TWebBrowser: Determine when a page with Frames is completed
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Question:
If I load a web page with TWebBrowser that contains frames then the OnDocumentComplete() is hit for each frame. How can I recognize that the page is completely loaded (no more frames missing)?
Answer:
Indeed, in case of multiple frames, OnDocumentComplete gets fired multiple times. Not every frame fires this event, but each frame that fires a DownloadBegin event will fire a corresponding DocumentComplete event.
How can the 'real completion' be recognized?
The OnDocumentComplete event sends parameter pDisp: IDispatch, which is the IDispatch of the frame (shdocvw) for which DocumentComplete is fired. The top-level frame fires the DocumentComplete in the end.
So, to check if a page is done downloading, you need to check if pDisp is same as the IDispatch of the WebBrowser control.
That's what the code below demonstrates.
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procedure TForm1.WebBrowser1DocumentComplete(Sender: TObject;
const pDisp: IDispatch; var URL: OLEvariant);
var
CurWebrowser : IWebBrowser;
TopWebBrowser: IWebBrowser;
Document : OLEvariant;
WindowName : string;
begin { TForm1.WebBrowser1DocumentComplete }
CurWebrowser := pDisp as IWebBrowser;
TopWebBrowser := (Sender as TWebBrowser).DefaultInterface;
if CurWebrowser=TopWebBrowser then
begin
ShowMessage('Document is complete.')
end
else
begin
Document := CurWebrowser.Document;
WindowName := Document.ParentWindow.Name;
ShowMessage('Frame ' + WindowName + ' is loaded.')
end;
end;
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