Add files via upload

docs/predefined_roi_sizes_gui.md

@@ -0,0 +1,41 @@
+### DRAW SHAPES OF USER-DEFINED METRIC SIZES
+
+First, open the `File (ROI)` drop-down menu at the head of the `Region of interest` window and click the `Draw ROIs of pre-defined sizes` option.
+
+![predefined_sizes_1](https://github.com/user-attachments/assets/d57d09ee-a909-4ad4-a025-6e54ab00c35a)
+
+Once clicked, you should see the following pop-up opening allowing you to draw a range of different shapes with specified sizes. If you need a shape-type that is missing, consider letting us know through [Gitter](https://app.gitter.im/#/room/#SimBA-Resource_community:gitter.im) or by opening en issue on [GithHub](https://github.com/sgoldenlab/simba/issues/new?assignees=&labels=&projects=&template=feature_request.md&title=).
+
+![predefined_sizes_2](https://github.com/user-attachments/assets/c76037f3-f15c-430f-b552-fd945c15862b)
+
+In the `SETTINGS` frame, fill in the name of your ROI, and choose its color, thickness, and ear tag size. 
+
+#### DRAW A RECTANGLE OF SET SIZE
+
+To draw a RECTANGLE of set size, fill in its metric width and height in millimeter and click ``ADD RECTANGLE`` as in the video below:
+
+[predefined_sizes_rectangle.webm](https://github.com/user-attachments/assets/f669e54a-c8d7-4e2c-b2a9-bb39dd483b3f)
+
+#### DRAW A CIRCLE OF A SPECIFIC RADIUS
+
+To draw a CIRCLE with a specific radius, fill in its metric radius in millimeter and click ``ADD CIRCLE`` as in the video below:
+
+[predefined_sizes_circle.webm](https://github.com/user-attachments/assets/9c745aa3-20bf-49fb-8e65-90144ac7e3c7)
+
+#### DRAW A HEXAGON SPECIFIC RADIUS
+
+To draw a HEXAGON with a specific radius, fill in its metric radius in millimeter and click ``ADD HEXAGON`` as in the video below:
+
+[predefined_sizes_hexagon.webm](https://github.com/user-attachments/assets/eda60da0-693f-414e-95c5-51a7fc5a033c)
+
+#### DRAW A HALF CIRCLE POINTING NORTH
+
+To draw a HALF CIRCLE with a specific radius with its chunky part pointing UP, fill in its metric radius in millimeter, choose `NORTH` in the `direction drop-down menu`, and click ``ADD HALF CIRCLE`` as in the video below:
+
+[predefined_sizes_half_circle_north.webm](https://github.com/user-attachments/assets/d0323574-f163-4038-bfcd-b8f2e4595d0c)
+
+#### DRAW A HALF CIRCLE POINTING WEST
+
+To draw a HALF CIRCLE with a specific radius with its chunky part pointing LEFT, fill in its metric radius in millimeter, choose `WEST` in the `direction drop-down menu`, and click ``ADD HALF CIRCLE`` as in the video below:
+
+[predefined_sizes_half_circle_west.webm](https://github.com/user-attachments/assets/3127e41f-ca83-4617-8ed8-7d9b6ece4079)