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

iced_widget/
qr_code.rs
