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HowTo: Drop files onto Silverlight controls
I was recently adding drop-files support to ClipFlair Studio, so I had to do some research on the related API that is available to Silverlight apps.
Silverlight supports a limited set of Drag-and-Drop interaction with the operating system (supposedly for security reasons, but most probably because of the classic cross-platform implementation pains).
For example it allows you to drop a collections of file objects from the operating system’s file explorer (or other similar application) onto a Silverlight drop target, but not the other way around.
Also, it doesn’t allow dropping other flavors of content, like text, images etc., only collections of file objects.
To allow dropping files onto a Silverlight control you set AllowDrop property to true and handle the Drop and optionally the DragEnter/DragOver/DragLeave events to provide visual feedback during the drop operation (mostly when over the drop target, unless you do Mouse Capturing).
<RichTextBox
x:Name="rtb"
…
AllowDrop="True"
Drop="rtb_Drop"
DragEnter="rtb_DragEnter"
DragOver="rtb_DragOver"
DragLeave="rtb_DragLeave"
/>
#region DragAndDrop
private void rtb_Drop(object sender, System.Windows.DragEventArgs e)
{
VisualStateManager.GoToState(this, "Normal", true);//the Drop event passes in an array of FileInfo objects for the list of files that were selected and drag-dropped onto the RichTextBox.
if (e.Data == null)
return;IDataObject f = e.Data as IDataObject;
if (f != null) //checks if the dropped objects are files
{
object data = f.GetData(DataFormats.FileDrop); //Silverlight only supports FileDrop
FileInfo[] files = data as FileInfo[]; //…GetData returns null if format is not supportede.Handled = true;
if (files != null)
//Walk through the list of FileInfo objects of the selected and drag-dropped files and parse the .txt and .docx files
//and insert their content in the RichTextBox.
foreach (FileInfo file in files)
Load(file, false);
}}
private void rtb_DragEnter(object sender, System.Windows.DragEventArgs e)
{
VisualStateManager.GoToState(this, "DragOver", true);
e.Handled = true;
}
private void rtb_DragOver(object sender, System.Windows.DragEventArgs e)
{
e.Handled = true;
//NOP
}private void rtb_DragLeave(object sender, System.Windows.DragEventArgs e)
{
VisualStateManager.GoToState(this, "Normal", true);
e.Handled = true;
}#endregion
For the visual feedback you can use VisualStateManager and respective VisualStates at say a Grid that wraps the drop target in the XAML layout.
<Grid x:Name="LayoutRoot">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="DragStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0:0:0.3">
<VisualTransition.GeneratedEasingFunction>
<CircleEase EasingMode="EaseIn"/>
</VisualTransition.GeneratedEasingFunction>
</VisualTransition>
</VisualStateGroup.Transitions>
<VisualState x:Name="Normal"/>
<VisualState x:Name="DragOver">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Control.Background).(SolidColorBrush.Color)" Storyboard.TargetName="rtb">
<EasingColorKeyFrame KeyTime="0" Value="#FFFFF7D1"/>
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
Note that on MacOS-X Safari doesn’t pass drop events automatically to plugins and you have to catch them via Javascript and pass them to Silverlight, plus I’ve read that in MacOS-X Firefox doesn’t support this at all.
Even worse, Microsoft’s workaround article has a typo in the Javascript (should call dragDrop instead of drop) and there is a chance it doesn’t work in latest version of Safari. For more see:
http://msdn.microsoft.com/en-us/library/ee670998%28v=vs.95%29.aspx
http://www.telerik.com/forums/dropping-files-using-safari-on-mac (this says one can use HTML5 events and the Silverlight HTML/Javascript Bridge to notify Silverlight)
http://www.thebuzzmedia.com/html5-drag-and-drop-and-file-api-tutorial/
HowTo: Remove Skype from Windows taskbar, keep as Taskbar tray icon
An annoying feature of Skype of recent Skype versions is that by default it shows an icon on the Windows taskbar apart from the one at the taskbar tray while you’re signed in. This also means it shows in the ALT+TAB key sequence when switching between open windows, which you might not always want to happen, since you may accidentally switch to it instead of the windows you’re working with at that moment.
If it (also) had an option “Keep Skype in the taskbar during a video conversation” it would be more useful I guess.
Luckily you can turn off that behaviour from Skype’s Tools/Options menu option, by going to Advanced and then Advanced settings part of it.
Tip: Quick way to change taskbar tray icon visibility
Windows 7 has kept the taskbar tray from previous versions of Windows, but is providing a different means of managing which icons always show up and when (e.g. can set a specific icon to show up only if they have notifications, or even to never show up on the tray). When you press the “up” arrow UI button that is just before the taskbar tray you see a popup with the hidden icons and pressing “Customize…” you see a dialog where you can set per icon options or select to “Always show all icons and notifications on the taskbar”.
A quick (and quite useful on both tablets and classic desktops/notebooks) trick though is that you don’t need to show that Customize dialog, you can just show the small popup with the hidden icons and drag an icon from there to the taskbar tray to make it always show up. The inverse is also true, you can drag an icon from the tray to that popup to make an icon show up only when it has notifications.
Note that if the Customize dialog is already open its UI gets updated with your changes on the fly, but you then have to press OK to keep the changes, pressing Cancel will undo even the changes you did via drag-drop.
Tip: Display Process Task menu without right click
You probably know already that on Windows 7 you can right click icons for executing tasks (applications) on the taskbar and select to Pin them there. You must have also noticed that Windows 7 aware applications show common tasks there, while Windows also shows recent files opened by some application even at cases where the application is not Windows 7 aware itself.
What you probably haven’t noticed yet (found out by accident myself recently too on a Tablet PC), is that apart from right clicking on the taskbar icons to see that popup menu, you can also drag them a bit outwards and presto!, you get the popup. Very useful with tablets, since for right click you have to hold down the finger for a while which is not as quick as this nifty shortcut.
Windows 7 issue: can’t copy filename of files on read-only media
Just came across one more case of trying to over-protect users and in the way losing functionality (maybe originally unforeseen functionality, but which is nevertheless useful to many end-users).
At Windows 7, Microsoft doesn’t allow you anymore to press F2 or click on a filename to enter edit more for it when the file resides on a read-only media (like a DVD-ROM).
Moreover when you right click the file and select Properties, the filename field at the properties dialog is at a disabled editbox and somebody from the Windows UI team must have taken “disabling” an editbox literally, making the action disable even selecting and copying text from it instead of just making it read-only.
So one would think they would be able to right-click the file, select Copy and then Paste the filepath onto an editbox. No, again no one thought of also putting a text flavor with the full file path on the clipboard so that user could paste it to a textbox (Clipboard supports multiple data flavours for copied items and when you paste an app can select which flavours it knows and might care to use). Think I have suggested that to Microsoft long time ago, but still not implemented.
George Birbilis @zoomicon 