Hi every one, sorry for my bad English.
I am newbie and I am doing a small tool to show and update Attribute table from a shapefile.
I can use Identified event to get Fields of the Selected shape, then show Attribure of this shape to a Datagridview in VB.Net.
I can either Generate Label for this data. The data in Datagridview and Label is good. You can see in the picture.
The problem is, when I turn on Editing mode, I change something in Attribute table, the label is updated successfully. Data still be OK. But when I save the shapefile by
sf.StopEditingTable(True)
The string in label and datagridview become unreadable. I think there is something wrong with unicode Encoding.
is only the text of your modified label after saving unreadable, or all other labels as well?
When you edit and save something you’re operating in the realms of MapWinGIS, depending on the type of layer you’re working with, the GlobalSetting.OgrStringEncoding might make a difference,
if you haven’t already playing with it.
I havn’t used GlobalSetting.OgrStringEncoding before. I searced for this class example but found nothing. Can you explain more detail or give me a way to solve this problem.
Many thanks.
i haven’t worked with that setting either, but i would suggest, that you try, when loading the form containing the ocx you generate a new MapWinGis.GlobalSettings-Object and set its StringEncoding.
In VBA it would mean placing these lines in the Form_Load-Event
DIM myGlobalSettings as New MapWinGis.GlobalSettings
myGlobalSettings.OgrStringEncoding = oseUtf8
If the value “oseUtf8” doesn’t work, you can try to set it to the other available value “oseAnsi”.
But as i wrote, this is just a suggestion and depends on the kind of layer you’re using.
It might help to post some of your code. I notice that you use StopEditingTable (rather than StopEditingShapes, which also saves the table data).
Also, if you are using a Shapefile, does it have a corresponding code page file (.CPG).
MapWinGIS will use the code page file, if present, and otherwise will assume UTF-8, and so it should handle your strings properly on the way in and on the way out.
Thanks so much for your help. I checked that every shapefile has “.cpg” file and it’s content is “UTF-8”.
When the first time I load the Attribute table to a Datagridview and generate Label for it, everything works well. But when I StartEditingTable and then immediately StopEditingTable with no changes (see code below), the string still become unreadable.
Private Sub Button4_Click_1(sender As Object, e As EventArgs) Handles Button4.Click
Dim sf As Shapefile = New Shapefile()
sf = AxM.get_Shapefile(txtLayerHandle.Text)
If sf IsNot Nothing Then
If sf.Table.StartEditingTable Then
WL("Turned on Editing.")
If sf.Table.StopEditingTable(True) Then
WL("Turned off Editing and Saved!")
End If
End If
End If
End Sub
Additional information:
Content of .cpg file:
Content become unreadble after click Button4 (Button4_Click_1)
Private Sub btnStartEditing_Click(sender As Object, e As EventArgs) Handles btnStartEditing.Click
If isEditingMode Then
saveEditing()
Else
isEditingMode = True
btnStartEditing.Text = "Stop editing"
Dim sf As Shapefile = New Shapefile()
sf = AxM.get_Shapefile(txtLayerHandle.Text)
If (Not sf.Table.StartEditingTable(Nothing)) Then
WL("Không thể bật chế độ Editing. Chi tiết: " & sf.Table.ErrorMsg(sf.LastErrorCode))
Else
WL("Đã bật chế độ Editting trên LayerHanle = " & txtLayerHandle.Text)
AxM.Identifier.IdentifierMode = tkIdentifierMode.imAllLayersStopOnFirst
AxM.CursorMode = tkCursorMode.cmIdentify
AxM.ZoomToLayer(layerHandle)
AxM.CurrentZoom -= 1
isEditingMode = True
End If
End If
btnAddShape.Enabled = isEditingMode
btnDeleteShape.Enabled = isEditingMode
End Sub
Save data sub
Private Sub saveEditing()
Dim sf As Shapefile = New Shapefile()
sf = AxM.get_Shapefile(txtLayerHandle.Text)
If sf IsNot Nothing And isDataChanged Then 'isDataChanged set to True when user make some changes on Attribute table
Select Case MsgBox("Bạn có muốn lưu lại kết quả đã chỉnh sửa?", vbYesNoCancel, "Thông báo")
Case MsgBoxResult.Yes
'WL is just the sub write log file
If sf.Table.StopEditingTable(True) Then
'Stop editing and Saved
WL("Đã tắt chế độ edit và Đã lưu bảng thuộc tính của shapefile.")
Else
'Cannot stop editing
WL("Error Stop Editing Shape: " & sf.ErrorMsg(sf.LastErrorCode))
End If
Case MsgBoxResult.No
'Stop editing and do not save
sf.Table.StopEditingTable(False)
WL("Đã tắt chế độ edit và Không lưu bảng thuộc tính của shapefile.")
Case MsgBoxResult.Cancel
Exit Sub
End Select
End If
isDataChanged = False
isEditingMode = False
isAddingShape = False
btnStartEditing.Text = "Start editing"
AxM.IdentifiedShapes.Clear()
For i As Integer = 0 To AxM.NumLayers - 1
Dim sfx As Shapefile = New Shapefile()
sfx = AxM.get_Shapefile(i)
sfx.SelectNone()
Next
AxM.CursorMode = tkCursorMode.cmPan
End Sub
Rather than going through the Table class (StartEditingTable and StopEditingTable), can you try instead using the higher level sf.StartEditShapes and sf.StopEditingShapes? These calls encapsulate the Table operations, and perform some additional steps, and I’m curious to see if the same problem occurs.
If there is still a problem, do you mind submitting the Shapefile, or a small subset of the shapefile with the encoded strings. I can debug the OCX on this end to determine where the problem lies.
Private Sub Button4_Click_1(sender As Object, e As EventArgs) Handles Button4.Click
Dim sf As Shapefile = New Shapefile()
sf = AxM.get_Shapefile(txtLayerHandle.Text)
If sf IsNot Nothing Then
If sf.StartEditingShapes(True) Then
WL("Turned on Editing.")
If sf.StopEditingShapes(True, True) Then
WL("Turned off Editing and Saved!")
End If
End If
End If
End Sub
I found and fixed the problem and got it working. I’m perplexed as to how this has been broken for so long without being more evident - perhaps because we’ve been fixing Unicode issues as related to OGR datasources, but not looking at the issues as related to Unicode Shapefiles (perhaps they are less common).
So as it is, I’ve still got some things to work through. In this case, the code was assuming the ANSI code page, and I’ve now accounted for Shapefiles specified as UTF-8, but I’m still uncertain about how we are handling other code pages.
Then I need to document the changes and create a Jira issue to log the bug and the fix.
At the moment, I don’t have a work-around to suggest for you. If @pmeems is willing, perhaps we can get an update soon that incorporates the most recent fixes.
I agree that Unicode Shapefiles is less common, primarily in the Asia.
I hope that this problem will be fix soon. I am eager to hear good news from you @jerryfaust@pmeems
You said that you found and fixed the problem and got it working. And in this case, the code was assuming the ANSI code page. So can you tell me the way to force this to UTF8 code page, because all of my shapefiles is in UTF8.
Thank you so much.
Without a code change to the OCX, the Shapefile output will default to ANSI. It occurs to me, however, that you may be able to get around the problem by opening the Shapefile as an OGR datasource. I don’t have time right now to give you more detail, but I may be able to review it this weekend.
