Winform嵌套的CefSharp浏览器，在触摸屏下，点击输入框无法自动弹出软键盘

在使用winforms和CefSharp的应用程序中，在触摸屏幕上，如果要调用系统软键盘以响应HTML输入框的点击，可以遵循以下步骤：

1. 将CefSettings.CefCommandLineArgs["touch-events"]设置为enabled。这将使CefSharp支持在触摸屏幕上接收触摸事件。

var settings = new CefSettings();
settings.CefCommandLineArgs.Add("touch-events", "enabled");
Cef.Initialize(settings);

2. 在WinForms表单中的Load事件处理程序中注册一个CefSharp.EventHandlerProxy，以便监视由CefSharp执行的任何JavaScript事件。

private void Form_Load(object sender, EventArgs e)
{
    browser.RegisterJsObject("boundAsync", new AsyncBoundObject(this));
    browser.FrameLoadEnd += Browser_FrameLoadEnd;
}

private void Browser_FrameLoadEnd(object sender, FrameLoadEndEventArgs e)
{
    if (e.Frame.IsMain)
    {
        var script = @"
            document.addEventListener('click', function(event) {
                if (event.target.tagName === 'INPUT') {
                    event.target.focus();
                    window.boundAsync.showKeyboard();
                }
            });";
        browser.ExecuteScriptAsync(script);
    }
}

3. 创建一个带有名为showKeyboard的方法的异步绑定对象，在该方法中，使用Windows API调用来显示系统软键盘。

public class AsyncBoundObject
{
    private readonly Form form;

    public AsyncBoundObject(Form form)
    {
        this.form = form;
    }

    public async void ShowKeyboard()
    {
        await Task.Run(() =>
        {
            IntPtr handle = GetForegroundWindow();
            if (handle != IntPtr.Zero)
            {
                PostMessage(handle, WM_SYSCOMMAND, SC_RESTORE, 0);
                IntPtr foregroundWindow = GetForegroundWindow();
                IntPtr focusedControl = GetFocus();

                if (focusedControl == IntPtr.Zero || !IsChild(foregroundWindow, focusedControl))
                {
                    // Send a message to the active window to display the soft keyboard.
                    PostMessage(foregroundWindow, WM_IME_SETCONTEXT, IntPtr.Zero, new IntPtr(1));
                    PostMessage(foregroundWindow, WM_IME_NOTIFY, IMN_OPENSTATUSWINDOW, 0);
                }
            }
        });
    }

    [DllImport("user32.dll")]
    private static extern IntPtr GetForegroundWindow();

    [DllImport("user32.dll")]
    private static extern bool IsChild(IntPtr hWndParent, IntPtr hWnd);

    [DllImport("user32.dll")]
    private static extern IntPtr GetFocus();

    [DllImport("user32.dll")]
    private static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

    private const uint WM_SYSCOMMAND = 0x0112;
    private const uint SC_RESTORE = 0xF120;
    private const uint WM_IME_SETCONTEXT = 0x0281;
    private const uint WM_IME_NOTIFY = 0x0282;
    private const uint IMN_OPENSTATUSWINDOW = 0x0002;
}

这些步骤将允许您在HTML输入框中单击以启动系统软键盘。