Which is the best way to load a string (HTML code) in TWebBrowser?

Question

I have a string var 'HTMLCode' that contains HTML code. I want to load this code into the browser.

This is Embarcadero's code:

procedure THTMLEdit.EditText(CONST HTMLCode: string);
{VAR
   Doc: IHTMLDocument2;
   TempFile: string; }
begin
 TempFile := GetTempFile('.html');  
 StringToFile(TempFile, HTMLCode);
 wbBrowser.Navigate(TempFile);

 Doc := GetDocument;
 if Doc <> NIL
 then Doc.Body.SetAttribute('contentEditable', 'true', 0);  //crash here when I load complex html files

 DeleteFile(TempFile);
end;

It has some problems so I replaced it with this one:

procedure THTMLEdit.EditText(CONST HTMLCode: string);
VAR
   TSL: TStringList;
   MemStream: TMemoryStream;
begin
 wbBrowser.Navigate('about:blank');
 WHILE wbBrowser.ReadyState < READYSTATE_INTERACTIVE
  DO Application.ProcessMessages;

 GetDocument.DesignMode := 'On';

 if Assigned(wbBrowser.Document) then
  begin
    TSL := TStringList.Create;
    TRY
      MemStream := TMemoryStream.Create;
      TRY
        TSL.Text := HTMLCode;
        TSL.SaveToStream(MemStream);
        MemStream.Seek(0, 0);
        (wbBrowser.Document as IPersistStreamInit).Load(TStreamAdapter.Create(MemStream));
      FINALLY
        MemStream.Free;
      end;
    FINALLY
      TSL.Free;
    end;
  end;
end;

But this one has problems also . First, when I insert links (...) into the HTML code, the browser will alter the code, appending 'about:' in front of my URLs. Second: it is slower than the first procedure (the one with temp file).

Can I load HTML code in browser without navigating first to 'about:blank'?

Answer 1

You could load your HTML code as the below

procedure THTMLEdit.EditText(CONST HTMLCode: string);
var
  Doc: Variant;
begin
  if NOT Assigned(wbBrowser.Document) then
    wbBrowser.Navigate('about:blank');

  Doc := wbBrowser.Document;
  Doc.Clear;
  Doc.Write(HTMLCode);
  Doc.Close;
end;

Answer 2

Your Questions:

• First, when I insert links (...) into the HTML code, the browser will alter the code, appending 'about:' in front of my URLs.

• Second: it is slower than the first procedure (the one with temp file).

• Can I load HTML code in browser without navigating first to 'about:blank'?

Answers:

• Yes it's possible without change to the link!
• No, it is not slower!
• Yes, it is possible, no need to Navigate first to about:blank

We start with code and the first procedure (only to show where the about: ... comes from).

{$R *.DFM}
var
Doc: IHTMLDocument2;
TempFile: string;
xBody   : IHTMLElement;
xLoaded : Boolean;
onlyOnce: Boolean;

procedure TForm1.WB_LoadHTML(HTMLCode: string);
var
  sl: TStringList;
  ms: TMemoryStream;
begin
  xLoaded := False;
  WebBrowser.Navigate('about:blank');
  while WebBrowser.ReadyState < READYSTATE_INTERACTIVE do
   Application.ProcessMessages;

  if Assigned(WebBrowser.Document) then
  begin
    sl := TStringList.Create;
    try
      ms := TMemoryStream.Create;
      try
        sl.Text := HTMLCode;
        sl.SaveToStream(ms);
        ms.Seek(0, 0);
        (WebBrowser.Document as IPersistStreamInit).Load(TStreamAdapter.Create(ms));
      finally
        ms.Free;
      end;
    finally
      sl.Free;
      Doc :=  WebBrowser.Document as IHTMLDocument2;
    end;
  end;
end;

procedure TForm1.LoadHTMLBtnClick(Sender: TObject);
begin
WB_LoadHTML(Memo1.Text);
end;

procedure TForm1.LoadFileBtnClick(Sender: TObject);
begin
Memo1.Lines.LoadFromFile('G:\Programme\Apache Group\Apache\htdocs\bearbeiten1.html');
end;

We have created 2 files (which are identical) only script differs to get an alert at load.
bearbeiten1.html

<script type="text/javascript">
alert ("bearbeiten1.html");      
</script>

bearbeiten3.html

<script type="text/javascript">
alert ("bearbeiten3.html");      
</script>

With click on Load File we load the "bearbeiten1.html" file
and with WB_LoadHTML we load it into Memory.

we get URL : about:blank

and the alert

now we create a link:
we select the blue part and click createlink

The link is created

and also the new "Doc.body.innerHTML"

procedure TForm1.createlinkBtnClick(Sender: TObject);
begin
Doc.execCommand('createlink', false,'bearbeiten3.html');
Memo1.Text := Doc.body.innerHTML;
end;

So far so good! But will it work...? No

After a click on the link all we get is a blank site with URL:

Now we try the new EditText() code

procedure TForm1.EditText(CONST HTMLPath: string);
begin
 TempFile := HTMLPath;
 xLoaded := False;
 WebBrowser.Navigate(TempFile);
 Doc :=  WebBrowser.Document as IHTMLDocument2;
 if Doc <> nil then  xLoaded := True;
end;

procedure TForm1.EditTextBtnClick(Sender: TObject);
begin
  EditText('G:\Programme\Apache Group\Apache\htdocs\bearbeiten1.html');
end;

With click on Load File we load the "bearbeiten1.html" file again and with EditTextBtnClick we load it direct. Looks much better! Will it work ...?

Let's click the link - we get the alert!! From number ...3.html"

and the .html file is loaded without problem.

To your other problem

 if Doc <> NIL
then Doc.Body.SetAttribute('contentEditable', 'true', 0);
//crash here when I load complex html files

You did it in the wrong place, as the body is only available after the site is loaded!!

So I put it in the event WebBrowserNavigateComplete2

Only a fast solution can be improved

procedure TForm1.WebBrowserNavigateComplete2(Sender: TObject;
  const pDisp: IDispatch; var URL: OleVariant);
begin
if xLoaded  = True then begin
    xBody := Doc.Get_body;
    if xBody <> nil then begin
       xBody.SetAttribute('contentEditable', 'true', 0);
       Memo1.Text := Doc.body.innerHTML;
       xLoaded := False;
    end;
end;
label2.Caption := URL;
end;

The complete code.

type
  TForm1 = class(TForm)
    WebBrowser: TWebBrowser;
    Label1: TLabel;
    Label2: TLabel;
    Memo1: TMemo;
    LoadHTMLBtn: TButton;
    LoadFileBtn: TButton;
    EditTextBtn: TButton;
    createlinkBtn: TButton;
    innerHTMLBtn: TButton;
    procedure LoadHTMLBtnClick(Sender: TObject);
    procedure LoadFileBtnClick(Sender: TObject);
    procedure EditTextBtnClick(Sender: TObject);
    procedure createlinkBtnClick(Sender: TObject);
    procedure WebBrowserNavigateComplete2(Sender: TObject;
      const pDisp: IDispatch; var URL: OleVariant);
    procedure innerHTMLBtnClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    procedure WB_LoadHTML(HTMLCode: string);
    procedure EditText(CONST HTMLPath: string);
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}
var
Doc: IHTMLDocument2;
TempFile: string;
xBody   : IHTMLElement;
xLoaded : Boolean;
onlyOnce: Boolean;

procedure TForm1.WB_LoadHTML(HTMLCode: string);
var
  sl: TStringList;
  ms: TMemoryStream;
begin
  xLoaded := False;
  WebBrowser.Navigate('about:blank');
  while WebBrowser.ReadyState < READYSTATE_INTERACTIVE do
   Application.ProcessMessages;

  if Assigned(WebBrowser.Document) then
  begin
    sl := TStringList.Create;
    try
      ms := TMemoryStream.Create;
      try
        sl.Text := HTMLCode;
        sl.SaveToStream(ms);
        ms.Seek(0, 0);
        (WebBrowser.Document as IPersistStreamInit).Load(TStreamAdapter.Create(ms));
      finally
        ms.Free;
      end;
    finally
      sl.Free;
      Doc :=  WebBrowser.Document as IHTMLDocument2;
    end;
  end;
end;

procedure TForm1.LoadHTMLBtnClick(Sender: TObject);
begin
WB_LoadHTML(Memo1.Text);
end;

procedure TForm1.LoadFileBtnClick(Sender: TObject);
begin
Memo1.Lines.LoadFromFile('G:\Programme\Apache Group\Apache\htdocs\bearbeiten1.html');
end;

procedure TForm1.EditText(CONST HTMLPath: string);
begin
 TempFile := HTMLPath;
 xLoaded  := False;
 WebBrowser.Navigate(TempFile);
 if onlyOnce then WebBrowser.Navigate(TempFile);
 onlyOnce := False;
 Doc :=  WebBrowser.Document as IHTMLDocument2;
 if Doc <> nil then  xLoaded := True;
end;

procedure TForm1.EditTextBtnClick(Sender: TObject);
begin
  EditText('G:\Programme\Apache Group\Apache\htdocs\bearbeiten1.html');
end;

procedure TForm1.createlinkBtnClick(Sender: TObject);
begin
Doc.execCommand('createlink', false,'bearbeiten3.html');
Memo1.Text := Doc.body.innerHTML;
end;

procedure TForm1.WebBrowserNavigateComplete2(Sender: TObject;
  const pDisp: IDispatch; var URL: OleVariant);
begin
if xLoaded then begin
    xBody := Doc.Get_body;
    if xBody <> nil then begin
       xBody.SetAttribute('contentEditable', 'true', 0);
       Memo1.Text := Doc.body.innerHTML;
       xLoaded := False;
    end;
end;
label2.Caption := URL;
end;

procedure TForm1.innerHTMLBtnClick(Sender: TObject);
begin
Memo1.Text := Doc.body.innerHTML;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 onlyOnce := True;
end;
end.

UPDATE:
I forgot to set the Tempfile Path in the code (copy paste error).
Also FormCreate added.
and only one time load the TempFile twice! (see code)

Important in the head tag of the TempFile must be a link

bearbeiten1.html same as bearbeiten3.html only alert ("bearbeiten3.html"); must be adapted!!

bearbeiten1.html

<head>
<link href="file:///G:\Programme\Apache Group\Apache\htdocs\maor.css" rel="stylesheet" media="screen">
</head>
<body leftmargin="0" marginheight="0" marginwidth="0" topmargin="0" bgcolor="#1F2E53">
<script type="text/javascript">
  alert ("bearbeiten1.html");        
</script>
    <table width="100%" border="0" cellspacing="0" cellpadding="0" >
      <tr height="211">
        <td width="2%" height="211"></td>
        <td valign="top" width="36%" height="211">
            <table width="448" border="0" cellspacing="0" cellpadding="0">
             <tr height="21">
                <td width="8" height="21"></td>
                <td class="FormControlrechts" width="150" height="21"></td>
                <td width="23" height="21"></td>
                <td class="FormControl" width="213" height="21">
                <p unselectable="on">Select any portion of the following blue text</p>
                <p id="p1" style="color= #3366CC">My favorite Web site. Don't forget to click the button! createlink</p>
                </td>
             </tr>
            </table>
    </table>
</body>

maor.css

body {}
p {}
td {}
h1 { color: #f5c391; font-weight: normal; font-size: 20px; font-family: verdana, serif; margin-bottom: 0.2em }
h2 { color: #eaeaea; font-weight: normal; font-size: 16px; margin-top: 0; margin-bottom: 0 }
form { margin-top: 0px }
a:link { font-weight:bold; color:#36f; text-decoration:none; }
a:visited { font-weight:bold; color:silver; text-decoration:none; }
a:focus { font-weight:bold; color:#d4d4d4; text-decoration:underline; }
a:hover { font-weight:bold; color:#c0c0c0; text-decoration:none; }
a:active { font-weight:bold; color:lime; text-decoration:underline; }
textarea, input { font-size: 8pt }
select, option { font-size: 9pt }
td { color: #333; font-size: 9pt; font-family: verdana, sans-serif }
td.FormControl   { color: #ffe78b; font-size: small; padding-top: 5px; padding-bottom: 5px; border-right: 1px solid #5dafb0; border-bottom: 1px solid #5dafb0 }
td.FormControlrechts   { color: #a88664; font-size: 8pt; text-align: right; padding-top: 5px; padding-bottom: 5px; border-top: #5dafb0; border-right: #5dafb0; border-bottom: 1px solid #5dafb0; border-left: #5dafb0 }
.class { }

Answer 3

The simplest way to display HTML code in Delphi:

WebBrowser1.Navigate('about:'+yourHTMLcode);