delphi操作mapx部分技巧

Delphi中使用Mapx目录一．在地图上创建图层 (1)二．在符号图元中使用自定义位图 (1)三．屏幕坐标向地图坐标的转换 (2)四．查找某一城市 (3)五.鼠标点击选中一片区域 (3)六．从数据库绘制MapX地图 (4)七．MapX使用数据库数据添加专题图 (6)八．在mapx中画圆 (10)九．动态加载一个目录下所有图层 (11)安装好MapX后，选择Delphi的Component->Import Active菜单添加，MapInfo MapX组件。

添加完成后，在ActiveX面板上，将会出来一个TMap控件。

拖一个TMap 控件到工程中改名为MainMap,这样就产生了一个TMap的对象。

一．在地图上创建图层使用Layers属性的CreateLayer函数来创建一个图层yers.CreateLayer(Name,[FileSpec],[Position],[KeyLength],[CoordSys]);参数说明:Name:指定图层的名称FileSpec:所创建图层的路径名。

如'c:\china.tab'Position:它在图层列表中的初始位置.（其实就是在图层列表中的一个序列号）CoorSys:指定存储新图层的坐标系。

附：图层类型参数:miLayerTypeNormalmiLayerTypeRastermiLayerTypeSeamlessmiLayerTypeUnknownmiLayerTypeUserDrawmiLayerTypeDrilldownFeatureFactory对象的方法使您可以创建新的地图图元，也可通过对现有图元执行操作（例如缓冲区）来创建图元。

以下是FeatureFactory对象的方法：BufferFeaturesCombineFeaturesCreateArcCreateCircularRegionCreateEllipticalRegionCreateLineCreateRegionCreateSymbolCreateTextEraseFeatureIntersectFeaturesIntersectionPointsIntersectionTest二．在符号图元中使用自定义位图定义一个cs:CMapXStyle做为图元的样式属性设置cs:=coStyle.Create;cs.SymbolType:=miSymbolTypeBitmap;cs.SymbolBitmapName:='HOUS2-32.BMP';cs.SymbolBitmapSize:=40;注意：自定义的位图一定要放到C:\Program Files\Common Files\MapInfo Shared\MapX Common\CUSTSYMB下，这是MapInfo安装的黩认共享路径。

三．屏幕坐标向地图坐标的转换procedure TMapForm.Map1MouseUp(Sender:TObject;Button:TMouseButton;Shift:TShiftState;X,Y:Integer);varlon,lat:Double;singleX,singleY:Single;fs:CMapXFeatures;pnt:CMapXPoint;name:String;beginif Map1.CurrentTool=miArrowTool thenbeginpnt:=CoPoint.Create;singleX:=X;singleY:=Y;Map1.ConvertCoord(singleX,singleY,lon,lat,miScreenToMap);pnt.Set_(lon,lat);fs:=yers.Item('US Top20Cities').SearchAtPoint(pnt);if fs.Count>0thenbeginname:=fs.Item(1).Name;Application.MessageBox(PChar(name),'Info',0)endelseApplication.MessageBox('Nothing found','Nope',0);end;end;备注：获取一个图元时最好用Layer.GetFeatureByID(FeatureKey);四．查找某一城市procedure TForm2.SearchForCapital(Capital:String);varFoundF:FindFeature;//在小城市层查beginFoundF:=yers.Item['US Minor Cities'].Find.Search(Capital, EmptyParam);//在us minor cities层中查找capitalif(FoundF.FindRC mod10)=1thenbeginyers.Item['US Minor Cities'].Selection.Replace(FoundF);Map1.Zoom:=60;//60英里Map1.CenterX:=FoundF.CenterX;Map1.CenterY:=FoundF.CenterY;endelseApplication.MessageBox('No exact match found.','Nope',0);end;五.鼠标点击选中一片区域procedure TForm2.Map1ToolUsed(ASender:TObject;ToolNum:Smallint;X1, Y1,X2,Y2,Distance:Double;Shift,Ctrl:WordBool;var EnableDefault:WordBool);varftrs:Features;//CMapXFeatures;newJersey:FindFeature;//CMapXFindFeature;usaLayer:Layer;//CMapXLayer;pt:Point;beginif ToolNum=miSelectTool thenbeginpt:=CoPoint.Create;pt.Set_(X1,Y1);usaLayer:=yers.Item['USA'];newJersey:=usaLayer.Find.Search('NY',EmptyParam);//找到ny500英里之内的区域ftrs:=usaLayer.SearchWithinDistance(pt,500,miUnitMile, miSearchTypePartiallyWithin);mon(usaLayer.SearchWithinDistance(newJersey,500,miUnitMile, miSearchTypePartiallyWithin));usaLayer.Selection.Replace(ftrs);//选中end;end;六．从数据库绘制MapX地图这里提供的是一种更为高效的从数据库绘制MapX地图的方法，我在数据库中建立了如下的数据表：表名称：XunitID：字符串//用于唯一标识各个图元，也可以是数字类型的NAME：字符串//图元的名称X：浮点数//图元横坐标Y：浮点数//图元纵坐标代码清单：//aqXUnit是一个TADOQuery，其中SQL语句为“SELECT*FROM XUNIT”。

procedure TfrmMain.DrawLayerFromDB;varoBLayer:BindLayer;SearchLayer:Layer;ds:Dataset;begin//使用这个过程必须保证aqXUnit表已经打开！if not aqXUnit.Active thenbeginGiveMsg('系统基础表没有打开！');//调用自定义提示方法exit;end;oBLayer:=coBindLayer.Create;yerName:='ARTEMIS';yerType:=miBindLayerTypeXY;//必须使用这个参数才能绑定XY坐标oBLayer.RefColumn1:='X';//第一个参数必须指定为横坐标oBLayer.RefColumn2:='Y';//纵坐标//添加数据集ds:=mapMain.Datasets.Add(12,//数据集类型，这是miDataSetADO，即ADO专用的aqXUnit.Recordset,//使用这个方法获得ADO中的_Recordset类型'DS_SK',//数据集名称'ID',//传入的是Xunit表中的字段ID的名称EmptyParam,oBLayer,//BindLayerEmptyParam,EmptyParam);//下边将设置新图层的各项属性searchLayer:=yers.Item('ARTEMIS');//字体颜色belProperties.Style.TextFontColor:=miColorPurple;belProperties.Style.TextFontHalo:=true;belProperties.Style.TextFontBackColor:=miColorWhite;//设置图元显示的标签belProperties.Dataset:=ds;belProperties.DataField:=ds.Fields.Item('NAME');belZoom:=true;//设置图层缩放比例范围searchLayer.ZoomMin:=0;searchLayer.ZoomMax:=200;searchLayer.ZoomLayer:=true;//设置标签缩放比例范围belZoomMin:=0;belZoomMax:=200;belZoom:=true;//自动标记图元searchLayer.AutoLabel:=true;end;七．MapX使用数据库数据添加专题图OBJECT.Add([Type],[Field],[Name],[ComputeTheme])OBJECT Represents a Themes object.Type Specifies the type of thematic map to create.This takes a ThemeTypeConstants value.This is an optional parameter,and if not specified(or specified as miThemeAuto),MapX will attempt to choose a good default based on the number of fields passed in as well as what other theme types are already being displayed.If MapX cannot choose a default theme type,an error is generated.Field(s)Specifies the field or fields to thematically map.A field can be specified by name,index,or by a Field object.If you are creating a theme using multiple variables(such as a bar chart or pie chart),pass in a Fields collection or an array of field names,indexes,or Field objects.This is an optional parameter, and if not specified,MapX uses the first numeric field of the Dataset.Name Specifies the name of the thematic map.This is a String parameter.This is an optional parameter,and if not specified,MapX generates a name such as StatesBySales.ComputeTheme Boolean.The default value is True which will calculate the theme from the table data.If the value is set to False an invisible theme object will be created with10ranges for IndividualValue themes and5ranges for Ranged themes. You can then manually set the minimum and maximum values to define the theme with Theme.DataMin and Theme.DataMax.For ranged themes you can manually set the theme ranges or calculate equal size ranges determined by the minimum(Theme.DataMin) and maximum(Theme.DataMax)values.关于专题图的风格共有以下几种：miThemeRanged=0miThemeBarChart=1miThemePieChart=2miThemeGradSymbol=3miThemeDotDensity=4miThemeIndividualValue=5miThemeAuto=6miThemeNone=9下面是我写的部分代码：unit Main;interfaceusesWindows,Messages,{略去一部分}SysUtils,Variants,Classes;typeTfrmMain=class(TForm)mapMain:TMap;{地图控件}private{Private declarations}ThemesList:TStringList;{用来保存多个专题图的名称列表} public{Public declarations}procedure ToAddThemes(style:integer;TheName:string);{添加专题图} procedure ToDeleteThemes;{删除专题图}end;varfrmMain:TfrmMain;implementation{$R*.dfm}{略去其他功能代码}{添加专题图，参数style表示专题图风格，TheName表示图例标题}procedure TfrmMain.ToAddThemes(style:integer;TheName:string);function DefaultName:string;{用来生成一唯一的名称}begin{我用的方法是取一个当前时间，两次调用本函数的时间间隔应该不会少于0.5秒，所以这个方法在这个项目中可以取得唯一的名称}Result:='YYT'+FormatDateTime('YYYYMMDDHHNNSSzzz',now);end;varflds:array of string;{字段列表}oBLayer:BindLayer;{绑定图层}ds:Dataset;{MapX数据集}i:integer;{循环变量}thm:theme;{MapX专题图}str:string;{用于保存字符串}begin{aqThemes可以是一个ADOQuery或者ADOTable，我使用的是ADOQuery。