如何实现文档坐标到视区坐标的转换？

• 回答：

  procedure TForm1.Button1Click(Sender: TObject);
  
   var
    pRet: MxDrawResbuf;
    h, w: double;
    ptMin        : IMxDrawPoint;
    ptMax       : IMxDrawPoint;
    ptOle        : OleVariant;
    begin
    if dlgSave1.Execute then
    begin
      pRet := MxDrawResbuf(MxDrawX1.Call('Mx_GetMcDbDatabaseBound', ''));
  
      if pRet.AtString(0) = 'Ok' then
      begin
        ptMin :=  CoMxDrawPoint.Create();
        ptMin.Set_x(pRet.AtDouble(1));
        ptMin.Set_y(pRet.AtDouble(2));
        ptOle := MxDrawX1.DocToViewCoord(ptMin);
        ptMin:=IMxDrawPoint(IDisPatch(ptOle));
  
        ptMax :=  CoMxDrawPoint.Create();
        ptMax.Set_x(pRet.AtDouble(3));
        ptMax.Set_y(pRet.AtDouble(4));
        ptOle := MxDrawX1.DocToViewCoord(ptMax);
        ptMax:=IMxDrawPoint(IDisPatch(ptOle));
  
  
        MxDrawX1.ViewColor := clWhite;
        w := ptMax.Get_x();
        w := w - ptMin.Get_x() + 1;
        h := ptMax.Get_y();
        h := ptMin.Get_y() - h  + 1;
  
        if not MxDrawX1.SaveJpgFile(dlgSave1.FileName, Round(w), Round(h),0) then
          Showmessage('失败')
        else
          Showmessage('成功');
      end;
    end;
    end;