Initial commit: application ColorPicker (palette, pipette ecran, couleur de dossier)

src/ScreenColorPickerForm.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.Windows.Forms;
+
+namespace ColorPickerApp
+{
+    /// <summary>
+    /// Superpose une fenetre transparente plein ecran (tous moniteurs) permettant
+    /// de capturer la couleur de n'importe quel pixel affiche a l'ecran.
+    /// </summary>
+    internal sealed class ScreenColorPickerForm : Form
+    {
+        private readonly Timer _timer;
+        private readonly MagnifierForm _magnifier;
+        private Color _hoverColor = Color.White;
+        private Point _lastScreenPoint;
+
+        public Color PickedColor { get; private set; }
+
+        public ScreenColorPickerForm()
+        {
+            FormBorderStyle = FormBorderStyle.None;
+            ShowInTaskbar = false;
+            StartPosition = FormStartPosition.Manual;
+            TopMost = true;
+            BackColor = Color.Black;
+            Opacity = 0.01; // fenetre quasi invisible, sert uniquement a capter la souris
+            Cursor = Cursors.Cross;
+            DoubleBuffered = true;
+            KeyPreview = true;
+
+            Bounds = SystemInformation.VirtualScreen;
+
+            _magnifier = new MagnifierForm();
+
+            _timer = new Timer { Interval = 40 };
+            _timer.Tick += (s, e) => UpdateHover();
+
+            MouseClick += OnMouseClick;
+            KeyDown += (s, e) => { if (e.KeyCode == Keys.Escape) { PickedColor = Color.Empty; Close(); } };
+        }
+
+        protected override void OnShown(EventArgs e)
+        {
+            base.OnShown(e);
+            _magnifier.Show(this);
+            _timer.Start();
+        }
+
+        protected override void OnFormClosed(FormClosedEventArgs e)
+        {
+            _timer.Stop();
+            _magnifier.Close();
+            base.OnFormClosed(e);
+        }
+
+        private void UpdateHover()
+        {
+            _lastScreenPoint = Cursor.Position;
+            try
+            {
+                using (var bmp = new Bitmap(1, 1, PixelFormat.Format32bppArgb))
+                {
+                    using (var g = Graphics.FromImage(bmp))
+                    {
+                        g.CopyFromScreen(_lastScreenPoint, Point.Empty, new Size(1, 1));
+                    }
+                    _hoverColor = bmp.GetPixel(0, 0);
+                }
+            }
+            catch
+            {
+                // ignore capture errors (ex: DPI change) et garder la derniere couleur connue
+            }
+
+            _magnifier.UpdateDisplay(_lastScreenPoint, _hoverColor);
+        }
+
+        private void OnMouseClick(object sender, MouseEventArgs e)
+        {
+            if (e.Button == MouseButtons.Left)
+            {
+                PickedColor = _hoverColor;
+                Close();
+            }
+            else
+            {
+                PickedColor = Color.Empty;
+                Close();
+            }
+        }
+    }
+}