3 files changed, 33 insertions, 20 deletions

diff --git a/src/app.rs b/src/app.rs
index 063f54f..f6e2b96 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -30,28 +30,30 @@ pub enum Mode {
 }
 
 pub struct AppState<'ctx> {
-    active_color: bool,
-    brush_size: u8,
-    canvas: Canvas<Window>,
-    context: &'ctx Sdl,
-    current_operation: Operation,
-    dither_level: u8,
-    grid: Grid,
-    last_point: Option<MapPoint>,
-    mode: Mode,
-    mouse: (i32, i32),
-    pixmap: Pixmap<bool>,
-    start: Point,
-    symmetry: Symmetry,
-    ttf_context: &'ctx Sdl2TtfContext,
-    undo_stack: UndoStack<Operation>,
-    command_box: CommandBox,
-    zoom: u8,
+    pub active_color: bool,
+    pub brush_size: u8,
+    pub canvas: Canvas<Window>,
+    pub command_box: CommandBox,
+    pub context: &'ctx Sdl,
+    pub current_operation: Operation,
+    pub dither_level: u8,
+    pub grid: Grid,
+    pub last_point: Option<MapPoint>,
+    pub lisp_env: Environment,
+    pub message: Message,
+    pub mode: Mode,
+    pub mouse: (i32, i32),
+    pub pixmap: Pixmap<bool>,
+    pub start: Point,
+    pub symmetry: Symmetry,
+    pub ttf_context: &'ctx Sdl2TtfContext,
+    pub undo_stack: UndoStack<Operation>,
+    pub zoom: u8,
 }
 
-struct Grid {
-    enabled: bool,
-    color: Color,
+pub struct Grid {
+    pub enabled: bool,
+    pub color: Color,
 }
 
 impl Grid {
@@ -563,6 +565,8 @@ impl<'ctx> AppState<'ctx> {
                                     Keycode::X => self.change_active_color(),
                                     // toggle grid
                                     Keycode::Tab => self.toggle_grid(),
+                                    // invert canvas
+                                    Keycode::I => self.pixmap.invert(),
                                     // line drawing
                                     Keycode::F => {
                                         let end: Point = (mouse.x(), mouse.y()).into();
diff --git a/src/bitmap.rs b/src/bitmap.rs
index d02cafb..c7e8fd4 100644
--- a/src/bitmap.rs
+++ b/src/bitmap.rs
@@ -231,6 +231,14 @@ where
     }
 }
 
+impl Pixmap<bool> {
+    pub fn invert(&mut self) {
+        for px in self.data.iter_mut() {
+            *px = !(*px);
+        }
+    }
+}
+
 fn abs_difference<T: Sub<Output = T> + Ord>(x: T, y: T) -> T {
     if x < y {
         y - x
diff --git a/src/lisp/error.rs b/src/lisp/error.rs
index b789f7f..7214753 100644
--- a/src/lisp/error.rs
+++ b/src/lisp/error.rs
@@ -3,4 +3,5 @@ use crate::lisp::lex::Span;
 #[derive(Debug, PartialEq, Copy, Clone)]
 pub enum LispError {
     ParseError,
+    EvalError,
 }