plotters/element/mod.rs
1/*!
2 Defines the drawing elements, the high-level drawing unit in Plotters drawing system
3
4 ## Introduction
5 An element is the drawing unit for Plotter's high-level drawing API.
6 Different from low-level drawing API, an element is a logic unit of component in the image.
7 There are few built-in elements, including `Circle`, `Pixel`, `Rectangle`, `Path`, `Text`, etc.
8
9 All element can be drawn onto the drawing area using API `DrawingArea::draw(...)`.
10 Plotters use "iterator of elements" as the abstraction of any type of plot.
11
12 ## Implementing your own element
13 You can also define your own element, `CandleStick` is a good sample of implementing complex
14 element. There are two trait required for an element:
15
16 - `PointCollection` - the struct should be able to return an iterator of key-points under guest coordinate
17 - `Drawable` - the struct is a pending drawing operation on a drawing backend with pixel-based coordinate
18
19 An example of element that draws a red "X" in a red rectangle onto the backend:
20
21 ```rust
22 use std::iter::{Once, once};
23 use plotters::element::{PointCollection, Drawable};
24 use plotters_backend::{BackendCoord, DrawingErrorKind, BackendStyle};
25 use plotters::style::IntoTextStyle;
26 use plotters::prelude::*;
27
28 // Any example drawing a red X
29 struct RedBoxedX((i32, i32));
30
31 // For any reference to RedX, we can convert it into an iterator of points
32 impl <'a> PointCollection<'a, (i32, i32)> for &'a RedBoxedX {
33 type Point = &'a (i32, i32);
34 type IntoIter = Once<&'a (i32, i32)>;
35 fn point_iter(self) -> Self::IntoIter {
36 once(&self.0)
37 }
38 }
39
40 // How to actually draw this element
41 impl <DB:DrawingBackend> Drawable<DB> for RedBoxedX {
42 fn draw<I:Iterator<Item = BackendCoord>>(
43 &self,
44 mut pos: I,
45 backend: &mut DB,
46 _: (u32, u32),
47 ) -> Result<(), DrawingErrorKind<DB::ErrorType>> {
48 let pos = pos.next().unwrap();
49 backend.draw_rect(pos, (pos.0 + 10, pos.1 + 12), &RED, false)?;
50 let text_style = &("sans-serif", 20).into_text_style(&backend.get_size()).color(&RED);
51 backend.draw_text("X", text_style, pos)
52 }
53 }
54
55 fn main() -> Result<(), Box<dyn std::error::Error>> {
56 let root = BitMapBackend::new(
57 "plotters-doc-data/element-0.png",
58 (640, 480)
59 ).into_drawing_area();
60 root.draw(&RedBoxedX((200, 200)))?;
61 Ok(())
62 }
63 ```
64 
65
66 ## Composable Elements
67 You also have an convenient way to build an element that isn't built into the Plotters library by
68 combining existing elements into a logic group. To build an composable element, you need to use an
69 logic empty element that draws nothing to the backend but denotes the relative zero point of the logical
70 group. Any element defined with pixel based offset coordinate can be added into the group later using
71 the `+` operator.
72
73 For example, the red boxed X element can be implemented with Composable element in the following way:
74 ```rust
75 use plotters::prelude::*;
76 fn main() -> Result<(), Box<dyn std::error::Error>> {
77 let root = BitMapBackend::new(
78 "plotters-doc-data/element-1.png",
79 (640, 480)
80 ).into_drawing_area();
81 let font:FontDesc = ("sans-serif", 20).into();
82 root.draw(&(EmptyElement::at((200, 200))
83 + Text::new("X", (0, 0), &"sans-serif".into_font().resize(20.0).color(&RED))
84 + Rectangle::new([(0,0), (10, 12)], &RED)
85 ))?;
86 Ok(())
87 }
88 ```
89 
90
91 ## Dynamic Elements
92 By default, Plotters uses static dispatch for all the elements and series. For example,
93 the `ChartContext::draw_series` method accepts an iterator of `T` where type `T` implements
94 all the traits a element should implement. Although, we can use the series of composable element
95 for complex series drawing. But sometimes, we still want to make the series heterogynous, which means
96 the iterator should be able to holds elements in different type.
97 For example, a point series with cross and circle. This requires the dynamically dispatched elements.
98 In plotters, all the elements can be converted into `DynElement`, the dynamic dispatch container for
99 all elements (include external implemented ones).
100 Plotters automatically implements `IntoDynElement` for all elements, by doing so, any dynamic element should have
101 `into_dyn` function which would wrap the element into a dynamic element wrapper.
102
103 For example, the following code counts the number of factors of integer and mark all prime numbers in cross.
104 ```rust
105 use plotters::prelude::*;
106 fn num_of_factor(n: i32) -> i32 {
107 let mut ret = 2;
108 for i in 2..n {
109 if i * i > n {
110 break;
111 }
112
113 if n % i == 0 {
114 if i * i != n {
115 ret += 2;
116 } else {
117 ret += 1;
118 }
119 }
120 }
121 return ret;
122 }
123 fn main() -> Result<(), Box<dyn std::error::Error>> {
124 let root =
125 BitMapBackend::new("plotters-doc-data/element-3.png", (640, 480))
126 .into_drawing_area();
127 root.fill(&WHITE)?;
128 let mut chart = ChartBuilder::on(&root)
129 .x_label_area_size(40)
130 .y_label_area_size(40)
131 .margin(5)
132 .build_cartesian_2d(0..50, 0..10)?;
133
134 chart
135 .configure_mesh()
136 .disable_x_mesh()
137 .disable_y_mesh()
138 .draw()?;
139
140 chart.draw_series((0..50).map(|x| {
141 let center = (x, num_of_factor(x));
142 // Although the arms of if statement has different types,
143 // but they can be placed into a dynamic element wrapper,
144 // by doing so, the type is unified.
145 if center.1 == 2 {
146 Cross::new(center, 4, Into::<ShapeStyle>::into(&RED).filled()).into_dyn()
147 } else {
148 Circle::new(center, 4, Into::<ShapeStyle>::into(&GREEN).filled()).into_dyn()
149 }
150 }))?;
151
152 Ok(())
153 }
154 ```
155 
156*/
157use plotters_backend::{BackendCoord, DrawingBackend, DrawingErrorKind};
158use std::borrow::Borrow;
159
160mod basic_shapes;
161pub use basic_shapes::*;
162
163mod basic_shapes_3d;
164pub use basic_shapes_3d::*;
165
166mod text;
167pub use text::*;
168
169mod points;
170pub use points::*;
171
172mod composable;
173pub use composable::{ComposedElement, EmptyElement};
174
175#[cfg(feature = "candlestick")]
176mod candlestick;
177#[cfg(feature = "candlestick")]
178pub use candlestick::CandleStick;
179
180#[cfg(feature = "errorbar")]
181mod errorbar;
182#[cfg(feature = "errorbar")]
183pub use errorbar::{ErrorBar, ErrorBarOrientH, ErrorBarOrientV};
184
185#[cfg(feature = "boxplot")]
186mod boxplot;
187#[cfg(feature = "boxplot")]
188pub use boxplot::Boxplot;
189
190#[cfg(feature = "bitmap_backend")]
191mod image;
192#[cfg(feature = "bitmap_backend")]
193pub use self::image::BitMapElement;
194
195mod dynelem;
196pub use dynelem::{DynElement, IntoDynElement};
197
198use crate::coord::CoordTranslate;
199use crate::drawing::Rect;
200
201/// A type which is logically a collection of points, under any given coordinate system.
202/// Note: Ideally, a point collection trait should be any type of which coordinate elements can be
203/// iterated. This is similar to `iter` method of many collection types in std.
204///
205/// ```ignore
206/// trait PointCollection<Coord> {
207/// type PointIter<'a> : Iterator<Item = &'a Coord>;
208/// fn iter(&self) -> PointIter<'a>;
209/// }
210/// ```
211///
212/// However,
213/// [Generic Associated Types](https://github.com/rust-lang/rfcs/blob/master/text/1598-generic_associated_types.md)
214/// is far away from stablize.
215/// So currently we have the following workaround:
216///
217/// Instead of implement the PointCollection trait on the element type itself, it implements on the
218/// reference to the element. By doing so, we now have a well-defined lifetime for the iterator.
219///
220/// In addition, for some element, the coordinate is computed on the fly, thus we can't hard-code
221/// the iterator's return type is `&'a Coord`.
222/// `Borrow` trait seems to strict in this case, since we don't need the order and hash
223/// preservation properties at this point. However, `AsRef` doesn't work with `Coord`
224///
225/// This workaround also leads overly strict lifetime bound on `ChartContext::draw_series`.
226///
227/// TODO: Once GAT is ready on stable Rust, we should simplify the design.
228///
229pub trait PointCollection<'a, Coord, CM = BackendCoordOnly> {
230 /// The item in point iterator
231 type Point: Borrow<Coord> + 'a;
232
233 /// The point iterator
234 type IntoIter: IntoIterator<Item = Self::Point>;
235
236 /// framework to do the coordinate mapping
237 fn point_iter(self) -> Self::IntoIter;
238}
239/// The trait indicates we are able to draw it on a drawing area
240pub trait Drawable<DB: DrawingBackend, CM: CoordMapper = BackendCoordOnly> {
241 /// Actually draws the element. The key points is already translated into the
242 /// image coordinate and can be used by DC directly
243 fn draw<I: Iterator<Item = CM::Output>>(
244 &self,
245 pos: I,
246 backend: &mut DB,
247 parent_dim: (u32, u32),
248 ) -> Result<(), DrawingErrorKind<DB::ErrorType>>;
249}
250
251pub trait CoordMapper {
252 type Output;
253 fn map<CT: CoordTranslate>(coord_trans: &CT, from: &CT::From, rect: &Rect) -> Self::Output;
254}
255
256pub struct BackendCoordOnly;
257
258impl CoordMapper for BackendCoordOnly {
259 type Output = BackendCoord;
260 fn map<CT: CoordTranslate>(coord_trans: &CT, from: &CT::From, rect: &Rect) -> BackendCoord {
261 rect.truncate(coord_trans.translate(from))
262 }
263}
264
265pub struct BackendCoordAndZ;
266
267impl CoordMapper for BackendCoordAndZ {
268 type Output = (BackendCoord, i32);
269 fn map<CT: CoordTranslate>(
270 coord_trans: &CT,
271 from: &CT::From,
272 rect: &Rect,
273 ) -> (BackendCoord, i32) {
274 let coord = rect.truncate(coord_trans.translate(from));
275 let z = coord_trans.depth(from);
276 (coord, z)
277 }
278}