added canvas sizes

canvas/src/lib.rs

@@ -1,13 +1,13 @@
 use color::Color;
 
-struct Canvas {
+pub struct Canvas {
     width: usize,
     height: usize,
     pixels: Vec<Vec<Color>>,
 }
 
 impl Canvas {
-    fn new(width: usize, height: usize) -> Canvas {
+    pub fn new(width: usize, height: usize) -> Canvas {
         Canvas {
             width,
             height,
@@ -16,6 +16,58 @@ impl Canvas {
     }
 }
 
+impl Canvas {
+    pub fn write_pixel(&mut self, x: usize, y: usize, color: Color) {
+        self.pixels[y][x] = color;
+    }
+
+    pub fn pixel(&self, x: usize, y: usize) -> Color {
+        self.pixels[y][x]
+    }
+
+    fn header(&self) -> String {
+        let mut ppm = String::new();
+        ppm.push_str("P3\n");
+        ppm.push_str(self.width.to_string().as_str());
+        ppm.push(' ');
+        ppm.push_str(self.height.to_string().as_str());
+        ppm.push('\n');
+        ppm.push_str("255");
+        ppm.push('\n');
+        ppm
+    }
+
+    pub fn to_ppm(&self) -> String {
+        let mut ppm = self.header();
+        for row in &self.pixels {
+            let mut ppm_row = String::new();
+            for pixel in row {
+                let pixel_str = pixel.ppm_str();
+                if pixel_str.len() + ppm_row.len() > 70 {
+                    let components: Vec<&str> = pixel_str.split(" ").collect();
+                    for component in components {
+                        if ppm_row.len() + component.len() > 70 {
+                            ppm_row.pop();
+                            ppm.push_str(&ppm_row);
+                            ppm.push_str("\n");
+                            ppm_row = String::new();
+                        }
+                        ppm_row.push_str(component);
+                        ppm_row.push_str(" ");
+                    }
+                } else {
+                    ppm_row.push_str(&pixel_str);
+                    ppm_row.push_str(" ");
+                }
+            }
+            ppm_row.pop();
+            ppm.push_str(&ppm_row);
+            ppm.push('\n');
+        }
+        ppm
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -33,4 +85,73 @@ mod tests {
             }
         }
     }
+
+    #[test]
+    fn write_pixels_to_canvas() {
+        let mut c = Canvas::new(10, 20);
+        let red = Color::new(1.0, 0.0, 0.0);
+        c.write_pixel(2, 3, red);
+        assert_eq!(red, c.pixel(2, 3));
+    }
+
+    #[test]
+    fn constructing_ppm_header() {
+        let c = Canvas::new(5, 3);
+        let ppm = c.to_ppm();
+
+        let expected = "P3
+5 3
+255";
+
+        let header = ppm.split("\n").take(3).collect::<Vec<&str>>().join("\n");
+
+        assert_eq!(expected, header);
+    }
+
+    #[test]
+    fn constructing_the_ppm_pixel_data() {
+        let mut c = Canvas::new(5, 3);
+        let c1 = Color::new(1.5, 0.0, 0.0);
+        let c2 = Color::new(0.0, 0.5, 0.0);
+        let c3 = Color::new(-0.5, 0.0, 1.0);
+
+        c.write_pixel(0, 0, c1);
+        c.write_pixel(2, 1, c2);
+        c.write_pixel(4, 2, c3);
+
+        let ppm = c.to_ppm();
+
+
+        let line_4 = "255 0 0 0 0 0 0 0 0 0 0 0 0 0 0";
+        let line_5 = "0 0 0 0 0 0 0 127 0 0 0 0 0 0 0";
+        let line_6 = "0 0 0 0 0 0 0 0 0 0 0 0 0 0 255";
+
+        let v : Vec<&str> = ppm.split("\n").collect();
+
+        print!("{}", ppm);
+
+        assert_eq!(line_4, *v.get(3).expect("must exist"));
+        assert_eq!(line_5, *v.get(4).expect("must exist"));
+        assert_eq!(line_6, *v.get(5).expect("must exist"));
+    }
+
+    #[test]
+    fn test_split_long_lines() {
+        let mut c = Canvas::new(10, 2);
+        for row in &mut c.pixels {
+            for pix in row {
+                *pix = Color::new(1.0, 0.8, 0.6);
+            }
+        }
+
+        let line4_7 = r#"255 204 153 255 204 153 255 204 153 255 204 153 255 204 153 255 204
+153 255 204 153 255 204 153 255 204 153 255 204 153
+255 204 153 255 204 153 255 204 153 255 204 153 255 204 153 255 204
+153 255 204 153 255 204 153 255 204 153 255 204 153
+"#;
+
+        let ppm = c.to_ppm();
+        let four_to_seven = ppm.split("\n").skip(3).collect::<Vec<&str>>().join("\n");
+        assert_eq!(line4_7, four_to_seven);
+    }
 }

color/src/lib.rs

@@ -18,6 +18,27 @@ impl Color {
             blue,
         }
     }
+
+    pub fn red(&self) -> f32 {
+        self.red
+    }
+
+    pub fn green(&self) -> f32 {
+        self.green
+    }
+
+    pub fn blue(&self) -> f32 {
+        self.blue
+    }
+
+    pub fn ppm_str(&self) -> String {
+        // need to scale 0 - 1 -> 0 - 255
+        let r = (self.red * 255.0) as u8;
+        let g = (self.green * 255.0) as u8;
+        let b = (self.blue * 255.0) as u8;
+
+        format!("{} {} {}", r, g, b)
+    }
 }
 
 impl PartialEq for Color {