An Alpha Channel Composited Windows Form with Designer Support

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

using AlphaForm;

#region notes

// This example shows how to use two instances of AlphaForm with one being the main
// window and the second being an animated drawer that slides in and out underneath
// the main form. The code here could be adapted to N slide out drawers as the logic
// for managing the animation and z-order issues is the same. It addresses the 
// following behaviours:
// 
// 1. The main form can be top-most or not as in either case the drawer window's 
//    ownership is set to the main form which keeps their z-order in sync.
// 2. A close event to either the main form or drawer window closes both.
// 3. Location changed event handlers enable dragging of both the main from and 
//    drawer window in tandem.

#endregion

namespace SlidingPanes
{
  public partial class Form1 : Form
  {

    public SlideOut m_drawer;
    Point m_drawerLocOld;
    Point m_mainLocOld;
    bool m_drawerOpen;
    bool m_lockLoc;
    
    
    public Form1()
    {
      InitializeComponent();
      m_drawer = new SlideOut();
      m_drawer.ShowInTaskbar = false;

      m_drawerOpen = false;
      m_lockLoc = false;
  	  
      LocationChanged += new EventHandler(MainFormLocationChanged);
      m_drawer.LocationChanged += new EventHandler(DrawerLocationChanged);

    }

    protected override void OnShown(EventArgs e)
    {
      alphaFormTransformer1.Fade(FadeType.FadeIn, false, false, 500);
      base.OnShown(e);
    }
    
    protected override void OnClosing(CancelEventArgs e)
    {
      // We want to close both the drawer window and the main form if either
      // receives a close event. So we use the Owner property as a flag to 
      // manage this. Also see OnClosing in SlideOut.cs.
      if (m_drawer.Owner != null)
        {
        m_drawer.Owner = null;
        m_drawer.Close(); 
        }
      alphaFormTransformer1.Fade(FadeType.FadeOut, true, false, 300);
      base.OnClosing(e);
    }

    private void Form1_Load(object sender, EventArgs e)
    {
      // It's going to fade in, so we must set opacity to 0.
      alphaFormTransformer1.TransformForm(0);
    }


    public void DrawerButton_Click(object sender, EventArgs e)
    {
      int ledge;

      // See docs in AlphaForm on this class
      Impulse imp = new Impulse(7.0);

      int frames;
      int duration;

      bool SaveTop = TopMost;

      // Suppress location changed event handlers for drawer and main form
      m_lockLoc = true;

      if (m_drawerOpen)
      {
        duration = 400;
        
        // owner must be null to guarantee drawer window will appear under
        // the main form's layered window.
        m_drawer.Owner = null;

        // Force main form to topmost so that drawer is underneath
        TopMost = true;

        ledge = m_drawer.Left;

        int op = 0;
        int uop = 0;

        // 30-40 fps is a reasonable median starting value (it will
        // be adjusted, on-the-fly, up or down to give 
        // the greatest frame rate for the requested duration)
        // The only risk to setting an initially high fps is on slower
        // graphics displays where this routine will make a larger
        // reduction in frame rate to meet the desired duration. Such
        // on-the-fly frame rate adjustments may be perceived as jitteryness.
        // The inverse is also true - setting it initially too low will force
        // a fast graphics system to make large increases to the frame rate.
        // (Convergence in either case is very fast though :-))
        
        frames = Math.Max((40 * duration) / 1000, 1);
        int inc = Math.Max(m_drawer.Width / frames, 1);
        int frameDur = duration / frames;

        // 0.92 figured by trial & error - because the frame of the drawer
        // window image includes some empty space, and I want it to slide in/out
        // right to the edge. If I wasn't so lazy, I'd crop the image in 
        // Photoshop instead of doing this :-) However this illustrates an
        // important point. If you need to rely on some fraction of the drawer
        // window width or height as an animation parameter, don't use an
        // absolute pixel value as that won't scale for different
        // DPI screens.
        int slideW = (int)(0.92 * m_drawer.Width);

        while (uop != slideW)
        {
          uop = (int)Math.Round(imp.Evaluate(op / (double)slideW) * (double)slideW);

          if (uop > slideW)
            uop = slideW;
          DateTime sf = DateTime.Now;
          m_drawer.SetDesktopLocation(ledge - uop, m_drawer.Location.Y);
          TimeSpan ts = DateTime.Now - sf;
          int wait = frameDur - ts.Milliseconds;

          m_drawer.Update(); // force contents to update

          // We either wait or speed up to maintain requested duration
          if (wait > 0)
          {
              System.Threading.Thread.Sleep(wait);
              if (wait <= frameDur/2 && inc > 1)
              {
                  inc = Math.Max(1, inc / 2);
                  frameDur /= 2;
              }
          }
          else if (Math.Abs(wait) >= frameDur)
          {
              inc *= 2;
              frameDur *= 2;
          }

          op += inc;
        }

        m_drawerOpen = false;

        // Hide the drawer window (it's closed - behind the main form now).
        // Note: We need to hide the composite window which includes the layered window.
        // The Visible property hides the base class property in SlideOut, and a utility function 
        // is called to set the property for both the form and layered window (see
        // SlideOut.cs).
        m_drawer.Visible = false;
        
        DrawerButton.Text = "Open Drawer ->";

      }
      else
      {
        // Setting TopMost on this form won't guarantee the drawer window will be shown 
        // underneath, and we want it to appear behind the main form when made visible.
        // An easy way to achieve this is to just show the drawer window off-screen first, display, then 
        // set TopMost on the main form to ensure the drawer is behind.
        m_drawer.Location = new Point(-1000000, -1000000);
        
        // Note: We need to show the composite window which includes the layered window.
        // The Visible property hides the base class property in SlideOut, and a utility function 
        // is called to set the property for both the form and layered window (see
        // SlideOut.cs).
        m_drawer.Visible = true;
        
        TopMost = true;
        
        // The drawer window is behind (z-order) and off-screen now, so move it into position
        // for animating.
        m_drawer.Location = new Point(Location.X + Width - m_drawer.Width, Location.Y + (Height - m_drawer.Height) / 2);

        ledge = m_drawer.Left;
        duration = 600; // arbitrary

        int op = 0;
        int uop = 0;
        
        // 30-40 fps is a reasonable median starting value (it will
        // be adjusted, on-the-fly, up or down to give 
        // the greatest frame rate for the requested duration)
        // The only risk to setting an initially high fps is on slower
        // graphics displays where this routine will make a larger
        // reduction in frame rate to meet the desired duration. Such
        // on-the-fly frame rate adjustments may be perceived as jitteryness.
        // The inverse is also true - setting it initially too low will force
        // a fast graphics system to make large increases to the frame rate.
        // (Convergence in either case is very fast though :-))
        
        frames = Math.Max((40 * duration) / 1000, 1);
        int inc = Math.Max(m_drawer.Width / frames, 1);
        int frameDur = duration / frames;
        
        // See note above on where this 0.92 comes from.
        int slideW = (int) (0.92 * m_drawer.Width);

        while (uop != slideW)
        {
          uop = (int)Math.Round(imp.Evaluate(op / (double)slideW) * (double)slideW);

          if (uop > slideW)
            uop = slideW;
          DateTime sf = DateTime.Now;
          m_drawer.SetDesktopLocation(ledge + uop, m_drawer.Location.Y);
          TimeSpan ts = DateTime.Now - sf;
          int wait = frameDur - ts.Milliseconds;

          m_drawer.Update(); // force contents to update

          // We either wait or speed up to maintain requested duration
          if (wait > 0)
          {
            System.Threading.Thread.Sleep(wait);

            if (wait <= frameDur / 2 && inc > 1)
            {
              inc = Math.Max(1, inc / 2);
              frameDur /= 2;
            }
          }
          else if (Math.Abs(wait) >= frameDur)
          {
            inc *= 2;
            frameDur *= 2;
          }

          op += inc;
        }

        // Once drawer is displayed, we set ownership to main form so that
        // the two are in sync with respect to activation and close events.
        m_drawer.Owner = this;
        m_drawerLocOld = m_drawer.Location;
        m_drawerOpen = true;
        DrawerButton.Text = "<-- Close Drawer";
      }

      TopMost = SaveTop;
      m_lockLoc = false;
    }

    // These location change event handlers enable synchroneous dragging of
    // the main form and the drawer window
    void DrawerLocationChanged(Object sender, EventArgs e)
    {
      bool saveLock = m_lockLoc;
      if (!m_lockLoc)
      {
        m_lockLoc = true;
        SetDesktopLocation(Location.X + m_drawer.Location.X - m_drawerLocOld.X, Location.Y + m_drawer.Location.Y - m_drawerLocOld.Y);
        m_mainLocOld = Location;
      }
      m_drawerLocOld = m_drawer.Location;
      m_lockLoc = saveLock;
    }

    void MainFormLocationChanged(Object sender, EventArgs e)
    {
      bool saveLock = m_lockLoc;
      if (!m_lockLoc)
      {
        m_lockLoc = true;
        m_drawer.SetDesktopLocation(m_drawer.Location.X + Location.X - m_mainLocOld.X, m_drawer.Location.Y + Location.Y - m_mainLocOld.Y);
        m_drawerLocOld = m_drawer.Location;
      }
      m_mainLocOld = Location;
      m_lockLoc = saveLock;
    }

    private void button1_Click(object sender, EventArgs e)
    {
      Close();
    }

 
  }
}