{

public:

// call when done with ISystem to clean up any memory allocation

virtual void Shutdown() = 0;

// called every frame

virtual void RunFrame() = 0;

// use this with the "open" command to launch web browsers/explorer windows, eg. ShellExecute("open", "www.valvesoftware.com")

virtual void ShellExecute(const char *command, const char *file) = 0;

// returns the time at the start of the frame, in seconds

virtual double GetFrameTime() = 0;

// returns the current time, in seconds

virtual double GetCurrentTime() = 0;

// returns the current time, in milliseconds

virtual long GetTimeMillis() = 0;

// clipboard access

virtual int GetClipboardTextCount() = 0;

virtual void SetClipboardText(const char *text, int textLen) = 0;

virtual void SetClipboardText(const wchar_t *text, int textLen) = 0;

virtual int GetClipboardText(int offset, char *buf, int bufLen) = 0;

virtual int GetClipboardText(int offset, wchar_t *buf, int bufLen) = 0;

// windows registry

virtual bool SetRegistryString(const char *key, const char *value) = 0;

virtual bool GetRegistryString(const char *key, char *value, int valueLen) = 0;

virtual bool SetRegistryInteger(const char *key, int value) = 0;

virtual bool GetRegistryInteger(const char *key, int &value) = 0;

// user config

virtual KeyValues *GetUserConfigFileData(const char *dialogName, int dialogID) = 0;

// sets the name of the config file to save/restore from. Settings are loaded immediately.

virtual void SetUserConfigFile(const char *fileName, const char *pathName) = 0;

// saves all the current settings to the user config file

virtual void SaveUserConfigFile() = 0;

// sets the watch on global computer use

// returns true if supported

virtual bool SetWatchForComputerUse(bool state) = 0;

// returns the time, in seconds, since the last computer use.

virtual double GetTimeSinceLastUse() = 0;

// Get a string containing the available drives

// If the function succeeds, the return value is the length, in characters,

// of the strings copied to the buffer,

// not including the terminating null character.

virtual int GetAvailableDrives(char *buf, int bufLen) = 0;

// exe command line options accessors

// returns whether or not the parameter was on the command line

virtual bool CommandLineParamExists(const char *paramName) = 0;

// returns the full command line, including the exe name

virtual const char *GetFullCommandLine() = 0;

// Convert a windows virtual key code to a VGUI key code.

virtual KeyCode KeyCode_VirtualKeyToVGUI( int keyCode ) = 0;

// returns the current local time and date

// fills in every field that a pointer is given to it for

virtual bool GetCurrentTimeAndDate(int *year, int *month, int *dayOfWeek, int *day, int *hour, int *minute, int *second) = 0;

// returns the amount of available disk space, in bytes, on the drive

// path can be any path, drive letter is stripped out

virtual double GetFreeDiskSpace(const char *path) = 0;

// shortcut (.lnk) modification functions

virtual bool CreateShortcut(const char *linkFileName, const char *targetPath, const char *arguments, const char *workingDirectory, const char *iconFile) = 0;

virtual bool GetShortcutTarget(const char *linkFileName, char *targetPath, char *arguments, int destBufferSizes) = 0;

virtual bool ModifyShortcutTarget(const char *linkFileName, const char *targetPath, const char *arguments, const char *workingDirectory) = 0;

// gets the string following a command line param

//!! move this function up on changing interface version number

virtual bool GetCommandLineParamValue(const char *paramName, char *value, int valueBufferSize) = 0;

// recursively deletes a registry key and all it's subkeys

//!! move this function next to other registry function on changing interface version number

virtual bool DeleteRegistryKey(const char *keyName) = 0;

virtual const char *GetDesktopFolderPath() = 0;

// use this with the "open" command to launch web browsers/explorer windows, eg. ShellExecute("open", "www.valvesoftware.com")

virtual void ShellExecuteEx( const char *command, const char *file, const char *pParams ) = 0;

// Copy a portion of the application client area to the clipboard

// (x1,y1) specifies the top-left corner of the client rect to copy

// (x2,y2) specifies the bottom-right corner of the client rect to copy

// Requires: x2 > x1 && y2 > y1

// Dimensions of the copied rectangle are (x2 - x1) x (y2 - y1)

// Pixel at (x1,y1) is copied, pixels at column x2 and row y2 are *not* copied

virtual void SetClipboardImage( void *pWnd, int x1, int y1, int x2, int y2 ) = 0;