iced_widget/
qr_code.rs

1//! QR codes display information in a type of two-dimensional matrix barcode.
2//!
3//! # Example
4//! ```no_run
5//! # mod iced { pub mod widget { pub use iced_widget::*; } pub use iced_widget::Renderer; pub use iced_widget::core::*; }
6//! # pub type Element<'a, Message> = iced_widget::core::Element<'a, Message, iced_widget::Theme, iced_widget::Renderer>;
7//! #
8//! use iced::widget::qr_code;
9//!
10//! struct State {
11//!    data: qr_code::Data,
12//! }
13//!
14//! #[derive(Debug, Clone)]
15//! enum Message {
16//!     // ...
17//! }
18//!
19//! fn view(state: &State) -> Element<'_, Message> {
20//!     qr_code(&state.data).into()
21//! }
22//! ```
23use crate::Renderer;
24use crate::canvas;
25use crate::core::layout;
26use crate::core::mouse;
27use crate::core::renderer::{self, Renderer as _};
28use crate::core::widget::tree::{self, Tree};
29use crate::core::{
30    Color, Element, Layout, Length, Pixels, Point, Rectangle, Size, Theme, Vector, Widget,
31};
32
33use std::cell::RefCell;
34use thiserror::Error;
35
36const DEFAULT_CELL_SIZE: f32 = 4.0;
37const QUIET_ZONE: usize = 2;
38
39/// A type of matrix barcode consisting of squares arranged in a grid which
40/// can be read by an imaging device, such as a camera.
41///
42/// # Example
43/// ```no_run
44/// # mod iced { pub mod widget { pub use iced_widget::*; } pub use iced_widget::Renderer; pub use iced_widget::core::*; }
45/// # pub type Element<'a, Message> = iced_widget::core::Element<'a, Message, iced_widget::Theme, iced_widget::Renderer>;
46/// #
47/// use iced::widget::qr_code;
48///
49/// struct State {
50///    data: qr_code::Data,
51/// }
52///
53/// #[derive(Debug, Clone)]
54/// enum Message {
55///     // ...
56/// }
57///
58/// fn view(state: &State) -> Element<'_, Message> {
59///     qr_code(&state.data).into()
60/// }
61/// ```
62pub struct QRCode<'a, Theme = crate::Theme>
63where
64    Theme: Catalog,
65{
66    data: &'a Data,
67    cell_size: f32,
68    class: Theme::Class<'a>,
69}
70
71impl<'a, Theme> QRCode<'a, Theme>
72where
73    Theme: Catalog,
74{
75    /// Creates a new [`QRCode`] with the provided [`Data`].
76    pub fn new(data: &'a Data) -> Self {
77        Self {
78            data,
79            cell_size: DEFAULT_CELL_SIZE,
80            class: Theme::default(),
81        }
82    }
83
84    /// Sets the size of the squares of the grid cell of the [`QRCode`].
85    pub fn cell_size(mut self, cell_size: impl Into<Pixels>) -> Self {
86        self.cell_size = cell_size.into().0;
87        self
88    }
89
90    /// Sets the size of the entire [`QRCode`].
91    pub fn total_size(mut self, total_size: impl Into<Pixels>) -> Self {
92        self.cell_size = total_size.into().0 / (self.data.width + 2 * QUIET_ZONE) as f32;
93
94        self
95    }
96
97    /// Sets the style of the [`QRCode`].
98    #[must_use]
99    pub fn style(mut self, style: impl Fn(&Theme) -> Style + 'a) -> Self
100    where
101        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
102    {
103        self.class = (Box::new(style) as StyleFn<'a, Theme>).into();
104        self
105    }
106
107    /// Sets the style class of the [`QRCode`].
108    #[cfg(feature = "advanced")]
109    #[must_use]
110    pub fn class(mut self, class: impl Into<Theme::Class<'a>>) -> Self {
111        self.class = class.into();
112        self
113    }
114}
115
116impl<Message, Theme> Widget<Message, Theme, Renderer> for QRCode<'_, Theme>
117where
118    Theme: Catalog,
119{
120    fn tag(&self) -> tree::Tag {
121        tree::Tag::of::<State>()
122    }
123
124    fn state(&self) -> tree::State {
125        tree::State::new(State::default())
126    }
127
128    fn size(&self) -> Size<Length> {
129        Size {
130            width: Length::Shrink,
131            height: Length::Shrink,
132        }
133    }
134
135    fn layout(
136        &mut self,
137        _tree: &mut Tree,
138        _renderer: &Renderer,
139        _limits: &layout::Limits,
140    ) -> layout::Node {
141        let side_length = (self.data.width + 2 * QUIET_ZONE) as f32 * self.cell_size;
142
143        layout::Node::new(Size::new(side_length, side_length))
144    }
145
146    fn draw(
147        &self,
148        tree: &Tree,
149        renderer: &mut Renderer,
150        theme: &Theme,
151        _style: &renderer::Style,
152        layout: Layout<'_>,
153        _cursor: mouse::Cursor,
154        _viewport: &Rectangle,
155    ) {
156        let state = tree.state.downcast_ref::<State>();
157
158        let bounds = layout.bounds();
159        let side_length = self.data.width + 2 * QUIET_ZONE;
160
161        let style = theme.style(&self.class);
162        let mut last_style = state.last_style.borrow_mut();
163
164        if Some(style) != *last_style {
165            self.data.cache.clear();
166
167            *last_style = Some(style);
168        }
169
170        // Reuse cache if possible
171        let geometry = self.data.cache.draw(renderer, bounds.size(), |frame| {
172            // Scale units to cell size
173            frame.scale(self.cell_size);
174
175            // Draw background
176            frame.fill_rectangle(
177                Point::ORIGIN,
178                Size::new(side_length as f32, side_length as f32),
179                style.background,
180            );
181
182            // Avoid drawing on the quiet zone
183            frame.translate(Vector::new(QUIET_ZONE as f32, QUIET_ZONE as f32));
184
185            // Draw contents
186            self.data
187                .contents
188                .iter()
189                .enumerate()
190                .filter(|(_, value)| **value == qrcode::Color::Dark)
191                .for_each(|(index, _)| {
192                    let row = index / self.data.width;
193                    let column = index % self.data.width;
194
195                    frame.fill_rectangle(
196                        Point::new(column as f32, row as f32),
197                        Size::UNIT,
198                        style.cell,
199                    );
200                });
201        });
202
203        renderer.with_translation(bounds.position() - Point::ORIGIN, |renderer| {
204            use crate::graphics::geometry::Renderer as _;
205
206            renderer.draw_geometry(geometry);
207        });
208    }
209}
210
211impl<'a, Message, Theme> From<QRCode<'a, Theme>> for Element<'a, Message, Theme, Renderer>
212where
213    Theme: Catalog + 'a,
214{
215    fn from(qr_code: QRCode<'a, Theme>) -> Self {
216        Self::new(qr_code)
217    }
218}
219
220/// The data of a [`QRCode`].
221///
222/// It stores the contents that will be displayed.
223#[derive(Debug)]
224pub struct Data {
225    contents: Vec<qrcode::Color>,
226    width: usize,
227    cache: canvas::Cache<Renderer>,
228}
229
230impl Data {
231    /// Creates a new [`Data`] with the provided data.
232    ///
233    /// This method uses an [`ErrorCorrection::Medium`] and chooses the smallest
234    /// size to display the data.
235    pub fn new(data: impl AsRef<[u8]>) -> Result<Self, Error> {
236        let encoded = qrcode::QrCode::new(data)?;
237
238        Ok(Self::build(encoded))
239    }
240
241    /// Creates a new [`Data`] with the provided [`ErrorCorrection`].
242    pub fn with_error_correction(
243        data: impl AsRef<[u8]>,
244        error_correction: ErrorCorrection,
245    ) -> Result<Self, Error> {
246        let encoded = qrcode::QrCode::with_error_correction_level(data, error_correction.into())?;
247
248        Ok(Self::build(encoded))
249    }
250
251    /// Creates a new [`Data`] with the provided [`Version`] and
252    /// [`ErrorCorrection`].
253    pub fn with_version(
254        data: impl AsRef<[u8]>,
255        version: Version,
256        error_correction: ErrorCorrection,
257    ) -> Result<Self, Error> {
258        let encoded = qrcode::QrCode::with_version(data, version.into(), error_correction.into())?;
259
260        Ok(Self::build(encoded))
261    }
262
263    fn build(encoded: qrcode::QrCode) -> Self {
264        let width = encoded.width();
265        let contents = encoded.into_colors();
266
267        Self {
268            contents,
269            width,
270            cache: canvas::Cache::new(),
271        }
272    }
273}
274
275#[derive(Debug, Clone, Copy, PartialEq, Eq)]
276/// The size of a [`QRCode`].
277///
278/// The higher the version the larger the grid of cells, and therefore the more
279/// information the [`QRCode`] can carry.
280pub enum Version {
281    /// A normal QR code version. It should be between 1 and 40.
282    Normal(u8),
283
284    /// A micro QR code version. It should be between 1 and 4.
285    Micro(u8),
286}
287
288impl From<Version> for qrcode::Version {
289    fn from(version: Version) -> Self {
290        match version {
291            Version::Normal(v) => qrcode::Version::Normal(i16::from(v)),
292            Version::Micro(v) => qrcode::Version::Micro(i16::from(v)),
293        }
294    }
295}
296
297/// The error correction level.
298///
299/// It controls the amount of data that can be damaged while still being able
300/// to recover the original information.
301///
302/// A higher error correction level allows for more corrupted data.
303#[derive(Debug, Clone, Copy, PartialEq, Eq)]
304pub enum ErrorCorrection {
305    /// Low error correction. 7% of the data can be restored.
306    Low,
307    /// Medium error correction. 15% of the data can be restored.
308    Medium,
309    /// Quartile error correction. 25% of the data can be restored.
310    Quartile,
311    /// High error correction. 30% of the data can be restored.
312    High,
313}
314
315impl From<ErrorCorrection> for qrcode::EcLevel {
316    fn from(ec_level: ErrorCorrection) -> Self {
317        match ec_level {
318            ErrorCorrection::Low => qrcode::EcLevel::L,
319            ErrorCorrection::Medium => qrcode::EcLevel::M,
320            ErrorCorrection::Quartile => qrcode::EcLevel::Q,
321            ErrorCorrection::High => qrcode::EcLevel::H,
322        }
323    }
324}
325
326/// An error that occurred when building a [`Data`] for a [`QRCode`].
327#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
328pub enum Error {
329    /// The data is too long to encode in a QR code for the chosen [`Version`].
330    #[error("The data is too long to encode in a QR code for the chosen version")]
331    DataTooLong,
332
333    /// The chosen [`Version`] and [`ErrorCorrection`] combination is invalid.
334    #[error("The chosen version and error correction level combination is invalid.")]
335    InvalidVersion,
336
337    /// One or more characters in the provided data are not supported by the
338    /// chosen [`Version`].
339    #[error(
340        "One or more characters in the provided data are not supported by the \
341        chosen version"
342    )]
343    UnsupportedCharacterSet,
344
345    /// The chosen ECI designator is invalid. A valid designator should be
346    /// between 0 and 999999.
347    #[error(
348        "The chosen ECI designator is invalid. A valid designator should be \
349        between 0 and 999999."
350    )]
351    InvalidEciDesignator,
352
353    /// A character that does not belong to the character set was found.
354    #[error("A character that does not belong to the character set was found")]
355    InvalidCharacter,
356}
357
358impl From<qrcode::types::QrError> for Error {
359    fn from(error: qrcode::types::QrError) -> Self {
360        use qrcode::types::QrError;
361
362        match error {
363            QrError::DataTooLong => Error::DataTooLong,
364            QrError::InvalidVersion => Error::InvalidVersion,
365            QrError::UnsupportedCharacterSet => Error::UnsupportedCharacterSet,
366            QrError::InvalidEciDesignator => Error::InvalidEciDesignator,
367            QrError::InvalidCharacter => Error::InvalidCharacter,
368        }
369    }
370}
371
372#[derive(Default)]
373struct State {
374    last_style: RefCell<Option<Style>>,
375}
376
377/// The appearance of a QR code.
378#[derive(Debug, Clone, Copy, PartialEq)]
379pub struct Style {
380    /// The color of the QR code data cells
381    pub cell: Color,
382    /// The color of the QR code background
383    pub background: Color,
384}
385
386/// The theme catalog of a [`QRCode`].
387pub trait Catalog {
388    /// The item class of the [`Catalog`].
389    type Class<'a>;
390
391    /// The default class produced by the [`Catalog`].
392    fn default<'a>() -> Self::Class<'a>;
393
394    /// The [`Style`] of a class with the given status.
395    fn style(&self, class: &Self::Class<'_>) -> Style;
396}
397
398/// A styling function for a [`QRCode`].
399pub type StyleFn<'a, Theme> = Box<dyn Fn(&Theme) -> Style + 'a>;
400
401impl Catalog for Theme {
402    type Class<'a> = StyleFn<'a, Self>;
403
404    fn default<'a>() -> Self::Class<'a> {
405        Box::new(default)
406    }
407
408    fn style(&self, class: &Self::Class<'_>) -> Style {
409        class(self)
410    }
411}
412
413/// The default style of a [`QRCode`].
414pub fn default(theme: &Theme) -> Style {
415    let palette = theme.palette();
416
417    Style {
418        cell: palette.text,
419        background: palette.background,
420    }
421}
iced_widget/qr_code.rs

iced_widget/
qr_code.rs
