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         // Number of items shown before and after the focus element
  32         protected int focus_first;
  33         protected int focus_end;
  34         protected int focus_size;
  35         protected int[] focus_starts;
  36         protected bool focus_locked;
  37         protected int focus_centre;
  38
  39         public FisheyeList()
  40         {
  41                 backing_store = null;
  42
  43                 list = new string[300];
  44                 for (int i = 0; i < 300; ++i)
  45                         list[i] = "Lorem Ipsum %d".printf(i);
  46
  47                 cur_el = 0;
  48                 focus_centre = 0;
  49                 focus_size = 20;
  50                 focus_starts = new int[focus_size + 1];
  51                 focus_locked = false;
  52                 distortion_factor = 30;
  53                 focus_layout();
  54
  55                 add_events(Gdk.EventMask.POINTER_MOTION_MASK
  56                          | Gdk.EventMask.BUTTON_PRESS_MASK
  57                          | Gdk.EventMask.BUTTON_RELEASE_MASK);
  58         }
  59
  60         /* Mouse button got pressed over widget */
  61         public override bool button_press_event(Gdk.EventButton event)
  62         {
  63                 stderr.printf("Mouse pressed on %d %s\n", cur_el, list[cur_el]);
  64                 return false;
  65         }
  66
  67         /* Mouse button got released */
  68         public override bool button_release_event(Gdk.EventButton event)
  69         {
  70                 stderr.printf("Mouse released on %d %s\n", cur_el, list[cur_el]);
  71                 // ...
  72                 return false;
  73         }
  74
  75         /* Mouse pointer moved over widget */
  76         public override bool motion_notify_event(Gdk.EventMotion event)
  77         {
  78                 int old_cur_el = cur_el;
  79                 int x = (int)event.x;
  80                 int y = (int)event.y;
  81
  82                 focus_locked = x < allocation.width/2 && y >= focus_starts[0] && y < focus_starts[focus_end - focus_first];
  83
  84                 if (focus_locked)
  85                 {
  86                         for (int idx = focus_first; idx < focus_end; ++idx)
  87                                 if (y < focus_starts[idx-focus_first+1])
  88                                 {
  89                                         cur_el = idx;
  90                                         break;
  91                                 }
  92
  93                 } else {
  94                         cur_el = y * list.length / allocation.height;
  95                         if (old_cur_el != cur_el)
  96                                 focus_layout();
  97                 }
  98
  99                 //stderr.printf("MOTION %f %f CE %d\n", event.x, event.y, cur_el);
 100                 if (old_cur_el != cur_el)
 101                 {
 102                         queue_draw();
 103                         old_cur_el = cur_el;
 104                 }
 105                 return false;
 106         }
 107
 108         public override bool configure_event (Gdk.EventConfigure event)
 109         {
 110                 backing_store = new Gdk.Pixmap(window, allocation.width, allocation.height, -1);
 111                 focus_layout();
 112                 queue_draw();
 113                 return false;
 114         }
 115
 116         /* Widget is asked to draw itself */
 117         public override bool expose_event (Gdk.EventExpose event)
 118         {
 119                 if (backing_store == null)
 120                         return false;
 121
 122                 draw(backing_store);
 123
 124                 window.draw_drawable(
 125                         get_style().fg_gc[Gtk.StateType.NORMAL],
 126                         backing_store,
 127                         event.area.x, event.area.y,
 128                         event.area.x, event.area.y,
 129                         event.area.width, event.area.height);
 130
 131                 return false;
 132         }
 133
 134         protected int el_y(int idx)
 135         {
 136                 // Undistorted Y
 137                 int undy = idx * allocation.height / list.length;
 138                 // Distorted position
 139                 int pos = fisheye(undy, focus_centre, distortion_factor, 0, allocation.height);
 140                 //stderr.printf("%d %f %f\n", idx, undy, pos);
 141                 return pos;
 142         }
 143
 144         protected void focus_layout()
 145         {
 146                 // Anchor point
 147                 focus_centre = cur_el*allocation.height/list.length;
 148
 149                 focus_first = cur_el > focus_size/2 ? cur_el-focus_size/2 : 0;
 150                 focus_end = focus_first + focus_size;
 151                 if (focus_end >= list.length) focus_end = list.length;
 152
 153                 // Compute starting positions for all items in focus
 154                 for (int idx = focus_first; idx < focus_end; ++idx)
 155                 {
 156                         int posprev = idx == 0 ? 0 : el_y(idx-1);
 157                         int pos = el_y(idx);
 158                         int posnext = idx == list.length-1 ? 1 : el_y(idx+1);
 159                         int y0 = (pos+posprev)/2;
 160                         int y1 = (pos+posnext)/2;
 161
 162                         focus_starts[idx - focus_first] = y0;
 163                         focus_starts[idx - focus_first + 1] = y1;
 164                 }
 165         }
 166
 167         protected void draw(Gdk.Drawable drawable)
 168         {
 169                 Gtk.Style style = get_style();
 170
 171                 // Background
 172                 drawable.draw_rectangle(style.bg_gc[Gtk.StateType.NORMAL], true, 0, 0, allocation.width, allocation.height);
 173
 174                 // Focus lock area
 175                 drawable.draw_rectangle(style.bg_gc[Gtk.StateType.ACTIVE], true,
 176                         0, focus_starts[0], allocation.width/2, focus_starts[focus_end - focus_first]);
 177
 178                 // Focus movement area
 179                 drawable.draw_rectangle(style.bg_gc[Gtk.StateType.INSENSITIVE], true,
 180                         allocation.width/2, 0, allocation.width, allocation.height);
 181
 182                 // Create a Cairo context
 183                 //var context = Gdk.cairo_create (drawable);
 184
 185                 // Paint items around focus
 186                 //context.select_font_face(style.font_desc.get_family(), Cairo.FontSlant.NORMAL, Cairo.FontWeight.NORMAL);
 187                 for (int idx = focus_first; idx < focus_end; ++idx)
 188                 {
 189                         int y0 = focus_starts[idx - focus_first];
 190                         int y1 = focus_starts[idx - focus_first + 1];
 191
 192                         Gtk.StateType itemState = Gtk.StateType.NORMAL;
 193                         if (idx == cur_el)
 194                         {
 195                                 itemState = Gtk.StateType.SELECTED;
 196                                 drawable.draw_rectangle(style.bg_gc[itemState], true,
 197                                         0, y0, allocation.width, y1-y0);
 198                         }
 199
 200                         var layout = create_pango_layout(list[idx]);
 201
 202                         var fd = style.font_desc.copy();
 203                         //fd.set_size((y1-y0)*Pango.SCALE);
 204                         int size = (y1-y0)*Pango.SCALE*80/100;
 205                         if (size <= 0) size = Pango.SCALE;
 206                         fd.set_absolute_size(size);
 207                         layout.set_font_description(fd);
 208                         //stderr.printf("AZAZA %p\n", layout.get_attributes());
 209                         //var attrlist = layout.get_attributes().copy();
 210                         //stderr.printf("AL %p\n", attrlist);
 211                         //var attrlist = new Pango.AttrList();
 212                         //stderr.printf("SIZE %d\n", y1-y0);
 213                         //attrlist.insert(new Pango.AttrSize(y1-y0));
 214                         //var attrlist = layout.get_attributes();
 215                         //attrlist.change(new Pango.AttrSize(y1-y0));
 216                         //layout.set_attributes(attrlist);
 217                         //layout.set_height(y1-y0);
 218                         //int w, h;
 219                         //layout.get_pixel_size(out w, out h);
 220                         Gdk.draw_layout(drawable, style.fg_gc[itemState], 0, y0, layout);
 221                 }
 222         }
 223
 224     /*
 225      * The following function is adapted from Prefuse's FisheyeDistortion.java.
 226      *
 227      * A relevant annotation from Prefuse:
 228      *
 229      * For more details on this form of transformation, see Manojit Sarkar and
 230      * Marc H. Brown, "Graphical Fisheye Views of Graphs", in Proceedings of
 231      * CHI'92, Human Factors in Computing Systems, p. 83-91, 1992. Available
 232      * online at <a href="http://citeseer.ist.psu.edu/sarkar92graphical.html">
 233      * http://citeseer.ist.psu.edu/sarkar92graphical.html</a>.
 234      */
 235
 236     /*
 237      * Distorts an item's coordinate.
 238      * @param x the undistorted coordinate
 239      * @param coordinate of the anchor or focus point
 240      * @param d disortion factor
 241      * @param min the beginning of the display
 242      * @param max the end of the display
 243      * @return the distorted coordinate
 244      */
 245     private int fisheye(int x, int a, double d, int min, int max)
 246     {
 247         if ( d != 0 ) {
 248             bool left = x<a;
 249             double v;
 250             int m = (left ? a-min : max-a);
 251             if ( m == 0 ) m = max-min;
 252             v = Math.fabs(x - a) / m;
 253             v = (d+1)/(d+(1/v));
 254             return (int)Math.round((left?-1:1)*m*v + a);
 255         } else {
 256             return x;
 257         }
 258     }
 259 }
 260
 261 public class Fisheye : Gtk.Window
 262 {
 263         public Fisheye()
 264         {
 265                 title = "Fisheye";
 266                 destroy += Gtk.main_quit;
 267
 268                 var list = new FisheyeList();
 269                 add(list);
 270         }
 271 }
 272
 273 static int main (string[] args) {
 274         Gtk.init (ref args);
 275
 276         var fe = new Fisheye();
 277         fe.set_size_request(200, 300);
 278         fe.show_all();
 279
 280         Gtk.main();
 281
 282         return 0;
 283 }