src/fisheye.vala

   1 /*
   2  * zavai - simple interface to the OpenMoko (or to the FSO stack)
   3  *
   4  * Copyright (C) 2009  Enrico Zini <enrico@enricozini.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 using GLib;
  22
  23 public class FisheyeList : Gtk.DrawingArea
  24 {
  25         protected Gdk.Pixmap backing_store;
  26
  27         private string[] list;
  28         protected int cur_el;
  29         protected double distortion_factor;
  30
  31         protected Pango.Layout[] pango_cache;
  32
  33         // Number of items shown before and after the focus element
  34         protected int focus_first;
  35         protected int focus_end;
  36         protected int focus_size;
  37         protected int[] focus_starts;
  38         protected bool focus_locked;
  39         protected int focus_centre;
  40
  41         public FisheyeList()
  42         {
  43                 backing_store = null;
  44
  45                 list = new string[300];
  46                 for (int i = 0; i < 300; ++i)
  47                         list[i] = "Lorem Ipsum %d".printf(i);
  48
  49                 pango_cache = new Pango.Layout[30];
  50                 for (int i = 0; i < 30; ++i)
  51                         pango_cache[i] = null;
  52
  53                 cur_el = 0;
  54                 focus_centre = 0;
  55                 focus_size = 20;
  56                 focus_starts = new int[focus_size + 1];
  57                 focus_locked = false;
  58                 distortion_factor = 30;
  59                 focus_layout();
  60
  61                 add_events(Gdk.EventMask.POINTER_MOTION_MASK
  62                          | Gdk.EventMask.BUTTON_PRESS_MASK
  63                          | Gdk.EventMask.BUTTON_RELEASE_MASK);
  64         }
  65
  66         /* Mouse button got pressed over widget */
  67         public override bool button_press_event(Gdk.EventButton event)
  68         {
  69                 stderr.printf("Mouse pressed on %d %s\n", cur_el, list[cur_el]);
  70                 return false;
  71         }
  72
  73         /* Mouse button got released */
  74         public override bool button_release_event(Gdk.EventButton event)
  75         {
  76                 stderr.printf("Mouse released on %d %s\n", cur_el, list[cur_el]);
  77                 // ...
  78                 return false;
  79         }
  80
  81         /* Mouse pointer moved over widget */
  82         public override bool motion_notify_event(Gdk.EventMotion event)
  83         {
  84                 int old_cur_el = cur_el;
  85                 int x = (int)event.x;
  86                 int y = (int)event.y;
  87
  88                 focus_locked = x < allocation.width/2 && y >= focus_starts[0] && y < focus_starts[focus_end - focus_first];
  89
  90                 if (focus_locked)
  91                 {
  92                         for (int idx = focus_first; idx < focus_end; ++idx)
  93                                 if (y < focus_starts[idx-focus_first+1])
  94                                 {
  95                                         cur_el = idx;
  96                                         break;
  97                                 }
  98
  99                 } else {
 100                         cur_el = y * list.length / allocation.height;
 101                         if (old_cur_el != cur_el)
 102                                 focus_layout();
 103                 }
 104
 105                 //stderr.printf("MOTION %f %f CE %d\n", event.x, event.y, cur_el);
 106                 if (old_cur_el != cur_el)
 107                 {
 108                         queue_draw();
 109                         old_cur_el = cur_el;
 110                 }
 111                 return false;
 112         }
 113
 114         public override bool configure_event (Gdk.EventConfigure event)
 115         {
 116                 backing_store = new Gdk.Pixmap(window, allocation.width, allocation.height, -1);
 117                 focus_layout();
 118                 queue_draw();
 119                 return false;
 120         }
 121
 122         /* Widget is asked to draw itself */
 123         public override bool expose_event (Gdk.EventExpose event)
 124         {
 125                 if (backing_store == null)
 126                         return false;
 127
 128                 draw(backing_store);
 129
 130                 window.draw_drawable(
 131                         get_style().fg_gc[Gtk.StateType.NORMAL],
 132                         backing_store,
 133                         event.area.x, event.area.y,
 134                         event.area.x, event.area.y,
 135                         event.area.width, event.area.height);
 136
 137                 return false;
 138         }
 139
 140         protected int el_y(int idx)
 141         {
 142                 // Undistorted Y
 143                 int undy = idx * allocation.height / list.length;
 144                 // Distorted position
 145                 int pos = fisheye(undy, focus_centre, distortion_factor, 0, allocation.height);
 146                 //stderr.printf("%d %f %f\n", idx, undy, pos);
 147                 return pos;
 148         }
 149
 150         protected void focus_layout()
 151         {
 152                 // Anchor point
 153                 focus_centre = cur_el*allocation.height/list.length;
 154
 155                 focus_first = cur_el > focus_size/2 ? cur_el-focus_size/2 : 0;
 156                 focus_end = focus_first + focus_size;
 157                 if (focus_end >= list.length) focus_end = list.length;
 158
 159                 // Compute starting positions for all items in focus
 160                 for (int idx = focus_first; idx < focus_end; ++idx)
 161                 {
 162                         int posprev = idx == 0 ? 0 : el_y(idx-1);
 163                         int pos = el_y(idx);
 164                         int posnext = idx == list.length-1 ? 1 : el_y(idx+1);
 165                         int y0 = (pos+posprev)/2;
 166                         int y1 = (pos+posnext)/2;
 167
 168                         focus_starts[idx - focus_first] = y0;
 169                         focus_starts[idx - focus_first + 1] = y1;
 170                 }
 171         }
 172
 173         protected void draw(Gdk.Drawable drawable)
 174         {
 175                 Gtk.Style style = get_style();
 176
 177                 // Background
 178                 drawable.draw_rectangle(style.bg_gc[Gtk.StateType.NORMAL], true, 0, 0, allocation.width, allocation.height);
 179
 180                 // Focus lock area
 181                 drawable.draw_rectangle(style.bg_gc[Gtk.StateType.ACTIVE], true,
 182                         0, focus_starts[0], allocation.width/2, focus_starts[focus_end - focus_first]);
 183
 184                 // Focus movement area
 185                 drawable.draw_rectangle(style.bg_gc[Gtk.StateType.INSENSITIVE], true,
 186                         allocation.width/2, 0, allocation.width, allocation.height);
 187
 188                 // Create a Cairo context
 189                 //var context = Gdk.cairo_create (drawable);
 190
 191                 // Paint items around focus
 192                 //context.select_font_face(style.font_desc.get_family(), Cairo.FontSlant.NORMAL, Cairo.FontWeight.NORMAL);
 193                 for (int idx = focus_first; idx < focus_end; ++idx)
 194                 {
 195                         int y0 = focus_starts[idx - focus_first];
 196                         int y1 = focus_starts[idx - focus_first + 1];
 197
 198                         Gtk.StateType itemState = Gtk.StateType.NORMAL;
 199                         if (idx == cur_el)
 200                         {
 201                                 itemState = Gtk.StateType.SELECTED;
 202                                 drawable.draw_rectangle(style.bg_gc[itemState], true,
 203                                         0, y0, allocation.width, y1-y0);
 204                         }
 205
 206
 207                         // TODO: cache pango contexts instead of fontdescs
 208                         int size = (y1-y0)*80/100;
 209                         if (size <= 0) size = 1;
 210                         if (size >= pango_cache.length) size = pango_cache.length - 1;
 211                         if (pango_cache[size] == null)
 212                         {
 213                                 var fd = style.font_desc.copy();
 214                                 fd.set_absolute_size(size*Pango.SCALE);
 215                                 var pc = create_pango_context();
 216                                 pc.set_font_description(fd);
 217                                 pango_cache[size] = new Pango.Layout(pc);
 218                         }
 219                         pango_cache[size].set_text(list[idx], -1);
 220                         var layout = pango_cache[size];
 221                         //stderr.printf("AZAZA %p\n", layout.get_attributes());
 222                         //var attrlist = layout.get_attributes().copy();
 223                         //stderr.printf("AL %p\n", attrlist);
 224                         //var attrlist = new Pango.AttrList();
 225                         //stderr.printf("SIZE %d\n", y1-y0);
 226                         //attrlist.insert(new Pango.AttrSize(y1-y0));
 227                         //var attrlist = layout.get_attributes();
 228                         //attrlist.change(new Pango.AttrSize(y1-y0));
 229                         //layout.set_attributes(attrlist);
 230                         //layout.set_height(y1-y0);
 231                         //int w, h;
 232                         //layout.get_pixel_size(out w, out h);
 233                         Gdk.draw_layout(drawable, style.fg_gc[itemState], 0, y0, layout);
 234                 }
 235         }
 236
 237     /*
 238      * The following function is adapted from Prefuse's FisheyeDistortion.java.
 239      *
 240      * A relevant annotation from Prefuse:
 241      *
 242      * For more details on this form of transformation, see Manojit Sarkar and
 243      * Marc H. Brown, "Graphical Fisheye Views of Graphs", in Proceedings of
 244      * CHI'92, Human Factors in Computing Systems, p. 83-91, 1992. Available
 245      * online at <a href="http://citeseer.ist.psu.edu/sarkar92graphical.html">
 246      * http://citeseer.ist.psu.edu/sarkar92graphical.html</a>.
 247      */
 248
 249     /*
 250      * Distorts an item's coordinate.
 251      * @param x the undistorted coordinate
 252      * @param coordinate of the anchor or focus point
 253      * @param d disortion factor
 254      * @param min the beginning of the display
 255      * @param max the end of the display
 256      * @return the distorted coordinate
 257      */
 258     private int fisheye(int x, int a, double d, int min, int max)
 259     {
 260         if ( d != 0 ) {
 261             bool left = x<a;
 262             double v;
 263             int m = (left ? a-min : max-a);
 264             if ( m == 0 ) m = max-min;
 265             v = (double)(x - a).abs() / m;
 266             v = (d+1)/(d+(1/v));
 267             return (int)Math.round((left?-1:1)*m*v + a);
 268         } else {
 269             return x;
 270         }
 271     }
 272 }
 273
 274 public class Fisheye : Gtk.Window
 275 {
 276         public Fisheye()
 277         {
 278                 title = "Fisheye";
 279                 destroy += Gtk.main_quit;
 280
 281                 var list = new FisheyeList();
 282                 add(list);
 283         }
 284 }
 285
 286 static int main (string[] args) {
 287         Gtk.init (ref args);
 288
 289         var fe = new Fisheye();
 290         fe.set_size_request(200, 300);
 291         fe.show_all();
 292
 293         Gtk.main();
 294
 295         return 0;
 296 }