src/slider.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file slider.cpp Implementation of the horizontal slider widget. */
   9
  10 #include "stdafx.h"
  11 #include "gfx_func.h"
  12 #include "palette_func.h"
  13 #include "slider_func.h"
  14 #include "strings_func.h"
  15 #include "window_gui.h"
  16 #include "zoom_func.h"
  17
  18 #include "safeguards.h"
  19
  20 static const int SLIDER_WIDTH = 3;
  21
  22 /**
  23  * Draw a slider widget with knob at given value
  24  * @param r Rectangle to draw the widget in
  25  * @param min_value Minimum value of slider
  26  * @param max_value Maximum value of slider
  27  * @param nmarks Number of marks to display (when mark_func is provided.)
  28  * @param value Value to put the slider at
  29  * @param mark_func Callback function to get the StringID to draw on a mark.
  30  */
  31 void DrawSliderWidget(Rect r, int min_value, int max_value, int nmarks, int value, SliderMarkFunc *mark_func)
  32 {
  33         /* Allow space for labels. We assume they are in the small font. */
  34         if (mark_func != nullptr) r.bottom -= GetCharacterHeight(FS_SMALL) + WidgetDimensions::scaled.hsep_normal;
  35
  36         max_value -= min_value;
  37
  38         /* Draw a wedge indicating low to high value. */
  39         const int ha = (r.bottom - r.top) / 5;
  40         const int sw = ScaleGUITrad(SLIDER_WIDTH);
  41         const int t = WidgetDimensions::scaled.bevel.top; /* Thickness of lines */
  42         int wx1 = r.left  + sw / 2;
  43         int wx2 = r.right - sw / 2;
  44         if (_current_text_dir == TD_RTL) std::swap(wx1, wx2);
  45         const uint shadow = GetColourGradient(COLOUR_GREY, SHADE_DARK);
  46         const uint fill = GetColourGradient(COLOUR_GREY, SHADE_LIGHTER);
  47         const uint light = GetColourGradient(COLOUR_GREY, SHADE_LIGHTEST);
  48         const std::vector<Point> wedge{ Point{wx1, r.bottom - ha}, Point{wx2, r.top + ha}, Point{wx2, r.bottom - ha} };
  49         GfxFillPolygon(wedge, fill);
  50         GfxDrawLine(wedge[0].x, wedge[0].y, wedge[2].x, wedge[2].y, light, t);
  51         GfxDrawLine(wedge[1].x, wedge[1].y, wedge[2].x, wedge[2].y, _current_text_dir == TD_RTL ? shadow : light, t);
  52         GfxDrawLine(wedge[0].x, wedge[0].y, wedge[1].x, wedge[1].y, shadow, t);
  53
  54         int x;
  55         if (mark_func != nullptr) {
  56                 for (int mark = 0; mark < nmarks; ++mark) {
  57                         const int mark_value = (max_value * mark) / (nmarks - 1);
  58
  59                         const StringID str = mark_func(nmarks, mark, mark_value + min_value);
  60                         if (str == INVALID_STRING_ID) continue;
  61
  62                         x = mark_value;
  63                         if (_current_text_dir == TD_RTL) x = max_value - mark_value;
  64                         x = r.left + (x * (r.right - r.left - sw) / max_value) + sw / 2;
  65                         GfxDrawLine(x, r.bottom - ha + 1, x, r.bottom + (str == STR_NULL ? 0 : WidgetDimensions::scaled.hsep_normal), shadow, t);
  66                         if (str == STR_NULL) continue;
  67
  68                         Dimension d = GetStringBoundingBox(str, FS_SMALL);
  69                         x = Clamp(x - d.width / 2, r.left, r.right - d.width);
  70                         DrawString(x, x + d.width, r.bottom + 1 + WidgetDimensions::scaled.hsep_normal, str, TC_BLACK, SA_CENTER, false, FS_SMALL);
  71                 }
  72         }
  73
  74         /* Draw a slider handle indicating current value. */
  75         value -= min_value;
  76         if (_current_text_dir == TD_RTL) value = max_value - value;
  77         x = r.left + (value * (r.right - r.left - sw) / max_value);
  78         DrawFrameRect(x, r.top, x + sw, r.bottom, COLOUR_GREY, FR_NONE);
  79 }
  80
  81 /**
  82  * Handle click on a slider widget to change the value
  83  * @param r      Rectangle of the widget
  84  * @param pt     Clicked point
  85  * @param min_value Minimum value of slider
  86  * @param max_value Maximum value of slider
  87  * @param nmarks Number of marks displayed. Value will be rounded to nearest mark.
  88  * @param value[in,out] Value to modify
  89  * @return       True if the value setting was modified
  90  */
  91 bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int nmarks, int &value)
  92 {
  93         max_value -= min_value;
  94
  95         const int sw = ScaleGUITrad(SLIDER_WIDTH);
  96         int new_value = Clamp((pt.x - r.left - sw / 2) * max_value / (r.right - r.left - sw), 0, max_value);
  97         if (_current_text_dir == TD_RTL) new_value = max_value - new_value;
  98         new_value += min_value;
  99
 100         if (nmarks > 0) {
 101                 const int step = max_value / (nmarks - 1);
 102                 new_value = ((new_value + step / 2) / step) * step;
 103         }
 104
 105         if (new_value != value) {
 106                 value = new_value;
 107                 return true;
 108         }
 109
 110         return false;
 111 }