refactor: revert back to image scale in centre

src/app.rs

@@ -2,7 +2,7 @@ use std::time::{Duration, Instant};
 
 use rdev::display_size;
 use cirrus_theming::Theme;
-use eframe::egui::{self, Color32, ImageSource, Margin, Pos2, Rect};
+use eframe::egui::{self, Color32, ImageSource, Margin, Rect};
 
 use crate::{image::{Image, ImageOptimization}, info_box::InfoBox, zoom_pan::ZoomPan};
 
@@ -63,7 +63,7 @@ impl eframe::App for Roseate {
             ..Default::default()
         };
 
-        self.zoom_pan.handle_zoom(ctx);
+        self.zoom_pan.handle_zoom_input(ctx);
         self.info_box.handle_input(ctx);
 
         egui::CentralPanel::default().frame(central_panel_frame).show(ctx, |ui| {
@@ -121,20 +121,9 @@ impl eframe::App for Roseate {
                     ctx, "image_scale_height", scaled_image_height, 1.5, simple_easing::cubic_in_out
                 ) as u32;
 
-                let window_size = window_rect.size();
-
-                // this needs to fucking go, terrible hack
-                let initial_image_position = Pos2::new(
-                    (window_size.x - scaled_image_width_animated as f32) / 2.0,
-                    (window_size.y - scaled_image_height_animated as f32) / 2.0,
-                );
-
-                let cursor_position = ctx.input(|i| i.pointer.hover_pos()).unwrap_or_default();
-
                 let (zoom_scaled_size, pan_image_position) = self.zoom_pan.get_transformation(
                     (scaled_image_width_animated as f32, scaled_image_height_animated as f32).into(), 
-                    initial_image_position,
-                    cursor_position
+                    ui.max_rect().center()
                 );
 
                 let zoom_pan_rect = Rect::from_min_size(pan_image_position, zoom_scaled_size);
@@ -148,7 +137,7 @@ impl eframe::App for Roseate {
                     .rounding(10.0)
                     .paint_at(ui, zoom_pan_rect);
 
-                self.zoom_pan.handle_pan(ctx, &response, self.info_box.response.as_ref());
+                self.zoom_pan.handle_pan_input(ctx, &response, self.info_box.response.as_ref());
             });
 
             ctx.request_repaint_after_secs(0.5); // We need to request repaints just in 

src/zoom_pan.rs

@@ -1,5 +1,4 @@
-use eframe::egui::{self, Pos2, Rect, Response, Vec2};
-use log::debug;
+use eframe::egui::{self, Pos2, Response, Vec2};
 
 /// Struct that controls the zoom and panning of the image.
 pub struct ZoomPan {
@@ -22,19 +21,20 @@ impl ZoomPan {
     }
 
     // Method to handle zoom input (scrolling)
-    pub fn handle_zoom(&mut self, ctx: &egui::Context) {
+    pub fn handle_zoom_input(&mut self, ctx: &egui::Context) {
         self.last_zoom_factor = self.zoom_factor;
 
         let scroll_delta = ctx.input(|i| i.smooth_scroll_delta.y);
 
         if scroll_delta != 0.0 {
             let zoom_delta = scroll_delta * self.zoom_factor * 0.004;
+
             self.zoom_factor = (self.zoom_factor + zoom_delta).clamp(0.5, 100.0);
         }
     }
 
     // Method to handle panning (dragging)
-    pub fn handle_pan(&mut self, ctx: &egui::Context, image_response: &Response, info_box_response: Option<&Response>) {
+    pub fn handle_pan_input(&mut self, ctx: &egui::Context, image_response: &Response, info_box_response: Option<&Response>) {
         let mut can_pan = false;
 
         // "&& self.is_panning" allows for the panning to continue even 
@@ -70,26 +70,11 @@ impl ZoomPan {
         }
     }
 
-    pub fn get_transformation(&mut self, image_size: Vec2, initial_image_position: Pos2, cursor_pos: Pos2) -> (Vec2, Pos2) {
-        // Get the cursor position relative to the image also while being zoomed.
-        let cursor_relative_to_image = (cursor_pos - initial_image_position) / self.zoom_factor;
-
-        debug!("--> {}", cursor_relative_to_image);
-
-        // Get the change since the last zoom factor.
-        let zoom_factor_change = self.zoom_factor / self.last_zoom_factor;
-
-        // Keep the image centred around the cursor by adjust 
-        // the pan offset relative to the cursor and zoom difference.
-        self.pan_offset += cursor_relative_to_image * (1.0 - zoom_factor_change);
-
-        // Now update the image position also relative to that.
+    pub fn get_transformation(&self, image_size: egui::Vec2, image_position: egui::Pos2) -> (Vec2, Pos2) {
         let scaled_size = image_size * self.zoom_factor;
-        let new_image_position = initial_image_position + self.pan_offset;
-
-        debug!(">> {} | {}", initial_image_position, new_image_position);
+        let image_position = image_position - scaled_size * 0.5 + self.pan_offset;
 
-        (scaled_size, new_image_position)
+        (scaled_size, image_position)
     }
 
     pub fn has_been_messed_with(&mut self) -> bool {