Pavel Chuchuva

Remember the problem with jQuery BBQ plugin in Internet Explorer 7? It’s not really a problem, just a minor glitch but let’s fix it anyway.

Steps to reproduce:

1. Open BBQ demo in Internet Explorer
2. Click Next button few times
3. Open history menu

Observe:

No page titles, just URLs. Definitely it would be nice to see photo numbers there.

First, let’s see how Asual jQuery Address fix this problem:

_title = _d.title = value;
if (_juststart && _frame && _frame.contentWindow &&
    _frame.contentWindow.document) {
    _frame.contentWindow.document.title = value;
    _juststart = FALSE;
}

Aha! For IE7 you need to set title of the hidden iframe in addition to setting document title. So this is how you set page title:

document.title = "New title";
var iframe = $("iframe:hidden");
if (iframe.length > 0 && iframe[0].contentWindow && iframe[0].contentWindow.document)
  iframe[0].contentWindow.document.title = "New title";

Updated demo should work correctly in Internet Explorer 7.

Click here to view demo

Let’s take previous demo and use jQuery BBQ plugin instead. Our goal is Ajax photo gallery that supports browser’s back button. We will display numbers instead of actual photos for now.

$(function ()
{
  $(window).bind('hashchange', function(e) {
    var i = parseInt(e.fragment, 10);
    if (!isNaN(i))
      switchTo(i);
  });
  $(window).trigger('hashchange');
});

function switchTo(i)
{
  if ($("#number").text() == i)
    return;
  $("#number").text(i);
  document.title = i;
  if (i > 1)
    $("#lnk_prev").attr("href", "#" + (i - 1)).removeClass("disabled");
  else
    $("#lnk_prev").removeAttr("href").addClass("disabled");
  if (i < 20)
    $("#lnk_next").attr("href", "#" + (i + 1)).removeClass("disabled");
  else
    $("#lnk_next").removeAttr("href").addClass("disabled");
}

Instead of handling click event we modify href attribute of the links. BBQ will fire hashchange event whenever we "navigate" to a new page. No need to prevent default processing – simple!

One gotcha to watch out for is changing page title. If you take naive approach and simply use document.title (like I did) to set page title you won't see your titles in the history menu in Internet Explorer 7:

Compare with Internet Explorer 8:

Click here to view demo

Let’s say you want to build photo gallery. Something like this:

You want to open next and previous photos without page reload, using Ajax. One problem with this is that browser’s back button stop working. Fortunately, it’s easy to fix with jQuery Address plugin from Asual. I tried using this plugin and it worked very well. I’ve put together a simple demo.

For simplicity, let’s display just a number instead of actual photo:

Every time you click right arrow the number increases; left arrow decrements the number by one. Simple! Back and forward buttons should work. Also, it would be nice to have different titles in the history:

The code:

$(function ()
{
  $.address.strict(false);
  $.address.externalChange(function(e)
  {
    switchTo(e.value);
  });

  $("#lnk_prev").click(function(e)
  {
    e.preventDefault();
    var i = $("#number").text() * 1 - 1;
    switchTo(i);
    $.address.value(i);
  });

  $("#lnk_next").click(function(e)
  {
    e.preventDefault();
    var i = $("#number").text() * 1 + 1;
    switchTo(i);
    $.address.value(i);
  });
});

function switchTo(i)
{
  $("#number").text(i);
  $.address.title(i);
}

The magic happens in click handler. $.address.value method changes page address and adds browser history point. You need to cancel navigation by calling e.preventDefault() – otherwise browser would follow the link and two history entries would get created.

Note that you need to disable plugin’s strict option, otherwise it would add slash symbol immediately after hash symbol, like this: /#11.

Have you ever encountered this error:

Invalid postback or callback argument.  Event validation is enabled using <pages enableEventValidation=”true”/> in configuration or <%@ Page EnableEventValidation=”true” %> in a page.  For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them.  If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

That’s pretty long error message. I get this exception if I add items to drop-down control from JavaScript. The question is how to use ClientScriptManager.RegisterForEventValidation method?

First, let’s reproduce the problem. Create a new website and copy/paste this code:

<asp:DropDownList ID="dd" runat="server">
  <asp:ListItem>One</asp:ListItem>
  <asp:ListItem>Two</asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button1" runat="server" Text="Test" />

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"
  type="text/javascript"></script>
<script type="text/javascript">
  $(function()
  {
    $("#<%= dd.ClientID %>").append($("<option />")
      .val(3)
      .text("Three!"));
  });
</script>

If you select option “Three” sure enough, exception is thrown. To prevent it you need to supply all possible values for drop-down control:

protected override void Render(HtmlTextWriter writer)
{
  Page.ClientScript.RegisterForEventValidation(dd.UniqueID, "3");
  Page.ClientScript.RegisterForEventValidation(dd.UniqueID, "4");
  Page.ClientScript.RegisterForEventValidation(dd.UniqueID, "11");
  // and so on
  base.Render(writer);
}

The exception is fixed but server variable for drop-down control is useless – it has no idea that you’ve added new item so dd.SelectedValue will give One, not 3. You need to read POST variable directly instead, like this:

protected void Page_Load(object sender, EventArgs e)
{
   if (IsPostBack)
      Response.Write(Request.Form[dd.UniqueID]);
}

Here’s how you can view whitespaces in Emacs:

M-x whitespace-mode RET

By default, Emacs uses bright colours to highlight whitespaces that are in wrong place (in Emacs’ opinion):

To disable colouring add the following to your .emacs file:

; disable colours in whitespace-mode
(setq whitespace-style '(space-mark tab-mark))

Now it’s much better:

I assign showing white spaces to Ctrl+Shift+8 to mimick Visual Studio behaviour:

(global-set-key (kbd "C-*") 'whitespace-mode)

When I work with WiX source code I need to create lots of GUIDs. In my Visual Studio 2005 editor all I need to do is to press Alt+G and new GUID magically appears at the cursor. Achieving this is very easy:

1. Open Macros IDE by selecting Tools | Macros | Macros IDE.
2. Create new macro:

Public Sub InsertGuid()

DTE.ActiveDocument.Selection.Text = Guid.NewGuid().ToString()

End Sub

3. Bind new macro to Alt+G keyboard shortcut. Open Options dialog, select Environment, then Keyboard on the left. Type “InsertGuid” to locate the macro you just created. Assign Alt+G to it.
   
   Fortunately, no standard command is assigned to Alt+G by default.

1. Locate Resources for Visual Basic.tlb in C:\Documents and Settings\All Users\Application Data\Adobe\InDesign\Version 5.0\Scripting Support\5.0 folder.

2. Open command prompt and execute:

TlbImp.exe "Resources for Visual Basic.tlb" /out:Interop.InDesign.dll

TlbImp.exe is located in C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\Bin folder on my machine. This will generate Interop.InDesign.dll file. This is an interop assembly.

3. Add reference to Interop.InDesign.dll to your project.

4. Use this code:

using System;
using InDesign;

namespace HelloInDesign
{
   class Program
   {
      static void Main(string[] args)
      {
         object missing = Type.Missing;
         Type type = Type.GetTypeFromProgID("InDesign.Application.CS3");
         if (type == null)
         {
            throw new Exception("Adobe InDesign CS3 is not installed");
         }
         _Application app = (_Application)Activator.CreateInstance(type);
         Document document = (Document)app.Documents.Add(true, missing);
         Page page = (Page)document.Pages[1];
         TextFrame textFrame = page.TextFrames.Add(missing,
            idLocationOptions.idUnknown, missing);
         textFrame.GeometricBounds = new string[] { "6p", "6p", "24p", "24p" };
         textFrame.Contents = "Hello from .Net!";
      }
   }
}

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