test3.java

// Instead of 4 loops, do 2 loops per diagonal direction.
// For "/" diagonals, let's start from:
//   - The bottom edge (y = bounds.y + bounds.height), x from bounds.x..bounds.x + width
//   - The left edge (x = bounds.x), y from bounds.y..bounds.y + height

// For "\" diagonals, let's start from:
//   - The top edge (y = bounds.y), x from bounds.x..bounds.x + width
//   - The left edge (x = bounds.x), y from bounds.y..bounds.y + height

//  Example for "/" diagonals:
for (int x = bounds.x; x <= bounds.x + bounds.width; x += spacing) {
    drawOneDiagonalLine(g, pixels, x, bounds, +1); 
}
for (int y = bounds.y + bounds.height; y >= bounds.y; y -= spacing) {
    drawOneDiagonalLine(g, pixels, y, bounds, +1); 
}

// Then do similarly for "\" diagonals, but pick top and left edges, for instance:
for (int x = bounds.x; x <= bounds.x + bounds.width; x += spacing) {
    drawOneDiagonalLine(g, pixels, x, bounds, -1); 
}
for (int y = bounds.y; y <= bounds.y + bounds.height; y += spacing) {
    drawOneDiagonalLine(g, pixels, y, bounds, -1);
}