GST: Add ability to rotate picture

Signed-off-by: Vasiliy Doylov <nekocwd@mainlining.org>

README.md

@@ -15,6 +15,7 @@ Mostly made for PostmarketOS phones
   - `CAM_CAPS` = auto max caps by default - String
   - `ONLY_FORMAT` = null - String, filter pixel formats to show only one (e.g `RGB`)
   - `CAM_PROVIDER` = `pipewiredeviceprovider` - String, camera provider name (e.g `libcameraprovider`)
+  - `ROTATE` = `0` - Int, Rotation
 
 ## Project TODO:
   - [ ] Fix cam/mode switching? (I can't reproduce errors)

src/gst.vala

@@ -51,6 +51,7 @@ public class EyeNeko.Gstreamer : Object {
     private Elements.Downscale downscale = new Elements.Downscale ();
     private Gst.Element camera_convert_caps = Gst.ElementFactory.make ("capsfilter");
     public Elements.QrScaner qr_scaner = new Elements.QrScaner ();
+    private Gst.Element rotate = Gst.ElementFactory.make ("glvideoflip");
 
     // Other Fields
     public Camera current_camera = null;
@@ -199,12 +200,13 @@ public class EyeNeko.Gstreamer : Object {
                                                        qr_scaner,
                                                        Gst.ElementFactory.make ("videoconvert"),
                                                        Gst.ElementFactory.make ("glupload"),
+                                                       rotate,
                                                        color_correction_matrix,
                                                        Gst.ElementFactory.make ("gldownload")
         ));
         camerabin.set_property ("image-filter", Gst.ElementFactory.make ("videoconvert"));
 
-
+        rotate.set ("method", int.parse (Env.get_variable_or ("ROTATE", "0")));
         camerabin.set_property ("video-filter",
                                 pipe_elements ("Video Processing",
                                                Gst.ElementFactory.make ("videoconvert"),