BasicBitmap

As the purpose of providing a simple compact, high-performance and platform independent Bitmap library, BasicBitmap is created based on a subset of my vector graphic library: https://github.com/skywind3000/pixellib .

Features

• Highly optimized C++ code which could be compiled and executed in any platform
• Multiple pixel formats from 8 to 32 bits: A8R8G8B8, R8G8B8, A4R4G4B4, R5G6B5, A8, etc.
• Blit in opaque or transparent mode (with a maskcolor/colorkey)
• Converting between different pixel formats
• Blending with different compositors
• Scaling with different filters (nearest, linear, bilinear)
• High quality resampling to different size (Bicubic/Bilinear)
• Loading bmp/tga from memory or file and saving bmp to file
• Loading png/jpg with gdiplus (only in windows xp or above)
• Saving bmp/ppm files
• Self-contained and not rely on other libraries
• Compact and portable, just copy BasicBitmap.h/.cpp into your project
• Core routines can be replaced by external (eg. SSE2 implementations)
• Blitting is 40% faster than DirectDraw FastBlt (with AVX/SSE2 optimizing enabled).
• Blending is 34% faster than GDI's AlphaBlend (with SSE2 enabled).

Interfaces

The BasicBitmap class provides these public methods below:

Method	Description
Fill	fill color in rectangle
Clear	clear the whole bitmap
Blit	blit from source bitmap with same bpp
Convert	convert from different pixel-format
SetPixel	draw pixel in raw color
GetPixel	read pixel in raw color
SetColor	draw pixel in A8R8G8B8
GetColor	read pixel in A8R8G8B8
Scale	scale bitmap using different filter and blend op
DrawLine	draw a line
QuickText	draw text with internal mini-8x8 ascii font
SampleBilinear	sample pixel with bilinear
SampleBicubic	sample pixel with bicubic
Resample	resample bitmap
LoadBmpFromMemory	load bmp file from memory
LoadTgaFromMemory	load tga file from memory
LoadBmp	load bmp file
LoadTga	load tga file
SaveBmp	save bmp file
SavePPM	save ppm file
DownSampleBy2	down sample 2x2 pixels into one pixel
SetDIBitsToDevice	(windows) draw bitmap to hdc
GetDIBits	(windows) get DIB bits to bitmap
GdiPlusInit	(windows) initialize gdiplus
GdiPlusLoadImageFromMemory	(windows) load jpg/png from memory
GdiPlusLoadImage	(windows) use gdiplus to load jpg/png
CreateBitmapInDIB	(windows) create bitmap with DIB section

Performance

Blit Performance

Full window (800x600) blitting (both opacity and transparent), compare to GDI/SDL/DirectDraw:

32 Bits Blit	Opacity	Transparent
BasicBitmap C++	fps=2325	fps=1368
BasicBitmap AVX/SSE2	fps=2904	fps=2531
GDI	fps=2333	fps=1167
SDL	fps=2671	fps=1015
DirectDraw	fps=2695	fps=2090

Note: use BltFast with DirectDrawSurface7 in System Memory to perform Opacity & Transparent blit. BitBlt and TransparentBlt(msimg32.dll) are used in the GDI testing case.

16 Bits Blit	Opacity	Transparent
BasicBitmap C++	fps=4494	fps=1253
BasicBitmap AVX/SSE2	fps=9852	fps=2909
DirectDraw BltFast	fps=5889	fps=861

Blitting performance in SDL & GDI are slower than DirectDraw, just compare to ddraw as well.

8 Bits Blit	Opacity	Transparent
BasicBitmap C++	fps=11142	fps=1503
BasicBitmap AVX/SSE2	fps=18181	fps=5449
DirectDraw BltFast	fps=14705	fps=4832

DirectDrawSurface in Video Memory takes the benefit of hardware acceleration which is definitely faster than BasicBitmap. If you really need hardware acceleration, use OpenGL/DX as well.

BasicBitmap is a software implementation which aims to achieve the best performance in all other software implementations: like GDI/GDI+, SDL/DirectDraw in System Memory, for examples.

So just compare to DirectDrawSurface in System Memory. Use it in the condition that you only need a lightweight software solution: GUI/Cross Platform/hardware unavailable/image processing/video compositing, etc.

Blending Performance

SRC OVER	FPS
BasicBitmap C++	594
BasicBitmap SSE2	1731
GDI (msimg32.dll)	1137

note: 800x600 full window src-over blending vs GDI's AlphaBlend function (in msimg32.dll).