我想将网页(即TWebBrowser
)渲染到设备上下文。我想使用 Internet Explorer 的布局引擎将内容呈现到设备上下文(即元文件、pdf 元文件)。
从 Internet Explorer 9 开始,IHTMLElementRender
接口(interface)不再受支持:
IHTMLElementRender interface
Use this interface to draw the contents of an element to a specified device context, normally a printer.
Members
The IHTMLElementRender interface inherits from the IUnknown interface but does not have additional members.
以至于他们不再提及 DrawToDC method甚至存在:
IHTMLElementRender::DrawToDC Method
Deprecated. Draws the contents of the element to the specified device context.
Syntax
HRESULT DrawToDC( HDC hDC );
Parameters
- hDC
[in] An HDC specifying the device to be drawn to, typically a printer.Return Value
Returns S_OK if successful, or an error value otherwise.
Remarks
As of Windows Internet Explorer 9, this method is deprecated and should not be used.
With some printers, running IHTMLElementRender::DrawToDC may cause problems. You can ensure that IHTMLElementRender::DrawToDC works properly on all printers by running IHTMLElementRender::SetDocumentPrinter method first, and then passing the modified device context to IHTMLElementRender::DrawToDC.
注意:我引用了所有文档,以便当 Microsoft 最终将其从 MSDN 中完全删除时仍然可以找到它。连同接口(interface)声明:
IHTMLElementRender = interface(IUnknown)
['{3050F669-98B5-11CF-BB82-00AA00BDCE0B}']
function DrawToDC(hdc: HDC): HResult; stdcall;
function SetDocumentPrinter(const bstrPrinterName: WideString; hdc: HDC): HResult; stdcall;
end;
<小时/>
使用IViewObject
接口(interface)
我尝试转换为使用 IViewObject
(例如 How to render HTML element without using web browser? ):
procedure RenderWebBrowserToMetafile(Browser: TWebBrowser; Metafilename: string);
var
view: IViewObject;
m: TMetafile;
mc: TMetafileCanvas;
w, h: Integer;
r: TRect;
dpix: Integer;
dpiy: Integer;
dc: HDC;
begin
w := WebBrowserScrollWidth(Browser);
h := WebBrowserScrollHeightStrict(Browser);
//96dpi screen to 300dpi metafile (destined for printer)
dc := GetDC(0);
try
dpix := GetDeviceCaps(GetDC(0), LOGPIXELSX);
dpiy := GetDeviceCaps(GetDC(0), LOGPIXELSY);
finally
ReleaseDC(0, dc);
end;
w := MulDiv(w, 300, dpix);
h := MulDiv(h, 300, dpiy);
view := Browser.Document as IViewObject;
m := TMetafile.Create;
try
m.Width := w;
m.Height := h;
r := Rect(0, 0, w, h);
mc := TMetafileCanvas.Create(m, 0);
try
view.Draw(
DVASPECT_CONTENT, //draw aspect
1, //index
nil, //pAspectInfo
nil, //pDVTargetDevice
0, //Target Device Context
mc.handle, //hdcDraw
@r, //target Bounds
@w, //window bounds (for metafiles)
nil, //continue function
0); //continue value
finally
mc.Free;
end;
m.SaveToFile(Metafilename);
finally
m.Free;
end;
end;
此代码的问题在于它仅呈现浏览器的可见区域(即没有滚动内容):
我需要渲染整个网页(例如用于打印)。
我尝试更改 draw aspect来自DVASPECT_CONTENT
(如 this example 所示),至 DVASPECT_DOCPRINT
:
DVASPECT_DOCPRINT
Provides a representation of the object on the screen as though it were printed to a printer using the Print command from the File menu. The described data may represent a sequence of pages.
结果相同;只渲染可见部分,而不是渲染页面:
如何让 IE9 渲染引擎进行渲染?
<小时/>我还尝试使用不同的索引以及DVASPECT_DOCPRINT
。虽然 IViewObject
没有记录,也许这就是打印不同“页面”的方式:
view.Draw(DVASPECT_DOCPRINT, 1, ...);
view.Draw(DVASPECT_DOCPRINT, 2, ...);
view.Draw(DVASPECT_DOCPRINT, 3, ...);
...
view.Draw(DVASPECT_DOCPRINT, n, ...);
但是 Web 浏览器并不关心索引是什么;它只关心索引是什么。仅渲染当前的View
(我认为在使用IViewObject
时这是有意义的)。
如何将浏览器渲染到设备上下文?
注意:该问题标有 delphi
,但该问题中没有任何 delphi 特定内容。
更新:我还尝试了方面和索引的其他组合:
view.Draw(DVASPECT_CONTENT, -1, ...);
view.Draw(DVASPECT_DOCPRINT, -1, ...);
view.Draw(DVASPECT_CONTENT, 0, ...);
view.Draw(DVASPECT_DOCPRINT, 0, ...);
最佳答案
使用 IViewObject,您可以创建当前视口(viewport)的屏幕截图。我使用一个技巧来创建网页(没有任何框架)或框架文档的屏幕截图。
- 使用scrollWidth/scrollHeight/scrollLeft/scrollTop计算完整文档大小(检查IHtmlDocument2和IHtmlDocument3接口(interface))
- 锁定窗口更新并将文档调整为计算出的完整尺寸
- 使用 IViewObject 创建快照(上面的代码似乎没问题)
- 将文档恢复至原始大小并解锁窗口更新
请注意当文档非常大时,您应该小心执行此操作。
关于delphi - 如何将 WebBrowser 渲染到设备上下文?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10884088/