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(svn r21768) -Fix [FS#4396]: Diagonal tile iterator needed a special case for A * 0 selections.

This commit is contained in:
frosch 2011-01-11 16:45:45 +00:00
parent 7e6ccf3a0a
commit 12b4fa7dba
1 changed files with 27 additions and 15 deletions
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42
src/tilearea.cpp
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@ -139,26 +139,38 @@ TileIterator &DiagonalTileIterator::operator++()
{
assert(this->tile != INVALID_TILE);
/* Determine the next tile, while clipping at map borders */
bool new_line = false;
do {
/* Iterate using the rotated coordinates. */
if (this->a_max > 0) {
this->a_cur += 2;
new_line = this->a_cur >= this->a_max;
} else {
this->a_cur -= 2;
new_line = this->a_cur <= this->a_max;
}
if (new_line) {
/* offset of initial a_cur: one tile in the same direction as a_max
* every second line.
*/
this->a_cur = abs(this->a_cur) % 2 ? 0 : (this->a_max > 0 ? 1 : -1);
if (this->a_max == 1 || this->a_max == -1) {
/* Special case: Every second column has zero length, skip them completely */
this->a_cur = 0;
if (this->b_max > 0) {
++this->b_cur;
this->b_cur = min(this->b_cur + 2, this->b_max);
} else {
--this->b_cur;
this->b_cur = max(this->b_cur - 2, this->b_max);
}
} else {
/* Every column has at least one tile to process */
if (this->a_max > 0) {
this->a_cur += 2;
new_line = this->a_cur >= this->a_max;
} else {
this->a_cur -= 2;
new_line = this->a_cur <= this->a_max;
}
if (new_line) {
/* offset of initial a_cur: one tile in the same direction as a_max
* every second line.
*/
this->a_cur = abs(this->a_cur) % 2 ? 0 : (this->a_max > 0 ? 1 : -1);
if (this->b_max > 0) {
++this->b_cur;
} else {
--this->b_cur;
}
}
}