LibreOffice Calc C# SDK插入图片至单元格遇XGraphic相关问题

背景 #

我正在编写程序将图片添加到LibreOffice Calc的单元格中，但LibreOffice近期修改了实现方式，网上现有示例都是已失效的旧方法。

注：技术上无法将图片“插入”单元格，这类图片是位于电子表格上方DrawPage上的叠加层，用于“装饰”表格。

采用新方式的核心步骤之一是创建包含图片的XGraphic对象：需要先创建XGraphicProvider，再传入指定图片文件URL的MediaProperties。

第一个问题：XGraphic为空（已排查出原因） #

最初实现时生成的XGraphic为空，LibreOffice SDK报错信息极少。相关代码如下：

// addpic
// add picture to spreadsheet - debug version

class OpenOfficeApp {

  [STAThread]
  static void Main(string[] args) {

    bool lreadonly;
    string pqfile;
    string pqURL;
    string pqpic;

    pqfile = "file:///D:/Documents/NSexeye/ODS%20File%20Access/"+
                                                     "addpix/addpic.ods";
    pqpic = "addpic2";
    pqURL = pqpic+".jpg";
    lreadonly = false;

    Console.WriteLine("Using: "+pqfile);

    // get the desktop
    XComponentContext XCC = uno.util.Bootstrap.bootstrap();
    XMultiComponentFactory XMCF =
                              (XMultiComponentFactory)XCC.getServiceManager();
    XMultiServiceFactory XMSF = (XMultiServiceFactory)XCC.getServiceManager();
    XComponentLoader XCL =
        (XComponentLoader)XMSF.createInstance("com.sun.star.frame.Desktop");

    // open the spreadsheet
    PropertyValue[] pPV = new PropertyValue[2];
    pPV[0] = new PropertyValue();
    pPV[0].Name = "Hidden";
    pPV[0].Value = new uno.Any(true);
    pPV[1] = new PropertyValue();
    pPV[1].Name = "ReadOnly";
    if (lreadonly) pPV[1].Value = new uno.Any(true);
    else pPV[1].Value = new uno.Any(false);
    XComponent XCo = XCL.loadComponentFromURL(pqfile,"_blank",0,pPV);

    // create graphic object containing image
    object oGP = XMCF.createInstanceWithContext(
                              "com.sun.star.graphic.GraphicProvider",XCC);
    if (oGP == null) {
      Console.WriteLine("oGP is null.  Aborting.");
      return;
    }
    XGraphicProvider XGP = (XGraphicProvider)oGP;
    if (XGP == null) {
      Console.WriteLine("XGP is null.  Aborting.");
      return;
    }
    pPV = new PropertyValue[1];
    pPV[0] = new PropertyValue();
    pPV[0].Name = "URL";
    pPV[0].Value = new uno.Any(pqURL);
    Console.WriteLine("Creating XGraphic containing "+pqURL);
    XGraphic XG = XGP.queryGraphic(pPV);

    // *** XG is null here
    if (XG == null) {
      Console.WriteLine("XG is null.  Aborting.");
      return;
    }

    // ... lots of stuff to be added here

    // save and close the spreadsheet
    XModifiable XM = (XModifiable)XCo;
    XM.setModified(true);
    XStorable XSt = (XStorable)XCo;
    XSt.store();
    XCloseable XCl = (XCloseable)XCo;
    XCl.close(true);

    // terminate LibreOffice
    // *** I want this to not terminate it if something else is open
    XDesktop XD = (XDesktop)XCL;
    if (XD != null) XD.terminate();
  }
}

排查后发现问题：向XGraphicProvider的URL属性传入了裸文件名，需要使用与电子表格文件名一致的file:///格式。

当前问题：XGraphic转uno.Any的编译错误 #

现在需要将XGraphic指定为GraphicObjectShape的Graphic属性，但setPropertyValue()要求参数为uno.Any类型，尝试直接传入XG或者new uno.Any(XG)都编译失败，相关代码如下：

// set image XGraphic
XPropertySet XPS = (XPropertySet)XS;
XPS.setPropertyValue("Graphic",XG);
XPS.setPropertyValue("Name",new uno.Any(pqpic));

我的目标是编写一个可运行的、向Calc单元格添加及操作图片的示例程序，这类需求较多但目前没有可用的最新示例，寻求LibreOffice SDK开发者的帮助。

内容的提问来源于stack exchange，提问作者user7505909