nanogui: Thread: GrArea

Hello:
	when I use the function GrArea like this: 
	GrArea(fl_window, fl_gc, 0, 0, WIDTH, HEIGHT, outtable, MWPF_PIXELVAL);
	the error occured and the error message is : assert "c<psd->ncolors" failor.
	why??
	how should I use the GrArea and GrReadArea?
	thanks 

	

: GrArea(fl_window, fl_gc, 0, 0, WIDTH, HEIGHT, outtable, MWPF_PIXELVAL);
: the error occured and the error message is : assert "c<psd->ncolors" failor.

Typically, you are not sending MWPF_PIXELVAL, which
is usually compiled in as an unsigned long.  Instead,
you are probably sending unsigned short or unsigned
char values.  If you're running in palette mode, try
specifying MWPF_PALETTE instead.  Or you can recompile
Microwindows with a different value in MWPF_PALETTE=
in the config file, and send that value directly.

When the blitter picks up the unsigned long value, rather
than the differently packed char or short, the assert
fails...

Regards,

Greg

Hello Greg:
thanks a lot!
	what is the meaning of the variable psd->ncolors ? 

additional:
the code blow is working ,no errors
void save()
	{	
		GR_PIXELVAL intable[WIDTH*HEIGHT];
		GrReadArea(fl_window, 0, MENU_HEIGHT, WIDTH, HEIGHT-MENU_HEIGHT, intable);
		write(handle, intable, 240*300);
		for(int i=0;i<300;i++) {
			for(int j=0;j<240;j++) {
				;;;;;		
			}
		}
		GrArea(fl_window, fl_gc, 0, MENU_HEIGHT, WIDTH, HEIGHT, intable, MWPF_PIXELVAL);
		redraw();
	 }

but this code blow will occured failure:
void save()
	{	
		GR_PIXELVAL intable[WIDTH*HEIGHT];
		GrReadArea(fl_window, 0, MENU_HEIGHT, WIDTH, HEIGHT-MENU_HEIGHT, intable);
		write(handle, intable, 240*300);
		for(int i=0;i<300;i++) {
			for(int j=0;j<240;j++) {
				intable[i*240+j]+=0x60;
			}
		}
		GrArea(fl_window, fl_gc, 0, MENU_HEIGHT, WIDTH, HEIGHT, intable, MWPF_PIXELVAL);//this line occured the c<psd->ncolors failure;
		redraw();
	 }
It seems that I cann't change the pixel color very effective via change the intable buffer, isn't it???????
if the type of intable is long then the last argument should be MWPF_TRUECOLOR332, isn't it?????
thanks!!!

I read the source code the definition of MWPF_PIXELVAL is
#define MWPF_RGB	   0	/* pseudo, convert from packed 32 bit RGB*/
#define MWPF_PIXELVAL	   1	/* pseudo, no convert from packed PIXELVAL*/
#define MWPF_PALETTE	   2	/* pixel is packed 8 bits 1, 4 or 8 pal index*/
#define MWPF_TRUECOLOR0888 3	/* pixel is packed 32 bits 8/8/8 truecolor*/
#define MWPF_TRUECOLOR888  4	/* pixel is packed 24 bits 8/8/8 truecolor*/
#define MWPF_TRUECOLOR565  5	/* pixel is packed 16 bits 5/6/5 truecolor*/
#define MWPF_TRUECOLOR332  6	/* pixel is packed 8 bits 3/3/2 truecolor*/.

regards!!! .
wls

####@####.#### wrote:
> 
>         what is the meaning of the variable psd->ncolors ?
> 

Number of colors.  It would be 16, 256, 65536 and huge for 4,8,16 and 24
bits respectively IIRC.

If you have an 8-bit display, and send color values larger than 255, then
the assert fails.  I guess this is what goes wrong in your case.

> I read the source code the definition of MWPF_PIXELVAL is
> #define MWPF_RGB           0    /* pseudo, convert from packed 32 bit RGB*/
> #define MWPF_PIXELVAL      1    /* pseudo, no convert from packed PIXELVAL*/
> #define MWPF_PALETTE       2    /* pixel is packed 8 bits 1, 4 or 8 pal index*/
> #define MWPF_TRUECOLOR0888 3    /* pixel is packed 32 bits 8/8/8 truecolor*/
> #define MWPF_TRUECOLOR888  4    /* pixel is packed 24 bits 8/8/8 truecolor*/
> #define MWPF_TRUECOLOR565  5    /* pixel is packed 16 bits 5/6/5 truecolor*/
> #define MWPF_TRUECOLOR332  6    /* pixel is packed 8 bits 3/3/2 truecolor*/.

Notice that the packing that you use for the GrArea call should match
the number of bits per pixel of the display, unless MWPF_RGB is used.
In this case, I believe you can rely on a translation (possibly slow).

We (screen media) uses MWPF_TRUECOLOR565 to avoid translations, and send
only as much image bits as needed (16 bit color display).

I don't have any experience with GrReadArea.

Regards,
Morten Rolland