Crop from one bitmap into another without drawing on screen

I have some bitmap on disk, which is monochrome. I need code sequence for crop some portion of this bitmap to memory. I'm don't need show bitmap on screen; I'm using VPascal and I'm limited to basic GDI (not gdi+).
I try this for few days, but now I'm totaly confused.

code maybe begin ...

char * buffer;
handle picture;
long left,top,width,height;

left=20;top=30;width=300;height=100;
buffer = malloc((width-left)*(height-top) /8);
picture= LoadImage(0,'picture.bmp,image_bitmap,0,0,LR_LOADFROMFILE |
LR_CREATEDIBSECTION);
...
...
...

Can someone explain rest of code or ...

thanks for advice

 

number1: use CreateCompatibleDC to create a memory device context.
then use BitBlt to copy your specifiq portion from source to newly created compatible DC. I think this will help you.

 

It is great,your opinion is very novelty thanks very much guy!.