using ESRI.ArcGIS;
using ESRI.ArcGIS.Carto;

IWorkspaceFactory featureWorkspace = (ESRI.ArcGIS.Geodatabase.IFeatureWorkspace)workspaceFactory.OpenFromFile(System.IO.Path.GetDirectoryName(@"C:\work\mypoint.shp"), 0);
IFeatureClass featureClass = featureWorkspace.OpenFeatureClass(System.IO.Path.GetFileNameWithoutExtension(@"mypoint"));
IFeatureLayer featureLayer = new ESRI.ArcGIS.Carto.FeatureLayerClass();
featureLayer.FeatureClass = featureClass;
featureLayer.Name = "ポイント";
featureLayer.Visible = true;

IRgbColor mskrgb = new RgbColorClass();
mskrgb.Red = 255;
mskrgb.Green = 255;
mskrgb.Blue = 255;

IPictureMarkerSymbol bitmapPictureMarkerSymbolCls = new PictureMarkerSymbolClass();
bitmapPictureMarkerSymbolCls.CreateMarkerSymbolFromFile(esriIPictureType.esriIPictureBitmap, "c:\\work\\flag.bmp");
bitmapPictureMarkerSymbolCls.Angle = 0;
bitmapPictureMarkerSymbolCls.BitmapTransparencyColor = mskrgb;
bitmapPictureMarkerSymbolCls.Size = 32;
bitmapPictureMarkerSymbolCls.XOffset = 0;
bitmapPictureMarkerSymbolCls.YOffset = 0;

IGeoFeatureLayer pGeoFeatureLayer = (IGeoFeatureLayer)featureLayer;
IFeatureRenderer pSimpleRenderer = new SimpleRenderer();
pSimpleRenderer.Symbol = (ISymbol)bitmapPictureMarkerSymbolCls;
pGeoFeatureLayer.Renderer = (IFeatureRenderer)pSimpleRenderer;

axMapControl1.AddLayer(featureLayer);