第五讲 MO图形的绘制.doc

1、第五讲 MO 图形的绘制MO 虽然不是绘图软件，但经常要用到在地图上画点标明位置，画矩形或多边形标明地图查询范围等操作，因此也需要用到一些基本的绘图功能。MO 的绘图就是在 MAP 上产生图形对象的过程，图形对象主要有：Point（点），Points（点集）、Line（线）、Rectangle（矩形）、Polygon（多边形）、Ellipse（椭圆）。绘图时，先要创建一个绘图对象，给他赋值（位置和尺寸），再在 Symbol 对象中定义显示方式，最后用 Drawshape 方法在地图上显示这个图形。定义 Symbol 对象，不仅可以设置线型、填充方式、尺寸、颜色和字体等，还可以画出多种预定义的符

2、号。Drawshape 方法绘图外，还可以用 AddEvent 方法在动态图层上画动态图形对象（GeoEvent）。另外还可以用 DrawText 方法在地图上写字。一、DrawShape 绘图方法1、DrawShape 定义DrawShape 方法的语法为：object.DrawShape shape, symbol其中，object：为绘图目的对象，一般为 Map 对象；shape：为绘图内容，是图形对象（Point, Points, Line, Rectangle, Polygon or Ellipse）或记录集（Recordset）对象；symbol：是一个 Symbol 对象，说明绘

3、图方式。注意：调用 DrawShape 必须在 LAYER 或 TrackingLayer 的 drawing 事件中，即AfterTrackingLayerDraw，BeforeLayerDraw，BeforeTrackingLayerDraw，AfterLayerDraw 事件过程中才有效。如果指定一个 Recordset 作为 DrawShape 的参数，该数据集必须是从 GeoDataset 获取，而不是从一个 Table 对象获取，同时 MO 从 shape 字段的第一个特征值开始，到最后一个结束，然后又指向第一个记录。2、画点（1）预定义画点：可以用 Point 对象画一个点，也可

4、以用 Points 对象画多个点。示例：Dim sym As New MapObjects2.SymbolDim p As PointDim pts As PointsPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)Set pts = New PointsSet p = Map1.ToMapPoint(1000, 1000)pts.Add p是 Points 对象中的一个函数，功能是增加一个 Point 成员到 Points 对象内。Set p = Map1.ToMapPoint(3000, 2000

5、)pts.Add psym.Color = moRedsym.SymbolType = moPointSymbolsym.Size = 3Map1.DrawShape pts, symEnd Sub（2）利用鼠标点击画点：通过鼠标点击屏幕获取点的坐标，进行画点操作。示例：Dim sym As New MapObjects2.SymbolDim p As PointDim pts As New PointsPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)If Not pts Is Nothing The

6、nsym.Color = moRedsym.SymbolType = moPointSymbolsym.Size = 3Map1.DrawShape pts, symMap1.DrawShape pts, symEnd IfEnd SubPrivate Sub Map1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)Set p = Map1.ToMapPoint(X, Y)pts.Add pMap1.TrackingLayer.Refresh True TrackingLayer 对象是 MAP

7、控件中的一个图层，它描述位置可以动态改变的地理目标，Refresh 是 TrackingLayer 对象的成员函数，强制刷新TrackingLayer 对象。End Sub3、画线MO 中画线的基本原理是先设置两个点，将他们添加到一个 Points 对象中，再将 Points 对象放到一个 Line 对象中，使用 DrawShape 方法就可以画出一条线段来。如果在 Points 对象中有 N 个点，则可以产生一条 N-1 段的折线。（1）预定义点画线，示例：Dim g_line As MapObjects2.LineDim pts As PointsDim p As PointDim sym

8、 As SymbolPrivate Sub Command1_Click()Set g_line = New MapObjects2.LineSet pts = New PointsSet p = Map1.ToMapPoint(1000, 1000)pts.Add pSet p = Map1.ToMapPoint(2000, 3000)pts.Add pg_line.Parts.Add pts Parts 是 Line 对象的一个属性，此属性指向一个 Parts 集合对象，通过 Parts 属性可以检索组成线的片断（Parts），而 Parts 的每一个成员是一个点集（Points）。Set

9、 pts = g_line.Parts(0)Map1.RefreshEnd SubPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)If Not g_line Is Nothing ThenDim sym As New SymbolIf pts.Count 1 Then Count 属性表示当前 Points 对象内成员的数目，这是一个只读值。sym.Color = moRedsym.SymbolType = moLineSymbolsym.Size = 5Map1.DrawShape g_line,

10、symEnd IfEnd IfEnd Sub（2）鼠标点击获取点并画线，示例：Dim g_line As MapObjects2.LineDim pts As PointsDim p As PointDim sym As SymbolPrivate Sub Command1_Click()设置清空按钮Set g_line = NothingSet pts = NothingMap1.RefreshEnd SubPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)Dim sym As New SymbolI

11、f Not g_line Is Nothing Thensym.Color = moBlackMap1.DrawShape pts, symIf pts.Count 1 Thensym.Color = moRedsym.SymbolType = moLineSymbolsym.Size = 5Map1.DrawShape g_line, symEnd IfEnd IfEnd SubPrivate Sub Map1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)If Button = 1 ThenI

12、f g_line Is Nothing ThenSet g_line = New MapObjects2.LineEnd IfIf pts Is Nothing ThenSet pts = New PointsEnd IfSet p = Map1.ToMapPoint(X, Y)pts.Add pIf pts.Count = 1 Theng_line.Parts.Add ptsSet pts = g_line.Parts(0)End IfMap1.TrackingLayer.Refresh TrueElseMsgBox “right“End IfEnd Sub4、画矩形和椭圆（1）预定义画矩形

13、：画矩形是先定义一个矩形对象，给它的 top、left、bottom、right属性赋值，再使用 DrawShape 方法就可以画出一个矩形来。定义矩形范围时，可以先确定一个中心点，再确定一个半径（或 X 方向半径和 Y 方向半径），得到 top、left、bottom、right 的值。示例：Option ExplicitDim rect As MapObjects2.RectanglePrivate Sub Command1_Click()Dim dist As DoubleDim pt As New PointSet rect = New MapObjects2.Rectangledis

14、t = 0.2Set pt = Map1.ToMapPoint(2500, 1500)这里可以动态设置中心点的位置rect.Right = pt.X + distrect.Left = pt.X - distrect.Top = pt.Y + distrect.Bottom = pt.Y - distMap1.RefreshEnd SubPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)If Not rect Is Nothing ThenDim sym As New Symbolsym.SymbolT

15、ype = moFillSymbolsym.Style = moDiagonalCrossFillsym.Color = moBlueMap1.DrawShape rect, symEnd IfEnd Sub（2）定义一个矩形框对象后，进行画矩形。示例：Option ExplicitDim rect As MapObjects2.RectanglePrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)Dim sym As New MapObjects2.SymbolIf Not rect Is Nothin

16、g Thensym.SymbolType = moFillSymbolsym.Style = moDiagonalCrossFillsym.Color = moBlueMap1.DrawShape rect, symEnd IfEnd SubPrivate Sub Map1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)Set rect = Map1.TrackRectangleMap1.TrackingLayer.Refresh TrueEnd Sub用同样的方法可以画出椭圆来。5、用 Trac

17、k 方法画图形在 MO 中还可以用一类方法在地图上半自动画图，如：TrackCircle 方法，点击产生圆心，拖动产生半径，放手成圆形；TrackRectangle 方法，点击产生一个角，拖动放大，放手形成矩形；TrackPolygon 方法，点击画几条直线，双击形成多边形图形。这一类方法都是以 Track 开头，所以称为 Track 画图方法，这和 TrackingLayer（动态图层）毫无关系。示例：Option ExplicitDim eli As MapObjects2.EllipseDim recs As MapObjects2.RectangleDim ply As MapObje

18、cts2.PolygonPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)Dim sym As New MapObjects2.Symbolsym.SymbolType = moFillSymbolsym.Style = moDiagonalCrossFillIf Not recs Is Nothing Thensym.Color = moBlueMap1.DrawShape recs, symEnd IfIf Not eli Is Nothing Thensym.Color = moRedMap1.D

19、rawShape eli, symEnd IfIf Not ply Is Nothing Thensym.Color = moGreenMap1.DrawShape ply, symEnd IfEnd SubPrivate Sub Map1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)If Option1 ThenSet recs = Map1.TrackRectangleElseIf Option2 ThenSet eli = Map1.TrackCircleElseSet ply = Map

20、1.TrackPolygonEnd IfMap1.TrackingLayer.Refresh TrueEnd Sub二、写文字MO 一般采用 DrawText 方法在地图上写文字，也可以用画点时的 motruetypemarker 方式，在地图上写各种地图上常用的符号。1、DrawText 方法用 DrawText 方法可以在地图上写文字，语法结构为：object.DrawText text, shape, symbol其中，object：对象，text：字符串，shape：参照图形，可以是点、点集、线和矩形；symbol：为一个 Textsymbol 显示对象。如果参照图形为点，则文字中心在

21、点上；如果为点集，则中心在点集的范围中心上；为直线，中心在线段的中心上，方向同线段的方向；为折线，则文字的中心和方向按照点集的样条插值计算；如果为矩形，则文字国矩形中心的水平线排列。（1）在点击出写文字示例：Option ExplicitDim p As MapObjects2.PointDim tSym As New TextSymbolPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)If Not p Is Nothing ThenDim sym As New SymboltSym.Color =

22、moRedMap1.DrawText Text1.Text, p, tSymEnd IfEnd SubPrivate Sub Map1_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)Set p = Map1.ToMapPoint(x, y)Map1.TrackingLayer.Refresh TrueEnd Sub（2）在线段上添加文字示例：Option ExplicitDim g_line As MapObjects2.LineDim pts As MapObjects2.PointsPriva

23、te Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE) make sure theres a lineIf Not g_line Is Nothing Then make sure theres at least two points in the lineIf pts.Count 1 ThenDim tSym As New TextSymbol use the font of the textbox controlSet tSym.Font = Text1.FontDim sym As New Symbolsym.

24、Color = moRedMap1.DrawShape g_line, symMap1.DrawText Text1.Text, g_line, tSymEnd IfEnd IfEnd SubPrivate Sub Map1_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)If Button = 1 Then create the line if it does not existIf g_line Is Nothing ThenSet g_line = New MapObjects2.LineEn

25、d IfIf pts Is Nothing ThenSet pts = New MapObjects2.PointsEnd If create a point and add it to the lineDim p As PointSet p = Map1.ToMapPoint(x, y)pts.Add pIf pts.Count = 1 Theng_line.Parts.Add ptsSet pts = g_line.Parts(0)End If refresh the trackingLayerMap1.TrackingLayer.Refresh TrueElseDim r As MapO

26、bjects2.RectangleSet r = Map1.TrackRectangleIf Not r Is Nothing Then Map1.Extent = rEnd IfEnd Sub三、SymbolSymbol 是控制地图上的特征或图形的显示方式的对象或属性，图上的特征都是通过设置图层的 Symbol 属性来实现的，如：layer.Symbol.Color = moRed，如果没有设置图层的 Symbol属性，MO 就会使用缺省的线型、填充方式、尺寸、字体和随机的颜色。在设置图形的显示方式时，要定义一个 Symbol 对象：Dim sym As New Symbol再设置 Symb

27、olType 属性，这说明显示对象是点、线还是面，使用的常量如下：Constant Value DescriptionmoPointSymbol 0 symbol for a Point or Points objectmoLineSymbol1 symbol for a Line objectmoFillSymbol2 symbols for a Polygon, Rectangle or Ellipse object例如：sym.SymbolType = moFillSymbol然后就可以设置 Symbol 的 style 属性，对于点来设置点的形状和预定义的符号，对于线对象来设置线型，对

28、于面对象来设置填充方式。最后来设置 size、color、font 等。使用预定义符号：在画点时，设置 Symbol 的 style 属性为 moTrueTypeMarker 方式，可以在地图上写各种地图上常用的符号，先设置：sym.Style = moTrueTypeMarker，然后再设置sym.CharacterIndex = 35。CharacterIndex 的序号是从 33 开始的。下面就是一个使用预定义字符的例子：Option ExplicitDim Pt(400) As MapObjects2.PointDim Pt1(400) As MapObjects2.PointDim

29、Sym(400) As New MapObjects2.SymbolDim tSym As New MapObjects2.TextSymbolPrivate Sub Form_Load()Dim i As IntegerDim Swidth As IntegerDim Sheight As Integer Swidth = Screen.Width Sheight = Screen.HeightSwidth = 800 * 15Sheight = 600 * 15Me.Height = Sheight - 100Me.Width = Swidth - 300Map1.Height = Me.

30、Height - 200Map1.Width = Me.Width - 200Map1.Top = 100Map1.Left = 100For i = 0 To 399With Sym(i).Style = moTrueTypeMarker.SymbolType = moPointSymbol.Font = “ESRI Transportation & Municipal“.Size = 20.Style = moTrueTypeMarker.Color = moBlackEnd WithNext itSym.Color = moBlacktSym.Font.Size = 10End SubP

31、rivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)Dim i As IntegerFor i = 0 To 399If Not Pt(i) Is Nothing ThenMap1.DrawShape Pt(i), Sym(i)Map1.DrawText 33 + i, Pt1(i), tSymEnd IfNext iEnd SubPrivate Sub Map1_Click()Dim i As Integer, j As Integer, k As IntegerConst Mx0 = 400Const

32、My0 = 300Const Mxc = 520Const Myc = 800k = 0j = 0For i = 0 To 199For i = 200 To 399Set Pt(i) = Map1.ToMapPoint(j * Mxc + Mx0, My0 + k * Myc)Set Pt1(i) = Map1.ToMapPoint(j * Mxc + Mx0, My0 + 400 + k * Myc)Sym(i).CharacterIndex = 33 + ij = j + 1If j = 20 Thenj = 0k = k + 1End IfNext iMap1.TrackingLaye

33、r.Refresh TrueEnd Sub画出交通和市政的预定义符号，符号代码如下：Option ExplicitDim Pt(400) As MapObjects2.PointDim Pt1(400) As MapObjects2.PointDim Sym(400) As New MapObjects2.SymbolDim tSym As New MapObjects2.TextSymbolPrivate Sub Form_Load()Dim i As IntegerDim Swidth As IntegerDim Sheight As IntegerDim fnt As New StdFo

34、ntfnt.Name = “Wingdings“ Swidth = Screen.Width Sheight = Screen.HeightSwidth = 800 * 15Sheight = 600 * 15Me.Height = Sheight - 100Me.Width = Swidth - 300Map1.Height = Me.Height - 200Map1.Width = Me.Width - 200Map1.Top = 100Map1.Left = 100For i = 0 To 399With Sym(i).Style = moTrueTypeMarker.SymbolTyp

35、e = moPointSymbol.Font = “ESRI Transportation & Municipal“.Font = fnt.Size = 20.Style = moTrueTypeMarker.Color = moBlackEnd WithNext itSym.Color = moBlacktSym.Font.Size = 10End SubPrivate Sub Map1_AfterTrackingLayerDraw(ByVal hDC As stdole.OLE_HANDLE)Dim i As IntegerFor i = 0 To 399If Not Pt(i) Is N

36、othing ThenMap1.DrawShape Pt(i), Sym(i)Map1.DrawText 33 + i, Pt1(i), tSymEnd IfNext iEnd SubPrivate Sub Map1_Click()Dim i As Integer, j As Integer, k As IntegerConst Mx0 = 400Const My0 = 300Const Mxc = 520Const Myc = 800k = 0j = 0For i = 0 To 199For i = 200 To 399Set Pt(i) = Map1.ToMapPoint(j * Mxc + Mx0, My0 + k * Myc)Set Pt1(i) = Map1.ToMapPoint(j * Mxc + Mx0, My0 + 400 + k * Myc)Sym(i).CharacterIndex = 33 + ij = j + 1If j = 20 Thenj = 0k = k + 1End IfNext iMap1.TrackingLayer.Refresh TrueEnd Sub