Improve visual's shift mode (#8)

rack-designer/src/app/state/widget_editor.rs

···
                     }
                 });
 
+                if let Mode::Shift(shift) = &mut c.mode {
+                    two_drag_value(ui, "Shift by", "X", "Y", &mut shift.x, &mut shift.y);
+                }
+
                 labelled_drag_value(ui, "Thickness", &mut c.thickness);
                 ui.separator();
             }

rack/src/visuals.rs

···
     vec2,
     Pos2,
     Rect,
+    Vec2,
 };
 use serde::{
     Deserialize,
···
 pub enum Mode {
     Static,
     Rotate,
-    ShiftX,
-    ShiftY,
+    Shift(Vec2),
 }
 
 impl std::fmt::Display for Mode {
···
 }
 
 impl Mode {
-    pub fn all() -> [Self; 4] {
+    pub fn all() -> [Self; 3] {
         use Mode::*;
-        [Static, Rotate, ShiftX, ShiftY]
+        [Static, Rotate, Shift(Vec2::default())]
     }
 }
 
···
                     let ny = y * value.cos() + x * value.sin();
                     widget_center + vec2(nx, ny)
                 }),
-                Mode::ShiftX => {
-                    Box::new(|pos: Pos2| widget_center + pos.to_vec2() + vec2(value, 0.0))
-                }
-                Mode::ShiftY => {
-                    Box::new(|pos: Pos2| widget_center + pos.to_vec2() + vec2(0.0, value))
+                Mode::Shift(shift) => {
+                    Box::new(move |pos: Pos2| widget_center + pos.to_vec2() + (shift * value))
                 }
             }
         };