void OutGraphicsCharFont1(int x, int y, int fontcolour, int backgroundcolour, int c, int Erase)
{
// using register variables (as opposed to stack based ones) may make execution faster
// depends on compiler and CPU
register int row, column, theX = x, theY = y ;
register int pixels ;
register char theColour = fontcolour ;
register int BitMask, theC = c ;
// if x,y coord off edge of screen don't bother
// XRES and YRES are #defined to be 800 and 480 respectively
if(((short)(x) > (short)(XRES-1)) || ((short)(y) > (short)(YRES-1)))
return ;
// if printable character subtract hex 20
if(((short)(theC) >= (short)(' ')) && ((short)(theC) <= (short)('~'))) {
theC = theC - 0x20 ;
for(row = 0; (char)(row) < (char)(7); row ++) {
// get the bit pattern for row 0 of the character from the software font
pixels = Font5x7[theC][row] ;
BitMask = 16 ;
for(column = 0; (char)(column) < (char)(5); column ++) {
// if a pixel in the character display it
if((pixels & BitMask))
WriteAPixel(theX+column, theY+row, theColour) ;
else {
if(Erase == 1)
// if pixel is part of background (not part of character)
// erase the background to value of variable BackGroundColour
WriteAPixel(theX+column, theY+row, backgroundcolour) ;
}
BitMask = BitMask >> 1 ;
}
}
}
void TestLine(int x1, int y1, int x2, int y2, int Colour)
{
int x = x1;
int y = y1;
int dx = abs(x2 - x1);
int dy = abs(y2 - y1);
int s1 = sign(x2 - x1);
int s2 = sign(y2 - y1);
int i, temp, interchange = 0, error ;
// if x1=x2 and y1=y2 then it is a line of zero length
if(dx == 0 && dy == 0)
return ;
// must be a complex line so use bresenhams algorithm
else {
// swap delta x and delta y depending upon slop of line
if(dy > dx) {
temp = dx ;
dx = dy ;
dy = temp ;
interchange = 1 ;
}
// initialise the error term to compensate for non-zero intercept
error = (dy << 1) - dx ; // (2 * dy) - dx
// main loop
for(i = 1; i <= dx; i++) {
WriteAPixel(x, y, Colour);
while(error >= 0) {
if(interchange == 1)
x += s1 ;
else
y += s2 ;
error -= (dx << 1) ; // times 2
}
if(interchange == 1)
y += s2 ;
else
x += s1 ;
error += (dy << 1) ; // times 2
}
}
}
/*
* Draw a circle (one pixel at a time)
* Prints an error message and returns without drawing anything if any points would be off screen
*/
void TestCircle(int x0, int y0, int radius, int color)
{
if (ASSERT_POINTS_ARE_VALID && !check_if_point_is_on_screen(x0, y0)) {
printf("ERROR: DrawCircle failed for center point (%d,%d)\n", x0, y0);
return;
}
if (ASSERT_POINTS_ARE_VALID && !check_if_point_is_on_screen(x0+radius, y0)) {
printf("ERROR: DrawCircle failed in positive x direction (%d,%d)\n", x0+radius, y0);
return;
}
if (ASSERT_POINTS_ARE_VALID && !check_if_point_is_on_screen(x0, y0+radius)) {
printf("ERROR: DrawCircle failed in positive y direction (%d,%d)\n", x0, y0+radius);
return;
}
if (ASSERT_POINTS_ARE_VALID && !check_if_point_is_on_screen(x0-radius, y0)) {
printf("ERROR: DrawCircle failed in negative x direction (%d,%d)\n", x0-radius, y0);
return;
}
if (ASSERT_POINTS_ARE_VALID && !check_if_point_is_on_screen(x0, y0-radius)) {
printf("ERROR: DrawCircle failed in negative y direction (%d,%d)\n", x0, y0-radius);
return;
}
int x = radius;
int y = 0;
int decisionOver2 = 1 - x; // Decision criterion divided by 2 evaluated at x=r, y=0
while( y <= x ) {
WriteAPixel( x + x0, y + y0, color); // Octant 1
WriteAPixel( y + x0, x + y0, color); // Octant 2
WriteAPixel(-x + x0, y + y0, color); // Octant 4
WriteAPixel(-y + x0, x + y0, color); // Octant 3
WriteAPixel(-x + x0, -y + y0, color); // Octant 5
WriteAPixel(-y + x0, -x + y0, color); // Octant 6
WriteAPixel( x + x0, -y + y0, color); // Octant 7
WriteAPixel( y + x0, -x + y0, color); // Octant 8
y++;
if (decisionOver2 <= 0) {
decisionOver2 += 2 * y + 1; // Change in decision criterion for y -> y+1
}
else {
x--;
decisionOver2 += 2 * (y - x) + 1; // Change for y -> y+1, x -> x-1
}
}
}
void TestVLine(int x1, int y1, int length, int Colour)
{
int i;
for(i = y1; i < y1+length; i++ )
WriteAPixel(x1, i, Colour);
}
void TestHLine(int x1, int y1, int length, int Colour)
{
int i;
for(i = x1; i < x1+length; i++ )
WriteAPixel(i, y1, Colour);
}
