WPF Borderless Window issues: Aero Snap & Maximizing

Question

I\'ve created a borderless WPF window by setting the following window properties in XAML:

... WindowStyle=\"None\" AllowsTransparency=\"True\" ...
         


        

Answer 1

I just went through this entire thing myself. It was a real chore, because you have to manually account for so much. It's funny, we take so much for granted these days, with something as simple as how a basic window operates. But a look at this sample code that I am providing is a good indication of just how much really goes into this problem.

I hope this helps, as it took me a little time to get here myself.

MainWindow.Xaml

MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp1
{
    public partial class MainWindow : Window
    {
        #region --- Declarations ---
        private Rect _location { get; set; }
        #endregion

        #region --- Constructors ---
        public MainWindow()
        {
            InitializeComponent();
        }
        #endregion

        #region --- Properties ---
        private Rect DesktopArea
        {
            get
            {
                var c = System.Windows.Forms.Cursor.Position;
                var s = System.Windows.Forms.Screen.FromPoint(c);
                var a = s.WorkingArea;
                return new Rect(a.Left, a.Top, a.Width, a.Height);
            }
        }
        #endregion

        #region --- Dependency Properties ---
        public static readonly DependencyProperty InternalWindowStateProperty = DependencyProperty.Register("InternalWindowState", typeof(WindowState), typeof(MainWindow), new PropertyMetadata(WindowState.Normal, new PropertyChangedCallback(OnInternalWindowStateChanged)));

        public WindowState InternalWindowState
        {
            get { return (WindowState)GetValue(InternalWindowStateProperty); }
            set { SetValue(InternalWindowStateProperty, value); }
        }

        private static void OnInternalWindowStateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            MainWindow instance = (MainWindow)d;
            instance.SetInternalWindowState((WindowState)e.NewValue);
        }
        #endregion

        #region --- Private Methods ---
        private void StoreLocation()
        {
            _location = new Rect(this.Left, this.Top, this.Width, this.Height);
        }

        private void RestoreLocation()
        {
            this.Width = _location.Width;
            this.Height = _location.Height;
            this.Top = _location.Top >= 0 ? _location.Top : 0;
            this.Left = _location.Left;
        }

        private void SetMaximizedState()
        {
            this.Width = DesktopArea.Width;
            this.Height = DesktopArea.Height;
            this.Top = DesktopArea.Top;
            this.Left = DesktopArea.Left;
        }

        private void SetInternalWindowState(WindowState state)
        {
            InternalWindowState = state;

            switch (InternalWindowState)
            {
                case WindowState.Normal:
                    this.WindowState = WindowState.Normal;
                    RestoreLocation();
                    break;
                case WindowState.Maximized:
                    this.WindowState = WindowState.Normal;
                    SetMaximizedState();
                    break;
                case WindowState.Minimized:
                    this.WindowState = WindowState.Minimized;
                    break;
            }
        }
        #endregion

        #region --- Sizing Routines --- 
        private void Thumb_DragDelta(object sender, System.Windows.Controls.Primitives.DragDeltaEventArgs e)
        {
            Thumb thumb = (Thumb)sender;
            int tag = Convert.ToInt32(thumb.Tag);
            if (thumb.Cursor == Cursors.SizeWE) HandleSizeWE(tag, e);
            if (thumb.Cursor == Cursors.SizeNS) HandleSizeNS(tag, e);
            if (thumb.Cursor == Cursors.SizeNESW) HandleSizeNESW(tag, e);
            if (thumb.Cursor == Cursors.SizeNWSE) HandleSizeNWSE(tag, e);
        }

        private void HandleSizeNWSE(int tag, DragDeltaEventArgs e)
        {
            if (tag == 0)
            {
                this.Top += e.VerticalChange;
                this.Height -= e.VerticalChange;
                this.Left += e.HorizontalChange;
                this.Width -= e.HorizontalChange;
            }
            else
            {
                this.Width += e.HorizontalChange;
                this.Height += e.VerticalChange;
            }
        }

        private void HandleSizeNESW(int tag, DragDeltaEventArgs e)
        {
            if (tag == 0)
            {
                this.Top += e.VerticalChange;
                this.Height -= e.VerticalChange;
                this.Width += e.HorizontalChange;
            }
            else
            {
                this.Left += e.HorizontalChange;
                this.Width -= e.HorizontalChange;
                this.Height += e.VerticalChange;
            }
        }

        private void HandleSizeNS(int tag, DragDeltaEventArgs e)
        {
            if (tag == 0)
            {
                this.Top += e.VerticalChange;
                this.Height -= e.VerticalChange;
            }
            else
                this.Height += e.VerticalChange;
        }

        private void HandleSizeWE(int tag, DragDeltaEventArgs e)
        {
            if (tag == 0)
            {
                this.Left += e.HorizontalChange;
                this.Width -= e.HorizontalChange;
            }
            else
                this.Width += e.HorizontalChange;
        }
        #endregion

        #region --- Event Handlers ---
        private void OnDragMoveWindow(Object sender, MouseButtonEventArgs e)
        {
            if (this.InternalWindowState == WindowState.Maximized)
            {
                var c = System.Windows.Forms.Cursor.Position;
                this.InternalWindowState = WindowState.Normal;
                this.Height = _location.Height;
                this.Width = _location.Width;
                this.Top = c.Y - (titleBar.ActualHeight / 2);
                this.Left = c.X - (_location.Width / 2);
            }
            this.DragMove();
        }

        private void OnMaximizeWindow(Object sender, MouseButtonEventArgs e)
        {
            if (this.InternalWindowState == WindowState.Maximized)
                this.InternalWindowState = WindowState.Normal;
            else
                this.InternalWindowState = WindowState.Maximized;
        }

        private void OnMinimizeWindow(Object sender, MouseButtonEventArgs e)
        {
            this.InternalWindowState = WindowState.Minimized;
        }

        private void OnCloseWindow(Object sender, MouseButtonEventArgs e)
        {
            Application.Current.Shutdown();
        }

        private void Window_StateChanged(object sender, EventArgs e)
        {
            if (this.WindowState == WindowState.Maximized)
            {
                this.InternalWindowState = WindowState.Maximized;
            }
        }

        private void Window_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            if (this.InternalWindowState != WindowState.Maximized)
                StoreLocation();
        }
        #endregion
    }
}