Add support for saving generated puzzles as PDFs

.gitignore

@@ -1,4 +1,5 @@
 /target
 /.idea
 *.iml
-Cargo.lock
+Cargo.lock
+*.pdf

Cargo.toml

@@ -10,4 +10,5 @@ edition = "2018"
 csv = "1.1.3"
 argparse = "0.2.2"
 rand = "0.7"
-rand_chacha = "0.2.2"
+rand_chacha = "0.2.2"
+printpdf = "0.3.2"

README.md

@@ -9,7 +9,7 @@ Two binaries, `solver` and `generator` will be generated in `target/release/`.
 
 Try running both of them, first with the `-h` flag to see what other arguments they take. 
 * `solver` reads a CSV file for a puzzle, prints it, solves it, and then prints the solved version. Some example CSV files are in the `puzzle` folder.
-* `generator` tries to generate a new puzzle from scratch. You can set a maximum number of hints that it will allow and it will try to generate a puzzle that meets that requirement. You can also optionally write it to a CSV file. 
+* `generator` tries to generate a new puzzle from scratch. You can set a maximum number of hints that it will allow and it will try to generate a puzzle that meets that requirement. You can also optionally write it to a CSV file or a PDF file (determined by file extension).
 
 Regarding code quality, I could probably have commented more and I certainly should have written more unit tests. 
 I also wish that I didn't rely so heavily on `Rc` & `RefCell`, which provide ways to get around (sometimes necessarily) the compiler's strict rules on references and ownership. 

src/bin/generator.rs

@@ -71,15 +71,21 @@ fn main() {
 
     match filename {
         Some(filename) => {
-            save_grid(&grid, &filename).unwrap();
-            println!("Grid saved to {}", filename);
+            // check if we save to a csv or a pdf
+            if filename.ends_with(".pdf") {
+                sudoku_solver::pdf::draw_grid(&grid, &filename).unwrap();
+                println!("Grid saved as pdf to {}", filename);
+            } else{
+                save_grid_csv(&grid, &filename).unwrap();
+                println!("Grid saved as CSV to {}", filename);
+            }
         },
         None => {}
     }
 
 }
 
-fn save_grid(grid: &Grid, filename: &str) -> Result<(), Box<dyn Error>>{
+fn save_grid_csv(grid: &Grid, filename: &str) -> Result<(), Box<dyn Error>>{
     // Not using the csv crate for writing because it's being difficult and won't accept raw integers
     let mut file = std::fs::File::create(filename)?;
 

src/lib.rs

@@ -1,3 +1,4 @@
 pub mod grid;
 pub mod solver;
-pub mod generator;
+pub mod generator;
+pub mod pdf;

src/pdf.rs

@@ -0,0 +1,131 @@
+use printpdf::*;
+use std::fs::File;
+use std::io::BufWriter;
+use crate::grid::{Grid, CellValue};
+
+const BOTTOM_LEFT_X : f64 = 10.0;
+const BOTTOM_LEFT_Y : f64 = 279.0 - 200.0 - 10.0;
+const GRID_DIMENSION : f64 = 190.0;
+
+const A4 : (Mm, Mm) = (Mm(215.0), Mm(279.0));
+
+pub fn draw_grid(grid: &Grid, filename: &str) -> Result<(), Box<dyn std::error::Error>>{
+    let (doc, page1, layer1) = PdfDocument::new("Sudoku Puzzle", A4.0, A4.1, "Layer 1");
+    let layer = doc.get_page(page1).get_layer(layer1);
+
+    let font = doc.add_builtin_font(BuiltinFont::HelveticaBold)?;
+    let font_size = 45;
+
+    draw_empty_grid(&layer);
+
+    // x represents position on left-right scale
+    // y represents position on up-down scale
+
+    // Now need to add any values
+    // One thing to note - higher y values are associated with the top of the page, while for my grid
+    //   higher row values are associated with the bottom of the page.
+
+    let x_offset = 6.1;
+    let y_offset = -16.5;
+
+
+    for r in 0..9 {
+        let y = Mm(BOTTOM_LEFT_Y + (GRID_DIMENSION / 9.0) * (9.0 - r as f64) + y_offset);
+
+        for c in 0..9 {
+            let x = Mm(BOTTOM_LEFT_X + (GRID_DIMENSION / 9.0) * (c as f64) + x_offset);
+
+            let cell = grid.get(r, c).unwrap();
+            let value = &*cell.value.borrow();
+            match value {
+                CellValue::Fixed(digit) => {
+                    let text = digit.to_string();
+                    layer.use_text(text, font_size, x, y, &font);
+                },
+                _ => {}
+            }
+        }
+    }
+
+    doc.save(&mut BufWriter::new(File::create(filename)?))?;
+
+    return Ok(());
+
+}
+
+fn draw_empty_grid(layer: &PdfLayerReference){
+
+    // x represents position on left-right scale
+    // y represents position on up-down scale
+
+    // Thick lines first
+
+    layer.set_outline_thickness(2.0);
+    // Horizontal first
+    {
+        let starting_x = Mm(BOTTOM_LEFT_X);
+        let ending_x = Mm(BOTTOM_LEFT_X + GRID_DIMENSION);
+        let y_increment = GRID_DIMENSION/3.0;
+        for i in 0..4 {
+            let y = Mm(BOTTOM_LEFT_Y + (i as f64) * y_increment);
+            draw_line(layer, Point::new(starting_x, y), Point::new(ending_x, y));
+        }
+    }
+
+    // Vertical lines next
+    {
+        let starting_y = Mm(BOTTOM_LEFT_Y);
+        let ending_y = Mm(BOTTOM_LEFT_Y + GRID_DIMENSION);
+        let x_increment = GRID_DIMENSION/3.0;
+        for i in 0..4 {
+            let x = Mm(BOTTOM_LEFT_X + (i as f64) * x_increment);
+            draw_line(layer, Point::new(x, starting_y), Point::new(x, ending_y));
+        }
+    }
+
+    // Thin lines next
+
+    layer.set_outline_thickness(0.0); // Special value to make line be 1px on all devices and zoom levels
+    // Horizontal first
+    {
+        let starting_x = Mm(BOTTOM_LEFT_X);
+        let ending_x = Mm(BOTTOM_LEFT_X + GRID_DIMENSION);
+        let y_increment = GRID_DIMENSION/9.0;
+        for i in 1..9 {
+            if i % 3 != 0{
+                let y = Mm(BOTTOM_LEFT_Y + (i as f64) * y_increment);
+                draw_line(layer, Point::new(starting_x, y), Point::new(ending_x, y));
+            }
+
+        }
+    }
+
+    // Vertical lines next
+    {
+        let starting_y = Mm(BOTTOM_LEFT_Y);
+        let ending_y = Mm(BOTTOM_LEFT_Y + GRID_DIMENSION);
+        let x_increment = GRID_DIMENSION/9.0;
+        for i in 1..9 {
+            if i % 3 != 0 {
+                let x = Mm(BOTTOM_LEFT_X + (i as f64) * x_increment);
+                draw_line(layer, Point::new(x, starting_y), Point::new(x, ending_y));
+            }
+        }
+    }
+}
+
+
+
+fn draw_line(layer: &PdfLayerReference, point1: Point, point2: Point){
+    let points = vec![(point1, false), (point2, false)];
+
+    let line = Line {
+        points,
+        is_closed: false,
+        has_fill: false,
+        has_stroke: true,
+        is_clipping_path: false
+    };
+
+    layer.add_shape(line);
+}