ArcEngine C# GIS开发入门作业 （三）Ex04——实现地图的简单渲染和唯一值渲染
作业说明：
此次实现主要落在了渲染上，所以没有采用IWorkSpace的方式打开要素，直接加载了MXD文件进行渲染。另外控件名称按照同学我的个人习惯作了修改，还是那句话，理解过程和看懂代码为主。
下面为我的窗体样式（图借的是舍友的）：
不说废话了直接上代码，下面的注释应该还够用，有的因为在前面的几个作业中有过描述就没有再重复了，新朋友可以看我前几篇文章。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using ESRI.ArcGIS;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.Display;
using ESRI.ArcGIS.Geodatabase;
namespace EX04副件
{
public partial class MainForm : Form
{
public MainForm()
{
InitializeComponent();
}
private void axMapControl1_OnMapReplaced(object sender, ESRI.ArcGIS.Controls.IMapControlEvents2_OnMapReplacedEvent e)
{
for (int i = 0; i < axMapControl1.LayerCount; i++)
{
ILayer pLayer = axMapControl1.get_Layer(i);
FeatureLayercomboBox.Items.Add(pLayer.Name);
}
}
private void FeatureLayercomboBox_SelectedIndexChanged(object sender, EventArgs e)
{
RedcomboBox.Items.Clear();
GreencomboBox.Items.Clear();
BluecomboBox.Items.Clear();
UniqueValuecomboBox.Items.Clear();
int index = FeatureLayercomboBox.SelectedIndex;//将FeatureLayercomboBox下拉框中选中的图层的引索赋予index
ILayer pLayer = axMapControl1.get_Layer(index);//将刚设置的index设置为axMapControl要get的图层引索号
pLayer.Visible = true;//将选中的图层设置为显示
axMapControl1.Refresh();//这里因为不刷新图层的变化将显示不出来，所以要刷新一下
IFeatureLayer pFeatureLayer = (FeatureLayer)pLayer;
IFeatureClass pFeatureClass = pFeatureLayer.FeatureClass;
int num = pFeatureClass.Fields.FieldCount;
for (int i = 0; i < num; i++)//将图层的各字段名字预设到UniqueValuecomboBox中以供选择
{
UniqueValuecomboBox.Items.Add(pFeatureClass.Fields.get_Field(i).Name);
}
for (int j = 1; j < 256; j++)//在RGB下拉框内预设0-255的值以供选择
{
RedcomboBox.Items.Add(j);
GreencomboBox.Items.Add(j);
BluecomboBox.Items.Add(j);
}
}
private void RenderLayer_Click(object sender, EventArgs e)
{
//单值渲染
ILayer pLayer = null;
int i = FeatureLayercomboBox.SelectedIndex;
if (SimpleradioButton.Checked == true /*&& i == 0*/)
{
//将各颜色combobox中的text类型值转化为int类型，方便后面将其赋给新创建pRgbColor。
if (RedcomboBox.Text == "") return;
int RedValue = Convert.ToInt32(RedcomboBox.Text);
int GreenValue = Convert.ToInt32(GreencomboBox.Text);
int BlueValue = Convert.ToInt32(BluecomboBox.Text);
pLayer = axMapControl1.get_Layer(i);
IGeoFeatureLayer pGeoFeatureLayer = pLayer as IGeoFeatureLayer;
//设定RGB三种填充颜色给pRgbColor,并再赋给pSimpleFillSymbol
ISimpleFillSymbol pSimpleFillSymbol = new SimpleFillSymbol();
IRgbColor pRgbColor = new RgbColor();
pRgbColor.Red = RedValue;
pRgbColor.Green = GreenValue;
pRgbColor.Blue = BlueValue;
pSimpleFillSymbol.Color = pRgbColor;
//将pSimpleFillSymbol赋给新创建的pRenderer，再将pRenderer赋给之前的pGeoFeatureLayer
ISimpleRenderer pRenderer = new SimpleRendererClass();
pRenderer.Symbol = pSimpleFillSymbol as ISymbol;
pGeoFeatureLayer.Renderer = pRenderer as IFeatureRenderer;
axMapControl1.Refresh();
axTOCControl1.Update();
}
//唯一值渲染：下面根据随机色给各个要素，按给定要素的属性字段值的不同赋予不同颜色
if(UniqueValueradioButton.Checked==true)
{
pLayer = axMapControl1.get_Layer(i);
IGeoFeatureLayer pGeoFeatureLayer = pLayer as IGeoFeatureLayer;
IUniqueValueRenderer pUniqueValueRenderer = new UniqueValueRendererClass();//构造一个UniqueValueRenderer
pUniqueValueRenderer.FieldCount = 1;
string FieldName = UniqueValuecomboBox.SelectedItem.ToString();//将UniqueValuecomboBox中所选的项目转换为字符类型，并赋给FieldName
pUniqueValueRenderer.set_Field(0,FieldName);//将唯一值渲染器pUniqueValueRenderer要渲染的字段设为FieldName所代表的UniquecomboBox中的Item
//要做到随机色渲染，需要先创建一个随机渲染的色谱范围，方便后面对uniqueValueRenderer赋予的颜色pRgbColor在所设定的色谱范围内随机读取
//（色谱的范围大致决定了所渲染出来的整体效果）
IRandomColorRamp pRandomColorRamp = new RandomColorRampClass();
pRandomColorRamp.StartHue = 0;//设置随机色带的起始色度
pRandomColorRamp.EndHue = 360;//设置随机色带的末尾色度
pRandomColorRamp.MinSaturation = 10;//设置随机色带的最小饱和度
pRandomColorRamp.MaxSaturation = 30;//设置随机色带的最大饱和度
pRandomColorRamp.MinValue = 100;//设置随机色带的最小纯度
pRandomColorRamp.MaxValue = 100;//设置随机色带的最小纯度
IQueryFilter pQueryFilter = new QueryFilterClass();
pQueryFilter.AddField(FieldName);
//根据渲染字段的唯一值的个数，设施一组随机颜色
pRandomColorRamp.Size = pGeoFeatureLayer.FeatureClass.FeatureCount(pQueryFilter);
bool out_outparameter = false;
pRandomColorRamp.CreateRamp(out out_outparameter);//创建随机颜色→需要输出参数，参数类型为bool类型
IEnumColors pEnumRamp = pRandomColorRamp.Colors;//创建颜色枚举
IColor pNextUniqueColor = null;//视为用来移动的指示颜色的指针
pQueryFilter = new QueryFilterClass();//刷新pQueryFilter的值
pQueryFilter.AddField(FieldName);//添加待查询字段
ITable pTable = pLayer as Table;
int FieldNumbero = pTable.FindField(FieldName);//将字段在表中的索引（即第几列）存入FieldNumbero
ICursor pCursor = pTable.Search(pQueryFilter,true);//true循环使用内存空间，false开辟新的内存空间（UpdateCursor用），
IRow pNextRow = pCursor.NextRow();
IRowBuffer pNextRowBuffer = null;
object codeValue = null;//创建移动指针，用来指向要渲染字段的每一个值
while (pNextRow != null)
{
pNextRowBuffer = pNextRow as RowBuffer;
codeValue = pNextRowBuffer.get_Value(FieldNumbero);//获取要渲染字段的每一个值
pNextUniqueColor = pEnumRamp.Next();//将pNextUniqueColor指向之前创建好的色带pEnumRamp的下一个颜色
//若为空值则返回色带的第一个颜色进行赋值
if (pNextUniqueColor == null)
{
pEnumRamp.Reset();//跳回pEnumRamp顶部
pNextUniqueColor = pEnumRamp.Next();//将pEnumRamp的第一个颜色赋予pNextUniqueColor
}
ISimpleFillSymbol pSimpleFillSymbol = new SimpleFillSymbolClass();//
pSimpleFillSymbol.Color = pNextUniqueColor;
pUniqueValueRenderer.AddValue(codeValue.ToString(),"",pSimpleFillSymbol as ISymbol);
pNextRow = pCursor.NextRow();
}
pGeoFeatureLayer.Renderer = pUniqueValueRenderer as IFeatureRenderer;
axMapControl1.Refresh();
axTOCControl1.Refresh();
}
}
}
}
最后运行成果是这样的