Fastest method for blitting from a pixel buffer in

问题:

Good evening,

I have several 32-bit images in memory buffers that I wish to "blit" to a device context, quickly. Speed is an issue here because the buffer will be manipulated constantly and need to be blitted to the DC repeatedly.

The color depth of the buffer is 32-bits, so it is already in the DIB-expected format of SetDIBits(). However, this is rather cumbersome since the bitmap target of SetDIBits() cannot be already selected into the DC prior to the operation. So I will need to constantly swap out the DC's bitmap, call SetDIBits(), swap the bitmap back into the DC, and then blit the DC to the Window's DC. To me, that just seems like a LOT of workload on the CPU and too much branching in the Windows API; way too much for optimal performance.

I would be interested in using DirectX if it didn't force me to use Device Contexts for 2D operations, or uploading textures to video memory before displaying them, because the contents of the image are constantly changing.

My question is simple (despite the long writeup). What would be the fastest way for me to blit an image from a pixel buffer in memory onto the screen? Direct access to the pixel buffer of a DC would be great, but I know that's not going to happen.

Thanks for reading my long writeup.

回答1:

There is an API method CreateDIBSection to create a DIB that applications can write to directly. This allows to continuously updating the bitmap (either memcopy or directly writing to it).

See MSDN article for further details.

Access to the bitmap must be synchronized. Do this by calling the GdiFlush function.