Webbrowser/es

This page summarizes various ways to display HTML pages from a Pascal program, ranging from calling an external browser to adding a component capable of rendering the html page into a form.

Starting a webbrowser to show a page/URL

Finding the default webbrowser

Every platform has a mechanism for its default platform. The LCL unit lazhelphtml contains a class THTMLBrowserHelpViewer to start a web browser for the LCL help system. You can use its method FindDefaultBrowser to find the default browser and the parameter to start. For example:

uses 
  Classes, ..., LCLProc, LazHelpHTML;

...

implementation

procedure TMainForm.Button1Click(Sender: TObject);
var
  v: THTMLBrowserHelpViewer;
  BrowserPath, BrowserParams: string;
begin
  v:=THTMLBrowserHelpViewer.Create(nil);
  v.FindDefaultBrowser(BrowserPath,BrowserParams);
  debugln(['Path=',BrowserPath,' Params=',BrowserParams]);
  v.Free;
end;

This gives for example under Ubuntu (Linux):

Browser=/usr/bin/xdg-open Params=%s

Under Windows you can get:

Browser=C:\windows\system32\rundll32.exe Params=url.dll,FileProtocolHandler %s

Starting the browser

Once you know the command line and parameters you can use TProcessUTF8 to start the browser:

uses 
  Classes, ..., LCLProc, LazHelpHTML, UTF8Process;

...

implementation

procedure TMainForm.Button1Click(Sender: TObject);
var
  v: THTMLBrowserHelpViewer;
  BrowserPath, BrowserParams: string;
  p: LongInt;
  URL: String;
  BrowserProcess: TProcessUTF8;
begin
  v:=THTMLBrowserHelpViewer.Create(nil);
  try
    v.FindDefaultBrowser(BrowserPath,BrowserParams);
    debugln(['Path=',BrowserPath,' Params=',BrowserParams]);

    URL:='http://www.lazarus.freepascal.org';
    p:=System.Pos('%s', BrowserParams);
    System.Delete(BrowserParams,p,2);
    System.Insert(URL,BrowserParams,p);

    // start browser
    BrowserProcess:=TProcessUTF8.Create(nil);
    try
      BrowserProcess.CommandLine:=BrowserPath+' '+BrowserParams;
      BrowserProcess.Execute;
    finally
      BrowserProcess.Free;
    end;
  finally
    v.Free;
  end;
end;

There is a much simpler way of opening URLs in general, the OpenURL function from the LCLIntf unit. Can be used for mail address of the form 'mailto:aname@AnAddress?subject=:::A subject line', web addresses 'http://' and files 'file:///'.

Using the turbopower internet pro control

Lazarus provides the package TurboPowerIPro (lazarus/components/turbopower_ipro/turbopoweripro.lpk) with the following features:

• It contains a control to put onto a form. When you install the package in the IDE, you get some new components in the palette, so you can drop them onto a form just like any LCL control.
• It is written completely in pascal and therefore works on all platforms out of the box without any extra installation.
• You have the full control, what files/urls are opened.
• It does not have all the features of a full webbrowser. No multimedia stuff, javascript or flash. This must be implemented by you.

There are some examples in lazarus/components/turbopower_ipro/examples demonstrating how to open a local html file with some images, hyperlinks and history buttons.

QT Webkit

When using the Qt WidgetSet, you can use the Qt WebKit to embed a browser into a LCL form.

Lazarus LCL/Qt WebKit Demo available on FPC Qt4 Binding Web Page

THtmlPort

THtmlPort is a Lazarus/Free Pascal version of Dave Baldwin's HTML Components, including THtmlViewer, TFrameViewer and TFrameBrowser.

THtmlPort wiki page

GeckoPort

GeckoPort is a Lazarus/Free Pascal version of Takanori Ito's Gecko SDK for Delphi, including the TGeckoBrowser component.

GeckoPort wiki page