add ColorDropper

src/Shared/HandyControl_Shared/Controls/ColorPicker/ColorDropper.cs

@@ -1,9 +1,69 @@
-using System.Windows.Controls;
+using System;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Input;
+using System.Windows.Media;
+using HandyControl.Data;
+using HandyControl.Tools;
+using HandyControl.Tools.Interop;
 
 namespace HandyControl.Controls
 {
-    public class ColorDropper : Control
+    internal class ColorDropper : Control
     {
-        
+        private Cursor _dropperCursor;
+
+        private readonly ColorPicker _colorPicker;
+
+        public ColorDropper(ColorPicker colorPicker)
+        {
+            _colorPicker = colorPicker;
+        }
+
+        public void Update(bool isShow)
+        {
+            if (isShow)
+            {
+                if (_dropperCursor == null)
+                {
+                    var info = Application.GetResourceStream(
+                        new Uri("pack://application:,,,/HandyControl;Component/Resources/dropper.cur"));
+                    if (info != null)
+                    {
+                        _dropperCursor = new Cursor(info.Stream);
+                    }
+                }
+
+                if (_dropperCursor == null) return;
+
+                Mouse.OverrideCursor = _dropperCursor;
+                MouseHook.Start();
+                MouseHook.StatusChanged += MouseHook_StatusChanged;
+            }
+            else
+            {
+                Mouse.OverrideCursor = Cursors.Arrow;
+            }
+        }
+
+        private void MouseHook_StatusChanged(object sender, MouseHookEventArgs e)
+        {
+            if (!_colorPicker.IsMouseOver && e.Message == MouseHookMessageType.LeftButtonDown)
+            {
+                var brush = new SolidColorBrush(GetColorAt(e.Point.X, e.Point.Y));
+                _colorPicker.SelectedBrush = brush;
+                //MouseHook.Stop();
+                //MouseHook.StatusChanged -= MouseHook_StatusChanged;
+            }
+        }
+
+        public static Color GetColorAt(int x, int y)
+        {
+            var desk = UnsafeNativeMethods.GetDesktopWindow();
+            var dc = UnsafeNativeMethods.GetWindowDC(desk);
+            var a = (int)UnsafeNativeMethods.GetPixel(dc, x, y);
+            UnsafeNativeMethods.ReleaseDC(desk, dc);
+            return Color.FromArgb(255, (byte) ((a >> 0) & 0xff), (byte) ((a >> 8) & 0xff), (byte) ((a >> 16) & 0xff));
+        }
     }
 }

src/Shared/HandyControl_Shared/Controls/ColorPicker/ColorPicker.cs

@@ -41,7 +41,7 @@ namespace HandyControl.Controls
 
         #region Data
 
-        private Cursor _dropperCursor;
+        private ColorDropper _colorDropper;
 
         private ToggleButton _toggleButtonDropper;
 
@@ -696,25 +696,12 @@ namespace HandyControl.Controls
 
         private void ToggleButtonDropper_Click(object sender, RoutedEventArgs e)
         {
-            if (_toggleButtonDropper.IsChecked == true)
+            if (_colorDropper == null)
             {
-                if (_dropperCursor == null)
-                {
-                    var info = Application.GetResourceStream(new Uri("pack://application:,,,/HandyControl;Component/Resources/dropper.cur"));
-                    if (info != null)
-                    {
-                        _dropperCursor = new Cursor(info.Stream);
-                    }
-                }
-
-                if (_dropperCursor == null) return;
-
-                Mouse.OverrideCursor = _dropperCursor;
-            }
-            else
-            {
-                Mouse.OverrideCursor = Cursors.Arrow;
+                _colorDropper = new ColorDropper(this);
             }
+            // ReSharper disable once PossibleInvalidOperationException
+            _colorDropper.Update(_toggleButtonDropper.IsChecked.Value);
         }
 
         public void Dispose() => System.Windows.Window.GetWindow(this)?.Close();