edppaint.cpp - horz. lines not drawn

[JustDaveIII]

void Paint::DrawLine(int x0, int y0, int x1, int y1, int colored)

Horizontal lines (and I suspect vertical ones too) are not drawn. The Bresenham algorithm is not fully / correctly implemented for the Arduino files that use edppaint.cpp

Never mind that I can test before calling to see if the line is Horz. or Vert. and then call the appropriate routine as this one should handle all edge cases. Below is my code correction. It also alters the duplicate "2 * err" code to execute only once.

`void Paint::DrawLine(int x0, int y0, int x1, int y1, int colored) {

/* Corrected  Bresenham algorithm */
int dx = x1 - x0 >= 0 ? x1 - x0 : x0 - x1;
int sx = x0 < x1 ? 1 : -1;
int dy = y1 - y0 <= 0 ? y1 - y0 : y0 - y1;
int sy = y0 < y1 ? 1 : -1;
int err = dx + dy;

int e2;

while(true)

{
if ((x0 == x1) && (y0 == y1)) break;

    DrawPixel(x0, y0 , colored);
    e2 = 2 * err;
    
    if (e2 >= dy) {
       if (x0 == x1) break;     
        err += dy;
        x0 += sx;
    }
    if (e2 <= dx) {
       if (y0 == y1) break;
        err += dx; 
        y0 += sy;
    }
}

}
`