Question

在Delphi RIO应用程序表单上有一个Align = alClient的Webbrowser1。滚动浏览Web浏览器的内容，因此显示的第一行不是Web浏览器内容的第一行。在这种情况下，当调整表单大小时，Web浏览器的第一个显示行会更改，这带来了不便。在调整大小之前，我得到了第一个显示的htmlelement，并在调整大小后尝试将其滚动到视图中。但是调整大小时，第一条显示的行仍在更改。

FirstDisplayedElement1:IHTMLElement;
// is declared in private section of TFormText

procedure TFormText.FormCanResize(Sender: TObject; var 
  NewWidth, NewHeight: Integer; var Resize: Boolean);
begin
  Resize:=True;
  FirstDisplayedElement1 := 
    GetFirstDisplayedElement(WebBrowser1);
end;

Function  TFormText.GetFirstDisplayedElement(WebBr:TWebBrowser):IHTMLELEMENT;
var
  ChildElems :IHTMLElementCOLLECTION;
  Element:IHTMLElement;
  iHTMLDoc: IHtmlDocument2;
  Element2:IHTMLElement2;
  ElemRect:IHTMLRect;
  i:integer;
begin
  Result:=Nil;
  if Supports(WebBr.Document, IHtmlDocument2, iHTMLDoc) 
then
  begin
    ChildElems:=(WebBr.Document as IHTMLDocument2).all;
    for i := 0 to ChildElems.length - 1 do
    begin
      Element := ChildElems.item(i, varEmpty) as IHTMLElement;
      Element2 := ChildElems.item(i, varEmpty) as 
IHTMLElement2;
      ElemRect:=Element2.getBoundingClientRect;
      if ElemRect.Top > 0 then
      begin
        Result:=Element;
        Exit;
      end;
    end;
  end;
end;

procedure TFormText.FormResize(Sender: TObject);
begin
  if FirstDisplayedElement1<> NIL then 
  FirstDisplayedElement1.scrollIntoView(True);
end;

我们如何保持显示的第一行不变？

Answer 1

在发生大小调整事件时，将过程FormCanResize调用三遍。 ResizeStep变量仅在FormCanResize首次执行时用于一次调用GetFirstDisplayedElement（WebBrowser1）。这样就行了。

ResizeStep:Integer;
FirstDisplayedElement1:IHTMLElement;
// are declared in private section of TFormText
// and are set to 0 and Nil in FormCreate

procedure TFormText.FormCanResize(Sender: TObject; var NewWidth,
  NewHeight: Integer; var Resize: Boolean);
begin
  Resize:=True;
  if ResizeStep = 0 then
  begin
    inc(ResizeStep);
    FirstDisplayedElement1:=GetFirstDisplayedElement(WebBrowser1);
  end;
  if ResizeStep > 1 then ResizeStep := 0;
end;

procedure TFormText.FormResize(Sender: TObject);
begin
  inc(ResizeStep);
  if FirstDisplayedElement1<> NIL then FirstDisplayedElement1.scrollIntoView(True);
end;

Function TFormText.GetFirstDisplayedElement(WebBr:TWebBrowser):IHTMLELEMENT;
var
  ChildElems :IHTMLElementCOLLECTION;
  Element:IHTMLElement;
  i:integer;
begin
  Result:=Nil;
  if Supports(WebBr.Document, IHtmlDocument2, iHTMLDoc) then
  begin
    ChildElems:=(iHTMLDoc.body.children AS IHTMLElementCOLLECTION);
    for i := 0 to ChildElems.length - 1 do
    begin
      Element := ChildElems.item(i, varEmpty) as IHTMLElement;
      if ((Element.offsetTop +Element.offsetHeight) > ((IHTMLDoc.body AS HTMLBODY).scrolltop)) then
      begin
        Result:=Element;
        Exit;
      end;
    end;
  end;
end;

在调整表单大小时，如何在webbrowser中保持第一行显示不变？

1 个答案: