+
+#if DEBUG_QUEUE
+ fprintf(stderr, "%s: constructing h\n", ql->name);
+#endif
+ /* Construct map from id to new and old structures */
+ hash *h = hash_new(sizeof(struct newqueue_data));
+ for(struct queue_entry *q = ql->q; q; q = q->next)
+ record_queue_map(h, q->id, q, NULL);
+ for(struct queue_entry *q = newq; q; q = q->next)
+ record_queue_map(h, q->id, NULL, q);
+
+ /* The easy bit: delete rows not present any more. In the same pass we
+ * update the secret column containing the queue_entry pointer. */
+#if DEBUG_QUEUE
+ fprintf(stderr, "%s: deleting rows...\n", ql->name);
+#endif
+ GtkTreeIter iter[1];
+ gboolean it = gtk_tree_model_get_iter_first(GTK_TREE_MODEL(ql->store),
+ iter);
+ int inserted = 0, deleted = 0, kept = 0;
+ while(it) {
+ struct queue_entry *q = ql_iter_to_q(GTK_TREE_MODEL(ql->store), iter);
+ const struct newqueue_data *nqd = hash_find(h, q->id);
+ if(nqd->new) {
+ /* Tell this row that it belongs to the new version of the queue */
+ gtk_list_store_set(ql->store, iter,
+ ql->ncolumns + QUEUEPOINTER_COLUMN, nqd->new,
+ -1);
+ it = gtk_tree_model_iter_next(GTK_TREE_MODEL(ql->store), iter);
+ /* We'll need the new start time */
+ nqd->new->when = q->when;
+ ++kept;
+ } else {
+ /* Delete this row (and move iter to the next one) */
+#if DEBUG_QUEUE
+ fprintf(stderr, " delete %s\n", q->id);
+#endif
+ it = gtk_list_store_remove(ql->store, iter);
+ ++deleted;
+ }
+ }
+
+ /* Now every row's secret column is right, but we might be missing new rows
+ * and they might be in the wrong order */
+
+ /* We're going to have to support arbitrary rearrangements, so we might as
+ * well add new elements at the end. */
+#if DEBUG_QUEUE
+ fprintf(stderr, "%s: adding rows...\n", ql->name);
+#endif
+ struct queue_entry *after = 0;
+ for(struct queue_entry *q = newq; q; q = q->next) {
+ const struct newqueue_data *nqd = hash_find(h, q->id);
+ if(!nqd->old) {
+ if(after) {
+ /* Try to insert at the right sort of place */
+ GtkTreeIter where[1];
+ gboolean wit = gtk_tree_model_get_iter_first(GTK_TREE_MODEL(ql->store),
+ where);
+ while(wit && ql_iter_to_q(GTK_TREE_MODEL(ql->store), where) != after)
+ wit = gtk_tree_model_iter_next(GTK_TREE_MODEL(ql->store), where);
+ if(wit)
+ gtk_list_store_insert_after(ql->store, iter, where);
+ else
+ gtk_list_store_append(ql->store, iter);
+ } else
+ gtk_list_store_prepend(ql->store, iter);
+ gtk_list_store_set(ql->store, iter,
+ ql->ncolumns + QUEUEPOINTER_COLUMN, q,
+ -1);
+#if DEBUG_QUEUE
+ fprintf(stderr, " add %s\n", q->id);
+#endif
+ ++inserted;
+ }
+ after = newq;
+ }
+
+ /* Now exactly the right set of rows are present, and they have the right
+ * queue_entry pointers in their secret column, but they may be in the wrong
+ * order.
+ *
+ * The current code is simple but amounts to a bubble-sort - we might easily
+ * called gtk_tree_model_iter_next a couple of thousand times.
+ */
+#if DEBUG_QUEUE
+ fprintf(stderr, "%s: rearranging rows\n", ql->name);
+ fprintf(stderr, "%s: target state:\n", ql->name);
+ dump_queue(newq, 0);
+ fprintf(stderr, "%s: current state:\n", ql->name);
+ dump_rows(ql);
+#endif
+ it = gtk_tree_model_get_iter_first(GTK_TREE_MODEL(ql->store), iter);
+ struct queue_entry *tq = newq; /* t-for-target */
+ int swaps = 0, searches = 0;
+ int row = 0;
+ while(it) {
+ struct queue_entry *cq = ql_iter_to_q(GTK_TREE_MODEL(ql->store), iter);
+ /* c-for-current */
+
+ /* Everything has the right queue pointer (see above) so it's sufficient to
+ * compare pointers to detect mismatches */
+ if(cq != tq) {
+#if DEBUG_QUEUE
+ fprintf(stderr, " pointer mismatch at row %d\n", row);
+ fprintf(stderr, " target id %s\n", tq->id);
+ fprintf(stderr, " actual id %s\n", cq->id);
+#endif
+ /* Start looking for the target row fromn the next row */
+ GtkTreeIter next[1] = { *iter };
+ gboolean nit = gtk_tree_model_iter_next(GTK_TREE_MODEL(ql->store), next);
+ while(nit) {
+ struct queue_entry *nq = ql_iter_to_q(GTK_TREE_MODEL(ql->store), next);
+#if DEBUG_QUEUE
+ fprintf(stderr, " candidate: %s\n", nq->id);
+#endif
+ if(nq == tq)
+ break;
+ nit = gtk_tree_model_iter_next(GTK_TREE_MODEL(ql->store), next);
+ ++searches;
+ }
+ /* Note that this assertion will fail in the face of duplicate IDs.
+ * q->id really does need to be unique. */
+ assert(nit);
+ gtk_list_store_swap(ql->store, iter, next);
+ *iter = *next;
+#if DEBUG_QUEUE
+ fprintf(stderr, "%s: found it. new row state:\n", ql->name);
+ dump_rows(ql);
+#endif
+ ++swaps;
+ }
+ /* ...and onto the next one */
+ it = gtk_tree_model_iter_next(GTK_TREE_MODEL(ql->store), iter);
+ tq = tq->next;
+ ++row;
+ }
+#if DEBUG_QUEUE
+ fprintf(stderr, "%6s: %3d kept %3d inserted %3d deleted %3d swaps %4d searches\n", ql->name,
+ kept, inserted, deleted, swaps, searches);
+ fprintf(stderr, "done\n");
+#endif
+ ql->q = newq;
+ /* Set the rest of the columns in new rows */
+ ql_update_list_store(ql);
+ --suppress_actions;
+}
+
+/* Drag and drop ------------------------------------------------------------ */
+
+/** @brief Identify the drop path
+ * @param w Destination tree view widget
+ * @param model Underlying tree model
+ * @param wx X coordinate
+ * @param wy Y coordinate
+ * @param posp Where to store relative position
+ * @return Target path or NULL
+ *
+ * This is used by ql_drag_motion() and ql_drag_data_received() to identify a
+ * drop would or does land. It's important that they use the same code since
+ * otherwise the visual feedback can be inconsistent with the actual effect!
+ *
+ * Remember to free the returned path.
+ */
+static GtkTreePath *ql_drop_path(GtkWidget *w,
+ GtkTreeModel *model,
+ int wx, int wy,
+ GtkTreeViewDropPosition *posp) {
+ GtkTreePath *path = NULL;
+ GtkTreeViewDropPosition pos;
+ GtkTreeIter iter[1], last[1];
+ int tx, ty;
+
+ gtk_tree_view_convert_widget_to_tree_coords(GTK_TREE_VIEW(w),
+ wx, wy, &tx, &ty);
+ if(gtk_tree_view_get_dest_row_at_pos(GTK_TREE_VIEW(w),
+ wx, wy,
+ &path,
+ &pos)) {
+ //fprintf(stderr, "gtk_tree_view_get_dest_row_at_pos() -> TRUE\n");
+ // Normalize drop position
+ switch(pos) {
+ case GTK_TREE_VIEW_DROP_INTO_OR_BEFORE:
+ pos = GTK_TREE_VIEW_DROP_BEFORE;
+ break;
+ case GTK_TREE_VIEW_DROP_INTO_OR_AFTER:
+ pos = GTK_TREE_VIEW_DROP_AFTER;
+ break;
+ default: break;
+ }
+ } else if(gtk_tree_model_get_iter_first(model, iter)) {
+ /* If the pointer isn't over any particular row then either it's below
+ * the last row, in which case we want the dropzone to be below that row;
+ * or it's above the first row (in the column headings) in which case we
+ * want the dropzone to be above that row. */
+ if(ty >= 0) {
+ /* Find the last row */
+ do {
+ *last = *iter;
+ } while(gtk_tree_model_iter_next(model, iter));
+ /* The drop target is just after it */
+ pos = GTK_TREE_VIEW_DROP_AFTER;
+ *iter = *last;
+ } else {
+ /* The drop target will be just before the first row */
+ pos = GTK_TREE_VIEW_DROP_BEFORE;
+ }
+ path = gtk_tree_model_get_path(model, iter);
+ }
+ *posp = pos;
+ return path;
+}
+
+#if 0
+static const char *act(GdkDragAction action) {
+ struct dynstr d[1];
+
+ dynstr_init(d);
+ if(action & GDK_ACTION_DEFAULT)
+ dynstr_append_string(d, "|DEFAULT");
+ if(action & GDK_ACTION_COPY)
+ dynstr_append_string(d, "|COPY");
+ if(action & GDK_ACTION_MOVE)
+ dynstr_append_string(d, "|MOVE");
+ if(action & GDK_ACTION_LINK)
+ dynstr_append_string(d, "|LINK");
+ if(action & GDK_ACTION_PRIVATE)
+ dynstr_append_string(d, "|PRIVATE");
+ if(action & GDK_ACTION_ASK)
+ dynstr_append_string(d, "|ASK");
+ dynstr_terminate(d);
+ return d->nvec ? d->vec + 1 : "";
+}
+#endif
+
+/** @brief Called when a drag moves within a candidate destination
+ * @param w Destination widget
+ * @param dc Drag context
+ * @param x Current pointer location
+ * @param y Current pointer location
+ * @param time_ Current time
+ * @param user_data Pointer to queuelike
+ * @return TRUE in a dropzone, otherwise FALSE
+ *
+ * This is the handler for the "drag-motion" signal.
+ */
+static gboolean ql_drag_motion(GtkWidget *w,
+ GdkDragContext *dc,
+ gint x,
+ gint y,
+ guint time_,
+ gpointer user_data) {
+ struct queuelike *const ql = user_data;
+ GdkDragAction action = 0;
+
+ // GTK_DEST_DEFAULT_MOTION vets actions as follows:
+ // 1) if dc->suggested_action is in the gtk_drag_dest_set actions
+ // then dc->suggested_action is taken as the action.
+ // 2) otherwise if dc->actions intersects the gtk_drag_dest_set actions
+ // then the lowest-numbered member of the intersection is chosen.
+ // 3) otherwise no member is chosen and gdk_drag_status() is called
+ // with action=0 to refuse the drop.
+ if(dc->suggested_action) {
+ if(dc->suggested_action & (GDK_ACTION_MOVE|GDK_ACTION_COPY))
+ action = dc->suggested_action;
+ } else if(dc->actions & GDK_ACTION_MOVE)
+ action = GDK_ACTION_MOVE;
+ else if(dc->actions & GDK_ACTION_COPY)
+ action = GDK_ACTION_COPY;
+ /* TODO this comes up with the wrong answer sometimes. If we are in the
+ * middle of a rearrange then the suggested action will be COPY, which we'll
+ * take, even though MOVE would actually be appropriate. The drag still
+ * seems to work, but it _is_ wrong. The answer is to take the target into
+ * account. */
+ /*fprintf(stderr, "suggested %s actions %s result %s\n",
+ act(dc->suggested_action), act(dc->actions), act(action));*/
+ if(action) {
+ // If the action is acceptable then we see if this widget is acceptable
+ if(gtk_drag_dest_find_target(w, dc, NULL) == GDK_NONE)
+ action = 0;
+ }
+ // Report the status
+ //fprintf(stderr, "drag action: %u\n", action);
+ gdk_drag_status(dc, action, time_);
+ if(action) {
+ GtkTreeViewDropPosition pos;
+
+ // Find the drop target
+ GtkTreePath *path = ql_drop_path(w, GTK_TREE_MODEL(ql->store), x, y, &pos);
+ // Highlight drop target
+ gtk_tree_view_set_drag_dest_row(GTK_TREE_VIEW(w), path, pos);
+ if(path)
+ gtk_tree_path_free(path);