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

iced_widget/
qr_code.rs
