steamcompmgr: Default to left_ptr from cursor font

Avoids having ugly X cursor by default.

Based in part on #280.

src/defer.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+namespace defer_detail
+{
+    template <typename Func>
+    class DeferHelper
+    {
+    public:
+        DeferHelper(Func func)
+            : m_func(func)
+        {
+        }
+        ~DeferHelper()
+        {
+            m_func();
+        }
+
+    private:
+        Func m_func;
+    };
+
+    template <typename Func>
+    DeferHelper<Func> CreateDeferHelper(Func func)
+    {
+        return DeferHelper<Func>(func);
+    }
+}
+
+#define DEFER_1(x, y) x##y
+#define DEFER_2(x, y) DEFER_1(x, y)
+#define DEFER_3(x)    DEFER_2(x, __COUNTER__)
+#define defer(code)   auto DEFER_3(_defer_) = defer_detail::CreateDeferHelper( [&](){ code; } )

src/meson.build

@@ -6,6 +6,7 @@ dep_xfixes = dependency('xfixes')
 dep_xxf86vm = dependency('xxf86vm')
 dep_xtst = dependency('xtst')
 dep_xres = dependency('xres')
+dep_xmu = dependency('xmu')
 
 drm_dep = dependency('libdrm', version: '>= 2.4.113')
 
@@ -113,7 +114,7 @@ endif
       dep_x11, dep_xdamage, dep_xcomposite, dep_xrender, dep_xext, dep_xfixes,
       dep_xxf86vm, dep_xres, drm_dep, wayland_server,
       xkbcommon, thread_dep, sdl_dep, wlroots_dep,
-      vulkan_dep, liftoff_dep, dep_xtst, cap_dep, pipewire_dep, librt_dep,
+      vulkan_dep, liftoff_dep, dep_xtst, dep_xmu, cap_dep, pipewire_dep, librt_dep,
       stb_dep, displayinfo_dep, openvr_dep,
     ],
     install: true,

src/steamcompmgr.cpp

@@ -66,6 +66,7 @@
 #include <spawn.h>
 #include <signal.h>
 #include <linux/input-event-codes.h>
+#include <X11/Xmu/CurUtil.h>
 
 #include "xwayland_ctx.hpp"
 
@@ -77,6 +78,7 @@
 #include "vblankmanager.hpp"
 #include "sdlwindow.hpp"
 #include "log.hpp"
+#include "defer.hpp"
 
 #if HAVE_PIPEWIRE
 #include "pipewire.hpp"
@@ -1167,6 +1169,38 @@ error_image:
 	return false;
 }
 
+bool MouseCursor::setCursorImageByName(const char *name)
+{
+	int screen = DefaultScreen(m_ctx->dpy);
+
+	XColor fg;
+	fg.pixel = WhitePixel(m_ctx->dpy, screen);
+	XQueryColor(m_ctx->dpy, DefaultColormap(m_ctx->dpy, screen), &fg);
+
+	XColor bg;
+	bg.pixel = BlackPixel(m_ctx->dpy, screen);
+	XQueryColor(m_ctx->dpy, DefaultColormap(m_ctx->dpy, screen), &bg);
+
+	int index = XmuCursorNameToIndex(name);
+	if (index < 0)
+		return false;
+
+	Font font = XLoadFont(m_ctx->dpy, "cursor");
+	if (!font)
+		return false;
+	defer( XUnloadFont(m_ctx->dpy, font) );
+
+	Cursor cursor = XCreateGlyphCursor(m_ctx->dpy, font, font, index, index + 1, &fg, &bg);
+	if ( !cursor )
+		return false;
+	defer( XFreeCursor(m_ctx->dpy, cursor) );
+
+	XDefineCursor(m_ctx->dpy, DefaultRootWindow(m_ctx->dpy), cursor);
+	XFlush(m_ctx->dpy);
+	setDirty();
+	return true;
+}
+
 void MouseCursor::constrainPosition()
 {
 	int i;
@@ -5594,6 +5628,10 @@ void init_xwayland_ctx(gamescope_xwayland_server_t *xwayland_server)
 		if (!load_mouse_cursor(ctx->cursor.get(), g_customCursorPath, g_customCursorHotspotX, g_customCursorHotspotY))
 			xwm_log.errorf("Failed to load mouse cursor: %s", g_customCursorPath);
 	}
+	else
+	{
+		ctx->cursor->setCursorImageByName("left_ptr");
+	}
 }
 
 void update_vrr_atoms(xwayland_ctx_t *root_ctx, bool force)

src/steamcompmgr.hpp

@@ -58,6 +58,7 @@ public:
 
 	// Will take ownership of data.
 	bool setCursorImage(char *data, int w, int h, int hx, int hy);
+	bool setCursorImageByName(const char *name);
 
 	void hide() { m_lastMovedTime = 0; checkSuspension(); }