prolooks/VuMeter.vala

   1 /*
   2     Copyright 2009 by Hans Baier, Krzysztof Foltman
   3     License: LGPLv2+
   4 */
   5
   6 using Gtk;
   7
   8 namespace Prolooks {
   9
  10 public class VuMeter : DrawingArea {
  11
  12     public enum VuMeterMode {
  13         VU_STANDARD,
  14         VU_MONOCHROME,
  15         VU_MONOCHROME_REVERSE
  16     }
  17     private Cairo.Surface? cache_surface = null;
  18     private VuMeterMode _mode = VuMeterMode.VU_STANDARD;
  19     private double _value = 0.5;
  20
  21     public double value {
  22         set {
  23             if (Math.fabs(_value - value) >= 0.0001)
  24                 queue_draw();
  25             _value = value;
  26         }
  27         get {
  28             return _value;
  29         }
  30     }
  31     public VuMeterMode mode {
  32         set {
  33             if (mode != _mode) {
  34                 mode = _mode;
  35                 queue_draw();
  36             }
  37         }
  38         get {
  39             return _mode;
  40         }
  41     }
  42
  43     public VuMeter () {
  44
  45         // Set favored widget size
  46         set_size_request (100, 14);
  47     }
  48
  49     /* Widget is asked to draw itself */
  50     public override bool expose_event (Gdk.EventExpose event) {
  51         int ox = 1, oy = 1;
  52         int sx = allocation.width - 2, sy = allocation.height - 2;
  53
  54         // Create a Cairo context
  55         var cr = Gdk.cairo_create (this.window);
  56
  57         if (cache_surface == null)
  58         {
  59             int x;
  60             // looks like its either first call or the widget has been resized.
  61             // create the cache_surface.
  62             cache_surface = new Cairo.Surface.similar (cr.get_target(),
  63                                                        Cairo.Content.COLOR,
  64                                                        allocation.width,
  65                                                        allocation.height );
  66
  67             // And render the meterstuff again.
  68
  69             Cairo.Context cache_cr = new Cairo.Context ( cache_surface );
  70             cache_cr.set_source_rgba (0, 0, 0, 0);
  71             cache_cr.rectangle (ox, oy, sx, sy);
  72             cache_cr.fill ();
  73             cache_cr.set_line_width (1);
  74
  75             for (x = ox; x <= ox + sx; x += 3)
  76             {
  77                 double ts = (x - ox) * 1.0 / sx;
  78                 double r = 0, g = 0, b = 0;
  79                 switch(mode)
  80                 {
  81                     case VuMeterMode.VU_STANDARD:
  82                     default:
  83                         if (ts < 0.75) {
  84                             r = ts / 0.75;
  85                             g = 1;
  86                             b = 0;
  87                         }
  88                         else {
  89                             r = 1;
  90                             g = 1 - (ts - 0.75) / 0.25;
  91                             b = 0;
  92                         }
  93                         break;
  94                     case VuMeterMode.VU_MONOCHROME_REVERSE:
  95                         r = 1;
  96                         g = 1;
  97                         b = 0;
  98                         break;
  99                     case VuMeterMode.VU_MONOCHROME:
 100                         r = 1;
 101                         g = 1;
 102                         b = 0;
 103                         break;
 104                 }
 105                 cache_cr.set_source_rgb(r, g, b);
 106                 cache_cr.move_to (x, oy);
 107                 cache_cr.line_to (x, oy + sy + 1);
 108                 cache_cr.move_to (x, oy + sy);
 109                 cache_cr.line_to (x, oy );
 110                 cache_cr.stroke  ();
 111             }
 112         }
 113
 114         // Set clipping area in order to avoid unnecessary drawing
 115         cr.rectangle (event.area.x, event.area.y,
 116                       event.area.width, event.area.height);
 117         cr.clip ();
 118
 119         cr.set_source_surface (cache_surface, 0, 0);
 120         cr.paint ();
 121         cr.set_source_rgba (0, 0, 0, 0.5);
 122
 123         if( mode == VuMeterMode.VU_MONOCHROME_REVERSE )
 124             cr.rectangle (ox, oy, _value * (sx - ox) + 1, sy - oy + 1);
 125         else
 126             cr.rectangle (ox + _value * (sx - ox), oy, sx - ox + 1, sy - oy + 1);
 127
 128         cr.fill ();
 129
 130         return false;
 131     }
 132 }
 133
 134 } // namespace Prolooks