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Home Forums Silverlight Programming Programming with .NET - General URGENT need help! Datagrid template column load event, strange behavior
15 replies. Latest Post by PrisonBreak on November 6, 2008.
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PrisonBreak
Member
31 points
61 Posts
09-17-2008 5:06 AM |
Hi SL masters,
I have a very strange problem and do not know the reason causes that.
I have a datagrid in my program which has a template column and some other regular columns. I used the template column because according to the data it contains I want it to change its backcolor. So I used a button control in my template column and added a loaded event to this button you can see the datagrid code. I implemented the loaded event in my code, I am pasting the loaded event source code, too. Now the problem: When my datagrid first loads everthing is ok the color is changed according to the condition in the event code and it works fine. The problem arises when I begin to scroll on my datagrid. The first picture below is the picture of my datagrid's first load, everthing is fine. The second picture is the picture when I scroll on my datagrid to the bottom and come back to the top. Why after some scrolling the template column changes its color randomly I can not understand...
Please somebody help me I have a demo of my project tomorrow I have to fix this problem. Looking forward for help...
1 <my1:DataGrid x:Name="HedefDataGrid" AlternatingRowBackground="Lavender" VerticalScrollBarVisibility="Visible" 2 AutoGenerateColumns="False" Width="auto" Height="auto" Grid.Row="0" Grid.Column="0" 3 Visibility="Collapsed" CanUserResizeColumns="False" SelectionChanged="HedefDataGrid_SelectionChanged" 4 IsReadOnly="True" ColumnHeaderStyle="{StaticResource DataGridStyle}">5 <my1:DataGrid.Columns>6 <my1:DataGridTextColumn Header="Alt Limit" DisplayMemberBinding="{Binding altLimit}" 7 Width="105" ElementStyle="{StaticResource DataGridTextColumnStyle}" />8 <my1:DataGridTextColumn Header="Hedef" DisplayMemberBinding="{Binding hedefDeger}" 9 Width="70" ElementStyle="{StaticResource DataGridTextColumnStyle}" />10 <my1:DataGridTextColumn Header="Üst Limit" DisplayMemberBinding="{Binding ustLimit}" 11 Width="105" ElementStyle="{StaticResource DataGridTextColumnStyle}" />12 13 <my1:DataGridTemplateColumn>14 <my1:DataGridTemplateColumn.Header>15 <TextBlock Text="Skor" IsHitTestVisible="False" FontSize="14" Width="70"16 TextWrapping="Wrap" Foreground="Black"/>17 </my1:DataGridTemplateColumn.Header>18 <my1:DataGridTemplateColumn.CellTemplate>19 <DataTemplate>20 <Button Content="{Binding skor}" Loaded="Score_Loaded" FontWeight="Bold"21 TextWrapping="Wrap" Width="70" Foreground="Black"22 VerticalContentAlignment="Center" HorizontalContentAlignment="Stretch"/>23 </DataTemplate>24 </my1:DataGridTemplateColumn.CellTemplate>25 </my1:DataGridTemplateColumn>26 27 <my1:DataGridTextColumn Header="Puan" DisplayMemberBinding="{Binding hedefPuan}" 28 Width="95" ElementStyle="{StaticResource DataGridTextColumnStyle}" />29 <my1:DataGridTextColumn Header="Ağırlıklı Puan" DisplayMemberBinding="{Binding agirlikliHedefPuan}" 30 Width="115" ElementStyle="{StaticResource DataGridTextColumnStyle}" /> 31 </my1:DataGrid.Columns>32 </my1:DataGrid>
1 Private Sub Score_Loaded(ByVal sender As System.Object, ByVal e As System.EventArgs)2 3 Dim columnSkor As Button = CType(sender, Button)4 Dim hedef As HedefGostergeServiceReference.hedef = CType(columnSkor.DataContext, HedefGostergeServiceReference.hedef)5 6 If hedef.ay = "12" AndAlso (Not (hedef.hedefDeger Is Nothing)) AndAlso (Not (hedef.skor Is Nothing)) AndAlso _7 (Not (hedef.altLimit Is Nothing)) AndAlso (Not (hedef.ustLimit Is Nothing)) Then8 Dim ustLimitDouble As Double9 Dim altLimitDouble As Double10 Dim skorDouble As Double11 Dim temp As Double12 Dim switchScoreLabels As Integer = 013 14 If hedef.hedefDeger.Length = 10 AndAlso hedef.hedefDeger.Chars(2).Equals("."c) AndAlso hedef.hedefDeger.Chars(5).Equals("."c) Then15 ustLimitDouble = handleDateFormat(hedef.ustLimit)16 altLimitDouble = handleDateFormat(hedef.altLimit)17 skorDouble = handleDateFormat(hedef.skor)18 ElseIf (Double.TryParse(hedef.altLimit, temp) AndAlso Double.TryParse(hedef.ustLimit, temp) AndAlso Double.TryParse(hedef.hedefDeger, temp) _19 AndAlso Double.TryParse(hedef.skor, temp) AndAlso Double.TryParse(hedef.agirlik, temp)) Then20 ustLimitDouble = Double.Parse(hedef.ustLimit, New CultureInfo("tr-TR"))21 altLimitDouble = Double.Parse(hedef.altLimit, New CultureInfo("tr-TR"))22 skorDouble = Double.Parse(hedef.skor, New CultureInfo("tr-TR"))23 Else24 Exit Sub25 End If26 27 If (altLimitDouble > ustLimitDouble) Then28 switchScoreLabels = 129 Dim temp2 As Double = ustLimitDouble30 ustLimitDouble = altLimitDouble31 altLimitDouble = temp232 End If33 34 If skorDouble < altLimitDouble Then35 If switchScoreLabels = 1 Then36 columnSkor.Background = New SolidColorBrush(Colors.Green)37 Else38 columnSkor.Background = New SolidColorBrush(Colors.Red)39 End If40 ElseIf skorDouble > ustLimitDouble Then41 If switchScoreLabels = 1 Then42 columnSkor.Background = New SolidColorBrush(Colors.Red)43 Else44 columnSkor.Background = New SolidColorBrush(Colors.Green)45 End If46 Else47 columnSkor.Background = New SolidColorBrush(Colors.Yellow)48 End If49 50 End If51 End Sub
simbuaar...
Participant
1172 points
405 Posts
09-17-2008 6:56 AM |
Hi prison
You go through this link its fully have data grid functions
Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}
http://blogs.msdn.com/scmorris/archive/2008/03/27/defining-columns-for-a-silverlight-datagrid.aspx
09-17-2008 7:04 AM |
Hi simbuaarumugam,
Thanks for the link but it does not tell the information related to the possible causes of my problem.
09-17-2008 8:49 AM |
Hi Prison
Your code is wright but in my thought are u using any third party tool in your project
09-17-2008 9:30 AM |
No I dont use any tools.
The problem is that when I scroll the datagrid the event that I associated with my template column is raised again and again but it is not generating the correct color as it did in the first load.
Any workaround solutions? Time is ticking :( tomorrow it should be done...
sladapter
All-Star
17445 points
3,173 Posts
09-17-2008 10:45 AM |
I can confirm your finding. I tried using Grid/Button/TextBlock as control in TemplateCell. Setting different background color or Fourground color to the control based on the row data. Everything works right when I first load the DataGrid. But as soon as I scroll the datagrid, the color on those controls changes randomly. I think it must be a bug.
Could you report this in the Bug forum?
OK I already appended this bug in one of the DataGrid bug thread in the Bug Forum: http://silverlight.net/forums/t/18436.aspx
09-18-2008 1:04 AM |
Hi sladapter, thanks for your answer. I think that should be a bug, too. By the way I put a break point to the button's load event and realized that when I scroll on the datagrid the event is raised randomly. As I know the rows of the datagrid is loaded at the beginning. Am I wrong? Why the loaded event is fired again and again and randomly
So I want to ask you and the other experienced SL users: Is there a workaround solution to achieve this column color stuff? I said to the customer that this will be done, if I can't do that it will be really bad for me.
09-18-2008 9:28 AM |
Yes, i saw that too. When I scroll the grid, the control loaded event fires redomely. But even that should not cause this rendom color change. Because the the data for those rows are still the same and so logic still stand the same as you first load. In my test, I did not even caught the loaded event fired by those rows that color changed to a wrong color. So I have no clue why the color are changing.
I have not found a workaround. If I did, I would post. Can you limit your page size so you do not need to scroll?
09-18-2008 9:46 AM |
sladapter:I have not found a workaround. If I did, I would post. Can you limit your page size so you do not need to scroll?
It is not possible because we don't have any idea how many records will come from database.
By the way sladapter is there a way to deattach the load event from the template column after the grid completes its first load?
hwsoderlund
411 points
118 Posts
09-18-2008 9:54 AM |
Just a thought about the random firing of Loaded: Isn't this due to the UI Virtualization built into the data grid? I.e. it doesn't load the actual rows until they should be displayed?
09-18-2008 10:03 AM |
hwsoderlund:Just a thought about the random firing of Loaded: Isn't this due to the UI Virtualization built into the data grid? I.e. it doesn't load the actual rows until they should be displayed?
It could be. When I was trying to catch the loaded event, the rows fired event when I was scrolling seems the one that originally out of the viewing area. I could do more testing to confirm that.
PrisonBreak:It is not possible because we don't have any idea how many records will come from database. By the way sladapter is there a way to deattach the load event from the template column after the grid completes its first load?
I don't think detach the loaded event would fix the problem, because I can not even confirm that randomly change color is caused by the randomly fire loaded event.
The loaded event is fired per row. If the logic in the loaded event is correct, no matter how many times it runs that code, we should still get the same result. We should not see the result change unless the data is changed.
mingliangli
12 points
7 Posts
09-18-2008 11:09 AM |
Look into this: http://leeontech.wordpress.com/2008/06/08/silverlight-datagrid-issues/ Maybe u need attach an unload event
09-18-2008 11:58 AM |
Mingliangli,
Thank you for the link. Glad someone already report this.
According to YIF (don't know if he is from MS) this is not even a bug. It's caused by Virtualization. The row gets reused.
yif from lee's blog: #2 This is not a bug either. Because of container recycling, the row gets reused for other items so the user needs to clean up any customizations from the Loading event in the UnLoading event. However, the recommended way to do this is to DataBind the customizations instead. In this example the Background could be bound to a calculated property of the item that returns a yellow brush if the City is London.
#2 This is not a bug either. Because of container recycling, the row gets reused for other items so the user needs to clean up any customizations from the Loading event in the UnLoading event. However, the recommended way to do this is to DataBind the customizations instead. In this example the Background could be bound to a calculated property of the item that returns a yellow brush if the City is London.
PrisonBreak,
Whether this is a bug it's debatable. but for now the most important thing is to find a workaround.
yif suggested use DataBiding to bind the Background to another Brush field. I thinkg you can bind the Background to the same Data field that you want to check, but use a IValueConverter to convert that data to a Brush object.
public class ValueConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { double data = value as double;
return new SolidColorBrush(Colors.Red); // check data then return a SolidColorBrush based on the data }
Actually, after I wrote this, I do think this is a better way to handle this than using the loaded event. Because in case you changed data, loaded event won't be called automatically to switch your button color, but binding should take care it. I'll do this from now on.
09-19-2008 8:12 AM |
Hi sladapter thanks for your workaround, also Yi-Lun has posted solution code over the link:
http://silverlight.net/forums/t/27467.aspx
I implemented the solution as he suggested but I have a problem, I have written there Yi-Lun has not answered yet. Can you check it and help me please?
mahendra...
136 points
158 Posts
11-04-2008 1:05 AM |
Hi everyone,
I m having the same datgrid scrooling issue. i used SL 2 beta 2.
Plz give any solution over this.
Thanks,
Mahendra
11-06-2008 10:25 AM |
Hi, check this thread http://silverlight.net/forums/t/27467.aspx
Yi-Lun's converter worked for me when using beta 2. I do not know the row load event ,is still acting like beta 2 or not because today I upgraded from beta 2 to RC1 and I did not try it yet. Try to do that in RC1 if still problem exists follow the solution in my link. If you have any problems with that solution let me know.
URGENT need help! Datagrid template column load event, strange behavior