TextADinosaur

EditGrid.ps1

using namespace System.Collections.Generic
using namespace System.Management.Automation.Host
using module .\Widget.psm1

class EditGrid : Widget
{
    [BufferCell[,]]$Grid
    [Coordinates]$Cursor
    [Bool]$CursorOn = $True

    #region constructor
    EditGrid([UInt32]$X, [UInt32]$Y, [UInt32]$Width, [UInt32]$Height)
    {
        $This.init([Rectangle]::new($X, $Y, $X + $Width, $Y + $Height))
    }
    EditGrid([Rectangle]$Position)
    {
        $This.init($Position)
    }
    EditGrid([Widget]$Clone)
    {
        $This = $Clone
        $This.GUID = New-Guid
    }
    EditGrid() # PowerShell 5.1.14393.1944 bug: inheritance requires default constructor
    {
        
    }

    init([Rectangle]$Position)
    {
        $This.Position = $Position
        $This.GUID = New-Guid
        $This.Children = [List[Widget]]::new()
        $this.Grid = $global:Host.Ui.RawUI.NewBufferCellArray($This.GetWidth(),$This.GetHeight(),$This.BlankChar)
        $This.Cursor = [Coordinates]::new(0,0)
    }
    #endregion

    [BufferCell[,]]GetBufferCellArray()
    {
        [BufferCell[,]]$buffer = $This.Grid.Clone()
        $IsCursor = if($This.CursorOn){[ConsoleColor]::DarkCyan}else{$This.BackgroundColor}
        Set-BufferCell $This.Grid $This.Cursor.X $This.Cursor.Y -BackgroundColor $IsCursor
        $This.CopyChildBuffers($buffer)
        return $buffer
    }

    [void]Background([guid]$focused)
    {
 #       Write-Host "got background call " + ([datetime]::Now)

    }

    [void]HandleKey([ConsoleKeyInfo]$Key, [guid]$focused)
    {
        if ($This.guid -eq $focused) 
        {
            if (('LeftArrow','RightArrow','UpArrow','DownArrow') -contains $Key.Key)
            {
                $This.MoveCursor($Key.Key)
            } else 
            {
                $This.SetChar($Key.KeyChar)
            }
        }
        
        # Detect rising focus edge
        if ($This.LastFocusState -eq $false)
        {
            $this.OnFocus()
        }

        if ($This.Children.Count -gt 0 -and $This.guid -ne $focused)
        {
            $This.Children[$This.SelectFocusedChild($focused)].HandleKey($Key, $focused)
        }

        $This.FocusEdge = $false
    }

    [void]MoveCursor([ConsoleKey]$Key)
    {
        Set-BufferCell $This.Grid $This.Cursor.X $This.Cursor.Y -BackgroundColor $This.BackgroundColor
        if($Key -eq 'UpArrow')
        {
            $This.Cursor = [Coordinates]::new(
                                            $This.Cursor.X,
                                            [Math]::Max(0,$This.Cursor.Y-1))
        }
        elseif($Key -eq 'DownArrow')
        {
            $This.Cursor = [Coordinates]::new(
                                            $This.Cursor.X,
                                            [Math]::Min($This.GetHeight()-1,$This.Cursor.Y+1))
        }
        elseif($Key -eq 'LeftArrow')
        {
            $This.Cursor = [Coordinates]::new(
                                            [Math]::Max(0,$This.Cursor.X-1),
                                            $This.Cursor.Y)
        }
        elseif($Key -eq 'RightArrow')
        {
            $This.Cursor = [Coordinates]::new(
                                            [Math]::Min($This.GetWidth()-1,$This.Cursor.X+1),
                                            $This.Cursor.Y)
        }
    }

    [void]SetChar([Char]$Character)
    {
        Set-BufferCell $This.Grid $This.Cursor.X $This.Cursor.Y $Character
    }

    [void]OnFocus()
    {
        #$this.CursorOn = $true
        $this.OnFocusCallbacks | ForEach-Object {
            $_.Invoke()
        }
    }
    [void]OnUnFocus()
    {
        #$this.CursorOn = $false
        $this.OnUnfocusCallbacks | ForEach-Object {
            $_.Invoke()
        }
    }
}

TextPaint.ps1

using module ..\..\Aster\
using module ..\..\Aster\Classes\EditGrid.psm1
using module ..\..\Aster\Classes\Controller.psm1
using module ..\..\Aster\Classes\Window.psm1

$Controller = [Controller]::new()
$PaintContainer = [Window]::new(0,0,52,26,"Color A Dinosaur")

$Paint = [EditGrid]::new(1,1,50,24)

$PaintContainer.AddWidget($Paint)

$Controller.AddWidget(@($PaintContainer), $true)
$Controller.focused = 1
$Controller.Start({})