Using Drag and Drop in PowerShell GUIs

Drag and drop is a wonderful facility that most of us will use every day without even thinking about it. This article shows how it can be implemented in PowerShell GUI applications.

For this particular script, we’ll implement drag and drop functionality to allow us to drag a file from explorer to a textbox in we’ve created. When the drag and drop operation is complete, the textbox will then show the path to the file.

You can find a copy of the PowerShell Studio form and exported PowerShell code at the PowerShell.Amsterdam repository.

Here is what we our application will do once we have completed it:

To achieve our objective, we need to make use of two events, DragOver, and DragDrop.

DragOver occurs when the mouse is over the control on which we wish to ‘drop’ our object. We’ll typically just use this for changing our pointer to show a move or copy operation is in operation.

DragDrop occurs once the actual operation is finished. That is, the object has been dragged into the form and over the control, and the mouse button released.

To implement this in our application, carry out the following:

  • Create a form
  • Create a Textbox on the form
  • Set the following properties for the Textbox
    • Name : txtDragandDrop
    • Label : Contents dragged:
    • AllowDrop : true

1 - form design and properties

We now define the events that will be processed, and their handlers.

  • DragDrop : txtDragandDrop_DragDrop
  • DragOver : txtDragandDrop_DragOver

2 - form design and events

For the event handler code, use the following :

If you are developing this application in PowerShell Studio, you will need to first export the code, either to a standalone EXE, or .PS1 file.

  • Run the application from either of the above.
  • Drag a file of you choice from explorer to the textbox.

The textbox will be populated with the filepath of the file that has been dragged and dropped over it.

4 - running

Thanks for reading!

Tim

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Sharing Events Handlers in PowerShell GUIs

When you setup an event handler and its code, it is helpful to know it can be shared amongst multiple controls whilst still allowing access to the specific control which raised the event.

The first apparent benefit of this is that it instantly reduces the amount of code and code replication in your scripts, but it also gives an insight into what information is received by an event handler.

Although there are some exceptions, a typical event will provide two sets of information that the hander can process

  • The calling object (referenced in your code by use of the variable $this), also known as the Sender
  • The event arguments, passed in as a pipelined object $_

To illustrate how we can use this, we’re going to create a form with two buttons, which share the same event handler, which change the background color to white when the mouse hovers over it, and then back to normal when the mouse leaves the button’s area. You can find a copy of the PowerShell Studio form, and exported .ps1 file (for looking at the pure PowerShell code) at my GitHub repository

  • Create a form with two buttons
  • Select the first button
  • For the MouseHover event, call its handler buttonHover
  • For the MouseLeave event, call its handler buttonLeave
  • Repeat the button setting for the second button
Sharing Events - Force and Event Design

The first buttons configuration

Sharing Events - Force and Event Design Button 2

The second buttons configuration

  For our the event code, use the following:

Shared events in action :

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Removing Items from Lists Using the Keyboard

In an earlier post, we created a form with two listgridview controls, and used both add and remove buttons, and double click functionality to allow an item to move an item from one control to another in an intuitive manner.

Todays post shows how we can use a remove items from a list by pressing a key. Specifically, we’ll be using the DELETE key for removing items. This will be carried out in Sapien’s PowerShell Studio 2015, but the same methodology applies to however you generate winforms in PowerShell.

For initial setup, carry out the following :

  • create a new form with a header and several items.
  • create a listview control called $lstControl
  • populate the control with a header
  • add some items to the listview control

Sample form and control layout

 

  • select the control
  • select Events in the properties pane
  • double click on KeyDown
  • Insert the following code :

The KeyDown event’s code

 

Go ahead and test it, adding an item to the control on the right hand side, selecting it, and then pressing the DELETE key.

Also, because the code loops through each selected item in the control, we can also use standard multiple selection functionality offered by the various use of the SHIFT and CTRL combinations.

Two items are selected using a click SHIFT combination

The DELETe key is pressed, and the previous selected items are removed from the list

You can find the files, if you are using PowerShell Studio 2015, or exported .ps1 file at my gitlab repository.

Additionally, there’s a (basic) video of this code in action at my channel on You Tube.

Thanks for reading, and feel free to provide feedback.

cheers,

Tim

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