Saving image from hDC

[edgebird]

Hello,

I'm a beginner in C# and I'm making an application for fun.
This application however requires me to do one hard thing with which I hope you guys can help.
(Small background: I hook BitBlt and would like to copy the source image thus getting source & destination IntPtr)

I get a hDC of a bitmap(you call it like that?) in the memory and I would like to convert it to a Bitmap so I can confirm some actions on it and eventually save it. However I really don't get see how I can do this. I searched on google and msdn for hours but couldn't come up with anything. I found some procedures which require me to call BitBlt but it really didn't make me any wiser. So I hope somebody might post some example code.


Thanks already.

Ps:
This is the only thing I could come up with after searching msdn, but it doesn't seem to work:

//IntPtr hObjSource;
System.Drawing.Bitmap bitmap = System.Drawing.Image.FromHbitmap(hObjSource);
// And then use bitmap.save(x,y,z);

[BigEd781]

So first I would ask if interop is really necessary here. Marshalling complex data structures can be tough, and while this can be achieved, it may be unnecessary. So, perhaps you could describe the larger problem to us.

Aside from that, you can create Bitmap objects from the pixel data. First tell us what "doesn't work" about using the FromHBitmap method. Have you read the documentation? What exactly doesn't work? You can also refer to the following article.

http://www.vbforums.com/showthread.php?t=358917

[edgebird]

Thanks for your reply. Hope this can clarify it a bit.

        // Interception
        static bool DBitBlt_Hooked(IntPtr hObject, int nXDest, int nYDest, int nWidth,int nHeight, IntPtr hObjSource, int nXSrc, int nYSrc, TernaryRasterOperations dwRop)   
       {
            try
            {
                Main This = (Main)HookRuntimeInfo.Callback;
                lock (This.capBitBlt)
                {
                    This.capBitBlt.Push("Start");
                    System.Drawing.Bitmap image1;
                    image1 = new System.Drawing.Bitmap (System.Drawing.Image.FromHbitmap(hObjSource));
                    
                    This.capBitBlt.Push("End");
                    // bitmap.Save();
                }

                // Gets the "bits" from the bitmap and copies them into a buffer 
                // which is pointed to by lpbitmap.

            }
            catch
            {
            }
            // Calling original BitBlt();
            return BitBlt(hObject, nXDest, nYDest, nWidth, nHeight, hObjSource, nXSrc, nYSrc, dwRop);
        }

I use easyhook to capture the calls. Seeing the fact only 'Start' gets displayed and not 'End' I know it crashes.. (lame method but yeahh.. told you i'm beginner ).
So I still would like to get the bitmap hope someone can help me.

[edgebird]

I forgot to mention that I looked at our URL but they all require you to have a bitmap already whereas I only got a hDC.

[edgebird]

Solved the problem.
This may be usefull to someone
http://www.codeproject.com/KB/graphi...rescreen1.aspx

[BigEd781]

Ok, glad to know that you have it solved, but in the future it would hep if you told us what you were trying to accomplish.

[memeloo]

...in the future it would hep if you told us what you were trying to accomplish.

I get a hDC of a bitmap(you call it like that?) in the memory and I would like to convert it to a Bitmap

no harm meant but wasn't it clear enough?

[BigEd781]

I meant that I would have found more relevant examples if I had known that the goal was to capture a screen shot. When you narrow your request to a specific implementation you do not allow for other alternatives which may be better solutions.

[memeloo]

I meant that I would have found more relevant examples if I had known that the goal was to capture a screen shot.

good point.

@edgebird: are you really taking a screenshot or is the example at codeproject only relevant because it shows how to utilize this hDC?

[edgebird]

Only relevant because it shows how to utilize the hDC.
I hook every BitBlt call the injected application makes and retrieve the source image(to whom i have the hDC).