再问如何遍历DWG文件中的图元
<p>我有个项目，需要用C#打开DWG文件，然后在程序窗口中画出。通过搜索引擎我解决了打开DWG文件，也可以遍历，但问题是，我怎么得到每个图元的属性呢？比如，我得到一个Entry，Entry.Name是椭圆，那怎么得到它的a/b半径和中心点？</p><p> </p>string progid = "ObjectDBX.AxDbDocument.16"; //注意，这是AutoCAD2004的写法，
// 若是AutoCAD2002和AutoCAD2000i则是”ObjectDBX.AxDbDocument.1“
AcadApplication acadApp = connector.Application;
dbx.AxDbDocument dbxDoc;
dbxDoc = (dbx.AxDbDocument)acadApp.GetInterfaceObject(progid);
dbxDoc.Open(filename, null);
foreach (dbx.AcadEntity entity in dbxDoc.ModelSpace)
{
Console.WriteLine("-------------");
Console.WriteLine("EntityName: {0}", entity.EntityName);
Console.WriteLine("ObjectName: {0}", entity.ObjectName);
Console.WriteLine("EntityLineType: {0}", entity.Linetype);
Console.WriteLine("Entity.ObjectID: {0}", entity.ObjectID);
if (entity.EntityName == "AcDbEllipse")
{
dbx.AcadEllipseClass ellipse = entity.Get
dbx.AcadEllipseClass ellipse = (dbx.AcadEllipseClass)
dbxDoc.ModelSpace.Database.ObjectIdToObject(entity.ObjectID);
//dbx.AcadEllipseClass ellipse = (dbx.AcadEllipseClass)entity;//.ObjectName;
Console.WriteLine("", ellipse.MajorRadius);
Point center = (Point)ellipse.Center;
Point major = (Point)ellipse.MajorAxis;
Point minor = (Point)ellipse.MinorAxis;
Console.WriteLine(" center{{0},{1}}", center.X, center.Y);
Console.WriteLine(" major{{0},{1}}", major.X, major.Y);
Console.WriteLine(" minor{{0},{1}}", minor.X, minor.Y);
xGraph.DrawEllipse(myPen,
center.X/100,
center.Y / 100,
major.X * 2 / 100,
minor.Y * 2 / 100);
}
if (entity.EntityName == "AcDbSpline")
{
//dbx.AcadSplineClass spline = (dbx.AcadSplineClass)entity;
}
if (entity.EntityName == "AcDbBlockReference")//判断实体是否是块参照
{
dbx.AcadBlockReference blkRef;
blkRef = (dbx.AcadBlockReference)entity;//将是块参照的实体强制转换为块参照类型
object[] atts = (object[])blkRef.GetAttributes();//获取块参照中的属性（为对象类型）
for (int i = 0; i < atts.Length; i++) //遍历块参照属性
{
dbx.AcadAttributeReference att;
att = (dbx.AcadAttributeReference)atts;//将块参照属性（对象类型）强制转换为块参照属性类型
Console.WriteLine("Tag: {0}\tValue: {1}\n",
att.TagString,
att.TextString);//显示块参照属性的Tag和Text的值
}
}
本帖最后由 作者 于 2008-9-22 0:13:48 编辑 <br /><br /> <p>我强制转换Entry为各个图元类，可是得到异常</p><p>System.InvalidCastException：<br/>无法将类型为“System.__ComObject”的 COM 对象强制转换为类类型“AXDBLib.AcadEllipseClass”。进入 CLR 且不支持 IProvideClassInfo 或没有注册任何互操作程序集的 COM 组件都将包装在 __ComObject 类型中。这种类型的实例不能强制转换为任何其他类；不过，只要基础 COM 组件支持对接口 IID 的 QueryInterface 调用，就能将这些实例强制转换为接口。</p><p>搜索网络，这个问题以前人家问过：<a href="http://www.mjtd.com/bbs/Archive_view.asp?boardID=4&ID=27173">http://www.mjtd.com/bbs/Archive_view.asp?boardID=4&ID=27173</a></p><p>回帖说：</p><p><strong>- AcadEntity不用转换为相应的实体啊，如果为不同的实体就有相应实体的属性.</strong></p><p><strong>- 没有错，是没有必要</strong></p><p>Dim ss As AcadSelectionSet<br/> ThisDrawing.SelectionSets("TT").Delete<br/> Set ss = ThisDrawing.SelectionSets.Add("TT")<br/> ss.Select acSelectionSetAll<br/> Dim poly As AcadPolyline<br/> For Each elem In ss \'对每一条折线提取顶点坐标<br/> If (elem.ObjectName = "AcDb3dPolyline") Then<br/> pnts = elem.Coordinates<br/> MsgBox pnts(0)<br/> End If</p><p><br/> Next elem<br/></p><p>---------------------------</p><p>那问题是到底怎么样得到各种图元的属性啊？</p><p>下面是我的代码示例，请前辈们帮帮忙：</p> 本帖最后由 作者 于 2008-9-22 0:07:47 编辑
foreach (dbx.AcadEntity entity in dbxDoc.ModelSpace)
{
Console.WriteLine("-------------");
Console.WriteLine("EntityName: {0}", entity.EntityName);
Console.WriteLine("ObjectName: {0}", entity.ObjectName);
Console.WriteLine("EntityLineType: {0}", entity.Linetype);
Console.WriteLine("Entity.ObjectID: {0}", entity.ObjectID);
if (entity.EntityName == "AcDbEllipse")
{
dbx.AcadEllipseClass ellipse = (dbx.AcadEllipseClass) entity;//异常抛出！！！
//得到椭圆属性（也不一定对）
Point center = (Point)ellipse.Center;
Point major = (Point)ellipse.MajorAxis;
Point minor = (Point)ellipse.MinorAxis;
Console.WriteLine(" center{{0},{1}}", center.X, center.Y);
Console.WriteLine(" major{{0},{1}}", major.X, major.Y);
Console.WriteLine(" minor{{0},{1}}", minor.X, minor.Y);
//画椭圆
xGraph.DrawEllipse(myPen,
center.X,
center.Y,
major.X * 2,
minor.Y * 2);
}
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