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Problems with button control containing text and image

 
 
David
Guest
Posts: n/a
 
      09-06-2006
Hello all. I am trying to implement my first server control and have
run into two problems that I cannot solve. I need the assistance of
someone with more experience.

My goal was to create an input button that would allow for both text
and an image on it. I am attempting to accomplish this by basing off
of the asp:button control. I added a property for the image url and
one to determine if the image is displayed on the left or right of the
text. I am also overriding the necessary methods so that the html that
is rendered is correct. (The code is included below.)

In my aspx file I put two instances of the control:

<tlic:ImageTextButton ID="btnSaveAll" runat="server" Text="Save All"
ImageUrl="Images/Diskette.gif" />
<tlic:ImageTextButton ID="btnEmailAll" runat="server" Text="Email All"
ImageUrl="Images/Envelope.gif" OnClientClick="return GetRecipients();"
/>

It renders the following in the html to the browser:

<button type="submit" name="btnSaveAll" value="Save All"
id="btnSaveAll"><img id="btnSaveAll_Img" name="btnSaveAll:Img"
src="Images/Diskette.gif" border="0" />&nbsp;Save All</button>
<button type="submit" name="btnEmailAll" value="Email All"
onclick="return GetRecipients();" language="javascript"
id="btnEmailAll"><img id="btnEmailAll_Img" name="btnEmailAll:Img"
src="Images/Envelope.gif" border="0" />&nbsp;Email All</button>

So far, all is good. The problems come in when I click one of the
buttons. The first problem is that ASP.NET complains when validating
the response because the value of the button is being returned as the
inner html rather than what is in the Value attribute. Since there is
an IMG tag there it thinks the data is suspect. Here is the form data:

__EVENTTARGET
__EVENTARGUMENT
__VIEWSTATE /wEPDwUKMTgzNj(snip)...
emailRecipients
gridAuthKeys:_ctl2:tbRANumber
gridAuthKeys:_ctl2:tbPONumber
gridAuthKeys:_ctl2:tbMustArriveBy
btnSaveAll <IMG id=btnSaveAll_Img src="Images/Diskette.gif" border=0
name=btnSaveAll:Img>&nbsp;Save All
btnEmailAll <IMG id=btnEmailAll_Img src="Images/Envelope.gif" border=0
name=btnEmailAll:Img>&nbsp;Email All

I figured I would deal with that later so I turned off page validation
to see if the rest of the processing would work. The second problem is
that no matter which button I click, ASP.NET fires off the event
handler for which ever is the last, or second, button, in this case
"email all". Again, I think the value of the button controls is
messing it up.

I tried setting the buttons to UseSubmit=False vs. True but that
didn't help. An interesting thing to note is that according to the
HTML spec, if a form contains more than one submit button, only the one
clicked is supposed to be included in the form data returned. This is
not what is happening here.

I would greatly appreciate any time that someone could spend to help me
with this.

Regards,

David

Here is the code for the control:

Imports Microsoft.VisualBasic
Imports System
Imports System.Web
Imports System.Web.UI
Imports System.ComponentModel
Imports System.Drawing.Design

Namespace TLI.Controls

''' <summary>
''' A control rendered as a button that has both an image and text.
''' </summary>
''' <remarks></remarks>
<ToolboxData("<{0}:ImageTextButton
runat=server></{0}:ImageTextButton>")> _
Public Class ImageTextButton
Inherits WebControls.Button

<Bindable(True), _
Category("Appearance"), _
DefaultValue(""), _
Editor("System.Windows.Forms.ImageEditorIndex, System.Design",
GetType(UITypeEditor)), _
Description("The image to appear on the button")> _
Public Property ImageUrl() As String
Get
Dim s As String = CStr(ViewState("ImageURL"))
Return IIf(s Is Nothing, "", s)
End Get
Set(ByVal value As String)
ViewState("ImageURL") = value
End Set
End Property

<Bindable(True), _
Category("Appearance"), _
DefaultValue(True), _
Description("True if the image is to appear to the left of the
text")> _
Public Property ImageLeft() As Boolean
Get
Dim o As Object = ViewState("ImageLeft")
Return IIf(o Is Nothing, True, CBool(o))
End Get
Set(ByVal value As Boolean)
ViewState("ImageLeft") = value
End Set
End Property

Protected Overrides ReadOnly Property TagKey() As
HtmlTextWriterTag
Get
Return HtmlTextWriterTag.Button
End Get
End Property

Protected Overrides Sub RenderContents(ByVal writer As
System.Web.UI.HtmlTextWriter)
If ImageLeft Then
RenderImage(writer)
writer.Write("&nbsp;")
End If
writer.Write(Text)
If Not ImageLeft Then
writer.Write("&nbsp;")
RenderImage(writer)
End If
End Sub

Private Sub RenderImage(ByVal writer As
System.Web.UI.HtmlTextWriter)
writer.AddAttribute(HtmlTextWriterAttribute.Id, ID &
"_Img")
writer.AddAttribute(HtmlTextWriterAttribute.Name, ID &
":Img")
writer.AddAttribute(HtmlTextWriterAttribute.Src, ImageUrl)
writer.AddAttribute(HtmlTextWriterAttribute.Border , "0")
writer.RenderBeginTag(HtmlTextWriterTag.Img)
writer.RenderEndTag()
End Sub
End Class
End Namespace

 
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Brennan Stehling
Guest
Posts: n/a
 
      09-07-2006
That is a tough one.

I have a partial fix. I placed your button control onto a page and it
does blow up in MSIE because it is trying to include HTML markup in the
value of a response. That is just a security precaution built into
ASP.NET.

Dim key1 As String = "Fix-" & ImageTextButton1.ClientID

If Not Page.ClientScript.IsOnSubmitStatementRegistered(ke y1)
Then
Dim script As String = "if (document.all) {document.all['"
& ImageTextButton1.ClientID & "'].value = '" & ImageTextButton1.Text &
"';}"
Page.ClientScript.RegisterOnSubmitStatement(Me.Get Type(),
key1, script)
End If

This is done inside the Load event handler of the page but you can just
as easily call RegisterOnSubmitStatement from a server control and
register the Javascript there.

That at least prevents the markup for the image inside the button tag
from being included when the form is submitted.

But then it causes problems on the postback. If you have more than one
of these image buttons on the page it will cause the last button to be
the one selected. I am not sure what is causing that.

But at this point it does not cause that server error.

Brennan Stehling
http://brennan.offwhite.net/blog/


David wrote:
> Hello all. I am trying to implement my first server control and have
> run into two problems that I cannot solve. I need the assistance of
> someone with more experience.
>
> My goal was to create an input button that would allow for both text
> and an image on it. I am attempting to accomplish this by basing off
> of the asp:button control. I added a property for the image url and
> one to determine if the image is displayed on the left or right of the
> text. I am also overriding the necessary methods so that the html that
> is rendered is correct. (The code is included below.)
>
> In my aspx file I put two instances of the control:
>
> <tlic:ImageTextButton ID="btnSaveAll" runat="server" Text="Save All"
> ImageUrl="Images/Diskette.gif" />
> <tlic:ImageTextButton ID="btnEmailAll" runat="server" Text="Email All"
> ImageUrl="Images/Envelope.gif" OnClientClick="return GetRecipients();"
> />
>
> It renders the following in the html to the browser:
>
> <button type="submit" name="btnSaveAll" value="Save All"
> id="btnSaveAll"><img id="btnSaveAll_Img" name="btnSaveAll:Img"
> src="Images/Diskette.gif" border="0" />&nbsp;Save All</button>
> <button type="submit" name="btnEmailAll" value="Email All"
> onclick="return GetRecipients();" language="javascript"
> id="btnEmailAll"><img id="btnEmailAll_Img" name="btnEmailAll:Img"
> src="Images/Envelope.gif" border="0" />&nbsp;Email All</button>
>
> So far, all is good. The problems come in when I click one of the
> buttons. The first problem is that ASP.NET complains when validating
> the response because the value of the button is being returned as the
> inner html rather than what is in the Value attribute. Since there is
> an IMG tag there it thinks the data is suspect. Here is the form data:
>
> __EVENTTARGET
> __EVENTARGUMENT
> __VIEWSTATE /wEPDwUKMTgzNj(snip)...
> emailRecipients
> gridAuthKeys:_ctl2:tbRANumber
> gridAuthKeys:_ctl2:tbPONumber
> gridAuthKeys:_ctl2:tbMustArriveBy
> btnSaveAll <IMG id=btnSaveAll_Img src="Images/Diskette.gif" border=0
> name=btnSaveAll:Img>&nbsp;Save All
> btnEmailAll <IMG id=btnEmailAll_Img src="Images/Envelope.gif" border=0
> name=btnEmailAll:Img>&nbsp;Email All
>
> I figured I would deal with that later so I turned off page validation
> to see if the rest of the processing would work. The second problem is
> that no matter which button I click, ASP.NET fires off the event
> handler for which ever is the last, or second, button, in this case
> "email all". Again, I think the value of the button controls is
> messing it up.
>
> I tried setting the buttons to UseSubmit=False vs. True but that
> didn't help. An interesting thing to note is that according to the
> HTML spec, if a form contains more than one submit button, only the one
> clicked is supposed to be included in the form data returned. This is
> not what is happening here.
>
> I would greatly appreciate any time that someone could spend to help me
> with this.
>
> Regards,
>
> David
>
> Here is the code for the control:
>
> Imports Microsoft.VisualBasic
> Imports System
> Imports System.Web
> Imports System.Web.UI
> Imports System.ComponentModel
> Imports System.Drawing.Design
>
> Namespace TLI.Controls
>
> ''' <summary>
> ''' A control rendered as a button that has both an image and text.
> ''' </summary>
> ''' <remarks></remarks>
> <ToolboxData("<{0}:ImageTextButton
> runat=server></{0}:ImageTextButton>")> _
> Public Class ImageTextButton
> Inherits WebControls.Button
>
> <Bindable(True), _
> Category("Appearance"), _
> DefaultValue(""), _
> Editor("System.Windows.Forms.ImageEditorIndex, System.Design",
> GetType(UITypeEditor)), _
> Description("The image to appear on the button")> _
> Public Property ImageUrl() As String
> Get
> Dim s As String = CStr(ViewState("ImageURL"))
> Return IIf(s Is Nothing, "", s)
> End Get
> Set(ByVal value As String)
> ViewState("ImageURL") = value
> End Set
> End Property
>
> <Bindable(True), _
> Category("Appearance"), _
> DefaultValue(True), _
> Description("True if the image is to appear to the left of the
> text")> _
> Public Property ImageLeft() As Boolean
> Get
> Dim o As Object = ViewState("ImageLeft")
> Return IIf(o Is Nothing, True, CBool(o))
> End Get
> Set(ByVal value As Boolean)
> ViewState("ImageLeft") = value
> End Set
> End Property
>
> Protected Overrides ReadOnly Property TagKey() As
> HtmlTextWriterTag
> Get
> Return HtmlTextWriterTag.Button
> End Get
> End Property
>
> Protected Overrides Sub RenderContents(ByVal writer As
> System.Web.UI.HtmlTextWriter)
> If ImageLeft Then
> RenderImage(writer)
> writer.Write("&nbsp;")
> End If
> writer.Write(Text)
> If Not ImageLeft Then
> writer.Write("&nbsp;")
> RenderImage(writer)
> End If
> End Sub
>
> Private Sub RenderImage(ByVal writer As
> System.Web.UI.HtmlTextWriter)
> writer.AddAttribute(HtmlTextWriterAttribute.Id, ID &
> "_Img")
> writer.AddAttribute(HtmlTextWriterAttribute.Name, ID &
> ":Img")
> writer.AddAttribute(HtmlTextWriterAttribute.Src, ImageUrl)
> writer.AddAttribute(HtmlTextWriterAttribute.Border , "0")
> writer.RenderBeginTag(HtmlTextWriterTag.Img)
> writer.RenderEndTag()
> End Sub
> End Class
> End Namespace


 
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David
Guest
Posts: n/a
 
      09-07-2006
Brennan,

Thanks for the help here. Your code does indeed take care of the
validation issue. I will keep working on the postback issue. Let me
know if you have an epiphany.

Thanks again.

David
----------------------------------------------------------
Brennan Stehling wrote:
> That is a tough one.
>
> I have a partial fix. I placed your button control onto a page and it
> does blow up in MSIE because it is trying to include HTML markup in the
> value of a response. That is just a security precaution built into
> ASP.NET.
>
> Dim key1 As String = "Fix-" & ImageTextButton1.ClientID
>
> If Not Page.ClientScript.IsOnSubmitStatementRegistered(ke y1)
> Then
> Dim script As String = "if (document.all) {document.all['"
> & ImageTextButton1.ClientID & "'].value = '" & ImageTextButton1.Text &
> "';}"
> Page.ClientScript.RegisterOnSubmitStatement(Me.Get Type(),
> key1, script)
> End If
>
> This is done inside the Load event handler of the page but you can just
> as easily call RegisterOnSubmitStatement from a server control and
> register the Javascript there.
>
> That at least prevents the markup for the image inside the button tag
> from being included when the form is submitted.
>
> But then it causes problems on the postback. If you have more than one
> of these image buttons on the page it will cause the last button to be
> the one selected. I am not sure what is causing that.
>
> But at this point it does not cause that server error.
>
> Brennan Stehling
> http://brennan.offwhite.net/blog/
>
>
> David wrote:
> > Hello all. I am trying to implement my first server control and have
> > run into two problems that I cannot solve. I need the assistance of
> > someone with more experience.
> >
> > My goal was to create an input button that would allow for both text
> > and an image on it. I am attempting to accomplish this by basing off
> > of the asp:button control. I added a property for the image url and
> > one to determine if the image is displayed on the left or right of the
> > text. I am also overriding the necessary methods so that the html that
> > is rendered is correct. (The code is included below.)
> >
> > In my aspx file I put two instances of the control:
> >
> > <tlic:ImageTextButton ID="btnSaveAll" runat="server" Text="Save All"
> > ImageUrl="Images/Diskette.gif" />
> > <tlic:ImageTextButton ID="btnEmailAll" runat="server" Text="Email All"
> > ImageUrl="Images/Envelope.gif" OnClientClick="return GetRecipients();"
> > />
> >
> > It renders the following in the html to the browser:
> >
> > <button type="submit" name="btnSaveAll" value="Save All"
> > id="btnSaveAll"><img id="btnSaveAll_Img" name="btnSaveAll:Img"
> > src="Images/Diskette.gif" border="0" />&nbsp;Save All</button>
> > <button type="submit" name="btnEmailAll" value="Email All"
> > onclick="return GetRecipients();" language="javascript"
> > id="btnEmailAll"><img id="btnEmailAll_Img" name="btnEmailAll:Img"
> > src="Images/Envelope.gif" border="0" />&nbsp;Email All</button>
> >
> > So far, all is good. The problems come in when I click one of the
> > buttons. The first problem is that ASP.NET complains when validating
> > the response because the value of the button is being returned as the
> > inner html rather than what is in the Value attribute. Since there is
> > an IMG tag there it thinks the data is suspect. Here is the form data:
> >
> > __EVENTTARGET
> > __EVENTARGUMENT
> > __VIEWSTATE /wEPDwUKMTgzNj(snip)...
> > emailRecipients
> > gridAuthKeys:_ctl2:tbRANumber
> > gridAuthKeys:_ctl2:tbPONumber
> > gridAuthKeys:_ctl2:tbMustArriveBy
> > btnSaveAll <IMG id=btnSaveAll_Img src="Images/Diskette.gif" border=0
> > name=btnSaveAll:Img>&nbsp;Save All
> > btnEmailAll <IMG id=btnEmailAll_Img src="Images/Envelope.gif" border=0
> > name=btnEmailAll:Img>&nbsp;Email All
> >
> > I figured I would deal with that later so I turned off page validation
> > to see if the rest of the processing would work. The second problem is
> > that no matter which button I click, ASP.NET fires off the event
> > handler for which ever is the last, or second, button, in this case
> > "email all". Again, I think the value of the button controls is
> > messing it up.
> >
> > I tried setting the buttons to UseSubmit=False vs. True but that
> > didn't help. An interesting thing to note is that according to the
> > HTML spec, if a form contains more than one submit button, only the one
> > clicked is supposed to be included in the form data returned. This is
> > not what is happening here.
> >
> > I would greatly appreciate any time that someone could spend to help me
> > with this.
> >
> > Regards,
> >
> > David
> >
> > Here is the code for the control:
> >
> > Imports Microsoft.VisualBasic
> > Imports System
> > Imports System.Web
> > Imports System.Web.UI
> > Imports System.ComponentModel
> > Imports System.Drawing.Design
> >
> > Namespace TLI.Controls
> >
> > ''' <summary>
> > ''' A control rendered as a button that has both an image and text.
> > ''' </summary>
> > ''' <remarks></remarks>
> > <ToolboxData("<{0}:ImageTextButton
> > runat=server></{0}:ImageTextButton>")> _
> > Public Class ImageTextButton
> > Inherits WebControls.Button
> >
> > <Bindable(True), _
> > Category("Appearance"), _
> > DefaultValue(""), _
> > Editor("System.Windows.Forms.ImageEditorIndex, System.Design",
> > GetType(UITypeEditor)), _
> > Description("The image to appear on the button")> _
> > Public Property ImageUrl() As String
> > Get
> > Dim s As String = CStr(ViewState("ImageURL"))
> > Return IIf(s Is Nothing, "", s)
> > End Get
> > Set(ByVal value As String)
> > ViewState("ImageURL") = value
> > End Set
> > End Property
> >
> > <Bindable(True), _
> > Category("Appearance"), _
> > DefaultValue(True), _
> > Description("True if the image is to appear to the left of the
> > text")> _
> > Public Property ImageLeft() As Boolean
> > Get
> > Dim o As Object = ViewState("ImageLeft")
> > Return IIf(o Is Nothing, True, CBool(o))
> > End Get
> > Set(ByVal value As Boolean)
> > ViewState("ImageLeft") = value
> > End Set
> > End Property
> >
> > Protected Overrides ReadOnly Property TagKey() As
> > HtmlTextWriterTag
> > Get
> > Return HtmlTextWriterTag.Button
> > End Get
> > End Property
> >
> > Protected Overrides Sub RenderContents(ByVal writer As
> > System.Web.UI.HtmlTextWriter)
> > If ImageLeft Then
> > RenderImage(writer)
> > writer.Write("&nbsp;")
> > End If
> > writer.Write(Text)
> > If Not ImageLeft Then
> > writer.Write("&nbsp;")
> > RenderImage(writer)
> > End If
> > End Sub
> >
> > Private Sub RenderImage(ByVal writer As
> > System.Web.UI.HtmlTextWriter)
> > writer.AddAttribute(HtmlTextWriterAttribute.Id, ID &
> > "_Img")
> > writer.AddAttribute(HtmlTextWriterAttribute.Name, ID &
> > ":Img")
> > writer.AddAttribute(HtmlTextWriterAttribute.Src, ImageUrl)
> > writer.AddAttribute(HtmlTextWriterAttribute.Border , "0")
> > writer.RenderBeginTag(HtmlTextWriterTag.Img)
> > writer.RenderEndTag()
> > End Sub
> > End Class
> > End Namespace


 
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David
Guest
Posts: n/a
 
      09-07-2006
I hit on a solution to get this to work. Evidently when IE submits the
form, it includes in the form data all elements of the <button>
variety, regardless of whether they are typed as Submit or Button.
This is messing up ASP.NET in that it must look through the form data
returned and assume that a button in the form data means that the
button was clicked. When it finds more than one, it takes the last one
in the form. This is true even if you are not using the submit
behavior of the button but are using the __doPostBack functionality
which sets the __EVENTTARGET variable.

So, I altered Brennan's code slightly and when submitting the form I
disable the buttons instead of changing their value. This coupled with
the control forcing the UseSubmitBehavior to false prevents the buttons
from being in the submitted form data so ASP.NET then uses the
__EVENTTARGET.

David wrote:
> Brennan,
>
> Thanks for the help here. Your code does indeed take care of the
> validation issue. I will keep working on the postback issue. Let me
> know if you have an epiphany.
>
> Thanks again.
>
> David
> ----------------------------------------------------------
> Brennan Stehling wrote:
> > That is a tough one.
> >
> > I have a partial fix. I placed your button control onto a page and it
> > does blow up in MSIE because it is trying to include HTML markup in the
> > value of a response. That is just a security precaution built into
> > ASP.NET.
> >
> > Dim key1 As String = "Fix-" & ImageTextButton1.ClientID
> >
> > If Not Page.ClientScript.IsOnSubmitStatementRegistered(ke y1)
> > Then
> > Dim script As String = "if (document.all) {document.all['"
> > & ImageTextButton1.ClientID & "'].value = '" & ImageTextButton1.Text &
> > "';}"
> > Page.ClientScript.RegisterOnSubmitStatement(Me.Get Type(),
> > key1, script)
> > End If
> >
> > This is done inside the Load event handler of the page but you can just
> > as easily call RegisterOnSubmitStatement from a server control and
> > register the Javascript there.
> >
> > That at least prevents the markup for the image inside the button tag
> > from being included when the form is submitted.
> >
> > But then it causes problems on the postback. If you have more than one
> > of these image buttons on the page it will cause the last button to be
> > the one selected. I am not sure what is causing that.
> >
> > But at this point it does not cause that server error.
> >
> > Brennan Stehling
> > http://brennan.offwhite.net/blog/
> >
> >
> > David wrote:
> > > Hello all. I am trying to implement my first server control and have
> > > run into two problems that I cannot solve. I need the assistance of
> > > someone with more experience.
> > >
> > > My goal was to create an input button that would allow for both text
> > > and an image on it. I am attempting to accomplish this by basing off
> > > of the asp:button control. I added a property for the image url and
> > > one to determine if the image is displayed on the left or right of the
> > > text. I am also overriding the necessary methods so that the html that
> > > is rendered is correct. (The code is included below.)
> > >
> > > In my aspx file I put two instances of the control:
> > >
> > > <tlic:ImageTextButton ID="btnSaveAll" runat="server" Text="Save All"
> > > ImageUrl="Images/Diskette.gif" />
> > > <tlic:ImageTextButton ID="btnEmailAll" runat="server" Text="Email All"
> > > ImageUrl="Images/Envelope.gif" OnClientClick="return GetRecipients();"
> > > />
> > >
> > > It renders the following in the html to the browser:
> > >
> > > <button type="submit" name="btnSaveAll" value="Save All"
> > > id="btnSaveAll"><img id="btnSaveAll_Img" name="btnSaveAll:Img"
> > > src="Images/Diskette.gif" border="0" />&nbsp;Save All</button>
> > > <button type="submit" name="btnEmailAll" value="Email All"
> > > onclick="return GetRecipients();" language="javascript"
> > > id="btnEmailAll"><img id="btnEmailAll_Img" name="btnEmailAll:Img"
> > > src="Images/Envelope.gif" border="0" />&nbsp;Email All</button>
> > >
> > > So far, all is good. The problems come in when I click one of the
> > > buttons. The first problem is that ASP.NET complains when validating
> > > the response because the value of the button is being returned as the
> > > inner html rather than what is in the Value attribute. Since there is
> > > an IMG tag there it thinks the data is suspect. Here is the form data:
> > >
> > > __EVENTTARGET
> > > __EVENTARGUMENT
> > > __VIEWSTATE /wEPDwUKMTgzNj(snip)...
> > > emailRecipients
> > > gridAuthKeys:_ctl2:tbRANumber
> > > gridAuthKeys:_ctl2:tbPONumber
> > > gridAuthKeys:_ctl2:tbMustArriveBy
> > > btnSaveAll <IMG id=btnSaveAll_Img src="Images/Diskette.gif" border=0
> > > name=btnSaveAll:Img>&nbsp;Save All
> > > btnEmailAll <IMG id=btnEmailAll_Img src="Images/Envelope.gif" border=0
> > > name=btnEmailAll:Img>&nbsp;Email All
> > >
> > > I figured I would deal with that later so I turned off page validation
> > > to see if the rest of the processing would work. The second problem is
> > > that no matter which button I click, ASP.NET fires off the event
> > > handler for which ever is the last, or second, button, in this case
> > > "email all". Again, I think the value of the button controls is
> > > messing it up.
> > >
> > > I tried setting the buttons to UseSubmit=False vs. True but that
> > > didn't help. An interesting thing to note is that according to the
> > > HTML spec, if a form contains more than one submit button, only the one
> > > clicked is supposed to be included in the form data returned. This is
> > > not what is happening here.
> > >
> > > I would greatly appreciate any time that someone could spend to help me
> > > with this.
> > >
> > > Regards,
> > >
> > > David
> > >
> > > Here is the code for the control:
> > >
> > > Imports Microsoft.VisualBasic
> > > Imports System
> > > Imports System.Web
> > > Imports System.Web.UI
> > > Imports System.ComponentModel
> > > Imports System.Drawing.Design
> > >
> > > Namespace TLI.Controls
> > >
> > > ''' <summary>
> > > ''' A control rendered as a button that has both an image and text.
> > > ''' </summary>
> > > ''' <remarks></remarks>
> > > <ToolboxData("<{0}:ImageTextButton
> > > runat=server></{0}:ImageTextButton>")> _
> > > Public Class ImageTextButton
> > > Inherits WebControls.Button
> > >
> > > <Bindable(True), _
> > > Category("Appearance"), _
> > > DefaultValue(""), _
> > > Editor("System.Windows.Forms.ImageEditorIndex, System.Design",
> > > GetType(UITypeEditor)), _
> > > Description("The image to appear on the button")> _
> > > Public Property ImageUrl() As String
> > > Get
> > > Dim s As String = CStr(ViewState("ImageURL"))
> > > Return IIf(s Is Nothing, "", s)
> > > End Get
> > > Set(ByVal value As String)
> > > ViewState("ImageURL") = value
> > > End Set
> > > End Property
> > >
> > > <Bindable(True), _
> > > Category("Appearance"), _
> > > DefaultValue(True), _
> > > Description("True if the image is to appear to the left of the
> > > text")> _
> > > Public Property ImageLeft() As Boolean
> > > Get
> > > Dim o As Object = ViewState("ImageLeft")
> > > Return IIf(o Is Nothing, True, CBool(o))
> > > End Get
> > > Set(ByVal value As Boolean)
> > > ViewState("ImageLeft") = value
> > > End Set
> > > End Property
> > >
> > > Protected Overrides ReadOnly Property TagKey() As
> > > HtmlTextWriterTag
> > > Get
> > > Return HtmlTextWriterTag.Button
> > > End Get
> > > End Property
> > >
> > > Protected Overrides Sub RenderContents(ByVal writer As
> > > System.Web.UI.HtmlTextWriter)
> > > If ImageLeft Then
> > > RenderImage(writer)
> > > writer.Write("&nbsp;")
> > > End If
> > > writer.Write(Text)
> > > If Not ImageLeft Then
> > > writer.Write("&nbsp;")
> > > RenderImage(writer)
> > > End If
> > > End Sub
> > >
> > > Private Sub RenderImage(ByVal writer As
> > > System.Web.UI.HtmlTextWriter)
> > > writer.AddAttribute(HtmlTextWriterAttribute.Id, ID &
> > > "_Img")
> > > writer.AddAttribute(HtmlTextWriterAttribute.Name, ID &
> > > ":Img")
> > > writer.AddAttribute(HtmlTextWriterAttribute.Src, ImageUrl)
> > > writer.AddAttribute(HtmlTextWriterAttribute.Border , "0")
> > > writer.RenderBeginTag(HtmlTextWriterTag.Img)
> > > writer.RenderEndTag()
> > > End Sub
> > > End Class
> > > End Namespace


 
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Brennan Stehling
Guest
Posts: n/a
 
      09-07-2006
David,

That solution works great. I posted my test page here...

http://www.offwhite.net/ButtonBug/

Brennan Stehling
http://brennan.offwhite.net/blog/

David wrote:
> I hit on a solution to get this to work. Evidently when IE submits the
> form, it includes in the form data all elements of the <button>
> variety, regardless of whether they are typed as Submit or Button.
> This is messing up ASP.NET in that it must look through the form data
> returned and assume that a button in the form data means that the
> button was clicked. When it finds more than one, it takes the last one
> in the form. This is true even if you are not using the submit
> behavior of the button but are using the __doPostBack functionality
> which sets the __EVENTTARGET variable.
>
> So, I altered Brennan's code slightly and when submitting the form I
> disable the buttons instead of changing their value. This coupled with
> the control forcing the UseSubmitBehavior to false prevents the buttons
> from being in the submitted form data so ASP.NET then uses the
> __EVENTTARGET.
>
> David wrote:
> > Brennan,
> >
> > Thanks for the help here. Your code does indeed take care of the
> > validation issue. I will keep working on the postback issue. Let me
> > know if you have an epiphany.
> >
> > Thanks again.
> >
> > David
> > ----------------------------------------------------------
> > Brennan Stehling wrote:
> > > That is a tough one.
> > >
> > > I have a partial fix. I placed your button control onto a page and it
> > > does blow up in MSIE because it is trying to include HTML markup in the
> > > value of a response. That is just a security precaution built into
> > > ASP.NET.
> > >
> > > Dim key1 As String = "Fix-" & ImageTextButton1.ClientID
> > >
> > > If Not Page.ClientScript.IsOnSubmitStatementRegistered(ke y1)
> > > Then
> > > Dim script As String = "if (document.all) {document.all['"
> > > & ImageTextButton1.ClientID & "'].value = '" & ImageTextButton1.Text &
> > > "';}"
> > > Page.ClientScript.RegisterOnSubmitStatement(Me.Get Type(),
> > > key1, script)
> > > End If
> > >
> > > This is done inside the Load event handler of the page but you can just
> > > as easily call RegisterOnSubmitStatement from a server control and
> > > register the Javascript there.
> > >
> > > That at least prevents the markup for the image inside the button tag
> > > from being included when the form is submitted.
> > >
> > > But then it causes problems on the postback. If you have more than one
> > > of these image buttons on the page it will cause the last button to be
> > > the one selected. I am not sure what is causing that.
> > >
> > > But at this point it does not cause that server error.
> > >
> > > Brennan Stehling
> > > http://brennan.offwhite.net/blog/
> > >
> > >
> > > David wrote:
> > > > Hello all. I am trying to implement my first server control and have
> > > > run into two problems that I cannot solve. I need the assistance of
> > > > someone with more experience.
> > > >
> > > > My goal was to create an input button that would allow for both text
> > > > and an image on it. I am attempting to accomplish this by basing off
> > > > of the asp:button control. I added a property for the image url and
> > > > one to determine if the image is displayed on the left or right of the
> > > > text. I am also overriding the necessary methods so that the html that
> > > > is rendered is correct. (The code is included below.)
> > > >
> > > > In my aspx file I put two instances of the control:
> > > >
> > > > <tlic:ImageTextButton ID="btnSaveAll" runat="server" Text="Save All"
> > > > ImageUrl="Images/Diskette.gif" />
> > > > <tlic:ImageTextButton ID="btnEmailAll" runat="server" Text="Email All"
> > > > ImageUrl="Images/Envelope.gif" OnClientClick="return GetRecipients();"
> > > > />
> > > >
> > > > It renders the following in the html to the browser:
> > > >
> > > > <button type="submit" name="btnSaveAll" value="Save All"
> > > > id="btnSaveAll"><img id="btnSaveAll_Img" name="btnSaveAll:Img"
> > > > src="Images/Diskette.gif" border="0" />&nbsp;Save All</button>
> > > > <button type="submit" name="btnEmailAll" value="Email All"
> > > > onclick="return GetRecipients();" language="javascript"
> > > > id="btnEmailAll"><img id="btnEmailAll_Img" name="btnEmailAll:Img"
> > > > src="Images/Envelope.gif" border="0" />&nbsp;Email All</button>
> > > >
> > > > So far, all is good. The problems come in when I click one of the
> > > > buttons. The first problem is that ASP.NET complains when validating
> > > > the response because the value of the button is being returned as the
> > > > inner html rather than what is in the Value attribute. Since there is
> > > > an IMG tag there it thinks the data is suspect. Here is the form data:
> > > >
> > > > __EVENTTARGET
> > > > __EVENTARGUMENT
> > > > __VIEWSTATE /wEPDwUKMTgzNj(snip)...
> > > > emailRecipients
> > > > gridAuthKeys:_ctl2:tbRANumber
> > > > gridAuthKeys:_ctl2:tbPONumber
> > > > gridAuthKeys:_ctl2:tbMustArriveBy
> > > > btnSaveAll <IMG id=btnSaveAll_Img src="Images/Diskette.gif" border=0
> > > > name=btnSaveAll:Img>&nbsp;Save All
> > > > btnEmailAll <IMG id=btnEmailAll_Img src="Images/Envelope.gif" border=0
> > > > name=btnEmailAll:Img>&nbsp;Email All
> > > >
> > > > I figured I would deal with that later so I turned off page validation
> > > > to see if the rest of the processing would work. The second problem is
> > > > that no matter which button I click, ASP.NET fires off the event
> > > > handler for which ever is the last, or second, button, in this case
> > > > "email all". Again, I think the value of the button controls is
> > > > messing it up.
> > > >
> > > > I tried setting the buttons to UseSubmit=False vs. True but that
> > > > didn't help. An interesting thing to note is that according to the
> > > > HTML spec, if a form contains more than one submit button, only the one
> > > > clicked is supposed to be included in the form data returned. This is
> > > > not what is happening here.
> > > >
> > > > I would greatly appreciate any time that someone could spend to help me
> > > > with this.
> > > >
> > > > Regards,
> > > >
> > > > David
> > > >
> > > > Here is the code for the control:
> > > >
> > > > Imports Microsoft.VisualBasic
> > > > Imports System
> > > > Imports System.Web
> > > > Imports System.Web.UI
> > > > Imports System.ComponentModel
> > > > Imports System.Drawing.Design
> > > >
> > > > Namespace TLI.Controls
> > > >
> > > > ''' <summary>
> > > > ''' A control rendered as a button that has both an image and text.
> > > > ''' </summary>
> > > > ''' <remarks></remarks>
> > > > <ToolboxData("<{0}:ImageTextButton
> > > > runat=server></{0}:ImageTextButton>")> _
> > > > Public Class ImageTextButton
> > > > Inherits WebControls.Button
> > > >
> > > > <Bindable(True), _
> > > > Category("Appearance"), _
> > > > DefaultValue(""), _
> > > > Editor("System.Windows.Forms.ImageEditorIndex, System.Design",
> > > > GetType(UITypeEditor)), _
> > > > Description("The image to appear on the button")> _
> > > > Public Property ImageUrl() As String
> > > > Get
> > > > Dim s As String = CStr(ViewState("ImageURL"))
> > > > Return IIf(s Is Nothing, "", s)
> > > > End Get
> > > > Set(ByVal value As String)
> > > > ViewState("ImageURL") = value
> > > > End Set
> > > > End Property
> > > >
> > > > <Bindable(True), _
> > > > Category("Appearance"), _
> > > > DefaultValue(True), _
> > > > Description("True if the image is to appear to the left of the
> > > > text")> _
> > > > Public Property ImageLeft() As Boolean
> > > > Get
> > > > Dim o As Object = ViewState("ImageLeft")
> > > > Return IIf(o Is Nothing, True, CBool(o))
> > > > End Get
> > > > Set(ByVal value As Boolean)
> > > > ViewState("ImageLeft") = value
> > > > End Set
> > > > End Property
> > > >
> > > > Protected Overrides ReadOnly Property TagKey() As
> > > > HtmlTextWriterTag
> > > > Get
> > > > Return HtmlTextWriterTag.Button
> > > > End Get
> > > > End Property
> > > >
> > > > Protected Overrides Sub RenderContents(ByVal writer As
> > > > System.Web.UI.HtmlTextWriter)
> > > > If ImageLeft Then
> > > > RenderImage(writer)
> > > > writer.Write("&nbsp;")
> > > > End If
> > > > writer.Write(Text)
> > > > If Not ImageLeft Then
> > > > writer.Write("&nbsp;")
> > > > RenderImage(writer)
> > > > End If
> > > > End Sub
> > > >
> > > > Private Sub RenderImage(ByVal writer As
> > > > System.Web.UI.HtmlTextWriter)
> > > > writer.AddAttribute(HtmlTextWriterAttribute.Id, ID &
> > > > "_Img")
> > > > writer.AddAttribute(HtmlTextWriterAttribute.Name, ID &
> > > > ":Img")
> > > > writer.AddAttribute(HtmlTextWriterAttribute.Src, ImageUrl)
> > > > writer.AddAttribute(HtmlTextWriterAttribute.Border , "0")
> > > > writer.RenderBeginTag(HtmlTextWriterTag.Img)
> > > > writer.RenderEndTag()
> > > > End Sub
> > > > End Class
> > > > End Namespace


 
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