get pixel size from fourcc to calculate pixel stride

include/pixels.h

@@ -22,3 +22,4 @@
 
 enum wl_shm_format fourcc_to_wl_shm(uint32_t in);
 uint32_t fourcc_from_wl_shm(enum wl_shm_format in);
+int pixel_size_from_fourcc(uint32_t fourcc);

src/buffer.c

@@ -91,9 +91,10 @@ struct wv_buffer* wv_buffer_create_shm(int width,
 	if (!self->wl_buffer)
 		goto shm_failure;
 
-	// TODO: Get the pixel size from the format instead of assuming it's 4.
+	int bpp = pixel_size_from_fourcc(fourcc);
+	assert(bpp > 0);
 	self->nvnc_fb = nvnc_fb_from_buffer(self->pixels, width, height, fourcc,
-			stride / 4);
+			stride / bpp);
 	if (!self->nvnc_fb) {
 		goto nvnc_fb_failure;
 	}

src/pixels.c

@@ -44,3 +44,40 @@ uint32_t fourcc_from_wl_shm(enum wl_shm_format in)
 
 	return in;
 }
+
+int pixel_size_from_fourcc(uint32_t fourcc)
+{
+	switch (fourcc & ~DRM_FORMAT_BIG_ENDIAN) {
+	case DRM_FORMAT_RGBA1010102:
+	case DRM_FORMAT_RGBX1010102:
+	case DRM_FORMAT_BGRA1010102:
+	case DRM_FORMAT_BGRX1010102:
+	case DRM_FORMAT_ARGB2101010:
+	case DRM_FORMAT_XRGB2101010:
+	case DRM_FORMAT_ABGR2101010:
+	case DRM_FORMAT_XBGR2101010:
+	case DRM_FORMAT_RGBA8888:
+	case DRM_FORMAT_RGBX8888:
+	case DRM_FORMAT_BGRA8888:
+	case DRM_FORMAT_BGRX8888:
+	case DRM_FORMAT_ARGB8888:
+	case DRM_FORMAT_XRGB8888:
+	case DRM_FORMAT_ABGR8888:
+	case DRM_FORMAT_XBGR8888:
+		return 4;
+	case DRM_FORMAT_BGR888:
+	case DRM_FORMAT_RGB888:
+		return 3;
+	case DRM_FORMAT_RGBA4444:
+	case DRM_FORMAT_RGBX4444:
+	case DRM_FORMAT_BGRA4444:
+	case DRM_FORMAT_BGRX4444:
+	case DRM_FORMAT_ARGB4444:
+	case DRM_FORMAT_XRGB4444:
+	case DRM_FORMAT_ABGR4444:
+	case DRM_FORMAT_XBGR4444:
+		return 2;
+	}
+
+	return 0;
+}