gl-renderer: Build as a loadable module

The time spent loading EGL and GLES libraries from disk can be a
considerable hit in some embedded use cases. If Weston is compiled
with EGL support, the binary will depend on those libraries, even if
a software renderer is in use.

This patch splits the GL renderer into a separate loadable module,
and moves the dependency on EGL and GLES to it. The backends still
need the EGL headers for the native types and EGLint. The function
load_module() is renamed to weston_load_module() and exported, so
that it can be used by the backends.

The gl renderer interface is changed so that there is only one symbol
that needs to be dlsym()'d. This symbol contains pointers to all the
functions and data necessary to interact with the renderer. As a side
effect, this change simplifies gl-renderer.h a great deal.

1 files changed, 27 insertions, 66 deletions

diff --git a/src/gl-renderer.h b/src/gl-renderer.h
index d16ade29..03421348 100644
--- a/src/gl-renderer.h
+++ b/src/gl-renderer.h
@@ -28,27 +28,6 @@
 
 #include <EGL/egl.h>
 
-extern const EGLint gl_renderer_opaque_attribs[];
-extern const EGLint gl_renderer_alpha_attribs[];
-
-int
-gl_renderer_create(struct weston_compositor *ec, EGLNativeDisplayType display,
-	const EGLint *attribs, const EGLint *visual_id);
-EGLDisplay
-gl_renderer_display(struct weston_compositor *ec);
-int
-gl_renderer_output_create(struct weston_output *output,
-				    EGLNativeWindowType window);
-void
-gl_renderer_output_destroy(struct weston_output *output);
-EGLSurface
-gl_renderer_output_surface(struct weston_output *output);
-void
-gl_renderer_set_border(struct weston_compositor *ec, int32_t width, int32_t height, void *data,
-			  int32_t *edges);
-
-void
-gl_renderer_print_egl_error_state(void);
 #else
 
 typedef int EGLint;
@@ -58,49 +37,31 @@ typedef intptr_t EGLNativeDisplayType;
 typedef intptr_t EGLNativeWindowType;
 #define EGL_DEFAULT_DISPLAY NULL
 
-static const EGLint gl_renderer_opaque_attribs[];
-static const EGLint gl_renderer_alpha_attribs[];
-
-inline static int
-gl_renderer_create(struct weston_compositor *ec, EGLNativeDisplayType display,
-	const EGLint *attribs, const EGLint *visual_id)
-{
-	return -1;
-}
-
-inline static EGLDisplay
-gl_renderer_display(struct weston_compositor *ec)
-{
-	return 0;
-}
-
-inline static int
-gl_renderer_output_create(struct weston_output *output,
-				    EGLNativeWindowType window)
-{
-	return -1;
-}
-
-inline static void
-gl_renderer_output_destroy(struct weston_output *output)
-{
-}
-
-inline static EGLSurface
-gl_renderer_output_surface(struct weston_output *output)
-{
-	return 0;
-}
-
-inline static void
-gl_renderer_set_border(struct weston_compositor *ec, int32_t width, int32_t height, void *data,
-			  int32_t *edges)
-{
-}
-
-inline static void
-gl_renderer_print_egl_error_state(void)
-{
-}
-
 #endif
+
+struct gl_renderer_interface {
+	const EGLint *opaque_attribs;
+	const EGLint *alpha_attribs;
+
+	int (*create)(struct weston_compositor *ec,
+		      EGLNativeDisplayType display,
+		      const EGLint *attribs,
+		      const EGLint *visual_id);
+
+	EGLDisplay (*display)(struct weston_compositor *ec);
+
+	int (*output_create)(struct weston_output *output,
+			     EGLNativeWindowType window);
+
+	void (*output_destroy)(struct weston_output *output);
+
+	EGLSurface (*output_surface)(struct weston_output *output);
+
+	void (*set_border)(struct weston_compositor *ec,
+			   int32_t width, int32_t height,
+			   void *data, int32_t *edges);
+
+	void (*print_egl_error_state)(void);
+};
+
+struct gl_renderer_interface gl_renderer_interface;