Powershell Textbox placeholder - winforms

Question

I create my from, define my TextBoxes, and for my placeholder text I'm using the following code:
$AssetText.Add_MouseClick({ $AssetText.text = “” })
$ErrorText.Add_MouseClick({ $ErrorText.text = “” })
$IssueText.Add_MouseClick({ $IssueText = “” })
$TestTagText.Add_MouseClick({ $TestTagText.text = “” })
$TroubleshootText.Add_MouseClick({ $TroubleshootText.text = “” })
$ResolutionText.Add_MouseClick({ $ResolutionText.text = “” })
It works to remove text from the TextBox, but if I type a fair amount of text in any TextBox and then click outside of it, then come back to it, it erases the text I was working on.
Is there another function I can use that would work better than this current method? So that initially I can click the $TextBox to make the text disappear, but when writing my own text in the box wont disappear after clicking in and outside of the $TextBox?

Answer 1

Here is another approach on setting Placeholder text for Textbox. The approach relies on handling WM_PAINT message and has been explained and implemented here.
The difference between this approach and the other approach (sending EM_SETCUEBANNER) is this approach works for multi-line TextBox as well.
using assembly System.Windows.Forms
using namespace System.Windows.Forms
using namespace System.Drawing
$assemblies = "System.Windows.Forms", "System.Drawing"
$code = #"
using System.Drawing;
using System.Windows.Forms;
public class ExTextBox : TextBox
{
string hint;
public string Hint
{
get { return hint; }
set { hint = value; this.Invalidate(); }
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == 0xf)
{
if (!this.Focused && string.IsNullOrEmpty(this.Text)
&& !string.IsNullOrEmpty(this.Hint))
{
using (var g = this.CreateGraphics())
{
TextRenderer.DrawText(g, this.Hint, this.Font,
this.ClientRectangle, SystemColors.GrayText , this.BackColor,
TextFormatFlags.Top | TextFormatFlags.Left);
}
}
}
}
}
"#
#Add the SendMessage function as a static method of a class
Add-Type -ReferencedAssemblies $assemblies -TypeDefinition $code -Language CSharp
# Create an instance of MyForm.
$form = [Form] #{
ClientSize = [Point]::new(400,100);
Text = "Placeholder Sample";
}
$form.Controls.AddRange(#(
($textBox1 = [ExTextBox] #{Location = [Point]::new(10,10); Hint = "Start typing!" })
($textBox2 = [ExTextBox] #{Location = [Point]::new(10,40); Hint = "Start typing!";
MultiLine = $true; Height = 50; })
))
$null = $form.ShowDialog()
$form.Dispose()

Answer 2

If you would like to have placeholder in native OS way, you can send EM_SETCUEBANNER to TextBox to set the placeholder text:
using assembly System.Windows.Forms
using namespace System.Windows.Forms
using namespace System.Drawing
$code = #"
[DllImport("user32.dll", CharSet = CharSet.Unicode)]
public static extern IntPtr SendMessage(IntPtr hWnd,
int msg, IntPtr wParam, string lParam);
public const int EM_SETCUEBANER = 0x1501;
"#
$Win32Helpers = Add-Type -MemberDefinition $code -Name "Win32Helpers" -PassThru
$form = [Form] #{
ClientSize = [Point]::new(400,100);
Text = "Placeholder Text";
}
$form.Controls.AddRange(#(
($textBox1 = [TextBox] #{Location = [Point]::new(10,10) })
($textBox2 = [TextBox] #{Location = [Point]::new(10,40) })
))
$textBox1.add_HandleCreated({
$Win32Helpers::SendMessage($textBox1.Handle,$Win32Helpers::EM_SETCUEBANER`
, [IntPtr]0, "Start typing ...")
$Win32Helpers::SendMessage($textBox2.Handle,$Win32Helpers::EM_SETCUEBANER`
, [IntPtr]0, "Start typing ...")
})
$null = $form.ShowDialog()
$form.Dispose()