public DenseGrid Flip_WE()
{
DenseGrid new_grid = new DenseGrid(this.width, this.height, 0);
DenseGrid.BlitFromAOntoB(this, new_grid, 0, 0);
// Starting with the outmost and working towards center,
// swap the contents of each paired vertical strip.
for (int W_xx = 0; W_xx < new_grid.center_x(); W_xx++) // VERIFY: is this correct for even widths?
{
int E_xx = new_grid.max_x() - W_xx;
for (int yy = 0; yy <= new_grid.max_y(); yy++) {
int W_value = contents_at_XY(W_xx, yy);
int E_value = contents_at_XY(E_xx, yy);
new_grid.set_contents_at_XY(W_xx, yy, E_value);
new_grid.set_contents_at_XY(E_xx, yy, W_value);
} // for(yy)
} // for(xx)
return new_grid;
}
public static DenseGrid BlitFromAOntoB(DenseGrid from_A, int from_x, int from_y,
DenseGrid to_B, int to_x, int to_y,
int blit_width, int blit_height)
{
// Blit from A onto B, with as many method arguments as possible.
if (from_A == null)
return null;
if (to_B == null)
return null;
// The from_x,y are relative to the origin of from_A.
if (from_x < from_A.min_x())
return null; // At least somewhat off-edge to the left
if (from_x > from_A.max_x())
return null; // Entirely to the right
if (from_y < from_A.min_y())
return null; // At least somewhat off-edge above
if (from_y > from_A.max_y())
return null; // Entirely below
// The to_x,y are relative to the origin of to_B.
if (to_x + blit_width < to_B.min_x())
return null; // Entirely to the left
if (to_x > to_B.max_x())
return null; // Entirely to the right
if (to_y + blit_height < to_B.min_y())
return null; // Entirely above
if (to_y > to_B.max_y())
return null; // Entirely below
// The blit width/height are clipped to avoid needless looping.
// Blit calls which overlap from_A or to_B are thus harmless.
// Indeed, calls overlapping to_B are common and ordinary,
// one reason being that from_A and to_B are often of different sizes.
int max_from_w = Math.Min(from_A.max_x(), from_x + blit_width);
int max_to_w = Math.Min(to_B.max_x(), to_x + blit_width);
int max_width = Math.Min(max_from_w, max_to_w);
blit_width = GridUtility2D.Clamp(blit_width, 1, max_width);
int max_from_h = Math.Min(from_A.max_y(), from_y + blit_height);
int max_to_h = Math.Min(to_B.max_y(), to_y + blit_height);
int max_height = Math.Min(max_from_h, max_to_h);
blit_height = GridUtility2D.Clamp(blit_height, 1, max_height);
// Iterate over the cells of from_A, and copy non-blank cells onto to_B:
for (int yy = 0; yy <= blit_height; yy++) {
for (int xx = 0; xx <= blit_width; xx++) {
// To find the from/to blit coordinates,
// add in the x,y offsets for from_A and to_B:
int from_ii = GridUtility2D.indexForXYW(from_x + xx, from_y + yy, from_A.width);
int to_ii = GridUtility2D.indexForXYW(to_x + xx, to_y + yy, to_B.width);
int contents = from_A.contents_at_XY(from_x + xx, from_y + yy);
if (contents != 0) {
// Non-zero, not a blank cell (blank cells are skipped)
to_B.set_contents_at_XY(to_x + xx, to_y + yy, contents);
}
} // for (xx)
} // for (yy)
return to_B; // to_B has been modified
}
public DenseGrid Flip_NS()
{
DenseGrid new_grid = new DenseGrid(this.width, this.height, 0);
DenseGrid.BlitFromAOntoB(this, new_grid, 0, 0);
// Starting with the outmost and working towards center,
// swap the contents of each paired horizontal strip.
for (int N_yy = 0; N_yy < new_grid.center_y(); N_yy++) // VERIFY: is this correct for even heights?
{
int S_yy = new_grid.max_y() - N_yy;
for (int xx = 0; xx <= new_grid.max_x(); xx++) {
int N_value = contents_at_XY(xx, N_yy);
int S_value = contents_at_XY(xx, S_yy);
new_grid.set_contents_at_XY(xx, N_yy, S_value);
new_grid.set_contents_at_XY(xx, S_yy, N_value);
} // for(yy)
} // for(xx)
return new_grid;
}