【WPF】取色器-Color Extractor

序

取色器是一个非常实用的小工具，网上也很多可供下载使用。为什么已有却还是想要自己去实现一个呢？一方面是因为工具虽小但毕竟涉及到操作系统 API 的使用。另一方面想要在技术上精进一些。

实现

实现思路测试通过 Hook 鼠标左键单击，获取到鼠标位于屏幕坐标位置，再获取当前位置所渲染的颜色。

Hook

订阅鼠标左键点击事件，将鼠标坐标获取到当前程序。

using System.Runtime.InteropServices;
using System.Windows;

namespace ColorExtractor
{
   
    public partial class GlobalMouseHook
    {
   
        private const int WH_MOUSE_LL = 14;
        private const int WM_LBUTTONDOWN = 0x0201;
        private const int WM_LBUTTONUP = 0x0202;

        public event EventHandler<Point> MouseReleased;

        private LowLevelMouseProc _proc;
        private IntPtr _hookID = IntPtr.Zero;

        public GlobalMouseHook()
        {
   
            _proc = HookCallback;
        }

        public void SetHook()
        {
   
            _hookID = SetWindowsHookEx(WH_MOUSE_LL, _proc, IntPtr.Zero, 0);
        }

        public void ReleaseHook()
        {
   
            UnhookWindowsHookEx(_hookID);
        }

        private IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
        {
   
            if (nCode >= 0)
            {
   
                if (wParam == (IntPtr)WM_LBUTTONUP)
                {
   
                    MSLLHOOKSTRUCT hookStruct = Marshal.PtrToStructure<MSLLHOOKSTRUCT>(lParam);
                    MouseReleased?.Invoke(this, new Point(hookStruct.pt.x, hookStruct.pt.y));
                }
            }
            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        }

        private delegate IntPtr LowLevelMouseProc(int nCode, IntPtr wParam, IntPtr lParam);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelMouseProc lpfn, IntPtr hMod, uint dwThreadId);

        [DllImport("user32.dll", CharSet = CharSet