src/Topography/ShapeRenderer.hpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #ifndef SHAPE_RENDERER_HPP
  25 #define SHAPE_RENDERER_HPP
  26
  27 #include "Screen/Pen.hpp"
  28 #include "Screen/Point.hpp"
  29 #include "Util/NonCopyable.hpp"
  30 #include "Util/AllocatedArray.hpp"
  31 #include "Screen/Canvas.hpp"
  32 #include "Screen/Brush.hpp"
  33
  34 #include <assert.h>
  35
  36 /**
  37  * A helper class optimized for doing bulk draws on OpenGL.
  38  */
  39 class ShapeRenderer : private NonCopyable {
  40   AllocatedArray<RasterPoint> points;
  41   unsigned num_points;
  42
  43   const Pen *pen;
  44   const Brush *brush;
  45
  46   enum { NONE, OUTLINE, SOLID } mode;
  47
  48 public:
  49   void Configure(const Pen *_pen, const Brush *_brush) {
  50     pen = _pen;
  51     brush = _brush;
  52     mode = NONE;
  53
  54     num_points = 0;
  55   }
  56
  57   void Begin(unsigned n) {
  58     assert(num_points == 0);
  59
  60     points.GrowDiscard(((n - 1) | 0x3ff) + 1);
  61   }
  62
  63   void AddPoint(RasterPoint pt) {
  64     assert(num_points < points.size());
  65
  66     points[num_points++] = pt;
  67   }
  68
  69   /**
  70    * Adds the point only if it a few pixels distant from the previous
  71    * one.  Useful to reduce the complexity of small figures.
  72    */
  73    void AddPointIfDistant(RasterPoint pt) {
  74     assert(num_points < points.size());
  75
  76     if (num_points == 0 || manhattan_distance(points[num_points - 1], pt) >= 8)
  77       AddPoint(pt);
  78   }
  79
  80   void FinishPolyline(Canvas &canvas) {
  81     if (mode != OUTLINE) {
  82       canvas.Select(*pen);
  83       mode = OUTLINE;
  84     }
  85
  86     canvas.DrawPolyline(points.begin(), num_points);
  87
  88     num_points = 0;
  89   }
  90
  91   void FinishPolygon(Canvas &canvas) {
  92     if (mode != SOLID) {
  93       canvas.SelectNullPen();
  94       canvas.Select(*brush);
  95       mode = SOLID;
  96     }
  97
  98     canvas.DrawPolygon(points.begin(), num_points);
  99
 100     num_points = 0;
 101   }
 102
 103   void Commit() {
 104     assert(num_points == 0);
 105   }
 106 };
 107
 108 #endif