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| 1 | +using CefSharp.WinForms; |
| 2 | +using Nacollector.Util; |
| 3 | +using System; |
| 4 | +using System.Runtime.InteropServices; |
| 5 | +using System.Text; |
| 6 | +using System.Threading; |
| 7 | +using System.Threading.Tasks; |
| 8 | +using System.Windows.Forms; |
| 9 | + |
| 10 | +namespace Nacollector.Browser.Handler |
| 11 | +{ |
| 12 | + /// <summary> |
| 13 | + /// Intercepts Windows messages sent to the ChromiumWebBrowser control's widget sub-window. |
| 14 | + /// |
| 15 | + /// It is necessary to listen to the widget sub-window because it receives all Windows messages |
| 16 | + /// and forwards them to CEF, rather than the ChromiumWebBrowser.Handle. |
| 17 | + /// |
| 18 | + /// The supplied Action delegate is fired upon each message. |
| 19 | + /// </summary> |
| 20 | + class ChromeWidgetMessageInterceptor : NativeWindow |
| 21 | + { |
| 22 | + private readonly ChromiumWebBrowser browser; |
| 23 | + private Action<Message> forwardAction; |
| 24 | + |
| 25 | + private ChromeWidgetMessageInterceptor(ChromiumWebBrowser browser, IntPtr chromeWidgetHostHandle, Action<Message> forwardAction) |
| 26 | + { |
| 27 | + AssignHandle(chromeWidgetHostHandle); |
| 28 | + |
| 29 | + this.browser = browser; |
| 30 | + browser.HandleDestroyed += BrowserHandleDestroyed; |
| 31 | + |
| 32 | + this.forwardAction = forwardAction; |
| 33 | + } |
| 34 | + |
| 35 | + /// <summary> |
| 36 | + /// Asynchronously wait for the Chromium widget window to be created for the given ChromiumWebBrowser, |
| 37 | + /// and when created hook into its Windows message loop. |
| 38 | + /// </summary> |
| 39 | + /// <param name="browser">The browser to intercept Windows messages for.</param> |
| 40 | + /// <param name="forwardAction">This action will be called whenever a Windows message is received.</param> |
| 41 | + internal static void SetupLoop(ChromiumWebBrowser browser, Action<Message> forwardAction) |
| 42 | + { |
| 43 | + Task.Factory.StartNew(() => |
| 44 | + { |
| 45 | + try |
| 46 | + { |
| 47 | + bool foundWidget = false; |
| 48 | + while (!foundWidget) |
| 49 | + { |
| 50 | + browser.Invoke((Action)(() => |
| 51 | + { |
| 52 | + IntPtr chromeWidgetHostHandle; |
| 53 | + if (ChromeWidgetHandleFinder.TryFindHandle(browser, out chromeWidgetHostHandle)) |
| 54 | + { |
| 55 | + foundWidget = true; |
| 56 | + new ChromeWidgetMessageInterceptor(browser, chromeWidgetHostHandle, forwardAction); |
| 57 | + } |
| 58 | + else |
| 59 | + { |
| 60 | + // Chrome hasn't yet set up its message-loop window. |
| 61 | + Thread.Sleep(10); |
| 62 | + } |
| 63 | + })); |
| 64 | + } |
| 65 | + } |
| 66 | + catch |
| 67 | + { |
| 68 | + // Errors are likely to occur if browser is disposed, and no good way to check from another thread |
| 69 | + } |
| 70 | + }); |
| 71 | + } |
| 72 | + |
| 73 | + private void BrowserHandleDestroyed(object sender, EventArgs e) |
| 74 | + { |
| 75 | + ReleaseHandle(); |
| 76 | + |
| 77 | + browser.HandleDestroyed -= BrowserHandleDestroyed; |
| 78 | + forwardAction = null; |
| 79 | + } |
| 80 | + |
| 81 | + protected override void WndProc(ref Message m) |
| 82 | + { |
| 83 | + base.WndProc(ref m); |
| 84 | + |
| 85 | + if (forwardAction != null) |
| 86 | + { |
| 87 | + forwardAction(m); |
| 88 | + } |
| 89 | + } |
| 90 | + } |
| 91 | + |
| 92 | + class ChromeWidgetHandleFinder |
| 93 | + { |
| 94 | + private delegate bool EnumWindowProc(IntPtr hwnd, IntPtr lParam); |
| 95 | + |
| 96 | + [DllImport("user32")] |
| 97 | + [return: MarshalAs(UnmanagedType.Bool)] |
| 98 | + private static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr lParam); |
| 99 | + |
| 100 | + private readonly IntPtr mainHandle; |
| 101 | + private string seekClassName; |
| 102 | + private IntPtr descendantFound; |
| 103 | + |
| 104 | + private ChromeWidgetHandleFinder(IntPtr handle) |
| 105 | + { |
| 106 | + this.mainHandle = handle; |
| 107 | + } |
| 108 | + |
| 109 | + private IntPtr FindDescendantByClassName(string className) |
| 110 | + { |
| 111 | + descendantFound = IntPtr.Zero; |
| 112 | + seekClassName = className; |
| 113 | + |
| 114 | + EnumWindowProc childProc = new EnumWindowProc(EnumWindow); |
| 115 | + EnumChildWindows(this.mainHandle, childProc, IntPtr.Zero); |
| 116 | + |
| 117 | + return descendantFound; |
| 118 | + } |
| 119 | + |
| 120 | + [DllImport("user32.dll", CharSet = CharSet.Auto)] |
| 121 | + public static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount); |
| 122 | + |
| 123 | + private bool EnumWindow(IntPtr hWnd, IntPtr lParam) |
| 124 | + { |
| 125 | + StringBuilder buffer = new StringBuilder(128); |
| 126 | + GetClassName(hWnd, buffer, buffer.Capacity); |
| 127 | + |
| 128 | + if (buffer.ToString() == seekClassName) |
| 129 | + { |
| 130 | + descendantFound = hWnd; |
| 131 | + return false; |
| 132 | + } |
| 133 | + |
| 134 | + return true; |
| 135 | + } |
| 136 | + |
| 137 | + /// <summary> |
| 138 | + /// Chrome's message-loop Window isn't created synchronously, so this may not find it. |
| 139 | + /// If so, you need to wait and try again later. |
| 140 | + /// </summary> |
| 141 | + public static bool TryFindHandle(ChromiumWebBrowser browser, out IntPtr chromeWidgetHostHandle) |
| 142 | + { |
| 143 | + var browserHandle = browser.Handle; |
| 144 | + var windowHandleInfo = new ChromeWidgetHandleFinder(browserHandle); |
| 145 | + const string chromeWidgetHostClassName = "Chrome_RenderWidgetHostHWND"; |
| 146 | + chromeWidgetHostHandle = windowHandleInfo.FindDescendantByClassName(chromeWidgetHostClassName); |
| 147 | + return chromeWidgetHostHandle != IntPtr.Zero; |
| 148 | + } |
| 149 | + } |
| 150 | +} |
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