect,Canvas,ClientRect);
Mapa.SaveToFile(NombreFichero);
Mapa.Destroy;
Screen.Cursor:=crDefault;
end;

Good luck

sa...@udc.es

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