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;
29use crate::core::widget::operation::accessible::{Accessible, Role};
30use crate::core::widget::tree::{self, Tree};
31use crate::core::{
32    Color, Element, Layout, Length, Pixels, Point, Rectangle, Size, Theme, Vector, Widget,
33};
34
35use std::cell::RefCell;
36use thiserror::Error;
37
38const DEFAULT_CELL_SIZE: f32 = 4.0;
39const QUIET_ZONE: usize = 2;
40
41/// A type of matrix barcode consisting of squares arranged in a grid which
42/// can be read by an imaging device, such as a camera.
43///
44/// # Example
45/// ```no_run
46/// # mod iced { pub mod widget { pub use iced_widget::*; } pub use iced_widget::Renderer; pub use iced_widget::core::*; }
47/// # pub type Element<'a, Message> = iced_widget::core::Element<'a, Message, iced_widget::Theme, iced_widget::Renderer>;
48/// #
49/// use iced::widget::qr_code;
50///
51/// struct State {
52///    data: qr_code::Data,
53/// }
54///
55/// #[derive(Debug, Clone)]
56/// enum Message {
57///     // ...
58/// }
59///
60/// fn view(state: &State) -> Element<'_, Message> {
61///     qr_code(&state.data).into()
62/// }
63/// ```
64pub struct QRCode<'a, Theme = crate::Theme>
65where
66    Theme: Catalog,
67{
68    data: &'a Data,
69    cell_size: f32,
70    class: Theme::Class<'a>,
71}
72
73impl<'a, Theme> QRCode<'a, Theme>
74where
75    Theme: Catalog,
76{
77    /// Creates a new [`QRCode`] with the provided [`Data`].
78    pub fn new(data: &'a Data) -> Self {
79        Self {
80            data,
81            cell_size: DEFAULT_CELL_SIZE,
82            class: Theme::default(),
83        }
84    }
85
86    /// Sets the size of the squares of the grid cell of the [`QRCode`].
87    pub fn cell_size(mut self, cell_size: impl Into<Pixels>) -> Self {
88        self.cell_size = cell_size.into().0;
89        self
90    }
91
92    /// Sets the size of the entire [`QRCode`].
93    pub fn total_size(mut self, total_size: impl Into<Pixels>) -> Self {
94        self.cell_size = total_size.into().0 / (self.data.width + 2 * QUIET_ZONE) as f32;
95
96        self
97    }
98
99    /// Sets the style of the [`QRCode`].
100    #[must_use]
101    pub fn style(mut self, style: impl Fn(&Theme) -> Style + 'a) -> Self
102    where
103        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
104    {
105        self.class = (Box::new(style) as StyleFn<'a, Theme>).into();
106        self
107    }
108
109    /// Sets the style class of the [`QRCode`].
110    #[cfg(feature = "advanced")]
111    #[must_use]
112    pub fn class(mut self, class: impl Into<Theme::Class<'a>>) -> Self {
113        self.class = class.into();
114        self
115    }
116}
117
118impl<Message, Theme> Widget<Message, Theme, Renderer> for QRCode<'_, Theme>
119where
120    Theme: Catalog,
121{
122    fn tag(&self) -> tree::Tag {
123        tree::Tag::of::<State>()
124    }
125
126    fn state(&self) -> tree::State {
127        tree::State::new(State::default())
128    }
129
130    fn size(&self) -> Size<Length> {
131        Size {
132            width: Length::Shrink,
133            height: Length::Shrink,
134        }
135    }
136
137    fn layout(
138        &mut self,
139        _tree: &mut Tree,
140        _renderer: &Renderer,
141        _limits: &layout::Limits,
142    ) -> layout::Node {
143        let side_length = (self.data.width + 2 * QUIET_ZONE) as f32 * self.cell_size;
144
145        layout::Node::new(Size::new(side_length, side_length))
146    }
147
148    fn draw(
149        &self,
150        tree: &Tree,
151        renderer: &mut Renderer,
152        theme: &Theme,
153        _style: &renderer::Style,
154        layout: Layout<'_>,
155        _cursor: mouse::Cursor,
156        _viewport: &Rectangle,
157    ) {
158        let state = tree.state.downcast_ref::<State>();
159
160        let bounds = layout.bounds();
161        let side_length = self.data.width + 2 * QUIET_ZONE;
162
163        let style = theme.style(&self.class);
164        let mut last_style = state.last_style.borrow_mut();
165
166        if Some(style) != *last_style {
167            self.data.cache.clear();
168
169            *last_style = Some(style);
170        }
171
172        // Reuse cache if possible
173        let geometry = self.data.cache.draw(renderer, bounds.size(), |frame| {
174            // Scale units to cell size
175            frame.scale(self.cell_size);
176
177            // Draw background
178            frame.fill_rectangle(
179                Point::ORIGIN,
180                Size::new(side_length as f32, side_length as f32),
181                style.background,
182            );
183
184            // Avoid drawing on the quiet zone
185            frame.translate(Vector::new(QUIET_ZONE as f32, QUIET_ZONE as f32));
186
187            // Draw contents
188            self.data
189                .contents
190                .iter()
191                .enumerate()
192                .filter(|(_, value)| **value == qrcode::Color::Dark)
193                .for_each(|(index, _)| {
194                    let row = index / self.data.width;
195                    let column = index % self.data.width;
196
197                    frame.fill_rectangle(
198                        Point::new(column as f32, row as f32),
199                        Size::UNIT,
200                        style.cell,
201                    );
202                });
203        });
204
205        renderer.with_translation(bounds.position() - Point::ORIGIN, |renderer| {
206            use crate::graphics::geometry::Renderer as _;
207
208            renderer.draw_geometry(geometry);
209        });
210    }
211
212    fn operate(
213        &mut self,
214        _tree: &mut Tree,
215        layout: Layout<'_>,
216        _renderer: &Renderer,
217        operation: &mut dyn widget::Operation,
218    ) {
219        operation.accessible(
220            None,
221            layout.bounds(),
222            &Accessible {
223                role: Role::Image,
224                ..Accessible::default()
225            },
226        );
227    }
228}
229
230impl<'a, Message, Theme> From<QRCode<'a, Theme>> for Element<'a, Message, Theme, Renderer>
231where
232    Theme: Catalog + 'a,
233{
234    fn from(qr_code: QRCode<'a, Theme>) -> Self {
235        Self::new(qr_code)
236    }
237}
238
239/// The data of a [`QRCode`].
240///
241/// It stores the contents that will be displayed.
242#[derive(Debug)]
243pub struct Data {
244    contents: Vec<qrcode::Color>,
245    width: usize,
246    cache: canvas::Cache<Renderer>,
247}
248
249impl Data {
250    /// Creates a new [`Data`] with the provided data.
251    ///
252    /// This method uses an [`ErrorCorrection::Medium`] and chooses the smallest
253    /// size to display the data.
254    pub fn new(data: impl AsRef<[u8]>) -> Result<Self, Error> {
255        let encoded = qrcode::QrCode::new(data)?;
256
257        Ok(Self::build(encoded))
258    }
259
260    /// Creates a new [`Data`] with the provided [`ErrorCorrection`].
261    pub fn with_error_correction(
262        data: impl AsRef<[u8]>,
263        error_correction: ErrorCorrection,
264    ) -> Result<Self, Error> {
265        let encoded = qrcode::QrCode::with_error_correction_level(data, error_correction.into())?;
266
267        Ok(Self::build(encoded))
268    }
269
270    /// Creates a new [`Data`] with the provided [`Version`] and
271    /// [`ErrorCorrection`].
272    pub fn with_version(
273        data: impl AsRef<[u8]>,
274        version: Version,
275        error_correction: ErrorCorrection,
276    ) -> Result<Self, Error> {
277        let encoded = qrcode::QrCode::with_version(data, version.into(), error_correction.into())?;
278
279        Ok(Self::build(encoded))
280    }
281
282    fn build(encoded: qrcode::QrCode) -> Self {
283        let width = encoded.width();
284        let contents = encoded.into_colors();
285
286        Self {
287            contents,
288            width,
289            cache: canvas::Cache::new(),
290        }
291    }
292}
293
294#[derive(Debug, Clone, Copy, PartialEq, Eq)]
295/// The size of a [`QRCode`].
296///
297/// The higher the version the larger the grid of cells, and therefore the more
298/// information the [`QRCode`] can carry.
299pub enum Version {
300    /// A normal QR code version. It should be between 1 and 40.
301    Normal(u8),
302
303    /// A micro QR code version. It should be between 1 and 4.
304    Micro(u8),
305}
306
307impl From<Version> for qrcode::Version {
308    fn from(version: Version) -> Self {
309        match version {
310            Version::Normal(v) => qrcode::Version::Normal(i16::from(v)),
311            Version::Micro(v) => qrcode::Version::Micro(i16::from(v)),
312        }
313    }
314}
315
316/// The error correction level.
317///
318/// It controls the amount of data that can be damaged while still being able
319/// to recover the original information.
320///
321/// A higher error correction level allows for more corrupted data.
322#[derive(Debug, Clone, Copy, PartialEq, Eq)]
323pub enum ErrorCorrection {
324    /// Low error correction. 7% of the data can be restored.
325    Low,
326    /// Medium error correction. 15% of the data can be restored.
327    Medium,
328    /// Quartile error correction. 25% of the data can be restored.
329    Quartile,
330    /// High error correction. 30% of the data can be restored.
331    High,
332}
333
334impl From<ErrorCorrection> for qrcode::EcLevel {
335    fn from(ec_level: ErrorCorrection) -> Self {
336        match ec_level {
337            ErrorCorrection::Low => qrcode::EcLevel::L,
338            ErrorCorrection::Medium => qrcode::EcLevel::M,
339            ErrorCorrection::Quartile => qrcode::EcLevel::Q,
340            ErrorCorrection::High => qrcode::EcLevel::H,
341        }
342    }
343}
344
345/// An error that occurred when building a [`Data`] for a [`QRCode`].
346#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
347pub enum Error {
348    /// The data is too long to encode in a QR code for the chosen [`Version`].
349    #[error("The data is too long to encode in a QR code for the chosen version")]
350    DataTooLong,
351
352    /// The chosen [`Version`] and [`ErrorCorrection`] combination is invalid.
353    #[error("The chosen version and error correction level combination is invalid.")]
354    InvalidVersion,
355
356    /// One or more characters in the provided data are not supported by the
357    /// chosen [`Version`].
358    #[error(
359        "One or more characters in the provided data are not supported by the \
360        chosen version"
361    )]
362    UnsupportedCharacterSet,
363
364    /// The chosen ECI designator is invalid. A valid designator should be
365    /// between 0 and 999999.
366    #[error(
367        "The chosen ECI designator is invalid. A valid designator should be \
368        between 0 and 999999."
369    )]
370    InvalidEciDesignator,
371
372    /// A character that does not belong to the character set was found.
373    #[error("A character that does not belong to the character set was found")]
374    InvalidCharacter,
375}
376
377impl From<qrcode::types::QrError> for Error {
378    fn from(error: qrcode::types::QrError) -> Self {
379        use qrcode::types::QrError;
380
381        match error {
382            QrError::DataTooLong => Error::DataTooLong,
383            QrError::InvalidVersion => Error::InvalidVersion,
384            QrError::UnsupportedCharacterSet => Error::UnsupportedCharacterSet,
385            QrError::InvalidEciDesignator => Error::InvalidEciDesignator,
386            QrError::InvalidCharacter => Error::InvalidCharacter,
387        }
388    }
389}
390
391#[derive(Default)]
392struct State {
393    last_style: RefCell<Option<Style>>,
394}
395
396/// The appearance of a QR code.
397#[derive(Debug, Clone, Copy, PartialEq)]
398pub struct Style {
399    /// The color of the QR code data cells
400    pub cell: Color,
401    /// The color of the QR code background
402    pub background: Color,
403}
404
405/// The theme catalog of a [`QRCode`].
406pub trait Catalog {
407    /// The item class of the [`Catalog`].
408    type Class<'a>;
409
410    /// The default class produced by the [`Catalog`].
411    fn default<'a>() -> Self::Class<'a>;
412
413    /// The [`Style`] of a class with the given status.
414    fn style(&self, class: &Self::Class<'_>) -> Style;
415}
416
417/// A styling function for a [`QRCode`].
418pub type StyleFn<'a, Theme> = Box<dyn Fn(&Theme) -> Style + 'a>;
419
420impl Catalog for Theme {
421    type Class<'a> = StyleFn<'a, Self>;
422
423    fn default<'a>() -> Self::Class<'a> {
424        Box::new(default)
425    }
426
427    fn style(&self, class: &Self::Class<'_>) -> Style {
428        class(self)
429    }
430}
431
432/// The default style of a [`QRCode`].
433pub fn default(theme: &Theme) -> Style {
434    let palette = theme.seed();
435
436    Style {
437        cell: palette.text,
438        background: palette.background,
439    }
440}
iced_widget/qr_code.rs

iced_widget/
qr_code.rs
