[fpc-pascal] Implementing AggPas with PtcGraph

[Graeme Geldenhuys]

On 2017-05-30 22:37, James Richters wrote:

> Putimage() takes
> Initial X position
> Initial Y position
> Pointer to beginning of memory bitmap

In that case the AggPas code should be even faster, because PutImage() 
only want a pointer to the bitmap data - thus no need to go through the 
slow FPImage code to generate a PNG or BMP image. The pixel-by-pixel 
conversions for FPImage is very slow.

>    Size := ImageSize(10, 20, 30, 40);
>    GetMem(Q, Size);   { Allocate memory on heap }

So you can do pretty much the same with AggPas then. Allocate the memory 
you need, and attach that as the rendering buffer or AggPas. As I 
mentioned before, AggPas just needs to know what memory it can write 
too, and in what format you want that rendered data to be. AggPas 
supports many render buffer formats. BGR, BGRA, RGB, RGBA, Gray8, 
rgb555, rgb565 etc etc. And if an existing render buffer format doesn't 
exist, it is really easy and quick to add a new one - just a few really 
simple procedures to implement.

See the pf_*.inc files for plenty of examples. The "pf_" prefix stands 
for "pixel format definition".


> I'm looking at it and I think getimage / putimage are just one byte per pixel... maybe?

I'll see if I can get graph or ptcgraph working working here under 
FreeBSD, then I'll take a look at what pixel format they use.


Regards,
   Graeme

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