ArcEnging 导入shp文件后自定义图层中各要素的颜色

经过前面一段时间狂乱的baidu&google，目前ArcEngine开的项目算是完成了基本的外观，这次解决的问题是从CAD导成shp文件后，先前在CAD中定义的颜色也是可以读取到的，只不过它的Color值是采用的 ACI 规范，需要转换成RGB我们才方便使用。当然主要的问题是MapControl导入shp文件时，它给每个图层中要素的颜色是随机的，不是原图中所定义的颜色，所以我们需要这样在google中搜索”ArcEngine 修改 图层颜色”，”ArcEngine 自定义要素颜色”，又是一阵狂乱的搜索，当然也能找到一些信息，但最后还是在看那个E文的MSDN帮助时找到了解决办法。上面直接有一例子，这里做了一些修改，贴出来:

 public static void DefineFeatureColor(IGeoFeatureLayer pGeoFeatureLayer, string fieldName)
        {
            //Make the renderer.
            IUniqueValueRenderer pUniqueValueRenderer = new UniqueValueRendererClass();

            //These properties should be set prior to adding values.
            pUniqueValueRenderer.FieldCount = 1;
            pUniqueValueRenderer.set_Field(0, fieldName);

            IDisplayTable pDisplayTable = pGeoFeatureLayer as IDisplayTable;
            IFeatureCursor pFeatureCursor = pDisplayTable.SearchDisplayTable(null, false) as IFeatureCursor;
            IFeature pFeature = pFeatureCursor.NextFeature();

            bool ValFound;
            int fieldIndex;

            IFields pFields = pFeatureCursor.Fields;
            fieldIndex = pFields.FindField(fieldName);
            while (pFeature != null)
            {
                string classValue = pFeature.get_Value(fieldIndex).ToString();

                IColor color =  ColorUtilities.GetColorByACI(Int16.Parse(classValue));
                IRgbColor rgb = color as  IRgbColor;
                //System.Console.WriteLine("KVL:" + classValue+"-->RGB"+ rgb.Red + "," + rgb.Green + "," + rgb.Blue);

                ISymbol pClassSymbol = getSymbolByShapType(pGeoFeatureLayer.FeatureClass.ShapeType, color);

                //Test to see if this value was added
                //to the renderer. If not, add it.
                ValFound = false;
                for (int i = 0; i <= pUniqueValueRenderer.ValueCount - 1; i++)
                {
                    if (pUniqueValueRenderer.get_Value(i) == classValue)
                    {
                        ValFound = true;
                        break; //Exit the loop if the value was found.
                    }
                }
                //If the value was not found, it is new and it will be added.
                if (ValFound == false)
                {
                    pUniqueValueRenderer.AddValue(classValue, fieldName, pClassSymbol as ISymbol);
                    pUniqueValueRenderer.set_Label(classValue, classValue);
                    pUniqueValueRenderer.set_Symbol(classValue, pClassSymbol as ISymbol);
                }
                pFeature = pFeatureCursor.NextFeature();
            }

            //'** If you didn't use a predefined color ramp
            //'** in a style, use "Custom" here. Otherwise,
            //'** use the name of the color ramp you selected.
            pUniqueValueRenderer.ColorScheme = "Custom";
            ITable pTable = pDisplayTable as ITable;
            bool isString = pTable.Fields.get_Field(fieldIndex).Type == esriFieldType.esriFieldTypeString;
            pUniqueValueRenderer.set_FieldType(0, isString);
            pGeoFeatureLayer.Renderer = pUniqueValueRenderer as IFeatureRenderer;

            //This makes the layer properties symbology tab
            //show the correct interface.
            IUID pUID = new UIDClass();
            pUID.Value = "{683C994E-A17B-11D1-8816-080009EC732A}";
            pGeoFeatureLayer.RendererPropertyPageClassID = pUID as UIDClass;

        }

上面的代码大部分来自帮助文档中的例子，做了一些逻辑上的修改，就是把原例子中的Random颜色换成读取要素Color转成RGB再渲染。参数fieldName其实可以不用要，我这里就是”Color”这个字段名。

转载自：https://blog.csdn.net/Rocye/article/details/84184026