ArcGis Engine中实现对符号的预览图输出

  ArcGis Engine中实现对符号的预览图输出 07-11-12 11:24:09 作者:Aji 出处：中国GIS资讯网
在ArcGis Engine中实现对符号的预览，生成预览图片。使用的时候只要调用SymbolToBitmp(符号，宽，高)就可以返回生成的图片了。关键代码如下：

//在ArcGis Engine中实现对符号的预览，生成预览图片。使用的时候只要调用SymbolToBitmp(符号，宽，高)就可以返回生成的图片了。关键代码如下：

 

        public static System.Drawing.Bitmap SymbolToBitmp(ISymbol pSymbol, int iwidth, int iheight, int wd)

        {

            //根据高宽创建图象

            Bitmap bmp = new Bitmap(iwidth, iheight);

            Graphics gImage = Graphics.FromImage(bmp);

            gImage.Clear(Color.White);

            double dpi = gImage.DpiX;

            IEnvelope pEnvelope = new EnvelopeClass();

            pEnvelope.PutCoords(0, 0, (double)bmp.Width, (double)bmp.Height);

 

            tagRECT deviceRect;

            deviceRect.left = 0;

            deviceRect.right = bmp.Width;

            deviceRect.top = 0;

            deviceRect.bottom = bmp.Height;

 

            IDisplayTransformation pDisplayTransformation = new DisplayTransformationClass();

            pDisplayTransformation.VisibleBounds = pEnvelope;

            pDisplayTransformation.Bounds = pEnvelope;

            pDisplayTransformation.set_DeviceFrame(ref deviceRect);

            pDisplayTransformation.Resolution = dpi;

 

            IGeometry pGeo = CreateSymShape(pSymbol, pEnvelope, wd);

 

            System.IntPtr hdc = new IntPtr();

            hdc = gImage.GetHdc();

 

            //将符号的形状绘制到图象中

            pSymbol.SetupDC((int)hdc, pDisplayTransformation);

            pSymbol.Draw(pGeo);

            pSymbol.ResetDC();

            gImage.ReleaseHdc(hdc);

            gImage.Dispose();

 

            return bmp;

 

        }

 

        public static ESRI.ArcGIS.Geometry.IGeometry CreateSymShape(ISymbol pSymbol, IEnvelope pEnvelope, int wd)

        {// 根据传入的符号以及外包矩形区域返回对应的几何空间实体（点，线、面）

            //判断是否为“点”符号

 

            if (pSymbol is IMarkerSymbol)

            {

                // 为“点”符号则返回IEnvelope的中心点

                IArea pArea;

                pArea = pEnvelope as IArea;

                return pArea.Centroid as IGeometry;

            }

            else

            {

                //判断是否为“线”符号

 

                if (pSymbol is ILineSymbol)

                {

 

                    IPolyline IpLine = new PolylineClass();

                    IpLine.FromPoint.PutCoords(0, pEnvelope.YMax / 2);

                    IpLine.ToPoint.PutCoords(pEnvelope.Width, pEnvelope.YMax / 2);

 

 

                    return IpLine as IGeometry;

                }

                else

                {

                    //直接返回一个IEnvelope矩形区域

                    IEnvelope pnewEnvelope = new EnvelopeClass();

                    pnewEnvelope.PutCoords(wd, wd, pEnvelope.Width - wd, pEnvelope.Height-wd);

 

                    return pnewEnvelope as IGeometry;

                }

            }

        }