'Create Bitmap on runtime' Thread RSS Feed

Create Bitmap on runtime

Fri, 29 Jun 2007 08:10:42 -0700

Hi,

I'm attempting to use c++, windows api GDI, to create a bitmap of something I painted on the screen. Once I create the bitmap I want to be able to move it about the window.

I couldn't find anything too great on google about it, so I broke down and I'm asking for your help.

If you don't know, possibly if you point me in the direction of a tutorial/code of how to make mspaint, I'd be able to figure it out.

Thanks.

Re: Create Bitmap on runtime

Sat, 07 Jul 2007 07:53:53 -0700

: Hi,
:
: I'm attempting to use c++, windows api GDI, to create a bitmap of
: something I painted on the screen. Once I create the bitmap I want
: to be able to move it about the window.
:
: I couldn't find anything too great on google about it, so I broke
: down and I'm asking for your help.
:
: If you don't know, possibly if you point me in the direction of a
: tutorial/code of how to make mspaint, I'd be able to figure it out.
:
: Thanks.
:
If you run Windows, the Windows API provides you with several bitmap operations which suit your needs.
http://msdn2.microsoft.com/en-us/library/ms532343.aspx

Re: Create Bitmap on runtime

Sun, 08 Jul 2007 04:14:14 -0700

1. Get a device context of the area you trying to snap shoot.
- use GetDC()

2. Create a DC compatible with DC from step 1.
- use CreateCompatibleDC()

3. Create a bitmap handle compatible with DC from step 1.
You will need to know the area size (width and height)
- use CreateCompatibleBitmap()

4. Select HBITMAP from step 3 into DC from step 2. You need
to preserve the return value (it is HBITMAP) of this operation.
- use SelectObject()

5. Make a snap shot of the area.
- use BitBlt()
- the source DC is from step 1
- the destination DC is from step 2
- the coordinates and size will define the area itself

6. Restore the HBITMAP in a DC from step 2 - use the returned value
in a call to SelectObject()

7. Get rid of DC from step 2
- use DeleteDC()

===

That's it - at this point you left with HBITMAP created in step 3 and it has the image of the are you need, so you can draw it somewhere else or save it as a file. To save it - you need to do more stuff...

When you finished with HBITMAP - do not forget to dismiss it using DeleteObject() function.

Re: Create Bitmap on runtime

Mon, 09 Jul 2007 05:21:50 -0700

Thanks to both of you.

Re: Create Bitmap on runtime

Fri, 11 Jan 2008 09:06:01 -0700

: Thanks to both of you.
:
I made a c++ class for working with the bitmap format. It works independent of the Windows API, though.

You can get the c++ source code here:
http://www.programmersheaven.com/d/click.aspx?ID=F54666