Another highlighting patch from Richard Boulton: immediately flag

any actual clashes (duplicate numbers in a row, column or block) in
red. This is a non-privileged deduction: it doesn't compare against
a known solution or consult a solver. It simply indicates reasons
why (no superset of) the current grid would cause the completion
flash to go off.

[originally from svn r5898]

diff --git a/solo.c b/solo.c
index c8fac6e513d77ba024e3641d1689f28094aac700..4a0f2791fc7a22001a7f355a900ea10722aeac8d 100644 (file)
--- a/solo.c
+++ b/solo.c
@@ -123,6 +123,7 @@ enum {
     COL_CLUE,
     COL_USER,
     COL_HIGHLIGHT,
+    COL_ERROR,
     COL_PENCIL,
     NCOLOURS
 };
@@ -1996,6 +1997,10 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     ret[COL_HIGHLIGHT * 3 + 1] = 0.85F * ret[COL_BACKGROUND * 3 + 1];
     ret[COL_HIGHLIGHT * 3 + 2] = 0.85F * ret[COL_BACKGROUND * 3 + 2];
 
+    ret[COL_ERROR * 3 + 0] = 1.0F;
+    ret[COL_ERROR * 3 + 1] = 0.0F;
+    ret[COL_ERROR * 3 + 2] = 0.0F;
+
     ret[COL_PENCIL * 3 + 0] = 0.5F * ret[COL_BACKGROUND * 3 + 0];
     ret[COL_PENCIL * 3 + 1] = 0.5F * ret[COL_BACKGROUND * 3 + 1];
     ret[COL_PENCIL * 3 + 2] = ret[COL_BACKGROUND * 3 + 2];
@@ -2064,10 +2069,10 @@ static void draw_number(frontend *fe, game_drawstate *ds, game_state *state,
     clip(fe, cx, cy, cw, ch);
 
     /* background needs erasing */
-    draw_rect(fe, cx, cy, cw, ch, hl == 1 ? COL_HIGHLIGHT : COL_BACKGROUND);
+    draw_rect(fe, cx, cy, cw, ch, (hl & 15) == 1 ? COL_HIGHLIGHT : COL_BACKGROUND);
 
     /* pencil-mode highlight */
-    if (hl == 2) {
+    if ((hl & 15) == 2) {
         int coords[6];
         coords[0] = cx;
         coords[1] = cy;
@@ -2086,7 +2091,7 @@ static void draw_number(frontend *fe, game_drawstate *ds, game_state *state,
            str[0] += 'a' - ('9'+1);
        draw_text(fe, tx + TILE_SIZE/2, ty + TILE_SIZE/2,
                  FONT_VARIABLE, TILE_SIZE/2, ALIGN_VCENTRE | ALIGN_HCENTRE,
-                 state->immutable[y*cr+x] ? COL_CLUE : COL_USER, str);
+                 state->immutable[y*cr+x] ? COL_CLUE : (hl & 16) ? COL_ERROR : COL_USER, str);
     } else {
         /* pencil marks required? */
         int i, j;
@@ -2120,6 +2125,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
                        float animtime, float flashtime)
 {
     int c = state->c, r = state->r, cr = c*r;
+    int entered_items[cr*cr];
     int x, y;
 
     if (!ds->started) {
@@ -2146,18 +2152,47 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
        }
     }
 
+    /*
+     * This array is used to keep track of rows, columns and boxes
+     * which contain a number more than once.
+     */
+    for (x = 0; x < cr * cr; x++)
+       entered_items[x] = 0;
+    for (x = 0; x < cr; x++)
+       for (y = 0; y < cr; y++) {
+           digit d = state->grid[y*cr+x];
+           if (d) {
+               int box = (x/r)+(y/c)*c;
+               entered_items[x*cr+d-1] |= ((entered_items[x*cr+d-1] & 1) << 1) | 1;
+               entered_items[y*cr+d-1] |= ((entered_items[y*cr+d-1] & 4) << 1) | 4;
+               entered_items[box*cr+d-1] |= ((entered_items[box*cr+d-1] & 16) << 1) | 16;
+           }
+       }
+
     /*
      * Draw any numbers which need redrawing.
      */
     for (x = 0; x < cr; x++) {
        for (y = 0; y < cr; y++) {
             int highlight = 0;
+            digit d = state->grid[y*cr+x];
+
             if (flashtime > 0 &&
                 (flashtime <= FLASH_TIME/3 ||
                  flashtime >= FLASH_TIME*2/3))
                 highlight = 1;
+
+            /* Highlight active input areas. */
             if (x == ui->hx && y == ui->hy)
                 highlight = ui->hpencil ? 2 : 1;
+
+           /* Mark obvious errors (ie, numbers which occur more than once
+            * in a single row, column, or box). */
+           if ((entered_items[x*cr+d-1] & 2) ||
+               (entered_items[y*cr+d-1] & 8) ||
+               (entered_items[((x/r)+(y/c)*c)*cr+d-1] & 32))
+               highlight |= 16;
+
            draw_number(fe, ds, state, x, y, highlight);
        }
     }