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81 lines
2.0 KiB
ObjectPascal
81 lines
2.0 KiB
ObjectPascal
unit BaseContentProvider;
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{$mode objfpc}{$H+}
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interface
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uses
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Classes, SysUtils, Controls;
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type
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{ TBaseContentProvider }
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TBaseContentProviderClass = Class of TBaseContentProvider;
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TBaseContentProvider = class(TObject)
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private
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fParent: TWinControl;
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public
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function CanGoBack: Boolean; virtual; abstract;
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function CanGoForward: Boolean; virtual; abstract;
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function GetHistory: TStrings; virtual; abstract;
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function LoadURL(const AURL: String; const AContext: THelpContext=-1): Boolean; virtual; abstract;
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procedure GoHome; virtual; abstract;
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procedure GoBack; virtual; abstract;
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procedure GoForward; virtual; abstract;
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class function GetProperContentProvider(const AURL: String): TBaseContentProviderClass; virtual; abstract;
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constructor Create(AParent: TWinControl); virtual;
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property Parent: TWinControl read fParent;
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end;
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// returns false if the protocol has already been registered
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function RegisterContentProvider(const Protocol: String; ContentProvider: TBaseContentProviderClass): Boolean;
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// example: RegisterContentProvider('chm://', TChmContentProvider);
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function GetContentProvider(const Protocol: String): TBaseContentProviderClass;
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implementation
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var
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ContentProviders: TStringList;
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function RegisterContentProvider(const Protocol: String;
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ContentProvider: TBaseContentProviderClass): Boolean;
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begin
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Result := False;
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if ContentProviders.IndexOf(Protocol) > -1 then exit;
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ContentProviders.AddObject(Protocol, TObject(ContentProvider));
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end;
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function GetContentProvider(const Protocol: String): TBaseContentProviderClass;
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var
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fIndex: Integer;
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begin
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Result := nil;
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fIndex := ContentProviders.IndexOf(Protocol);
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if fIndex = -1 then Exit;
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Result := TBaseContentProviderClass(ContentProviders.Objects[fIndex]);
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end;
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{ TBaseContentProvider }
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constructor TBaseContentProvider.Create(AParent: TWinControl);
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begin
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fParent:= AParent;
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end;
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initialization
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ContentProviders := TStringList.Create;
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finalization
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ContentProviders.Free;
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end.
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