八个mapx技巧汇总
一、在mapx中查找对象的方法
两种方式：
1．使用Find对象的Search方法。
在mapx3.5中只能作到完全匹配查找，在MapX4.0中SearchEx方法则可以找到多个匹配的记录，其结果由FindResult.Matches获取。详细请参看
有关Find.SearchEx 方法的文档以及示例。
2． 使用Layer 对象的OBJECT.Search (strWhere)方法。其参数为SQL查询的WHERE子句。例如：
Set ftrs = lyr.Search("Character_Name = ""北京市""") ；
Set ftrs = lyrUSA.Search("TOTPOP > 1000000")
注意：
1。字符串外加两个双引号。
2。首先将图层加入数据集Datasets 才能使用查询。
模糊查询最方便的方法是使用第二种方法例如
Set ftrs = lyr.Search("Character_Name like ""%市""") ；
二、在mapx中如何紧缩表
在Mapx4.51下可以使用LayerInfo 的创建带结构的临时表和新表的功能来完成紧缩：
Set lyr = Formmain.Map1.Layers(ToolBars.combo1.Text)
Set ds = Formmain.Map1.Datasets.add(6, lyr)
'获取被紧缩表的路径及表名
filespec = Formmain.Map1.Layers.Item(ToolBars.combo1.Text).filespec
layername = lyr.Name '将表临时存放于内存
LayerInfo.Type = 6 'miLayerInfoTypeTemp
LayerInfo.AddParameter "TableStorageType", "MemTable" '临时文件保存在磁盘上还是内存。
LayerInfo.AddParameter "Name", "lyrpack"
LayerInfo.AddParameter "Fields", ds.Fields
LayerInfo.AddParameter "Features", lyr.AllFeatures
Formmain.Map1.Layers.add LayerInfo, LayerPos
Set LayerInfo = Nothing
'从地图窗口删除原表
Formmain.Map1.Datasets.Remove (ds.Name)
Formmain.Map1.Layers.Remove (lyr.Name)
Formmain.Map1.Refresh
Set lyr = Nothing
Set ds = Nothing
Set lyr = Formmain.Map1.Layers("lyrpack")
Set ds = Formmain.Map1.Datasets.add(6, lyr)
'从磁盘删除原表
Kill filespec
三、在mapx中如何使用自定义栅格符号
使用自定义符号首先需要设定style.SymbolType 为miSymbolTypeBitmap，然后指定SymbolBitmapName 为栅格图像名即可。
下面的代码演示了如何在delphi中使用自定义的栅格符号
首先调用自定义工具画点
procedure TForm1.new1Click(Sender: TObject);
begin
map1.ControlInterface.CurrentTool :=111;
end;
在tooluses事件中如下：
procedure TForm1.Map1ToolUsed(Sender: TObject; ToolNum: Smallint; X1, Y1,
X2, Y2, Distance: Double; Shift, Ctrl: WordBool;
var EnableDefault: WordBool);
var
ssymbol :cmapxstyle;
p: CMapXPoint;
f: cmapxfeature;
begin
ssymbol:=costyle.create;
ssymbol.SymbolType :=1;
ssymbol.SymbolBitmapSize:=25;
{请注意将test.bmp文件考到mapx “共有文件路径”+“"CUSTSYMB”路径下,例如C:"Program Files"Common Files"MapInfo Shared"MapX
Common 是 MapX 共有文件的缺省安装路径}
ssymbol.SymbolBitmapName:='test.BMP';
p := CoPoint.Create;
f :=cofeature.Create ;
p.Set_(x1,y1);
if toolnum=111 then begin
f:=map1.ControlInterface.FeatureFactory.CreateSymbol(p,ssymbol);
map1.ControlInterface.Layers.Item(1).AddFeature(f,EmptyParam);
end;
四、在mapx中如何使用自定义鼠标
在mapx4.0，及以上版本中允许用户自定义鼠标。程序如下：
Map1.MousePointer = miCustomCursor
Map1.MouseIcon = "c:"windows"cursors"globe.ani"
mapx 中还对鼠标滚动轮提供支持，属性如下
Map.MouseWheelSupport=miMousewheelNoAutoScroll
五、mapx 打印地图时的参数如何设置
在mapx 的 printmap方法：PrintMap (hDC x, y, w, h)之中，w,h,x,y的单位为himetric，1 himetric=0.01毫米。所以，打印地图时需要将w
，h 乘100换算为毫米。
在vb 中例子：
Private Sub Command4_Click()
On Error GoTo ErrorHandler ` Set up error handler.
' coords must be in himetric
' print same size as on screen, in upper left of page
ScaleMode = 6 `set mode to mm
' there is no Printer.StartDoc method, it seems it is done
' implicitly when you use one of the printer.print methods
' so we need to print something before we print our map
' to start the page
Printer.CurrentX = 0
Printer.CurrentY = 0
Printer.Print " "
Map1.PrintMap Printer.hDC, 0, 0, Map1.Width * 100, _
Map1.Height * 100
Printer.NewPage ` Send new page.
Printer.EndDoc ` Printing is finished.
Exit Sub
在vc中例子
// Map.PaperUnit Property
// Map.PrintMap Method
void CSampleProjectView::OnPrintMap(CDC* pDC,CPrintInfo* pInfo) {
try {
// get paper width in mm and convert to HIMETRIC (100th of a mm)
m_Map.SetPaperUnit(miUnitMillimeter);
double pw = m_Map.GetMapPaperWidth() * 100;
double ph = m_Map.GetMapPaperHeight()* 100;
m_Map.PrintMap((long)pDC->m_hDC,
pInfo->m_rectDraw.left,pInfo->m_rectDraw.
top,(long)pw,(long)ph);
} catch (COleDispatchException *e) {
e->ReportError();
e->Delete();
} catch (COleException *e) {
e->ReportError();
e->Delete();
}
}
六、mapx中创建测距工具示例
首先创建测距工具
global const calculatedistance=1
Private Sub Form_Load()
map1.CreateCustomTool(calcilatedistance,miToolTypepoly ,microsscursor)
End Sub
Private Sub Distances_Click()
map1.currenttool=calculatetool
End Sub
然后在mapx的PolyToolUsed事件中， 用Distance( x1,y1,x2,y2 )计算距离，由状态条中或label显示。
Private Sub Map1_PolyToolUsed(ByVal ToolNum As Integer, ByVal Flags As Long, ByVal points As Object, ByVal bShift As Boolean,
ByVal bCtrl As Boolean, EnableDefault As Boolean)
Dim DisSum As Double
Dim Dis As Double
Dim n As Integer
Dim pts As New MapXLib.points
Dim x1 As Double, y1 As Double, x2 As Double, y2 As Double
Set pts = points
DisSum = 0
MDIForm1.StatusBar1.Panels.Item(3).Text= Format(Str(DisSum), "#,##0.000000")
Select Case Flags
Case miPolyToolBegin
Case miPolyToolInProgress
If ToolNum = CalculateDistance Then
For i = 1 To pts.Count - 1
x1 = pts.Item(i).X
y1 = pts.Item(i).Y
x2 = pts.Item(i + 1).X
y3 = pts.Item(i + 1).Y
Dis = Map1.Distance(x1, y1, x2, y2)
DisSum = DisSum + Dis
MDIForm1.StatusBar1.Panels.Item(3).Text = Format(Str(DisSum), "#,##0.000000")
Next i
End If
Case miPolyToolEnd
End Select
七、在mapx中如何实现自动滚屏
mapx 支持 MouseMove 事件，可以在此事件中实现自动滚屏，示例如下：
Private Sub Map1_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
If map_move = True Then
If X > Map1.MapScreenWidth - 10 Then
Map1.CenterX = Map1.CenterX + 0.05
Map1.Refresh
Else
If X < 10 Then
Map1.CenterX = Map1.CenterX - 0.05
Map1.Refresh
Else
If Y > Map1.MapScreenHeight - 10 Then
Map1.CenterY = Map1.CenterY - 0.05
Map1.Refresh
Else
If Y < 10 Then
Map1.CenterY = Map1.CenterY + 0.05
Map1.Refresh
End If
End If
End If
End If
End If
End Sub
八、在mapx中如何实现图元的拖拽
以下方法实现将选中图元移到点击处。
Private Sub Map1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
Dim ftr As Feature
Dim lyr As Layer
Dim MapX As Double
Dim MapY As Double
'convert where the mouse is clicked to the map's current coordinate system
Map1.ConvertCoord X, Y, MapX, MapY, miScreenToMap
'iterate through each selected feature in each layer
For Each lyr In Map1.Layers
For Each ftr In lyr.Selection
'change the offset of the feature
ftr.Offset MapX - ftr.CenterX, MapY - ftr.CenterY
'update the feature to make the change permanent
ftr.Update
Next
Next
End SUb