[client] input: add display server behaviour tests

Extract input policy from the Wayland and X11 protocol handlers.

Exercise both implementations against literal Wayland event traces.

client/displayservers/X11/input_event.h

@@ -0,0 +1,69 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _H_LG_X11_INPUT_EVENT_
+#define _H_LG_X11_INPUT_EVENT_
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "../input.h"
+
+typedef struct X11Input
+{
+  const LG_DSInputSink * sink;
+  void                 * opaque;
+  uint32_t               buttons;
+  uint32_t               previousPressTime;
+  uint32_t               previousReleaseTime;
+  uint32_t               previousPressButton;
+  uint32_t               previousReleaseButton;
+  uint32_t               previousMotionTime;
+  double                 previousMotionX;
+  double                 previousMotionY;
+  bool                   entered;
+  bool                   focused;
+}
+X11Input;
+
+void x11InputInit(X11Input * input, const LG_DSInputSink * sink,
+    void * opaque);
+
+bool x11InputFocus(X11Input * input, bool focused, double x, double y,
+    const uint32_t * keys, size_t count);
+bool x11InputPointerEnter(X11Input * input, bool mainWindow,
+    bool normal, double x, double y);
+bool x11InputPointerLeave(X11Input * input, bool mainWindow,
+    bool normal, bool captureMode, double x, double y);
+void x11InputPointerMotion(X11Input * input, double x, double y,
+    bool pointerGrabbed);
+void x11InputPointerButton(X11Input * input, unsigned int button,
+    bool pressed, bool raw, uint32_t time, bool inputActive);
+void x11InputRelativeMotion(X11Input * input, uint32_t time,
+    double x, double y, double rawX, double rawY, bool inputActive);
+void x11InputKeyboardKey(X11Input * input, unsigned int keycode,
+    int minKeycode, bool pressed, bool raw, bool inputActive,
+    const char * text);
+void x11InputKeyboardState(X11Input * input,
+    bool ctrl, bool shift, bool alt, bool super,
+    bool numLock, bool capsLock, bool scrollLock);
+
+#endif