src/driver.h

   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 driver.h Base for all drivers (video, sound, music, etc). */
   9
  10 #ifndef DRIVER_H
  11 #define DRIVER_H
  12
  13 #include "core/enum_type.hpp"
  14 #include "core/string_compare_type.hpp"
  15 #include <map>
  16
  17 const char *GetDriverParam(const char * const *parm, const char *name);
  18 bool GetDriverParamBool(const char * const *parm, const char *name);
  19 int GetDriverParamInt(const char * const *parm, const char *name, int def);
  20
  21 /** A driver for communicating with the user. */
  22 class Driver {
  23 public:
  24         /**
  25          * Start this driver.
  26          * @param parm Parameters passed to the driver.
  27          * @return nullptr if everything went okay, otherwise an error message.
  28          */
  29         virtual const char *Start(const char * const *parm) = 0;
  30
  31         /**
  32          * Stop this driver.
  33          */
  34         virtual void Stop() = 0;
  35
  36         virtual ~Driver() { }
  37
  38         /** The type of driver */
  39         enum Type {
  40                 DT_BEGIN = 0, ///< Helper for iteration
  41                 DT_MUSIC = 0, ///< A music driver, needs to be before sound to properly shut down extmidi forked music players
  42                 DT_SOUND,     ///< A sound driver
  43                 DT_VIDEO,     ///< A video driver
  44                 DT_END,       ///< Helper for iteration
  45         };
  46
  47         /**
  48          * Get the name of this driver.
  49          * @return The name of the driver.
  50          */
  51         virtual const char *GetName() const = 0;
  52 };
  53
  54 DECLARE_POSTFIX_INCREMENT(Driver::Type)
  55
  56
  57 /** Base for all driver factories. */
  58 class DriverFactoryBase {
  59 private:
  60         friend class MusicDriver;
  61         friend class SoundDriver;
  62         friend class VideoDriver;
  63
  64         Driver::Type type;       ///< The type of driver.
  65         int priority;            ///< The priority of this factory.
  66         const char *name;        ///< The name of the drivers of this factory.
  67         const char *description; ///< The description of this driver.
  68
  69         typedef std::map<const char *, DriverFactoryBase *, StringCompare> Drivers; ///< Type for a map of drivers.
  70
  71         /**
  72          * Get the map with drivers.
  73          */
  74         static Drivers &GetDrivers()
  75         {
  76                 static Drivers &s_drivers = *new Drivers();
  77                 return s_drivers;
  78         }
  79
  80         /**
  81          * Get the active driver for the given type.
  82          * @param type The type to get the driver for.
  83          * @return The active driver.
  84          */
  85         static Driver **GetActiveDriver(Driver::Type type)
  86         {
  87                 static Driver *s_driver[3] = { nullptr, nullptr, nullptr };
  88                 return &s_driver[type];
  89         }
  90
  91         /**
  92          * Get the driver type name.
  93          * @param type The type of driver to get the name of.
  94          * @return The name of the type.
  95          */
  96         static const char *GetDriverTypeName(Driver::Type type)
  97         {
  98                 static const char * const driver_type_name[] = { "music", "sound", "video" };
  99                 return driver_type_name[type];
 100         }
 101
 102         static bool SelectDriverImpl(const char *name, Driver::Type type);
 103
 104 protected:
 105         DriverFactoryBase(Driver::Type type, int priority, const char *name, const char *description);
 106
 107         virtual ~DriverFactoryBase();
 108
 109 public:
 110         /**
 111          * Shuts down all active drivers
 112          */
 113         static void ShutdownDrivers()
 114         {
 115                 for (Driver::Type dt = Driver::DT_BEGIN; dt < Driver::DT_END; dt++) {
 116                         Driver *driver = *GetActiveDriver(dt);
 117                         if (driver != nullptr) driver->Stop();
 118                 }
 119         }
 120
 121         static void SelectDriver(const char *name, Driver::Type type);
 122         static char *GetDriversInfo(char *p, const char *last);
 123
 124         /**
 125          * Get a nice description of the driver-class.
 126          * @return The description.
 127          */
 128         const char *GetDescription() const
 129         {
 130                 return this->description;
 131         }
 132
 133         /**
 134          * Create an instance of this driver-class.
 135          * @return The instance.
 136          */
 137         virtual Driver *CreateInstance() const = 0;
 138 };
 139
 140 #endif /* DRIVER_H */