Add antialiasing for line (xiaolin wu's line algorithm

README.md

@@ -199,6 +199,53 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
 ![output](./images/5.png)
 
+# Line
+
+```rust
+use omage::colors::*;
+use omage::{Components, Config, Image, Rgba};
+
+const HEIGHT: u32 = 600;
+const WIDTH: u32 = 800;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+ let config = Config::new(
+ WIDTH,
+ HEIGHT,
+ BLACK,
+ Some(GREEN),
+ "output.png",
+ Some("./fonts/Roboto-Medium.ttf"),
+ );
+
+ let mut image = Image::new();
+
+ let line1 = Components::Line(0, 0, WIDTH, HEIGHT, GREEN);
+ let line2 = Components::Line(WIDTH, 0, 0, HEIGHT, GREEN);
+ let circle = Components::Circle(WIDTH / 2, HEIGHT / 2, 100, Rgba([0, 255, 0, 150]));
+ let text = Components::Text(
+ WIDTH / 2 - 210,
+ HEIGHT / 2 - 250,
+ 40,
+ "Xiaolin Wu's Line Algorithm",
+ BLACK,
+ Some((GREEN, 3)),
+ );
+
+ image
+ .config(config)
+ .init()?
+ .add_components(vec![&line1, &line2, &circle, &text])
+ .draw()?;
+ Ok(())
+}
+
+```
+
+### Output:
+
+![output](./images/6.png)
+
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.

examples/line.rs

@@ -0,0 +1,37 @@
+use omage::colors::*;
+use omage::{Components, Config, Image, Rgba};
+
+const HEIGHT: u32 = 600;
+const WIDTH: u32 = 800;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+ let config = Config::new(
+ WIDTH,
+ HEIGHT,
+ BLACK,
+ Some(GREEN),
+ "output.png",
+ Some("./fonts/Roboto-Medium.ttf"),
+ );
+
+ let mut image = Image::new();
+
+ let line1 = Components::Line(0, 0, WIDTH, HEIGHT, GREEN);
+ let line2 = Components::Line(WIDTH, 0, 0, HEIGHT, GREEN);
+ let circle = Components::Circle(WIDTH / 2, HEIGHT / 2, 100, Rgba([0, 255, 0, 150]));
+ let text = Components::Text(
+ WIDTH / 2 - 210,
+ HEIGHT / 2 - 250,
+ 40,
+ "Xiaolin Wu's Line Algorithm",
+ BLACK,
+ Some((GREEN, 3)),
+ );
+
+ image
+ .config(config)
+ .init()?
+ .add_components(vec![&line1, &line2, &circle, &text])
+ .draw()?;
+ Ok(())
+}

src/components/line.rs

@@ -30,76 +30,119 @@ impl Line {
 }
 
 impl ComponentTrait for Line {
- /// Draws the line on the provided image buffer using the specified configuration.
- ///
- /// # Arguments
- ///
- /// * `config` - Configuration for the drawing canvas.
- /// * `buffer` - Image buffer to draw the line on.
- ///
- /// # Errors
- ///
- /// Returns an error if the line goes beyond the canvas boundaries.
  fn draw(
  &self,
- config: Config,
+ _config: Config,
  buffer: &mut ImageBuffer<Rgba<u8>, Vec<u8>>,
  ) -> Result<(), Box<dyn Error>> {
- let mut x1 = self.x1.clone();
- let mut x2 = self.x2.clone();
- let mut y1 = self.y1.clone();
- let mut y2 = self.y2.clone();
+ let x0 = self.x1 as i32;
+ let y0 = self.y1 as i32;
+ let x1 = self.x2 as i32;
+ let y1 = self.y2 as i32;
 
- let dx: f32 = self.x2 as f32 - self.x1 as f32;
- let dy: f32 = self.y2 as f32 - self.y1 as f32;
+ let steep = absolute(y1 as f32 - y0 as f32) > absolute(x1 as f32 - x0 as f32);
 
- if dx != 0.0 {
- let k: f32 = dy / dx;
- let c: f32 = self.y1 as f32 - (k * self.x1 as f32);
+ let (mut x0, mut y0, mut x1, mut y1) = if steep {
+ (y0, x0, y1, x1)
+ } else {
+ (x0, y0, x1, y1)
+ };
 
- if x2 < x1 {
- x1 = self.x2;
- x2 = self.x1;
- }
+ if x0 > x1 {
+ swap(&mut x0, &mut x1);
+ swap(&mut y0, &mut y1);
+ }
+
+ let dx = x1 - x0;
+ let dy = y1 - y0;
+ let gradient = dy as f32 / dx as f32;
 
-  if k == 0.0 {
-  for x in x1..x2 {
-  buffer.get_pixel_mut(x, y1).blend(&self.color)
-  }
-  } else {
-  for x in x1..x2 {
-  let by1 = k * x as f32 + c;
-  let by2 = k * (x + 3) as f32 + c;
-
-  if by1 > by2 {
-  for y in by2 as u32..by1 as u32 {
-  if x < config.width && y < config.height {
-  buffer.get_pixel_mut(x, y).blend(&self.color)
-  }
-  }
-  }
-  if by2 > by1 {
- for y in by1 as u32..by2 as u32 {
-  if x < config.width && y < config.height {
-  buffer.get_pixel_mut(x, y).blend(&self.color)
-  }
-  }
-  }
- }
+ let xend = round_number(x0 as f32);
+ let yend = y0 as f32 + gradient * (xend as f32 - x0 as f32);
+ let xgap = rfpart(x0 as f32 + 0.5);
+ let xpxl1 = xend; // this will be used in the main loop
+ let ypxl1 = ipart(yend);
+ draw_pixel(buffer, xpxl1, ypxl1, rfpart(yend) * xgap, &self.color);
+ draw_pixel(buffer, xpxl1, ypxl1 + 1, fpart(yend) * xgap, &self.color);
+ let mut intery = yend + gradient; // first y-intersection for the main loop
+
+ // handle second endpoint
+ let xend = round_number(x1 as f32);
+ let yend = y1 as f32 + gradient * (xend as f32 - x1 as f32);
+ let xgap = fpart(x1 as f32 + 0.5);
+ let xpxl2 = xend; // this will be used in the main loop
+ let ypxl2 = ipart(yend);
+ draw_pixel(buffer, xpxl2, ypxl2, rfpart(yend) * xgap, &self.color);
+ draw_pixel(buffer, xpxl2, ypxl2 + 1, fpart(yend) * xgap, &self.color);
+
+ // main loop
+ if steep {
+ for x in xpxl1 + 1..xpxl2 {
+ draw_pixel(buffer, ipart(intery), x, rfpart(intery), &self.color);
+ draw_pixel(buffer, ipart(intery) + 1, x, fpart(intery), &self.color);
+ intery += gradient;
  }
  } else {
- if y2 < y1 {
- y1 = self.y2;
- y2 = self.y1;
- }
-
- for y in y1..y2 {
- if x1 < config.width && y < config.height {
- buffer.get_pixel_mut(x1, y).blend(&self.color)
- }
+ for x in xpxl1 + 1..xpxl2 {
+ draw_pixel(buffer, x, ipart(intery), rfpart(intery), &self.color);
+ draw_pixel(buffer, x, ipart(intery) + 1, fpart(intery), &self.color);
+ intery += gradient;
  }
  }
 
  Ok(())
  }
 }
+
+fn draw_pixel(
+ buffer: &mut ImageBuffer<Rgba<u8>, Vec<u8>>,
+ x: u32,
+ y: u32,
+ brightness: f32,
+ color: &Rgba<u8>,
+) {
+ let new_color = Rgba([
+ color[0],
+ color[1],
+ color[2],
+ (color[3] as f32 * brightness) as u8,
+ ]);
+
+ if x < buffer.width() && y < buffer.height() {
+ buffer.get_pixel_mut(x, y).blend(&new_color);
+ }
+}
+
+fn swap(a: &mut i32, b: &mut i32) {
+ let temp = *a;
+ *a = *b;
+ *b = temp;
+}
+
+fn absolute(x: f32) -> f32 {
+ if x < 0.0 {
+ -x
+ } else {
+ x
+ }
+}
+
+fn ipart(x: f32) -> u32 {
+ x as u32
+}
+
+fn round_number(x: f32) -> u32 {
+ x as u32
+}
+
+fn fpart(x: f32) -> f32 {
+ if x > 0.0 {
+ x - ipart(x) as f32
+ } else {
+ x - (ipart(x) + 1) as f32
+ }
+}
+
+fn rfpart(x: f32) -> f32 {
+ 1.0 - fpart(x)
+}