www.pudn.com > mpeg4_DECORE.rar > GEN_DRAW.C

// gen_draw.c // 
 
#include "mp4_decoder.h" 
 
#include "gen_draw.h" 
 
/** 
 * 
**/ 
 
extern int MV[2][6][MBR+1][MBC+2]; // motion vectors 
extern int modemap[MBR+1][MBC+2]; // macroblock modes 
 
/***/ 
 
static void colorBlock_mv(unsigned char *buff, int stride, int mb_xpos, int mb_ypos, int bnum, int xsize, int ysize); 
static void drawline(int stride, int x0, int y0, int dx, int dy, unsigned char *buff, char colour, int xsize, int ysize); 
static void check_and_colour(unsigned char *buff, int x0, int y0, int xsize, int ysize, char colour); 
 
/***/ 
 
// Purpose: draw motion vectors in a displayable buffer 
void colorBuffer_mv(unsigned char *buff, int stride, int xsize, int ysize) 
{ 
	int mb_xsize, mb_ysize; 
	int mb_xpos, mb_ypos; 
	int bnum; 
 
	mb_xsize = xsize>>4; 
	mb_ysize = ysize>>4; 
 
	for (mb_ypos = 0; mb_ypos < mb_ysize; mb_ypos++) 
	{ 
		for (mb_xpos = 0; mb_xpos < mb_xsize; mb_xpos++) 
		{ 
			switch (modemap[mb_xpos+1][mb_ypos+1]) 
			{ 
			case MODE_INTER: case MODE_INTER_Q: 
				{ 
					colorBlock_mv(buff, stride, mb_xpos, mb_ypos, -1, xsize, ysize); 
				} 
				break; 
			case MODE_INTER4V: case MODE_INTER4V_Q: 
				{ 
					for (bnum = 0; bnum < 4; bnum++) 
					{ 
						colorBlock_mv(buff, stride, mb_xpos, mb_ypos, bnum, xsize, ysize); 
					} 
				} 
				break; 
			default: 
				break; 
			} 
		} 
	} 
} 
 
/***/ 
 
// Purpose: draw motion vector for this block, bnum is -1 if it's an entire macroblock 
static void colorBlock_mv(unsigned char *buff, int stride, int mb_xpos, int mb_ypos, int bnum, int xsize, int ysize) 
{ 
	int mvx, mvy; 
	int xpos = mb_xpos<<4; 
	int ypos = mb_ypos<<4; 
 
	if (bnum == -1) { 
		xpos += 8; 
		ypos += 8; 
		bnum = 0; // retrieve correct block number for MV extraction 
	}  
	else { 
		xpos += (bnum & 1) ? 12 : 4; 
		ypos += (bnum & 2) ? 12 : 4; 
	} 
 
	mvx = MV[0][bnum][mb_xpos+1][mb_ypos+1]; 
	mvy = MV[1][bnum][mb_xpos+1][mb_ypos+1]; 
 
	drawline(stride, xpos, ypos, mvx, mvy, buff, 0, xsize, ysize); 
} 
 
/***/ 
 
// John Funnell < johnf@mail.nu > 
// Purpose: line drawing function - pilfered from the Net 
static void drawline(int stride, int x0, int y0, int dx, int dy, unsigned char *buff, char colour, int xsize, int ysize) { 
	int y1 = y0 + dy; 
	int x1 = x0 + dx; 
	int stepx, stepy; 
	int fraction; 
 
	if (dy < 0) {  
		dy = -dy;  stepy = -stride;  
	}  
	else {  
		stepy = stride;  
	} 
	if (dx < 0) {  
		dx = -dx;  stepx = -1;  
	} else {  
		stepx = 1;  
	} 
 
	// retrieve pixel coord 
	dy <<= 1;  
	dx <<= 1; 
 
	// retrieve image coordinates 
	y0 *= stride; 
	y1 *= stride; 
 
	check_and_colour(buff, x0, y0, xsize, ysize, colour); 
	if (dx > dy) { 
		fraction = dy - (dx >> 1); 
		while (x0 != x1) { 
			if (fraction >= 0) { 
				y0 += stepy; 
				fraction -= dx; 
			} 
			x0 += stepx; 
			fraction += dy; 
			check_and_colour(buff, x0, y0, xsize, ysize, colour); 
		} 
	} else { 
		fraction = dx - (dy >> 1); 
		while (y0 != y1) { 
			if (fraction >= 0) { 
				x0 += stepx; 
				fraction -= dy; 
			} 
			y0 += stepy; 
			fraction += dx; 
			check_and_colour(buff, x0, y0, xsize, ysize, colour); 
		} 
	} 
} 
 
/***/ 
 
static void check_and_colour(unsigned char *buff, int x0, int y0, int xsize, int ysize, char colour) 
{ 
	if (x0 < 0) 
		return; 
	if (x0 > xsize) 
		return; 
	if (y0 < 0) 
		return; 
	if (y0 > (xsize*(ysize-1))) 
		return; 
 
	buff[x0+y0] = colour; 
}