| 1 | /* |
| 2 | * Copyright (C) 2009 Richard Kettlewell |
| 3 | * |
| 4 | * Note that this license ONLY applies to multidrag.c and multidrag.h, not to |
| 5 | * the rest of DisOrder. |
| 6 | * |
| 7 | * Permission is hereby granted, free of charge, to any person |
| 8 | * obtaining a copy of this software and associated documentation files |
| 9 | * (the "Software"), to deal in the Software without restriction, |
| 10 | * including without limitation the rights to use, copy, modify, merge, |
| 11 | * publish, distribute, sublicense, and/or sell copies of the Software, |
| 12 | * and to permit persons to whom the Software is furnished to do so, |
| 13 | * subject to the following conditions: |
| 14 | * |
| 15 | * The above copyright notice and this permission notice shall be |
| 16 | * included in all copies or substantial portions of the Software. |
| 17 | * |
| 18 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 19 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 20 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| 21 | * NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE |
| 22 | * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF |
| 23 | * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
| 24 | * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| 25 | */ |
| 26 | /** @file disobedience/multidrag.c |
| 27 | * @brief Drag multiple rows of a GtkTreeView |
| 28 | * |
| 29 | * Normally when you start a drag, GtkTreeView sets the selection to just row |
| 30 | * you dragged from (because it can't cope with dragging more than one row at a |
| 31 | * time). |
| 32 | * |
| 33 | * Disobedience needs more. |
| 34 | * |
| 35 | * Firstly it intercepts button-press-event and button-release event and for |
| 36 | * clicks that might be the start of drags, suppresses changes to the |
| 37 | * selection. A consequence of this is that it needs to intercept |
| 38 | * button-release-event too, to restore the effect of the click, if it turns |
| 39 | * out not to be drag after all. |
| 40 | * |
| 41 | * The location of the initial click is stored in object data called @c |
| 42 | * multidrag-where. |
| 43 | * |
| 44 | * Secondly it intercepts drag-begin and constructs an icon from the rows to be |
| 45 | * dragged. |
| 46 | * |
| 47 | * Inspired by similar code in <a |
| 48 | * href="http://code.google.com/p/quodlibet/">Quodlibet</a> (another software |
| 49 | * jukebox, albeit as far as I can see a single-user one). |
| 50 | */ |
| 51 | #include <config.h> |
| 52 | |
| 53 | #include <string.h> |
| 54 | #include <glib.h> |
| 55 | #include <gtk/gtk.h> |
| 56 | |
| 57 | #include "multidrag.h" |
| 58 | |
| 59 | static gboolean multidrag_selection_block(GtkTreeSelection attribute((unused)) *selection, |
| 60 | GtkTreeModel attribute((unused)) *model, |
| 61 | GtkTreePath attribute((unused)) *path, |
| 62 | gboolean attribute((unused)) path_currently_selected, |
| 63 | gpointer data) { |
| 64 | return *(const gboolean *)data; |
| 65 | } |
| 66 | |
| 67 | static void block_selection(GtkWidget *w, gboolean block, |
| 68 | int x, int y) { |
| 69 | static const gboolean which[] = { FALSE, TRUE }; |
| 70 | GtkTreeSelection *s = gtk_tree_view_get_selection(GTK_TREE_VIEW(w)); |
| 71 | gtk_tree_selection_set_select_function(s, |
| 72 | multidrag_selection_block, |
| 73 | (gboolean *)&which[!!block], |
| 74 | NULL); |
| 75 | // Remember the pointer location |
| 76 | int *where = g_object_get_data(G_OBJECT(w), "multidrag-where"); |
| 77 | if(!where) { |
| 78 | where = g_malloc(2 * sizeof (int)); |
| 79 | g_object_set_data_full(G_OBJECT(w), "multidrag-where", where, |
| 80 | g_free); |
| 81 | } |
| 82 | where[0] = x; |
| 83 | where[1] = y; |
| 84 | } |
| 85 | |
| 86 | static gboolean multidrag_button_press_event(GtkWidget *w, |
| 87 | GdkEventButton *event, |
| 88 | gpointer attribute((unused)) user_data) { |
| 89 | /* By default we assume that anything this button press does should |
| 90 | * act as normal */ |
| 91 | block_selection(w, TRUE, -1, -1); |
| 92 | /* We are only interested in left-button behavior */ |
| 93 | if(event->button != 1) |
| 94 | return FALSE; |
| 95 | /* We are only interested in unmodified clicks (not SHIFT etc) */ |
| 96 | if(event->state & GDK_MODIFIER_MASK) |
| 97 | return FALSE; |
| 98 | /* We are only interested if a well-defined path is clicked */ |
| 99 | GtkTreePath *path = NULL; |
| 100 | if(!gtk_tree_view_get_path_at_pos(GTK_TREE_VIEW(w), |
| 101 | event->x, event->y, |
| 102 | &path, |
| 103 | NULL, |
| 104 | NULL, NULL)) |
| 105 | return FALSE; |
| 106 | /* We are only interested if a selected row is clicked */ |
| 107 | GtkTreeSelection *s = gtk_tree_view_get_selection(GTK_TREE_VIEW(w)); |
| 108 | if(gtk_tree_selection_path_is_selected(s, path)) { |
| 109 | /* We block subsequent selection changes and remember where the |
| 110 | * click was */ |
| 111 | block_selection(w, FALSE, event->x, event->y); |
| 112 | } |
| 113 | if(path) |
| 114 | gtk_tree_path_free(path); |
| 115 | return FALSE; /* propagate */ |
| 116 | } |
| 117 | |
| 118 | static gboolean multidrag_button_release_event(GtkWidget *w, |
| 119 | GdkEventButton *event, |
| 120 | gpointer attribute((unused)) user_data) { |
| 121 | int *where = g_object_get_data(G_OBJECT(w), "multidrag-where"); |
| 122 | |
| 123 | /* Did button-press-event do anything? We just check the outcome rather than |
| 124 | * going through all the conditions it tests. */ |
| 125 | if(where && where[0] != -1) { |
| 126 | // Remember where the down-click was |
| 127 | const int x = where[0], y = where[1]; |
| 128 | // Re-allow selections |
| 129 | block_selection(w, TRUE, -1, -1); |
| 130 | if(x == event->x && y == event->y) { |
| 131 | // If the up-click is at the same location as the down-click, |
| 132 | // it's not a drag. |
| 133 | GtkTreePath *path = NULL; |
| 134 | GtkTreeViewColumn *col; |
| 135 | if(gtk_tree_view_get_path_at_pos(GTK_TREE_VIEW(w), |
| 136 | event->x, event->y, |
| 137 | &path, |
| 138 | &col, |
| 139 | NULL, NULL)) { |
| 140 | gtk_tree_view_set_cursor(GTK_TREE_VIEW(w), path, col, FALSE); |
| 141 | } |
| 142 | if(path) |
| 143 | gtk_tree_path_free(path); |
| 144 | } |
| 145 | } |
| 146 | return FALSE; /* propagate */ |
| 147 | } |
| 148 | |
| 149 | /** @brief State for multidrag_begin() and its callbacks */ |
| 150 | struct multidrag_begin_state { |
| 151 | GtkTreeView *view; |
| 152 | multidrag_row_predicate *predicate; |
| 153 | int rows; |
| 154 | int index; |
| 155 | GdkPixmap **pixmaps; |
| 156 | }; |
| 157 | |
| 158 | /** @brief Callback to construct a row pixmap */ |
| 159 | static void multidrag_make_row_pixmaps(GtkTreeModel attribute((unused)) *model, |
| 160 | GtkTreePath *path, |
| 161 | GtkTreeIter *iter, |
| 162 | gpointer data) { |
| 163 | struct multidrag_begin_state *qdbs = data; |
| 164 | |
| 165 | if(qdbs->predicate(path, iter)) { |
| 166 | qdbs->pixmaps[qdbs->index++] |
| 167 | = gtk_tree_view_create_row_drag_icon(qdbs->view, path); |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | /** @brief Called when a drag operation starts |
| 172 | * @param w Source widget (the tree view) |
| 173 | * @param dc Drag context |
| 174 | * @param user_data Row predicate |
| 175 | */ |
| 176 | static void multidrag_drag_begin(GtkWidget *w, |
| 177 | GdkDragContext attribute((unused)) *dc, |
| 178 | gpointer user_data) { |
| 179 | struct multidrag_begin_state qdbs[1]; |
| 180 | GdkPixmap *icon; |
| 181 | GtkTreeSelection *sel; |
| 182 | |
| 183 | //fprintf(stderr, "drag-begin\n"); |
| 184 | memset(qdbs, 0, sizeof *qdbs); |
| 185 | qdbs->view = GTK_TREE_VIEW(w); |
| 186 | qdbs->predicate = (multidrag_row_predicate *)user_data; |
| 187 | sel = gtk_tree_view_get_selection(qdbs->view); |
| 188 | /* Find out how many rows there are */ |
| 189 | if(!(qdbs->rows = gtk_tree_selection_count_selected_rows(sel))) |
| 190 | return; /* doesn't make sense */ |
| 191 | /* Generate a pixmap for each row */ |
| 192 | qdbs->pixmaps = g_new(GdkPixmap *, qdbs->rows); |
| 193 | gtk_tree_selection_selected_foreach(sel, |
| 194 | multidrag_make_row_pixmaps, |
| 195 | qdbs); |
| 196 | /* Might not have used all rows */ |
| 197 | qdbs->rows = qdbs->index; |
| 198 | /* Determine the size of the final icon */ |
| 199 | int height = 0, width = 0; |
| 200 | for(int n = 0; n < qdbs->rows; ++n) { |
| 201 | int pxw, pxh; |
| 202 | gdk_drawable_get_size(qdbs->pixmaps[n], &pxw, &pxh); |
| 203 | if(pxw > width) |
| 204 | width = pxw; |
| 205 | height += pxh; |
| 206 | } |
| 207 | if(!width || !height) |
| 208 | return; /* doesn't make sense */ |
| 209 | /* Construct the icon */ |
| 210 | icon = gdk_pixmap_new(qdbs->pixmaps[0], width, height, -1); |
| 211 | GdkGC *gc = gdk_gc_new(icon); |
| 212 | gdk_gc_set_colormap(gc, gtk_widget_get_colormap(w)); |
| 213 | int y = 0; |
| 214 | for(int n = 0; n < qdbs->rows; ++n) { |
| 215 | int pxw, pxh; |
| 216 | gdk_drawable_get_size(qdbs->pixmaps[n], &pxw, &pxh); |
| 217 | gdk_draw_drawable(icon, |
| 218 | gc, |
| 219 | qdbs->pixmaps[n], |
| 220 | 0, 0, /* source coords */ |
| 221 | 0, y, /* dest coords */ |
| 222 | pxw, pxh); /* size */ |
| 223 | y += pxh; |
| 224 | gdk_drawable_unref(qdbs->pixmaps[n]); |
| 225 | qdbs->pixmaps[n] = NULL; |
| 226 | } |
| 227 | g_free(qdbs->pixmaps); |
| 228 | qdbs->pixmaps = NULL; |
| 229 | // TODO scale down a bit, the resulting icons are currently a bit on the |
| 230 | // large side. |
| 231 | gtk_drag_source_set_icon(w, |
| 232 | gtk_widget_get_colormap(w), |
| 233 | icon, |
| 234 | NULL); |
| 235 | } |
| 236 | |
| 237 | static gboolean multidrag_default_predicate(GtkTreePath attribute((unused)) *path, |
| 238 | GtkTreeIter attribute((unused)) *iter) { |
| 239 | return TRUE; |
| 240 | } |
| 241 | |
| 242 | /** @brief Allow multi-row drag for @p w |
| 243 | * @param w A GtkTreeView widget |
| 244 | * @param predicate Function called to test rows for draggability, or NULL |
| 245 | * |
| 246 | * Suppresses the restriction of selections when a drag is started, and |
| 247 | * intercepts drag-begin to construct an icon. |
| 248 | * |
| 249 | * @p predicate should return TRUE for draggable rows and FALSE otherwise, to |
| 250 | * control what goes in the icon. If NULL, equivalent to a function that |
| 251 | * always returns TRUE. |
| 252 | */ |
| 253 | void make_treeview_multidrag(GtkWidget *w, |
| 254 | multidrag_row_predicate *predicate) { |
| 255 | if(!predicate) |
| 256 | predicate = multidrag_default_predicate; |
| 257 | g_signal_connect(w, "button-press-event", |
| 258 | G_CALLBACK(multidrag_button_press_event), NULL); |
| 259 | g_signal_connect(w, "button-release-event", |
| 260 | G_CALLBACK(multidrag_button_release_event), NULL); |
| 261 | g_signal_connect(w, "drag-begin", |
| 262 | G_CALLBACK(multidrag_drag_begin), predicate); |
| 263 | } |
| 264 | |
| 265 | /* |
| 266 | Local Variables: |
| 267 | c-basic-offset:2 |
| 268 | comment-column:40 |
| 269 | fill-column:79 |
| 270 | indent-tabs-mode:nil |
| 271 | End: |
| 272 | */ |