Reputation: 569
Insert STYLEs into TWebBrowser
I am using TWebBrowser as editor GUI for users. I want to be able to insert web controls into the document. A simple example would be a check box. (I can elaborate why if needed). I have all this working when I first assemble the HTML document (with its STYLE and SCRIPTS sections) and then pass it en-block to the TWebBrowser. But now I want to be able to insert my elements into an existing document.
I have this code, below, but it is causing and OLE error (see in comments in code):
procedure THTMLTemplateDocument.EnsureStylesInWebDOM;
var StyleBlock : IHTMLElement;
StyleText: string;
begin
StyleBlock := FWebBrowser.GetDocStyle;
if not assigned(StyleBlock) then
raise Exception.Create('Unable to access <STYLE> block in web document');
StyleText := FCumulativeStyleCodes.Text;
StyleBlock.InnerText := StyleText; <--- generates "OLE ERROR 800A0258"
end;
The called functions from the above code are as follows:
function THtmlObj.GetDocStyle: IHTMLElement;
//Return pointer to <STYLE> block, creating this if it was not already present.
var
Document: IHTMLDocument2; // IHTMLDocument2 interface of Doc
Elements: IHTMLElementCollection; // all tags in document body
AElement: IHTMLElement; // a tag in document body
Style, Head: IHTMLElement;
I: Integer; // loops thru Elements in document body
begin
Result := nil;
if not Supports(Doc, IHTMLDocument2, Document) then
raise Exception.Create('Invalid HTML document');
Elements := Document.all;
for I := 0 to Pred(Elements.length) do begin
AElement := Elements.item(I, EmptyParam) as IHTMLElement;
if UpperCase(AElement.tagName) <> 'STYLE' then continue;
result := AElement;
break;
end;
if not assigned(Result) then begin
Head := GetDocHead;
if assigned(Head) then begin
Style := Document.CreateElement('STYLE');
(Head as IHTMLDOMNode).AppendChild(Style as IHTMLDOMNode);
Result := Style;
end;
end;
end;
and
function THtmlObj.GetDocHead: IHTMLElement;
//Return pointer to <HEAD> block, creating this if it was not already present.
var
Document: IHTMLDocument2; // IHTMLDocument2 interface of Doc
Elements: IHTMLElementCollection; // all tags in document body
AElement: IHTMLElement; // a tag in document body
Body: IHTMLElement2; // document body element
Head: IHTMLElement;
I: Integer; // loops thru Elements in document body
begin
Result := nil;
if not Supports(Doc, IHTMLDocument2, Document) then
raise Exception.Create('Invalid HTML document');
if not Supports(Document.body, IHTMLElement2, Body) then
raise Exception.Create('Can''t find <body> element');
Elements := Document.all;
for I := 0 to Pred(Elements.length) do begin
AElement := Elements.item(I, EmptyParam) as IHTMLElement;
if UpperCase(AElement.tagName) <> 'HEAD' then continue;
Result := AElement;
break;
end;
if not assigned(Result) then begin
Head := Document.CreateElement('HEAD');
(Body as IHTMLDOMNode).insertBefore(Head as IHTMLDOMNode, Body as IHTMLDOMNode);
//now look for it again
Elements := Document.all;
for I := 0 to Pred(Elements.length) do begin
AElement := Elements.item(I, EmptyParam) as IHTMLElement;
if UpperCase(AElement.tagName) <> 'HEAD' then continue;
Result := AElement;
break;
end;
end;
end;
When I run this, StyleText =
'.selected {'#$D#$A' font-weight : bold;'#$D#$A' //background-color : yellow;'#$D#$A'}'#$D#$A'.unselected {'#$D#$A' font-weight : normal;'#$D#$A' //background-color : white;'#$D#$A'}'#$D#$A#$D#$A
But I tried making StyleText to be something simple like 'hello', and it still crashed.
A Google search for "OLE ERROR 800A0258" reveals several other people who have had similar problems, such as here and here -- this later user seems to indicate he fixed the problem by using .OuterHTML, but I tried this with similar error generated. This thread seems to indicate the .InnerText is read only. But in the interface declaration (see below), it seems to have a method for setting (i.e. not read-only).
// *********************************************************************//
// Interface: IHTMLElement
// Flags: (4416) Dual OleAutomation Dispatchable
// GUID: {3050F1FF-98B5-11CF-BB82-00AA00BDCE0B}
// *********************************************************************//
IHTMLElement = interface(IDispatch)
['{3050F1FF-98B5-11CF-BB82-00AA00BDCE0B}']
...
procedure Set_innerHTML(const p: WideString); safecall;
function Get_innerHTML: WideString; safecall;
procedure Set_innerText(const p: WideString); safecall;
function Get_innerText: WideString; safecall;
procedure Set_outerHTML(const p: WideString); safecall;
function Get_outerHTML: WideString; safecall;
procedure Set_outerText(const p: WideString); safecall;
function Get_outerText: WideString; safecall;
...
property innerHTML: WideString read Get_innerHTML write Set_innerHTML;
property innerText: WideString read Get_innerText write Set_innerText;
property outerHTML: WideString read Get_outerHTML write Set_outerHTML;
property outerText: WideString read Get_outerText write Set_outerText;
...
end;
Can anyone help be figure out how to set up STYLES in the <STYLE> section of an existing HTML document in a TWebBrowser?
Upvotes: 1
Views: 1269
Answers (2)
Reputation: 569
Based on guidance from @Zamrony P. Juhara, I came up with the following code. I am posting in case it can help anyone else in the future.
procedure THtmlObj.AddStylesToExistingStyleSheet(StyleSheet: IHTMLStyleSheet; SelectorSL, CSSLineSL : TStringList);
//NOTE: There must be a 1:1 correlation between SelectorSL and CSSLineSL
// The first SL will contain the selector text
// the second SL will contain all the CSS in one line (divided by ";"'s)
var
SLIdx, RuleIdx, p: integer;
SelectorText, CSSText, OneCSSEntry : string;
begin
if not assigned(StyleSheet) then begin
raise Exception.Create('Invalid StyleSheet');
end;
for SLIdx := 0 to SelectorSL.Count - 1 do begin
SelectorText := SelectorSL.Strings[SLIdx];
if SlIdx > (CSSLineSL.Count - 1) then break;
CSSText := CSSLineSL.Strings[SLIdx];
while CSSText <> '' do begin
p := Pos(';', CSSText);
if p > 0 then begin
OneCSSEntry := MidStr(CSSText, 1, p);
CSSText := MidStr(CSSText, p+1, Length(CSSText));
end else begin
OneCSSEntry := CSSText;
CSSText := '';
end;
RuleIdx := StyleSheet.Rules.length;
StyleSheet.addRule(SelectorText, OneCSSEntry, RuleIdx);
end;
end;
end;
function THtmlObj.AddStyles(SelectorSL, CSSLineSL : TStringList) : IHTMLStyleSheet;
//NOTE: There must be a 1:1 correlation between SelectorSL and CSSLineSL
// The first SL will contain the selector text
// the second SL will contain all the CSS in one line (divided by ";"'s)
var
Document: IHTMLDocument2; // IHTMLDocument2 interface of Doc
StyleSheets: IHTMLStyleSheetsCollection; // document's style sheets
StyleSheet: IHTMLStyleSheet; // reference to a style sheet
OVStyleSheet: OleVariant; // variant ref to style sheet
Idx: integer;
begin
Result := nil;
if not Supports(Doc, IHTMLDocument2, Document) then begin
raise Exception.Create('Invalid HTML document');
end;
StyleSheets := Document.styleSheets;
Idx := Document.StyleSheets.length;
OVStyleSheet := Document.createStyleSheet('',Idx);
if not VarSupports(OVStyleSheet, IHTMLStyleSheet, StyleSheet) then begin
raise Exception.Create('Unable to create valid style sheet');
end;
Result := StyleSheet;
AddStylesToExistingStyleSheet(StyleSheet, SelectorSL, CSSLineSL);
end; //AddStyles
Upvotes: 1
Reputation: 5262
If you have valid IHTMLDocument2, then you can call its createStyleSheet(). It will return IHTMLStyleSheet instance. You can use its cssText property to set style.
Make sure you take account of document's character encoding.
Upvotes: 2