examples: add descriptions to missing files

While at it, move all descriptions to the top of the file.

examples/cairo-buffer.c

@@ -1,3 +1,7 @@
+/* Simple scene-graph example with a custom buffer drawn by Cairo.
+ *
+ * Input is unimplemented. Surfaces are unimplemented.
+ */
 
 #include <stdbool.h>
 #include <stdlib.h>
@@ -13,10 +17,6 @@
 #include <wlr/util/log.h>
 #include <wlr/interfaces/wlr_buffer.h>
 
-/* Simple scene-graph example with a custom buffer drawn by Cairo.
- *
- * Input is unimplemented. Surfaces are unimplemented. */
-
 struct cairo_buffer {
 	struct wlr_buffer base;
 	cairo_surface_t *surface;

examples/embedded.c

@@ -1,3 +1,9 @@
+/* Embed a minimal xdg-shell compositor backed by a scene-graph into a
+ * wl_subsurface displayed inside a parent Wayland compositor.
+ *
+ * Input is unimplemented.
+ */
+
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <GLES2/gl2.h>

examples/fullscreen-shell.c

@@ -1,3 +1,7 @@
+/*
+ * A minimal fullscreen-shell server. It only supports rendering.
+ */
+
 #include <getopt.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -16,10 +20,6 @@
 #include <wlr/util/log.h>
 #include <wlr/util/transform.h>
 
-/**
- * A minimal fullscreen-shell server. It only supports rendering.
- */
-
 struct fullscreen_server {
 	struct wl_display *wl_display;
 	struct wlr_backend *backend;

examples/output-layers.c

@@ -1,3 +1,11 @@
+/* Simple compositor making use of the output layers API. The compositor will
+ * attempt to display client surfaces with output layers. Input is
+ * unimplemented.
+ *
+ * New surfaces are stacked on top of the existing ones as they appear.
+ * Surfaces that don't make it into an output layer are rendered as usual.
+ */
+
 #include <getopt.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -16,13 +24,6 @@
 #include <wlr/types/wlr_xdg_shell.h>
 #include <wlr/util/log.h>
 
-/* Simple compositor making use of the output layers API. The compositor will
- * attempt to display client surfaces with output layers. Input is
- * unimplemented.
- *
- * New surfaces are stacked on top of the existing ones as they appear.
- * Surfaces that don't make it into an output layer are rendered as usual. */
-
 struct server {
 	struct wl_display *wl_display;
 	struct wlr_backend *backend;

examples/output-layout.c

@@ -1,3 +1,8 @@
+/* Bounces a cat picture inside an output layout.
+ *
+ * Arrow keys nudge the cat in a direction.
+ */
+
 #include <drm_fourcc.h>
 #include <limits.h>
 #include <math.h>

examples/pointer.c

@@ -1,3 +1,10 @@
+/* Paints a cursor and moves it based on pointer, touch and tablet events.
+ *
+ * Left, middle and right pointer buttons change the background color to blue,
+ * green and red respectively. Axis pointer events change the brightness of the
+ * background color.
+ */
+
 #include <assert.h>
 #include <math.h>
 #include <stdio.h>

examples/rotation.c

@@ -1,3 +1,10 @@
+/* Scrolls across a mosaic of cats.
+ *
+ * Arrow keys change the scroll direction.
+ *
+ * The -r CLI option sets the output transform.
+ */
+
 #include <drm_fourcc.h>
 #include <getopt.h>
 #include <math.h>

examples/scene-graph.c

@@ -1,3 +1,8 @@
+/* Simple compositor making use of the scene-graph API. Input is unimplemented.
+ *
+ * New surfaces are stacked on top of the existing ones as they appear.
+ */
+
 #include <assert.h>
 #include <getopt.h>
 #include <stdbool.h>
@@ -15,10 +20,6 @@
 #include <wlr/types/wlr_xdg_shell.h>
 #include <wlr/util/log.h>
 
-/* Simple compositor making use of the scene-graph API. Input is unimplemented.
- *
- * New surfaces are stacked on top of the existing ones as they appear. */
-
 static const int border_width = 3;
 
 struct server {

examples/simple.c

@@ -1,3 +1,5 @@
+/* Animates the background color. */
+
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>