I copied a background bitmap to my window with the following steps: 1. GetDC 2. CreateCompatibleDC 3. SelectObject 4. BitBlt 5. DeleteObject 6. DeleteDC 7. ReleaseDC But I have to bitmaps which have to be copied into the mainwindow! Thats the best way to copy the second bitmap without repeating the whole procedure (GetDC,...ReleaseDC)?
hansWurst, After you have BitBlt'd the first bitmap, you can select the second bitmap into the compatible DC then Blt again, there's no need to go through the whole process again :- 1. GetDC 2. CreateCompatibleDC 3. SelectObject (first bitmap) 4. BitBlt 5. SelectObject (second bitmap) 6. BitBlt 7. DeleteObject 8. DeleteDC 9. ReleaseDC umbongo
Theres also a function, SetDIBitsToDevice or something like that, you'll find working code for it in the ShowDib example with masm32. This allows you to copy a 32bit dib (ie bitmap) directly to a hdc, no creation of tmp dc and selecting objects into it. It probably also works for 16bit and 24bit but I never tried it. I have a question regarding this though, does anyone know if its any faster or slower than BitBlt. I found that for large bitmaps ie 512*512 it got too slow for game graphics, I never got around to rewriting the code to BitBlt to compare speed but if someone else haas then maybe they'd share their findings.
According to win32.hlp, BitBlt is faster than SetDIBitsToDevice, and should be preffered for animation.
Depending on how much of a resource hog you care to be, you can create some DC's once, load the bitmaps to them, then keep them around for a while (even from program start to program finish). This way, you always have the bitmaps mounted and ready to blit from. Just be aware you are hogging resources this way, and use it sparingly.
Yes, I just managed to rewrite my BitBlting procedure from SetDIB... to BitBlt and its alot faster. One more question, are API hardware accelerated, I just changed my tnt2 to a Radeon All-in-Wonder and the speed of the routines doubled. Actually for large bitmaps its almost four times as fast. Is it just a better card, or could the dirivers or something be hardware accelerating BitBlt, I don't think this is possible though.
The GDI routines will use video memory if they can, I suspect your card has more RAM that the last one, so it will store you bitmaps in the gfx RAM rather than system RAM. This will make it alot faster. umbongo This message was edited by umbongo, on 6/25/2001 7:07:58 PM
Here is a tip for fast manipulation of DCs by nesting creation and setting of DCs with push/pop. Since 'SelectObject' returns the handle to the deselection handle of the GDI object, you don't need to save the GDI object in a memory variable. When you 'pop' the value you had returned from SelectObject, you can immediately 'Deselect' the object by calling SelectObject again. The following snippet creates a DC compatible with the screen, then creates and selects into it a bitmap, then creates and selects into it a brush and pen. The example uses just one memory variable and cleaning up GDI after the DC has been used is just a question of calling: pop eax invoke SelectObject,hDC,eax invoke DeleteObject,eax :- to match the number of times the DC had selected objects during the creation. LOCAL hDC :DWord invoke CreateCompatibleDC,0 mov hDC,eax invoke CreateCompatibleBitmap,hDC,100,100 invoke SelectObject,hDC,eax push eax invoke CreateSolidBrush,0ffh invoke SelectObject,hDC,eax push eax invoke CreatePen,PS_SOLID,1,0ffh invoke SelectObject,hDC,eax push eax ;------------------ ; Use hDC ;------------------- pop eax invoke SelectObject,hDC,eax invoke DeleteObject,eax pop eax invoke SelectObject,hDC,eax invoke DeleteObject,eax pop eax invoke SelectObject,hDC,eax invoke DeleteObject,eax invoke DeleteDC,hDC