camera: improve handling front-facing camera images

Reflect the image being written to the screen, so it behaves like a
mirror or a selfie-camera, with the image reversed.  Note the underlying
image as passed to the callback is not reversed (vital for QR scanning).

main/Kconfig.projbuild

@@ -240,20 +240,20 @@ menu "Blockstream Jade"
             default -1
     endmenu
 
-    config HAS_CAMERA
-        bool "Enable Camera Functions"
-        help
-            Enables camera functionality
-            default y if BOARD_TYPE_JADE_V2 || BOARD_TYPE_JADE_V1_1 || BOARD_TYPE_JADE || (ETH_USE_OPENETH && HTTPD_WS_SUPPORT) || BOARD_TYPE_M5_CORES3 || BOARD_TYPE_TTGO_TDISPLAYS3PROCAMERA
-
     config JADE_USE_USB_JTAG_SERIAL
         bool "Use USB JTAG serial instead of CDC tinyusb"
         depends on IDF_TARGET_ESP32S3
         help
             Enables USB JTAG serial rather than CDC tinyusb, implies no tinyusb/host storage/etc
             default n
 
-    menu "Camera Rotation"
+    config HAS_CAMERA
+        bool "Enable Camera Functions"
+        help
+            Enables camera functionality
+            default y if BOARD_TYPE_JADE_V2 || BOARD_TYPE_JADE_V1_1 || BOARD_TYPE_JADE || (ETH_USE_OPENETH && HTTPD_WS_SUPPORT) || BOARD_TYPE_M5_CORES3 || BOARD_TYPE_TTGO_TDISPLAYS3PROCAMERA
+
+    menu "Camera Orientation"
         visible if HAS_CAMERA && BOARD_TYPE_CUSTOM
 
         config CAMERA_ROTATE_90
@@ -271,7 +271,13 @@ menu "Blockstream Jade"
             default y if BOARD_TYPE_TTGO_TDISPLAYS3PROCAMERA
             default n
 
+        config CAMERA_FRONT_FACING
+            bool "Front-facing camera"
+            default y if BOARD_TYPE_M5_CORES3
+            default n
+
     endmenu
+
     menu "Camera Pin Mapping"
         visible if HAS_CAMERA && (BOARD_TYPE_CUSTOM || BOARD_TYPE_M5_CORES3)
 

main/camera.c

@@ -91,7 +91,18 @@ static inline void copy_pixel(uint8_t dest[DISPLAY_IMAGE_HEIGHT][DISPLAY_IMAGE_W
     JADE_ASSERT(srcx < CAMERA_IMAGE_WIDTH);
     JADE_ASSERT(srcy < CAMERA_IMAGE_HEIGHT);
 #endif
+
+    // For a front-facing camera, write the image from right-to-left, so it 'moves' the way
+    // the user would expect, ie. behaves like a mirror.  In the final image any writing would be backwards...
+    // NOTE: this is only done here for the image going to the screen - the source data remains as
+    // presented by the camera, so in the source frame-buffer (ie. as passed to the processing callback)
+    // any writing would be 'correct'.  This is important for text *and QR codes* (and is why we can't use
+    // sensor->set_hmirror(i) which would reverse what the hw places in the framebuffer).
+#ifdef CONFIG_CAMERA_FRONT_FACING
+    dest[desty][(DISPLAY_IMAGE_WIDTH - 1) - destx] = src[srcy][srcx];
+#else
     dest[desty][destx] = src[srcy][srcx];
+#endif
 }
 
 // Loops to copy the camera image