diff options
| -rw-r--r-- | pearl.c | 36 |
1 files changed, 35 insertions, 1 deletions
@@ -1891,6 +1891,11 @@ struct game_drawstate { char *draglines; /* size w*h; lines flipped by current drag */ }; +static void interpret_ui_drag(const game_state *state, const game_ui *ui, + bool *clearing, int i, int *sx, int *sy, + int *dx, int *dy, int *dir, + int *oldstate, int *newstate); + static void update_ui_drag(const game_state *state, game_ui *ui, int gx, int gy) { @@ -1919,13 +1924,42 @@ static void update_ui_drag(const game_state *state, game_ui *ui, * the drag path so far has the effect of truncating the path back * to that square, so a player can back out part of an uncommitted * drag without having to let go of the mouse. + * + * An exception is that you're allowed to drag round in a loop + * back to the very start of the drag, provided that doesn't + * create a vertex of the wrong degree. This allows a player who's + * after an extra challenge to draw the entire loop in a single + * drag, without it cancelling itself just before release. */ - for (i = 0; i < ui->ndragcoords; i++) + for (i = 1; i < ui->ndragcoords; i++) if (pos == ui->dragcoords[i]) { ui->ndragcoords = i+1; return; } + if (pos == ui->dragcoords[0]) { + /* More complex check for a loop-shaped drag, which has to go + * through interpret_ui_drag to decide on the final degree of + * the start/end vertex. */ + ui->dragcoords[ui->ndragcoords] = pos; + bool clearing = true; + int lines = state->lines[pos] & (L|R|U|D); + for (i = 0; i < ui->ndragcoords; i++) { + int sx, sy, dx, dy, dir, oldstate, newstate; + interpret_ui_drag(state, ui, &clearing, i, &sx, &sy, &dx, &dy, + &dir, &oldstate, &newstate); + if (sx == gx && sy == gy) + lines ^= (oldstate ^ newstate); + if (dx == gx && dy == gy) + lines ^= (F(oldstate) ^ F(newstate)); + } + if (NBITS(lines) > 2) { + /* Bad vertex degree: fall back to the backtracking behaviour. */ + ui->ndragcoords = 1; + return; + } + } + /* * Otherwise, dragging the mouse into a square that's a rook-move * away from the last one on the path extends the path. |