5 files changed, 76 insertions, 13 deletions

diff --git a/src/app.rs b/src/app.rs
index 4a4e2cc..243b196 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -1,22 +1,24 @@
 use crate::{
-    bitmap::{positive_angle_with_x, MapPoint, Pixmap},
+    bitmap::{positive_angle_with_x, Axis, MapPoint, Pixmap},
     brush::{Brush, CircleBrush, LineBrush},
     cache::Cache,
     command::CommandBox,
     consts::{colors::*, FONT_PATH, RC_PATH, STDLIB_PATH},
     dither,
     error::AppError,
+    guide::Guide,
     lisp::{eval, lex::Lexer, parse::Parser, prelude, EnvList},
     message::Message,
     rect,
     symmetry::Symmetry,
     undo::{ModifyRecord, OpKind, PaintRecord, UndoStack},
-    utils::{draw_text, handle_error, is_copy_event, is_paste_event, load_script},
+    utils::{self, draw_text, handle_error, is_copy_event, is_paste_event, load_script},
     widget::{Container, HorAlign, Offset, Size, VertAlign},
 };
 
 use std::{
     cell::RefCell,
+    collections::HashMap,
     convert::From,
     fs::File,
     io::prelude::*,
@@ -52,6 +54,7 @@ pub struct AppState<'ctx> {
     pub current_operation: Vec<PaintRecord>,
     pub dither_level: u8,
     pub file_name: Option<PathBuf>,
+    pub guides: HashMap<Guide, bool>,
     pub grid: Grid,
     pub lisp_env: EnvList,
     pub message: Message,
@@ -604,6 +607,7 @@ impl<'ctx> AppState<'ctx> {
             command_box: CommandBox::new(),
             context,
             cache: RefCell::new(None),
+            guides: HashMap::new(),
             current_operation: Vec::new(),
             dither_level: 16,
             file_name,
diff --git a/src/bitmap.rs b/src/bitmap.rs
index 2bf8556..8010a4b 100644
--- a/src/bitmap.rs
+++ b/src/bitmap.rs
@@ -4,6 +4,8 @@ use std::{
     ops::{Add, Sub},
 };
 
+use crate::lisp::{error::EvalError, expr::LispExpr};
+
 #[derive(Debug)]
 pub struct Pixmap<T> {
     pub width: u32,
@@ -71,12 +73,38 @@ impl Sub for MapPoint {
     }
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum Axis {
     X,
     Y,
 }
 
+impl Into<LispExpr> for Axis {
+    fn into(self) -> LispExpr {
+        LispExpr::Quote(
+            Box::new(LispExpr::Ident(match self {
+                Self::X => "X".into(),
+                Self::Y => "Y".into(),
+            })),
+            1,
+        )
+    }
+}
+
+impl TryFrom<&LispExpr> for Axis {
+    type Error = EvalError;
+    fn try_from(value: &LispExpr) -> Result<Self, Self::Error> {
+        match value {
+            LispExpr::Ident(id) => match id.as_ref() {
+                "x" => Ok(Axis::X),
+                "y" => Ok(Axis::Y),
+                _ => Err(EvalError::TypeMismatch),
+            },
+            _ => Err(EvalError::TypeMismatch),
+        }
+    }
+}
+
 #[derive(Debug, Copy, Clone)]
 pub enum Quadrant {
     I,
diff --git a/src/guide.rs b/src/guide.rs
index 006566e..85d0594 100644
--- a/src/guide.rs
+++ b/src/guide.rs
@@ -1,7 +1,21 @@
-use crate::bitmap::Axis;
+use crate::{
+    bitmap::Axis,
+    lisp::{expr::LispExpr, number::LispNumber},
+};
 
-#[derive(Debug)]
+use std::convert::Into;
+
+#[derive(Debug, Hash, PartialEq, Eq, Copy, Clone)]
 pub struct Guide {
-    axis: Axis,
-    offset: u32,
+    pub axis: Axis,
+    pub offset: u32,
+}
+
+impl Into<LispExpr> for Guide {
+    fn into(self) -> LispExpr {
+        LispExpr::List(vec![
+            self.axis.into(),
+            LispExpr::Number(LispNumber::Integer(self.offset as i64)),
+        ])
+    }
 }
diff --git a/src/lisp/expr.rs b/src/lisp/expr.rs
index 2319601..d2066e7 100644
--- a/src/lisp/expr.rs
+++ b/src/lisp/expr.rs
@@ -1,11 +1,13 @@
 use std::{cmp::PartialEq, convert::TryFrom, fmt};
 
-use crate::app::AppState;
-use crate::lisp::{
-    error::{EvalError, LispError},
-    eval::lookup,
-    number::LispNumber,
-    EnvList,
+use crate::{
+    app::AppState,
+    lisp::{
+        error::{EvalError, LispError},
+        eval::lookup,
+        number::LispNumber,
+        EnvList,
+    },
 };
 
 #[derive(Debug, Copy, PartialEq, Clone)]
diff --git a/src/lisp/prelude.rs b/src/lisp/prelude.rs
index 336dbaf..aebff98 100644
--- a/src/lisp/prelude.rs
+++ b/src/lisp/prelude.rs
@@ -1,6 +1,7 @@
 use crate::{
     bitmap::MapPoint,
     brush::Brush,
+    guide::Guide,
     lisp::{
         error::{EvalError, LispError},
         expr::{Arity, LispExpr},
@@ -413,5 +414,19 @@ pub fn new_env() -> Result<Environment, LispError> {
         return Ok(LispExpr::Unit);
     });
 
+    primitive!(env, Arity::Exact(2), "add-guide!", |args, app| {
+        match args {
+            [axis, LispExpr::Number(LispNumber::Integer(offset))] => {
+                let guide = Guide {
+                    axis: axis.try_into()?,
+                    offset: *offset as u32,
+                };
+                app.guides.insert(guide, true);
+                return Ok(LispExpr::Unit);
+            }
+            _ => return Err(EvalError::TypeMismatch.into()),
+        }
+    });
+
     Ok(env)
 }