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use radians::{self, Radians}; use turtle_window::TurtleWindow; use event::MouseButton; use {Speed, Color, Event}; #[derive(Debug, Clone, Copy, PartialEq, Eq)] enum AngleUnit { Degrees, Radians, } impl AngleUnit { fn to_radians(&self, angle: Angle) -> Radians { match *self { AngleUnit::Degrees => Radians::from_degrees_value(angle), AngleUnit::Radians => Radians::from_radians_value(angle), } } fn to_angle(&self, angle: Radians) -> Angle { match *self { AngleUnit::Degrees => angle.to_degrees(), AngleUnit::Radians => angle.to_radians(), } } } /// A point in 2D space: [x, y] /// /// ```rust /// # extern crate turtle; /// # use turtle::Point; /// # fn main() { /// let p: Point = [100., 120.]; /// // get x coordinate /// let x = p[0]; /// assert_eq!(x, 100.); /// // get y coordinate /// let y = p[1]; /// assert_eq!(y, 120.); /// # } pub type Point = [f64; 2]; /// Any distance value (positive or negative) pub type Distance = f64; /// An angle value without a unit /// /// The unit with which this angle will be interpreted depends on whether the Turtle is set to use /// degrees or radians. See the [`use_degrees()`](struct.Turtle.html#method.use_degrees) or /// [`use_radians()`](struct.Turtle.html#method.use_radians) methods for more information. pub type Angle = f64; /// A turtle with a pen attached to its tail /// /// **The idea:** You control a turtle with a pen tied to its tail. As it moves /// across the screen, it draws the path that it follows. You can use this to draw /// any picture you want just by moving the turtle across the screen. /// /// ![turtle moving forward](https://github.com/sunjay/turtle/raw/master/forward.gif) /// /// See the documentation for the methods below to learn about the different drawing commands you /// can use with the turtle. pub struct Turtle { window: TurtleWindow, angle_unit: AngleUnit, } impl Turtle { /// Create a new turtle. /// /// This will immediately open a new window with the turtle at the center. As each line in /// your program runs, the turtle shown in the window will update. /// /// ```rust,no_run /// # #![allow(unused_variables, unused_mut)] /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// // Do things with the turtle... /// } /// ``` pub fn new() -> Turtle { Turtle { window: TurtleWindow::new(), angle_unit: AngleUnit::Degrees, } } /// Move the turtle forward by the given amount of `distance`. If the pen is down, the turtle /// will draw a line as it moves. /// /// The turtle takes very small steps (measured in "pixels"). So if you want it to move more, /// use a bigger value to make the turtle walk further. /// The `distance` can be a negative value in which case the turtle will move backward. /// /// # Example /// /// ```rust /// # #![allow(unused_variables, unused_mut)] /// # extern crate turtle; /// # use turtle::Turtle; /// # fn main() { /// # let mut turtle = Turtle::new(); /// // Move forward 10 tiny turtle steps, drawing a line as you move /// turtle.forward(10.0); /// /// // Move forward 100 tiny turtle steps, drawing a much longer line /// turtle.forward(100.0); /// /// // Move backward 223 tiny turtle steps, without drawing anything /// turtle.pen_up(); /// turtle.forward(-223.0); /// # assert_eq!(turtle.position()[1].round(), -113.0); /// # } /// ``` pub fn forward(&mut self, distance: Distance) { self.window.forward(distance); } /// Move the turtle backwards by the given amount of `distance`. If the pen is down, the turtle /// will draw a line as it moves. /// /// The turtle takes very small steps (measured in "pixels"). So if you want it to move more, /// use a bigger value to make the turtle walk further. /// The `distance` can be a negative value in which case the turtle will move forward. /// /// # Example /// /// ```rust /// # #![allow(unused_variables, unused_mut)] /// # extern crate turtle; /// # use turtle::Turtle; /// # fn main() { /// # let mut turtle = Turtle::new(); /// // Move backward 10 tiny turtle steps, drawing a line as you move /// turtle.backward(10.0); /// /// // Move backward 100 tiny turtle steps, drawing a much longer line /// turtle.backward(100.0); /// /// // Move forward 179 tiny turtle steps, without drawing anything /// turtle.pen_up(); /// turtle.backward(-179.0); /// # assert_eq!(turtle.position()[1].round(), 69.0); /// # } /// ``` pub fn backward(&mut self, distance: Distance) { // Moving backwards is essentially moving forwards with a negative distance self.window.forward(-distance); } /// Instruct the turtle to turn right (clockwise) by the given angle. Since the turtle rotates /// in place, its position will not change and it will not draw anything while it turns. /// /// The `angle` parameter is a floating point number that represents how much you want the /// turtle to rotate. /// The unit of `angle` is "degrees" by default. You can change that by using the /// [`use_degrees()`](struct.Turtle.html#method.use_degrees) or /// [`use_radians()`](struct.Turtle.html#method.use_radians) methods. /// /// # Example /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// // rotate right by 30 degrees /// turtle.right(30.0); /// /// // rotate right by 1 radian (57.2957795 degrees) /// turtle.use_radians(); /// turtle.right(1.0); /// // Use PI for precise angles in radians /// use std::f64::consts::PI; /// // This is the same as turning 45.0 degrees /// turtle.right(PI/4.0); /// # assert_eq!( /// # (turtle.heading() * 1e5).trunc(), /// # (((90f64 - 30f64).to_radians() - 1.0 - PI/4.0) * 1e5).trunc() /// # ); /// # } /// ``` pub fn right(&mut self, angle: Angle) { let angle = self.angle_unit.to_radians(angle); self.window.rotate(angle, true); } /// Instruct the turtle to turn left (counterclockwise) by the given angle. Since the turtle /// rotates in place, its position will not change and it will not draw anything while it /// turns. /// /// The `angle` parameter is a floating point number that represents how much you want the /// turtle to rotate. /// The unit of `angle` is "degrees" by default. You can change that by using the /// [`use_degrees()`](struct.Turtle.html#method.use_degrees) or /// [`use_radians()`](struct.Turtle.html#method.use_radians) methods. /// /// # Example /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// // rotate left by 30 degrees /// turtle.left(30.0); /// /// // rotate left by 1 radian (57.2957795 degrees) /// turtle.use_radians(); /// turtle.left(1.0); /// // Use PI for precise angles in radians /// use std::f64::consts::PI; /// // This is the same as turning 45.0 degrees /// turtle.left(PI/4.0); /// # assert_eq!( /// # (turtle.heading() * 1e5).trunc(), /// # (((90f64 + 30f64).to_radians() + 1.0 + PI/4.0) * 1e5).trunc() /// # ); /// # } /// ``` pub fn left(&mut self, angle: Angle) { let angle = self.angle_unit.to_radians(angle); self.window.rotate(angle, false); } /// Returns the current speed of the turtle /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.set_speed(8); /// assert_eq!(turtle.speed(), Speed::Eight); /// # } /// ``` pub fn speed(&self) -> Speed { self.window.turtle().speed } /// Set the turtle's movement speed to the given setting. This speed affects the animation of /// the turtle's movement and rotation. The turtle's speed is limited to values between 0 and /// 10. If you pass in values that are not integers or outside of that range, the closest /// possible value will be chosen. /// /// This method's types make it so that it can be called in a number of different ways: /// /// ```rust,no_run /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.set_speed("normal"); /// turtle.set_speed("fast"); /// turtle.set_speed(2); /// turtle.set_speed(10); /// // Directly using a Speed variant works, but the methods above are usually more convenient. /// turtle.set_speed(Speed::Six); /// # } /// ``` /// /// If input is a number greater than 10 or smaller than 1, /// speed is set to 0 (`Speed::Instant`). Strings are converted as follows: /// /// | String | Value | /// | ----------- | -------------- | /// | `"slowest"` | `Speed::One` | /// | `"slow"` | `Speed::Three` | /// | `"normal"` | `Speed::Six` | /// | `"fast"` | `Speed::Eight` | /// | `"fastest"` | `Speed::Ten` | /// | `"instant"` | `Speed::Instant` | /// /// Anything else will cause the program to `panic!` at runtime. /// /// ## Moving Instantly /// /// A speed of zero (`Speed::Instant`) results in no animation. The turtle moves instantly /// and turns instantly. This is very useful for moving the turtle from its "home" position /// before you start drawing. By setting the speed to instant, you don't have to wait for /// the turtle to move into position. /// /// ## Learning About Conversion Traits /// /// Using this method is an excellent way to learn about conversion /// traits `From` and `Into`. This method takes a *generic type* as its speed parameter. That type /// is specified to implement the `Into` trait for the type `Speed`. That means that *any* type /// that can be converted into a `Speed` can be passed to this method. /// /// We have implemented that trait for several types like strings and 32-bit integers so that /// those values can be passed into this method. /// Rather than calling this function and passing `Speed::Six` directly, you can use just `6`. /// Rust will then allow us to call `.into()` as provided by the `Into<Speed>` trait to get the /// corresponding `Speed` value. /// /// You can pass in strings, 32-bit integers, and even `Speed` enum variants because they all /// implement the `Into<Speed>` trait. pub fn set_speed<S: Into<Speed>>(&mut self, speed: S) { self.window.turtle_mut().speed = speed.into(); } /// Returns the turtle's current location (x, y) /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.forward(100.0); /// let pos = turtle.position(); /// # // Cheating a bit here for rounding... /// # let pos = [pos[0].round(), pos[1].round()]; /// assert_eq!(pos, [0.0, 100.0]); /// # } /// ``` pub fn position(&self) -> Point { self.window.turtle().position } /// Returns the turtle's current heading. /// /// Units are by default degrees, but can be set using the /// [`use_degrees()`](struct.Turtle.html#method.use_degrees) or /// [`use_radians()`](struct.Turtle.html#method.use_radians) methods. /// /// The heading is relative to the positive x axis (east). When first created, the turtle /// starts facing north. That means that its heading is 90.0 degrees. The following chart /// contains many common directions and their angles. /// /// | Cardinal Direction | Heading (degrees) | Heading (radians) | /// | ------------------ | ----------------- | ----------------- | /// | East | 0.0° | `0.0` | /// | North | 90.0° | `PI/2` | /// | West | 180.0° | `PI` | /// | South | 270.0° | `3*PI/2` | /// /// You can test the result of `heading()` with these values to see if the turtle is facing /// a certain direction. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// // Turtles start facing north /// let mut turtle = Turtle::new(); /// // The rounding is to account for floating-point error /// assert_eq!(turtle.heading().round(), 90.0); /// turtle.right(31.0); /// assert_eq!(turtle.heading().round(), 59.0); /// turtle.left(193.0); /// assert_eq!(turtle.heading().round(), 252.0); /// turtle.left(130.0); /// // Angles should not exceed 360.0 /// assert_eq!(turtle.heading().round(), 22.0); /// # } /// ``` pub fn heading(&self) -> Angle { let heading = self.window.turtle().heading; self.angle_unit.to_angle(heading) } /// Returns true if `Angle` values will be interpreted as degrees. /// /// See [`use_degrees()`](struct.Turtle.html#method.use_degrees) for more information. pub fn is_using_degrees(&self) -> bool { self.angle_unit == AngleUnit::Degrees } /// Returns true if `Angle` values will be interpreted as radians. /// /// See [`use_radians()`](struct.Turtle.html#method.use_degrees) for more information. pub fn is_using_radians(&self) -> bool { self.angle_unit == AngleUnit::Radians } /// Change the angle unit to degrees. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// # turtle.use_radians(); /// assert!(!turtle.is_using_degrees()); /// turtle.use_degrees(); /// assert!(turtle.is_using_degrees()); /// /// // This will now be interpreted as 1.0 degree /// turtle.right(1.0); /// # } /// ``` pub fn use_degrees(&mut self) { self.angle_unit = AngleUnit::Degrees; } /// Change the angle unit to radians. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// assert!(!turtle.is_using_radians()); /// turtle.use_radians(); /// assert!(turtle.is_using_radians()); /// /// // This will now be interpreted as 1.0 radian /// turtle.right(1.0); /// # } /// ``` pub fn use_radians(&mut self) { self.angle_unit = AngleUnit::Radians; } /// Return true if pen is down, false if it’s up. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// assert!(turtle.is_pen_down()); /// turtle.pen_up(); /// assert!(!turtle.is_pen_down()); /// turtle.pen_down(); /// assert!(turtle.is_pen_down()); /// # } /// ``` pub fn is_pen_down(&self) -> bool { self.window.drawing().pen.enabled } /// Pull the pen down so that the turtle draws while moving. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// # turtle.pen_up(); /// assert!(!turtle.is_pen_down()); /// // This will move the turtle, but not draw any lines /// turtle.forward(100.0); /// turtle.pen_down(); /// assert!(turtle.is_pen_down()); /// // The turtle will now draw lines again /// turtle.forward(100.0); /// # } /// ``` pub fn pen_down(&mut self) { self.window.drawing_mut().pen.enabled = true; } /// Pick the pen up so that the turtle does not draw while moving /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// assert!(turtle.is_pen_down()); /// // The turtle will move and draw a line /// turtle.forward(100.0); /// turtle.pen_up(); /// assert!(!turtle.is_pen_down()); /// // Now, the turtle will move, but not draw anything /// turtle.forward(100.0); /// # } /// ``` pub fn pen_up(&mut self) { self.window.drawing_mut().pen.enabled = false; } /// Returns the size (thickness) of the pen. The thickness is measured in pixels. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.set_pen_size(25.0); /// assert_eq!(turtle.pen_size(), 25.0); /// # } /// ``` /// /// See [`set_pen_size()`](struct.Turtle.html#method.set_pen_size) for more details. pub fn pen_size(&self) -> f64 { self.window.drawing().pen.thickness } /// Sets the thickness of the pen to the given size. The thickness is measured in pixels. /// /// The turtle's pen has a flat tip. The value you set the pen's size to will change the /// width of the stroke created by the turtle as it moves. See the example below for more /// about what this means. /// /// # Example /// /// ```rust,no_run /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// /// turtle.pen_up(); /// turtle.right(90.0); /// turtle.backward(300.0); /// turtle.pen_down(); /// /// turtle.set_pen_color("#2196F3"); // blue /// turtle.set_pen_size(1.0); /// turtle.forward(200.0); /// /// turtle.set_pen_color("#f44336"); // red /// turtle.set_pen_size(50.0); /// turtle.forward(200.0); /// /// turtle.set_pen_color("#4CAF50"); // green /// turtle.set_pen_size(100.0); /// turtle.forward(200.0); /// } /// ``` /// /// This will produce the following: /// /// ![turtle pen thickness](https://github.com/sunjay/turtle/raw/gh-pages/assets/images/docs/pen_thickness.png) /// /// Notice that while the turtle travels in a straight line, it produces different thicknesses /// of lines which appear like large rectangles. pub fn set_pen_size(&mut self, thickness: f64) { self.window.drawing_mut().pen.thickness = thickness; } /// Returns the color of the pen. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.set_pen_color("blue"); /// assert_eq!(turtle.pen_color(), "blue".into()); /// # } /// ``` /// /// See the [`color` module](color/index.html) for more information about colors. pub fn pen_color(&self) -> Color { self.window.drawing().pen.color } /// Sets the color of the pen to the given color. /// /// Any type that can be converted into a color can be passed into this function. /// See the [`color` module](color/index.html) for more information. /// /// # Example /// /// ```rust,no_run /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// turtle.set_background_color("light grey"); /// turtle.set_pen_size(3.0); /// /// let colors = ["red", "green", "blue"]; /// /// for i in 0..36 { /// turtle.set_pen_color(colors[i % colors.len()]); /// turtle.forward(25.0); /// turtle.right(10.0); /// } /// } /// ``` /// /// This will produce the following: /// /// ![turtle pen color](https://github.com/sunjay/turtle/raw/gh-pages/assets/images/docs/colored_circle.png) pub fn set_pen_color<C: Into<Color>>(&mut self, color: C) { self.window.drawing_mut().pen.color = color.into(); } /// Returns the color of the background. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.set_background_color("purple"); /// assert_eq!(turtle.background_color(), "purple".into()); /// # } /// ``` /// /// See the [`color` module](color/index.html) for more information about colors. pub fn background_color(&self) -> Color { self.window.drawing().background } /// Sets the color of the background to the given color. /// /// Any type that can be converted into a color can be passed into this function. /// See the [`color` module](color/index.html) for more information. /// /// # Example /// /// ```rust,no_run /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// turtle.set_background_color("orange"); /// } /// ``` /// /// This will produce the following: /// /// ![turtle background](https://github.com/sunjay/turtle/raw/gh-pages/assets/images/docs/orange_background.png) pub fn set_background_color<C: Into<Color>>(&mut self, color: C) { self.window.drawing_mut().background = color.into(); } /// Returns the current fill color. /// /// This will be used to fill the shape when /// [`begin_fill()`](struct.Turtle.html#method.begin_fill) and /// [`end_fill()`](struct.Turtle.html#method.end_fill) are called. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// turtle.set_fill_color("coral"); /// assert_eq!(turtle.fill_color(), "coral".into()); /// # } /// ``` /// /// See the [`color` module](color/index.html) for more information about colors. pub fn fill_color(&self) -> Color { self.window.drawing().fill_color } /// Sets the fill color to the given color. /// /// **Note:** The fill color must be set **before** `begin_fill()` is called in order to be /// used when filling the shape. /// /// Any type that can be converted into a color can be passed into this function. /// See the [`color` module](color/index.html) for more information. /// /// # Example /// /// See [`begin_fill()`](struct.Turtle.html#method.begin_fill) for an example. pub fn set_fill_color<C: Into<Color>>(&mut self, color: C) { self.window.drawing_mut().fill_color = color.into(); } /// Begin filling the shape drawn by the turtle's movements. /// /// **Rule of thumb:** For every call to [`begin_fill()`](struct.Turtle.html#method.begin_fill), /// there should be a corresponding call to [`end_fill()`](struct.Turtle.html#method.end_fill). /// /// # Example /// /// The following example will draw a circle filled with the color red and then a square with /// no fill. /// /// **Note:** The fill color must be set **before** `begin_fill()` is called in order to be /// used when filling the shape. /// /// ```rust,no_run /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// turtle.right(90.0); /// turtle.set_pen_size(3.0); /// /// turtle.set_pen_color("blue"); /// turtle.set_fill_color("red"); /// turtle.begin_fill(); /// for _ in 0..360 { /// turtle.forward(2.0); /// turtle.right(1.0); /// } /// turtle.end_fill(); /// /// turtle.set_pen_color("green"); /// turtle.forward(120.0); /// for _ in 0..3 { /// turtle.right(90.0); /// turtle.forward(240.0); /// } /// turtle.right(90.0); /// turtle.forward(120.0); /// } /// ``` /// /// This will result in the following: /// /// ![turtle fill example](https://github.com/sunjay/turtle/raw/gh-pages/assets/images/docs/red_circle.png) pub fn begin_fill(&mut self) { self.window.begin_fill(); } /// Stop filling the shape drawn by the turtle's movements. /// /// **Rule of thumb:** For every call to [`begin_fill()`](struct.Turtle.html#method.begin_fill), /// there should be a corresponding call to [`end_fill()`](struct.Turtle.html#method.end_fill). /// /// See [`begin_fill()`](struct.Turtle.html#method.begin_fill) for more information. pub fn end_fill(&mut self) { self.window.end_fill(); } /// Returns true if the turtle is visible. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// let mut turtle = Turtle::new(); /// assert!(turtle.is_visible()); /// turtle.hide(); /// assert!(!turtle.is_visible()); /// turtle.show(); /// assert!(turtle.is_visible()); /// # } /// ``` pub fn is_visible(&self) -> bool { self.window.turtle().visible } /// Makes the turtle invisible. The shell will not be shown, but drawings will continue. /// /// Useful for some complex drawings. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// assert!(turtle.is_visible()); /// turtle.hide(); /// assert!(!turtle.is_visible()); /// # } /// ``` pub fn hide(&mut self) { self.window.turtle_mut().visible = false; } /// Makes the turtle visible. /// /// ```rust /// # extern crate turtle; /// # use turtle::*; /// # fn main() { /// # let mut turtle = Turtle::new(); /// # turtle.hide(); /// assert!(!turtle.is_visible()); /// turtle.show(); /// assert!(turtle.is_visible()); /// # } /// ``` pub fn show(&mut self) { self.window.turtle_mut().visible = true; } /// Delete the turtle's drawings from the screen. /// /// Does not move turtle. Position, speed and heading of the turtle are not affected. The /// background color and any other settings (pen color, size, etc.) all remain the same. /// /// # Example /// /// ```rust,no_run /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// turtle.right(32.0); /// turtle.forward(150.0); /// /// turtle.wait_for_click(); /// turtle.clear(); /// } /// ``` /// /// This will produce the following: /// /// ![turtle clear before click](https://github.com/sunjay/turtle/raw/gh-pages/assets/images/docs/clear_before_click.png) /// /// Once you click on the screen, the drawings will be cleared: /// /// ![turtle clear before click](https://github.com/sunjay/turtle/raw/gh-pages/assets/images/docs/clear_after_click.png) pub fn clear(&mut self) { self.window.clear(); } /// Rotates the turtle to face the given coordinates. /// Coordinates are relative to the center of the window. /// /// If the coordinates are the same as the turtle's current position, no rotation takes place. /// Always rotates the least amount necessary in order to face the given point. /// /// ## UNSTABLE /// This feature is currently unstable and completely buggy. Do not use it until it is fixed. pub fn turn_towards(&mut self, target: Point) { let target_x = target[0]; let target_y = target[1]; let position = self.position(); let x = position[0]; let y = position[1]; if (target_x - x).abs() < 0.1 && (target_y - y).abs() < 0.1 { return; } let heading = self.window.turtle().heading; let angle = (target_y - y).atan2(target_x - x); let angle = Radians::from_radians_value(angle); let angle = (angle - heading) % radians::TWO_PI; // Try to rotate as little as possible let angle = if angle.abs() > radians::PI { // Using signum to deal with negative angles properly angle.signum()*(radians::TWO_PI - angle.abs()) } else { angle }; self.window.rotate(angle, false); } /// Convenience function that waits for a click to occur before returning. /// /// Useful for when you want your program to wait for the user to click before continuing so /// that it doesn't start right away. /// /// This method uses [`poll_event()`](struct.Turtle.html#method.poll_event) internally and /// ignores any other events that take place before the click is received. /// /// # Example /// /// ```rust,no_run /// extern crate turtle; /// use turtle::Turtle; /// /// fn main() { /// let mut turtle = Turtle::new(); /// turtle.wait_for_click(); /// // The turtle will wait for the screen to be clicked before continuing /// turtle.forward(100.0); /// } /// ``` pub fn wait_for_click(&mut self) { loop { if let Some(Event::MouseButtonReleased(MouseButton::Left)) = self.poll_event() { break; } } } /// Returns the next event (if any). Returns `None` if there are no events to be processed at the /// current moment. This **does not** mean that there will never be events later on as the /// application continues to run. /// /// See the [`Event` enum](event/enum.Event.html) for the complete list of events that you can /// handle in Turtle. /// /// # Example /// /// To use this advanced method, you need to create what is known as an "event loop". An "event /// loop" is any loop that handles the events generated by the application. The reason that it /// is important to create a loop like this is because events in Turtle are "polled". That /// means that every time an event happens, it is placed in a queue (a list) until you ask to /// look at it. If you do not check for events continuously, there is a chance that the events /// you ask for from `poll_event()` will be outdated. /// /// Even if you do not use every kind of event, you should aim to poll events using this method /// until there are none left to poll. If you do not poll events for a significant amount of /// time during your application, favor the events that come later as you poll since those will /// be the most recent. This can happen if you run many animations between loop iterations. /// /// See the [`examples/`](https://github.com/sunjay/turtle/raw/master/examples) directory in /// the source code of this library for more examples of how to use events. /// /// The following is an example of a basic event loop. Notice that it uses two loops. One to /// move the turtle continuously, and another to handle all the events available at a given /// moment. If it suits your purposes, you may also just use a single loop to handle events /// and move the turtle from within that loop. This example is of a more complex case where /// it really matters that the most recent information is taken into consideration before any /// further movements take place. /// /// ```rust,no_run /// extern crate turtle; /// /// use turtle::Turtle; /// use turtle::event::Key::{Left, Right}; /// use turtle::Event::KeyPressed; /// /// fn main() { /// let mut turtle = Turtle::new(); /// /// loop { /// turtle.forward(1.0); /// /// while let Some(event) = turtle.poll_event() { /// match event { /// KeyPressed(key) => match key { /// Left => { /// turtle.set_speed(8); /// for _ in 0..20 { /// turtle.forward(1.0); /// turtle.left(4.5); /// } /// turtle.set_speed(4); /// }, /// Right => { /// turtle.set_speed(8); /// for _ in 0..20 { /// turtle.forward(1.0); /// turtle.right(4.5); /// } /// turtle.set_speed(4); /// }, /// _ => {}, /// }, /// _ => {}, /// } /// } /// } /// } /// ``` pub fn poll_event(&mut self) -> Option<Event> { self.window.poll_event() } } #[cfg(test)] mod tests { use super::*; #[test] fn is_using_radians_degrees() { // is_using_radians and is_using_degrees should be inverses of each other let mut turtle = Turtle::new(); assert!(!turtle.is_using_radians()); assert!(turtle.is_using_degrees()); turtle.use_radians(); assert!(turtle.is_using_radians()); assert!(!turtle.is_using_degrees()); turtle.use_degrees(); assert!(!turtle.is_using_radians()); assert!(turtle.is_using_degrees()); } }