[display] Refactor to avoid implicit framebuffer allocation.

include/dev/display.h

Index: include/dev/display.h
diff --git a/include/dev/display.h b/include/dev/display.h
index 451057374675ea8ab5e167910f36778195b8d6b5..6337d981cdef169acbb5211058f17043c37852ca 100644
--- a/include/dev/display.h
+++ b/include/dev/display.h
@@ -35,30 +35,57 @@ int display_enable(bool enable);
 void display_pre_freq_change(void);
 void display_post_freq_change(void);
 
-#define DISPLAY_FORMAT_NONE         (-1)
-#define DISPLAY_FORMAT_RGB_565      (0)
-#define DISPLAY_FORMAT_RGB_332      (1)
-#define DISPLAY_FORMAT_RGB_2220     (2)
-#define DISPLAY_FORMAT_ARGB_8888    (3)
-#define DISPLAY_FORMAT_RGB_x888     (4)
-#define DISPLAY_FORMAT_RGB_x111     (5)
-#define DISPLAY_FORMAT_MONO_1       (6)
-#define DISPLAY_FORMAT_MONO_8       (7)
+enum display_format {
+    DISPLAY_FORMAT_UNKNOWN,
+    DISPLAY_FORMAT_MONO_1,
+    DISPLAY_FORMAT_RGB_111,
+    DISPLAY_FORMAT_RGB_565,
+    DISPLAY_FORMAT_RGB_x888,
+    DISPLAY_FORMAT_ARGB_8888,
+};
+
+enum image_format {
+    IMAGE_FORMAT_UNKNOWN,
+    IMAGE_FORMAT_MONO_1,
+    IMAGE_FORMAT_MONO_8,
+    IMAGE_FORMAT_RGB_x111,
+    IMAGE_FORMAT_RGB_332,
+    IMAGE_FORMAT_RGB_565,
+    IMAGE_FORMAT_RGB_2220,
+    IMAGE_FORMAT_RGB_x888,
+    IMAGE_FORMAT_ARGB_8888,
+};
 
 struct display_info {
-    void *framebuffer;
-    int format;
+    enum display_format format;
     uint width;
     uint height;
-    uint stride;
+};
+
+status_t display_get_info(struct display_info *info) __NONNULL((1));
 
+struct display_image {
+    enum image_format format;
+    void *pixels;
+    uint width;
+    uint height;
+    int stride; // row length in pixels
+    int rowbytes; // row length in bytes
+};
+
+status_t display_present(struct display_image *image, uint starty, uint endy)
+    __NONNULL((1));
+
+struct display_framebuffer {
+    enum display_format format;
+    struct display_image image;
     // Update function
     void (*flush)(uint starty, uint endy);
 };
 
-status_t display_get_info(struct display_info *info);
+status_t display_get_framebuffer(struct display_framebuffer *fb)
+    __NONNULL((1));
 
 __END_CDECLS
 
 #endif
-