GUI_FillEllipse(400, 250, 400, 200);生成的图形不对

yuanxinfei · 发表于 2014-10-15 08:54:51

GUI_FillEllipse(400, 250, 400, 200);生成的图形不对，生成的图片成这样了，我想要的是一个正规的椭圆，这是为什么呀

正点原子 · 发表于 2014-10-15 08:54:52

[mw_shl_code=c,true]//画任意线 //x0,y0:起点 x1,y1:终点 //color:颜色 void gui_draw_line(u16 x0,u16 y0,u16 x1,u16 y1,u16 color) { u16 t; int xerr=0,yerr=0,delta_x,delta_y,distance; int incx,incy,uRow,uCol; delta_x=x1-x0; //计算坐标增量 delta_y=y1-y0; uRow=x0; uCol=y0; if(delta_x>0)incx=1; //设置单步方向 else if(delta_x==0)incx=0;//垂直线 else {incx=-1;delta_x=-delta_x;} if(delta_y>0)incy=1; else if(delta_y==0)incy=0;//水平线 else{incy=-1;delta_y=-delta_y;} if( delta_x>delta_y)distance=delta_x; //选取基本增量坐标轴 else distance=delta_y; for(t=0;t<=distance+1;t++ )//画线输出 { gui_phy.draw_point(uRow,uCol,color);//画点 xerr+=delta_x ; yerr+=delta_y ; if(xerr>distance) { xerr-=distance; uRow+=incx; } if(yerr>distance) { yerr-=distance; uCol+=incy; } } } //画椭圆 //x0,y0:坐标 //rx:x方向半径 //ry:y方向半径 //color:椭圆的颜色 void gui_draw_ellipse(u16 x0, u16 y0, u16 rx, u16 ry,u16 color) { u32 OutConst, Sum, SumY; u16 x,y; u16 xOld; u32 _rx = rx; u32 _ry = ry; if(rx>x0||ry>y0)return;//非法. OutConst = _rx*_rx*_ry*_ry+(_rx*_rx*_ry>>1); // Constant as explaint above // To compensate for rounding xOld = x = rx; for (y=0; y<=ry; y++) { if (y==ry)x=0; else { SumY =((u32)(rx*rx))*((u32)(y*y)); // Does not change in loop while(Sum = SumY + ((u32)(ry*ry))*((u32)(x*x)),(x>0) && (Sum>OutConst)) x--; } // Since we draw lines, we can not draw on the first iteration if (y) { gui_draw_line(x0-xOld,y0-y+1,x0-x,y0-y,color); gui_draw_line(x0-xOld,y0+y-1,x0-x,y0+y,color); gui_draw_line(x0+xOld,y0-y+1,x0+x,y0-y,color); gui_draw_line(x0+xOld,y0+y-1,x0+x,y0+y,color); } xOld = x; } }[/mw_shl_code]