Archive
Gotcha: VBScript DropHandler doesn’t support Unicode filenames
It seems VBScript (.vbs) script file’s DropHandler on Windows is broken regarding Unicode filenames, as described at https://stackoverflow.com/a/4366906/903783
A workaround suggested by user DG there (https://stackoverflow.com/a/13587850/903783) was to use a batch file to accept the dropped file, then pass the filename(s) to the VBScript script file (.vbs) as command-line parameters. If you just care about a single instead of multiple dropped files, there’s a simpler version of a batch file one can use, as I suggested at https://stackoverflow.com/a/52239049/903783. Copying below:
Based on DG’s answer, if you just want to accept one file as drop target then you can write a batch file (if you have it named as "x.bat" place VBscript with filename "x.bat.vbs" at same folder) that just contains:
@"%0.vbs" %1the @ means to not output the row on the display (I found it to show garbage text even if you use chcp 1250 as first command)
don’t use double-quotes around %1, it won’t work if your VBScript uses logic like the following (code I was using below was from http://jeffkinzer.blogspot.com/2012/06/vbscript-to-convert-excel-to-csv.html). Tested it and it works fine with spaces in the file and folder names:
Dim strExcelFileName
strExcelFileName = WScript.Arguments.Item(0) 'file name to parse
' get path where script is running
strScript = WScript.ScriptFullName
Dim fso
Set fso = CreateObject ("Scripting.FileSystemObject")
strScriptPath = fso.GetAbsolutePathName(strScript & "\..")
Set fso = Nothing
' If the Input file is NOT qualified with a path, default the current path
LPosition = InStrRev(strExcelFileName, "\")
if LPosition = 0 Then 'no folder path
strExcelFileName = strScriptPath & "\" & strExcelFileName
strScriptPath = strScriptPath & "\"
else 'there is a folder path, use it for the output folder path also
strScriptPath = Mid(strExcelFileName, 1, LPosition)
End If
' msgbox LPosition & " - " & strExcelFileName & " - " & strScriptPathGotcha: use parentheses around ternary op conditional expressions
Just came across the following case in C# that puzzled me momentarily, especially since the strings involved were long enough and the expression was broken on multiple lines:
bool flag = true;
string test1 = flag? "xa" : "xb";
string test2 = "x" + (flag? "a" : "b");
string test3 = "x" + flag? "a" : "b";
The test3 case fails since the compiler tries to evaluate the "x" + flag expression at the left side of the operator ?, complaining that it cannot implicitly convert string to bool.
e.g I accidentally produced the following wrong code while I was trying to refactor some third-party code to make it more readable:
string test3 = “some long string here” +
(someFlag)?
“some other long string”
:
“some alternative long string”;
whereas the correct was:
string test3 = “some long string here” +
( (someFlag)?
“some other long string”
:
“some alternative long string” );
The correct one needs the whole conditional expression enclosed in parentheses. In fact, the parentheses around (someFlag) can be skipped. In usually prefer them visually, even when I use just a boolean variable instead of a more complex boolean expression, but in case like this one the x + (someFlag)? a : b can be confusing to the reader of the code, not seeing x + (someFlag) will be treated as the conditional instead of someFlag.
Luckily the C# compiler is deterministic enough and not trying to imply meaning from one’s wrong syntax. Had it been some futuristic AI-based interpreter, well, it might have gotten confused there too.
To avoid this confusion in the first place, probably one could have designed a (bool)?x:y operator instead with parentheses being required around the boolean expression, but people coming from other languages (say C++) might then end up writing bool && (bool)?x:y and expect the condition to be bool && (bool) instead of just (bool), so even that syntax would be problematic.
Speaking of other languages, quoting from Wikipedia article on ternary operator:
C++
Unlike in C, the precedence of the
?:operator in C++ is the same as that of the assignment operator (=orOP=), and it can return an lvalue. This means that expressions likeq ? a : b = cand(q ? a : b) = care both legal and are parsed differently, the former being equivalent toq ? a : (b = c).
So confusion even between languages that share a C-style syntax might not be avoided.
Gotcha: WPF UserControl SizeChanged event not firing at resizing
Useful to know:
If you set the Width and Height on the UserControl though, you have set a fixed size and thus even if its parent tool window changes size, the UserControl never will. You should not set Width and Height on the UserControl if you want that event to be raised as the parent tool window changes size.
from:
http://www.actiprosoftware.com/community/thread/20365/size-change-event-for-the-usercontrol
Gotcha: MarkerReached event of MediaElement returns new Markers
I just checked in the implementation code for a new feature for ClipFlair Studio’s Captions/Revoicing component:
When playing back recorded (or loaded from a WAV or MP3 file) audio for a caption/revoicing entry, the playback is now limited to the duration of the respective caption, (End-Start) time that is (btw that component has a duration column too that is hidden by default and can be shown by flipping it with the gear button on its titlebar and selecting the respective option to show the column).
The original audio is not affected and is stored in whole inside the saved state of the component/activity, so that you can adjust the caption entries timerange at any time to fit all or part of that recorded audio entry if you wish.
Will see into adding an “Limit playback” option to the backpanel of that component (it will default to true/checked) for any ClipFlair activities that don’t use the Start/End/Duration columns (e.g. if some activity just wants a grid of Captions and Audio entries for practicing and maybe for comparing to audio samples provided by the activity author or teacher at the optional “Comments (Audio)” column).
While implementing this feature, there were some “gotchas” that caused me some headache to spot:
1) When MediaOpened event is called by the MediaElement control, the Markers collection has just been reset and you need at that point to add your TimelineMediaMarker that will notify you when the playback limit point has been reached to stop the playback. In the case above this event is called after recording some audio or loading some WAV or MP3 audio file at an AudioRecorderControl (one is used at each row of the captions grid)
2) One shouldn’t remove an added marker at MediaEnded or MediaFailed events. This is since those will fire at each revoicing entry playback, whereas the MediaOpened while only occur once when the Audio property is populated at the AudioRecorderControl. As I mention above, MediaElement clears the Markers collection every time new content is loaded to it, so we need not worry about removing the marker we had added before.
3) Maybe the least obvious issue and the one that caused me most of headache to spot was that the MediaElement’s MarkerReached event gets back a MediaMarker that isn’t the same Marker instance as the one you had added to the Markers collection. So you have to use the Text property of the marker when you create it and then compare with the text from the one you got in the event to see if they are equal strings (btw, when C# compares strings it does it by content even if you use == instead of Equals method, unlike Java, where you shouldn’t use == to compare strings)
Gotcha: Worksheets property is read-only, Sheets is not – Excel Workbook
My contribution to:
Seems Worksheets property is read-only
Returns a Sheets collection that represents all the worksheets in the specified workbook. Read-only Sheets object.
https://msdn.microsoft.com/en-us/library/office/ff835542(v=office.15).aspx
whereas Sheets is the real thing where you can also add Sheets dynamically
A collection of all the sheets in the specified or active workbook.
https://msdn.microsoft.com/en-us/library/office/ff193217(v=office.15).aspx
Gotcha: MediaElement Source=null releases stream, SetSource(null) fails
This is my contribution to:
If you use MediaElement, make sure you don’t get bitten by this one: http://msdn.microsoft.com/en-us/library/cc626563(v=vs.95).aspx
ArgumentNullException – The mediaStreamSource is null.
…After calling this method, MediaElement.Source returns null. If this is called and MediaElement.Source is set, the last operation wins.
If a MediaElement is removed from the UI tree while is has an opened MediaStreamSource, subsequent calls to SetSource may be ignored. To ensure featureSetSource calls will work, set the Source property to null before detaching the MediaElement from the UI tree.
naturally one would expect, if they only use SetSource(somestream) to use SetSource(null) to release the resources. Nope, they thought "better", you have to use Source=null instead to release resources and SetSource(null) throws ArgumentNullException
that is what I call a design bug (breaks the rule of "least expected" behavior and causes bugs that bite you at runtime only [unless somebody has made a static analysis rule to catch such a thing – would need metadata of course that some argument can’t be null, like in Code Contracts])
I managed to introduce this bug while refactoring some code in ClipFlair Studio‘s AudioRecorder control the other day 😦
Note that you can’t use at MediaElement something like Source = stream to open a Stream, since that is a Uri property (not an Object property to also accept Stream) and you have to use SetSource(stream) instead, so you’d also expect to be able to use SetSource(null) to release the resources.
Update: Fixed this in AudioRecorderView class (uses MVVM pattern) of AudioRecorderControl, at Audio property’s "set" accessor it needed the following null-guarding pattern:
if (mediaStreamSource != null)
player.SetSource(mediaStreamSource);
//must set the source once, not every time we play the same audio,
//else with Mp3MediaSource it will throw DRM error
else
player.Source = null;
Gotcha: MediaElement must be in visual tree for MediaOpened, MediaEnded to be fired
At ClipFlair’s AudioRecorderControl (used in Captions/Revoicing component of ClipFlair Studio), I use the following code to initialize a MediaElement to use for playback.
After a long time a found out that if the MediaElement is not in the visual tree (for example defined in XAML, or defined in code and then added to the visual tree), then it will not always fire MediaOpened and MediaEnded events, which are crucial if you want to have a two-state Play/Stop button (a ToggleButton).
public MediaElement Player
{ get { return player; }
set {
if (player != null) {
player.MediaOpened -= MediaElement_MediaOpened;
player.MediaEnded -= MediaElement_MediaEnded;
}
player = value;
if (player != null) {
player.MediaOpened += MediaElement_MediaOpened;
player.MediaEnded += MediaElement_MediaEnded;
player.AutoPlay = false;
player.PlaybackRate = 1.0;
player.Balance = 0;
Volume = DEFAULT_VOLUME;
}
}
}
protected void MediaElement_MediaOpened(object sender, RoutedEventArgs e)
{
try {
//player.Position = TimeSpan.Zero;
player.Stop(); //this stops current playback (if any) and rewinds
player.Play();
} catch (Exception ex) {
PlayCommandUncheck(); //depress playback toggle button
//don't talk to ToggleButton directly
Status = MSG_PLAY_FAILED + ex.Message;
}
}
protected void MediaElement_MediaEnded(object sender, RoutedEventArgs e)
{
PlayCommandUncheck(); //depress play button to stop playback
//don't talk to ToggleButton directly
}
Gotcha: MediaElement AutoPlay faster than doing Play at MediaOpened
Just added the following comment to: https://github.com/loarabia/ManagedMediaHelpers/issues/15
Managed Media Helpers contains the very useful Mp3MediaSource class for .NET / Silverlight / Windows Phone.
Added compile-time SWITCHES and respective code to Silverlight demo code for PRELOAD (into memory stream) and AUTOPLAY (this was a bit tricky, need to call Play at MediaOpened event, not right after setting the source to the MediaElement).
Also seems to be 2-3 sec slower than AutoPlay (!) irrespective of using PRELOAD. Maybe it is faster to set the source again every time you want to play and just keep AutoPlay=true
Update: had a bug at the following code, obviously you first must set the MediaOpened event handler, then set the Source to the MediaPlayer. Also, one could set that handler once at the InitializeComponent method.
//———————————————————————–
// <copyright file="Page.xaml.cs" company="Larry Olson">
// (c) Copyright Larry Olson.
// This source is subject to the Microsoft Public License (Ms-PL)
// See http://code.msdn.microsoft.com/ManagedMediaHelpers/Project/License.aspx
// All other rights reserved.
// </copyright>
//
// Edited by George Birbilis (http://zoomicon.com)
//———————————————————————–#define AUTOPLAY
//#define PRELOADnamespace Mp3MediaStreamSourceDemo
{
using Media;
using System;
using System.IO;
using System.Windows;
using System.Windows.Controls;/// <summary>
/// A Page of a Silvelight Application.
/// </summary>
public partial class Page : UserControl
{
/// <summary>
/// Initializes a new instance of the Page class.
/// </summary>
public Page()
{
InitializeComponent();me.Volume = 1.0; //set max volume
#if !AUTOPLAY
me.AutoPlay = false;me.MediaOpened += (s, e) =>
{
//me.Position = TimeSpan.Zero;
me.Stop(); //this stops current playback (if any) and rewinds back to start
//me.PlaybackRate = 1.0;
try
{
me.Play();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
};
#endif
}/// <summary>
/// Event handler for the Button on the Page.
/// </summary>
/// <param name="sender">
/// The button which was clicked.
/// </param>
/// <param name="e">
/// The state when this event was generated.
/// </param>
private void OpenMedia(object sender, RoutedEventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog();
ofd.ShowDialog();Stream data = ofd.File.OpenRead();
#if PRELOAD
Stream m = new MemoryStream((int)ofd.File.Length);
data.CopyTo(m);
m.Position = 0;
data = m;
#endif
Mp3MediaStreamSource mediaSource = new Mp3MediaStreamSource(data);
me.SetSource(mediaSource);
}
}
}
Gotcha: JS replace on document.location fails, use document location.href
This is my contribution to:
http://stackoverflow.com/questions/2652816/what-is-the-difference-between-document-location-href-and-document-location
Here is an example of the practical significance of the difference and how it can bite you if you don’t realize it (document.location being an object and document.location.href being a string):
We use MonoX Social CMS (http://mono-software.com) free version at http://social.ClipFlair.net and we wanted to add the language bar WebPart at some pages to localize them, but at some others (e.g. at discussions) we didn’t want to use localization. So we made two master pages to use at all our .aspx (ASP.net) pages, in the first one we had the language bar WebPart and the other one had the following script to remove the /lng/el-GR etc. from the URLs and show the default (English in our case) language instead for those pages
<script>
var curAddr = document.location; //MISTAKE
var newAddr = curAddr.replace(new RegExp("/lng/[a-z]{2}-[A-Z]{2}", "gi"), "");
if (curAddr != newAddr)
document.location = newAddr;
</script>But this code isn’t working, replace function just returns Undefined (no exception thrown) so it tries to navigate to say x/lng/el-GR/undefined instead of going to url x. Checking it out with Mozilla Firefox’s debugger (F12 key) and moving the cursor over the curAddr variable it was showing lots of info instead of some simple string value for the URL. Selecting Watch from that popup you could see in the watch pane it was writing "Location -> …" instead of "…" for the url. That made me realize it was an object
One would have expected replace to throw an exception or something, but now that I think of it the problem was that it was trying to call some non-existent "replace" method on the URL object which seems to just give back "undefined" in Javascript.
The correct code in that case is:
<script>
var curAddr = document.location.href; //CORRECT
var newAddr = curAddr.replace(new RegExp("/lng/[a-z]{2}-[A-Z]{2}", "gi"), "");
if (curAddr != newAddr)
document.location = newAddr;
</script>Gotcha: don’t use ‘{$…}’ syntax or ‘$…’ syntax in XSL-XPath’s concat
<xsl:template match="cxml:Item" mode="col">
<xsl:variable name="FILENAME" select="…someXPathQuery…"/>
<xsl:variable name="IMAGE" select="concat(‘http://gallery.clipflair.net/activity/image/’, $FILENAME, ‘.png’)"/>
…
I got confused a bit today after a long day of fiddling with XSL and ClipFlair Activity Gallery’s CXML (Collection XML) data (as used in PivotViewer control), and didn’t understand why I couldn’t use an XSL variable’s (FILENAME in the sample above) calculated value inside the definition of another variable.
That other variable (IMAGE) was using “concat” function of XPath and I was getting a literal string concatenated, instead of the value of the FILENAME one.
After a while I noticed that I was using string quotes arround the respective argument passed to the “concat” function. One needs to use $FILENAME there, not ‘$FILENAME’ and of course not ‘{$FILENAME}’ (the last one is used inside say HTML argument values used for output, like <img href=”{$IMAGE}” />)
George Birbilis @zoomicon 