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{
plugins.pas
Controls the plugins
Copyright (C) 1998 - 2007 Harri Pyy, Chris O'Donnell, Felipe Monteiro de Carvalho
This file is part of Virtual Magnifying Glass.
Virtual Magnifying Glass is free software;
you can redistribute it and/or modify it under the
terms of the GNU General Public License version 2
as published by the Free Software Foundation.
Virtual Magnifying Glass 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. See the GNU General Public License for more details.
Please note that the General Public License version 2 does not permit
incorporating Virtual Magnifying Glass into proprietary
programs.
AUTHORS: Chris O'Donnell, Felipe Monteiro de Carvalho and Harri Pyy
}
unit plugins;
{$IFDEF FPC}
{$MODE DELPHI}{$H+}
{$ENDIF}
{$IFDEF Win32}
{$DEFINE Windows}
{$ENDIF}
interface
uses
{$IFDEF FPC}
dynlibs, lcltype,
{$ELSE}
Windows,
{$ENDIF}
Classes, SysUtils, Forms, Dialogs, constants, plugininfo;
type
TFunc_Initialize = function (vPluginData: TPluginData): Cardinal; cdecl;
TFunc_Finalize = procedure; cdecl;
TFunc_HandlePluginMessage = procedure(AMessage: Cardinal); cdecl;
{ TPlugins }
TPlugins = class(TObject)
private
Handle: THandle;
vInitialize: TFunc_Initialize;
vFinalize: TFunc_Finalize;
vHandlePluginMessage: TFunc_HandlePluginMessage;
public
Loaded: Boolean;
Initialized: Boolean;
{ Methods }
procedure LoadPlugin;
procedure UnloadPlugin;
function Initialize: Cardinal;
procedure Finalize;
procedure HandlePluginMessage(AMessage: Cardinal);
end;
var
vPlugins: TPlugins;
implementation
uses glass, appsettings;
{ TPlugins }
{*******************************************************************
* TPlugins.LoadPlugin ()
*
* DESCRIPTION: Loads a plugin.
*
* PARAMETERS: AName - The name of the library of the plugin to be loaded
*
* RETURNS: Nothing
*
*******************************************************************}
procedure TPlugins.LoadPlugin;
begin
{$IFDEF FPC}
Handle := LoadLibrary(vConfigurations.PluginName);
{$ELSE}
Handle := LoadLibrary(PChar(vConfigurations.PluginName));
{$ENDIF}
if Handle = 0 then
begin
Application.MessageBox(lpCannotLoadPlugin, lpPluginError, MB_OK);
Exit;
end;
{$IFDEF FPC}
vInitialize := GetProcedureAddress(Handle, 'Initialize');
vFinalize := GetProcedureAddress(Handle, 'Finalize');
vHandlePluginMessage := GetProcedureAddress(Handle, 'HandlePluginMessage');
{$ELSE}
vInitialize := GetProcAddress(Handle, 'Initialize');
vFinalize := GetProcAddress(Handle, 'Finalize');
vHandlePluginMessage := GetProcAddress(Handle, 'HandlePluginMessage');
{$ENDIF}
Loaded := True;
end;
{*******************************************************************
* TPlugins.UnloadPlugin ()
*
* DESCRIPTION: Unloads the currently loaded plugin.
*
* PARAMETERS: None
*
* RETURNS: Nothing
*
*******************************************************************}
procedure TPlugins.UnloadPlugin;
begin
{$IFDEF FPC}
UnloadLibrary(Handle);
{$ELSE}
FreeLibrary(Handle);
{$ENDIF}
Handle := 0;
Loaded := False;
end;
{*******************************************************************
* TPlugins.Initialize ()
*
* DESCRIPTION: Initializes the plugin.
*
* PARAMETERS: None
*
* RETURNS: Nothing
*
*******************************************************************}
function TPlugins.Initialize: Cardinal;
var
vPluginData: TPluginData;
begin
Initialized := False;
Result := VMG_ERROR;
if (Handle = 0) then Exit;
{ System Information }
vPluginData.DesktopPos.Left := vGlass.XScreen;
vPluginData.DesktopPos.Top := vGlass.YScreen;
vPluginData.DesktopPos.Right := vGlass.XScreen + vGlass.CXScreen;
vPluginData.DesktopPos.Bottom := vGlass.YScreen + vGlass.CYScreen;
vPluginData.Application := @Application;
{ Glass information }
vPluginData.Magnification := @vConfigurations.iMagnification;
vPluginData.GlassTop := @vGlass.GlassTop;
vPluginData.GlassLeft := @vGlass.GlassLeft;
vPluginData.GlassWidth := @vGlass.GlassWidth;
vPluginData.GlassHeight := @vGlass.GlassHeight;
vPluginData.PluginData := vConfigurations.PluginData;
{ Callbacks for utility function in the main application }
vPluginData.CalculateViewRectFunc := vGlass.CalculateViewRect;
Result := vInitialize(vPluginData);
Initialized := True;
end;
{*******************************************************************
* TPlugins.Finalize ()
*
* DESCRIPTION: Finalizes the plugin.
*
* PARAMETERS: None
*
* RETURNS: Nothing
*
*******************************************************************}
procedure TPlugins.Finalize;
begin
if Handle <> 0 then vFinalize();
Initialized := False;
end;
procedure TPlugins.HandlePluginMessage(AMessage: Cardinal);
begin
if not Initialized then Exit;
vHandlePluginMessage(AMessage);
end;
initialization
vPlugins := TPlugins.Create;
finalization
if vPlugins.Initialized then vPlugins.Finalize;
if vPlugins.Loaded then vPlugins.UnloadPlugin;
FreeAndNil(vPlugins);
end.
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