Google PageRank components for Delphi (GPRD) - v1.5.0 (Freeware!)

Introduction

Yes! Now Delphi developers can embed Google PageRank retrieving functionality into own applications. This components allows you to easily retrieve Google's PageRank value and also show it by manner similar to Google Toolbar.

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Requirements

• Borland Delphi 5,6,7,2005(Win32),2006(Win32).

Installation

Unzip the PRFREE.ZIP file with preserving folders structure. Start Delphi IDE and open package file ("Delphi ?\pagerank_d?.dpk", where "?" your Delphi version). Click on "Compile" and then on "Install" buttons. Delphi should report you that two new components has been installed: TPageRank and TPageRankControl. This components you can find on the "Internet" page of components palette.

Overview

The module named PageRank(pagerank.pas) contain two classes and two function. You can use non-visual component TPageRank to retrieve the PR value and the TPageRankControl to show this value. Also you can use GetURLQuery function to make PageRank value retrieving query and the StrToPageRank function to convert receiving document to PR value.

TPageRank

TPageRank component declaration:

type
  TOnGetRank = function (const Page: string; var Rank: string): Boolean of object;
  TPageRank = class(TComponent)
  public
    property Control: TControl read FControl write FControl;
    procedure UpdatePageRank;
    function IsExecuted: Boolean;
  published
    property Rank: Integer read GetFRank;
    property Page: string read FPage write SetFPage;
    property Auto: Boolean read FAuto write FAuto;
    property NonBlock: Boolean read FNonBlock write FNonBlock;
    property OnGetRank: TOnGetRank read FOnGetRank write FOnGetRank;
  end;

Properties and methods description:

public

property Control: TControl;

 — link to visual component, that should refresh when the Pagerank value is changed. The Invalidate method of this component is called when Pagerank value is changed.

procedure UpdatePageRank;

 — call this method to update Pagerank value manually.

function IsExecuted: Boolean;

 — indicate that the Pagerank value retrieving process in progress.

published

property Rank: Integer;

 — Pagerank value. Note, that actual pagerank value is contained only in low byte, i.e. you should make Rank and 255 to get real Pagerank value.

property Page: string;

 — URL to page whose pagerank value want to retrieve.

property Auto: Boolean;

 — auto-retrieve pagerank value - the UpdatePageRank method called is currently Rank value is empty.

property NonBlock: Boolean;

 — execute pagerank retrieving process in separate thread.

property OldVersion: Boolean;

 — Use old Google Toolbar (prior to 2.0.114) queries algorithm.

property OnGetRank: TOnGetRank;

 — this event occur when need send request to Google servers. The input parameter Pagecontain the URL for this request. The event handler should return received document in Rank parameter and result TRUE when success or FALSE when fail. See below for sample of implementation of this event handler.

Although GPRD intended to work with internet, it's not contain any networking code. Such decision is selected because of every developer has own solutions and use different methods for access to net. All networking code should be provided by developer as handler of OnGetRank event.

The simplest example of implementation of OnGetRank event handler provided in the code below. In the demo project, shipped with components you can see another implementation of this event handler.

uses
  ActiveX, URLMon;

function TForm1.OnGetRank(const URL: string; var Rank: string): Boolean;
var
  I: Integer;
  Stream: IStream;
begin
  Result := FALSE;
  if URLOpenBlockingStream(nil, PChar(URL), Stream, 0, nil) = S_OK then begin
    SetLength(Rank, 32);
    if Stream.Read(PChar(Rank), 32, @I) = S_OK then begin
      SetLength(Rank, I);
      Result := TRUE
    end;
  end;
end;

TPageRankControl

TPageRankControl is visual component intended to show the pagerank value as colored bar like one on the Google toolbar and as optional text. The TPageRankControl declaration:

type
  TPageRankControl = class(TGraphicControl)
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    property PageRank: TPageRank read FPageRank write SetFPageRank;
    property BorderColor: TColor read FBorderColor write SetFBorderColor default clGray;
    property FillerColor: TColor read FFillerColor write SetFFillerColor default clGreen;
    property FilledColor: TColor read FFilledColor write SetFFilledColor default clWhite;
    property ShowText: Boolean read FShowText write SetFShowText default TRUE;
    property BarWidth: Integer read FBarWidth write SetFBarWidth default 7;
    property Align;
    property Anchors;
    property Color;
    property Font;
    property Hint;
    property ParentColor;
    property ParentFont;
    property ParentShowHint;
    property ShowHint;
    property PopupMenu;
    property Visible;
    property OnClick;
    property OnDblClick;
    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnContextPopup;
  end;

published

property PageRank: TPageRank;

 — TPageRank control used to get the PR value.

property BorderColor: TColor;

 — color of pagerank bar border.

property FillerColor: TColor;

 — color of empty part of pagerank bar.

property FilledColor: TColor;

 — color of empty part of pagerank bar.

property ShowText: Boolean;

 — show text with pagerank value above pagerank bar.

property BarWidth: Integer;

 — thickness of pagerank bar in pixels.

Other properties is simply inherited from TControl and moved to published section for more conveniences.

Functions

If you don't want to use any components, you can use those two functions to retrieve pagerank value. The first function, GetURLQuery make query string for specified page. For example, for http://www.irnis.net/ it will return http://toolbarqueries.google.com/search?client=navclient-auto&ch=62887370433&ie=UTF-8&features=Rank&q=info:http://www.irnis.net/. The next, StrToPageRank help to extract the pagerank value from recieved content.

  

function GetURLQuery(const URL: string): string;

function StrToPageRank(const S: string): Integer;

The simple example of using those function for retrieveng pagerank value:

uses
  ActiveX, URLMon;

function GetRank(const URL: string): Integer;
var
  S: string;
  I: Integer;
  Stream: IStream;
begin
  Result := -1;
  S := GetURLQuery(URL);
  if URLOpenBlockingStream(nil, PChar(S), Stream, 0, nil) = S_OK then begin
    SetLength(S, 32);
    if Stream.Read(PChar(S), 32, @I) = S_OK then begin
      SetLength(S, I);
      Result := StrToPageRank(S) and 255
    end;
  end;
end;

Changes history

Licenses

All copyrights to Google PageRank for Delphi are exclusively owned by the author - Irnis Haliullin.

More details see in License.txt, shipped with components.

Contact

If you have any questions or suggestions about Google PageRank for Delphi, please contact by mail to irnis@irnis.net.