"Bill Woodruff" <msnwsgroups@dotscience.com> wrote in message
news:OpdBZ9miHHA.4872@TK2MSFTNGP03.phx.gbl...
>I really hate writing Paint Events ! (it showed ?)
>
> One strategy I explored to avoid writing a Paint Event in the case of a
> control with a partially transparent background placed over a second
> control
> (where, as we all know too well, only the Form background, not the second
> control background, will show through) ...
>
> Was to try in the Form Load event : (C#)
>
> 1. create a new Bitmap of size of the Form (I experimented with both
> PixelFormat Format32bppRgb and Format24bppRgb settings)
>
> 2. get the Form Window handle using Graphics.FromHwnd(this.handle)
>
> 3. using DrawImage on the Form Window handle : copy the Form background
> into
> the new Bitmap
>
> I then tried setting the Form.BackgroundImage property of the Form to the
> new Bitmap to check and see if the first stage of 'copying' was working.
> Nope : while it doesn't throw an error (as long as you don't call
> Dispose()
> on the new bitmap) : the form background is now all black.
>
> My idea was to see if I could copy the Form's current background, bitblt a
> picture of a control background onto this copy in the right place and then
> set that compound bitmap to be the Form's BackgroundImage property. Then,
> so
> I hoped, I could place my second control (a pointer or indicator) over the
> Form and have the transparent areas of the second control do the right
> thing. And so cheat that infernal master the Paint Event !

"Bill Woodruff" <msnwsgroups@dotscience.com> wrote in message
news:OpdBZ9miHHA.4872@TK2MSFTNGP03.phx.gbl...
>I really hate writing Paint Events ! (it showed ?)
>
> One strategy I explored to avoid writing a Paint Event in the case of a
> control with a partially transparent background placed over a second
> control
> (where, as we all know too well, only the Form background, not the second
> control background, will show through) ...
>
> Was to try in the Form Load event : (C#)
>
> 1. create a new Bitmap of size of the Form (I experimented with both
> PixelFormat Format32bppRgb and Format24bppRgb settings)
>
> 2. get the Form Window handle using Graphics.FromHwnd(this.handle)
>
> 3. using DrawImage on the Form Window handle : copy the Form background
> into
> the new Bitmap
>
> I then tried setting the Form.BackgroundImage property of the Form to the
> new Bitmap to check and see if the first stage of 'copying' was working.
> Nope : while it doesn't throw an error (as long as you don't call
> Dispose()
> on the new bitmap) : the form background is now all black.
>
> My idea was to see if I could copy the Form's current background, bitblt a
> picture of a control background onto this copy in the right place and then
> set that compound bitmap to be the Form's BackgroundImage property. Then,
> so
> I hoped, I could place my second control (a pointer or indicator) over the
> Form and have the transparent areas of the second control do the right
> thing. And so cheat that infernal master the Paint Event !
>
> Any thoughts ?
>
> thanks, Bill
>
>
>