mirror of
https://github.com/Laex/Delphi-OpenCV.git
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197 lines
8.0 KiB
ObjectPascal
197 lines
8.0 KiB
ObjectPascal
unit sdlticks;
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{
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$Id: sdlticks.pas,v 1.2 2006/11/08 08:22:48 savage Exp $
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}
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{******************************************************************************}
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{ }
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{ JEDI-SDL : Pascal units for SDL - Simple DirectMedia Layer }
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{ SDL GetTicks Class Wrapper }
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{ }
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{ }
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{ The initial developer of this Pascal code was : }
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{ Dominique Louis <Dominique@SavageSoftware.com.au> }
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{ }
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{ Portions created by Dominique Louis are }
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{ Copyright (C) 2004 - 2100 Dominique Louis. }
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{ }
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{ }
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{ Contributor(s) }
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{ -------------- }
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{ Dominique Louis <Dominique@SavageSoftware.com.au> }
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{ }
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{ Obtained through: }
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{ Joint Endeavour of Delphi Innovators ( Project JEDI ) }
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{ }
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{ You may retrieve the latest version of this file at the Project }
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{ JEDI home page, located at http://delphi-jedi.org }
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{ }
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{ The contents of this file are used with permission, subject to }
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{ the Mozilla Public License Version 1.1 (the "License"); you may }
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{ not use this file except in compliance with the License. You may }
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{ obtain a copy of the License at }
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{ http://www.mozilla.org/MPL/MPL-1.1.html }
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{ }
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{ Software distributed under the License is distributed on an }
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{ "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or }
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{ implied. See the License for the specific language governing }
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{ rights and limitations under the License. }
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{ }
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{ Description }
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{ ----------- }
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{ SDL Window Wrapper }
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{ }
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{ }
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{ Requires }
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{ -------- }
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{ SDL.dll on Windows platforms }
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{ libSDL-1.1.so.0 on Linux platform }
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{ }
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{ Programming Notes }
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{ ----------------- }
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{ }
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{ }
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{ }
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{ }
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{ Revision History }
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{ ---------------- }
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{ }
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{ September 23 2004 - DL : Initial Creation }
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{
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$Log: sdlticks.pas,v $
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Revision 1.2 2006/11/08 08:22:48 savage
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updates tp sdlgameinterface and sdlticks functions.
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Revision 1.1 2004/09/30 22:35:47 savage
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Changes, enhancements and additions as required to get SoAoS working.
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}
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{******************************************************************************}
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interface
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uses
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sdl;
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type
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TSDLTicks = class
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private
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FStartTime : UInt32;
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FTicksPerSecond : UInt32;
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FElapsedLastTime : UInt32;
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FFPSLastTime : UInt32;
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FLockFPSLastTime : UInt32;
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public
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constructor Create;
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destructor Destroy; override; // destructor
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{*****************************************************************************
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Init
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If the hi-res timer is present, the tick rate is stored and the function
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returns true. Otherwise, the function returns false, and the timer should
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not be used.
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*****************************************************************************}
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function Init : boolean;
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{***************************************************************************
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GetGetElapsedSeconds
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Returns the Elapsed time, since the function was last called.
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***************************************************************************}
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function GetElapsedSeconds : Single;
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{***************************************************************************
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GetFPS
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Returns the average frames per second.
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If this is not called every frame, the client should track the number
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of frames itself, and reset the value after this is called.
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***************************************************************************}
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function GetFPS : single;
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{***************************************************************************
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LockFPS
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Used to lock the frame rate to a set amount. This will block until enough
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time has passed to ensure that the fps won't go over the requested amount.
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Note that this can only keep the fps from going above the specified level;
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it can still drop below it. It is assumed that if used, this function will
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be called every frame. The value returned is the instantaneous fps, which
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will be less than or equal to the targetFPS.
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***************************************************************************}
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procedure LockFPS( targetFPS : Byte );
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end;
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implementation
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{ TSDLTicks }
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constructor TSDLTicks.Create;
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begin
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inherited;
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FTicksPerSecond := 1000;
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end;
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destructor TSDLTicks.Destroy;
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begin
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inherited;
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end;
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function TSDLTicks.GetElapsedSeconds : Single;
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var
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currentTime : Cardinal;
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begin
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currentTime := SDL_GetTicks;
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result := ( currentTime - FElapsedLastTime ) / FTicksPerSecond;
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// reset the timer
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FElapsedLastTime := currentTime;
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end;
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function TSDLTicks.GetFPS : Single;
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var
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currentTime, FrameTime : UInt32;
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fps : single;
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begin
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currentTime := SDL_GetTicks;
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FrameTime := ( currentTime - FFPSLastTime );
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if FrameTime = 0 then
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FrameTime := 1;
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fps := FTicksPerSecond / FrameTime;
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// reset the timer
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FFPSLastTime := currentTime;
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result := fps;
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end;
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function TSDLTicks.Init : boolean;
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begin
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FStartTime := SDL_GetTicks;
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FElapsedLastTime := FStartTime;
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FFPSLastTime := FStartTime;
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FLockFPSLastTime := FStartTime;
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result := true;
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end;
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procedure TSDLTicks.LockFPS( targetFPS : Byte );
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var
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currentTime : UInt32;
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targetTime : single;
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begin
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if ( targetFPS = 0 ) then
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targetFPS := 1;
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targetTime := FTicksPerSecond / targetFPS;
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// delay to maintain a constant frame rate
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repeat
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currentTime := SDL_GetTicks;
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until ( ( currentTime - FLockFPSLastTime ) > targetTime );
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// reset the timer
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FLockFPSLastTime := currentTime;
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end;
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end.
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