Add from_data

examples/main.rs

@@ -1,23 +1,36 @@
 use eframe::{Frame, NativeOptions};
-use egui::{CentralPanel, Context, Widget};
+use egui::{CentralPanel, Context, TextEdit, TopBottomPanel, Widget};
 use egui_qr::QrCodeWidget;
-use qrcode::QrCode;
 
 fn main() {
     let _ = eframe::run_native(
         "egui_qr",
         NativeOptions::default(),
-        Box::new(|_| Box::new(App)),
+        Box::new(|_| Box::new(App::new())),
     );
 }
 
-struct App;
+struct App {
+    data: String,
+}
+
+impl App {
+    pub fn new() -> Self {
+        Self {
+            data: String::new(),
+        }
+    }
+}
 
 impl eframe::App for App {
-    fn update(&mut self, ctx: &Context, frame: &mut Frame) {
+    fn update(&mut self, ctx: &Context, _frame: &mut Frame) {
-        let code = QrCode::new(b"hello").unwrap();
+        TopBottomPanel::top("main").show(ctx, |ui| TextEdit::singleline(&mut self.data).ui(ui));
         CentralPanel::default().show(ctx, |ui| {
-            QrCodeWidget::new(&code).ui(ui);
+            if let Ok(q) = QrCodeWidget::from_data(self.data.as_bytes()) {
+                q.ui(ui)
+            } else {
+                ui.label("Invalid data")
+            }
         });
     }
 }

src/lib.rs

@@ -1,13 +1,28 @@
 use egui::{vec2, Color32, Rect, Response, Rounding, Sense, Stroke, Ui, Widget};
+use qrcode::types::QrError;
 use qrcode::{Color, QrCode};
 
+enum CodeSrc<'a> {
+    Ref(&'a QrCode),
+    Owned(QrCode),
+}
+
 pub struct QrCodeWidget<'a> {
-    code: &'a QrCode,
+    code: CodeSrc<'a>,
 }
 
 impl<'a> QrCodeWidget<'a> {
     pub fn new(code: &'a QrCode) -> Self {
-        QrCodeWidget { code }
+        QrCodeWidget {
+            code: CodeSrc::Ref(code),
+        }
+    }
+
+    pub fn from_data(data: &[u8]) -> Result<Self, QrError> {
+        let code = QrCode::new(data)?;
+        Ok(QrCodeWidget {
+            code: CodeSrc::Owned(code),
+        })
     }
 }
 
@@ -15,25 +30,39 @@ impl Widget for QrCodeWidget<'_> {
     fn ui(self, ui: &mut Ui) -> Response {
         let size = ui.available_size();
 
-        let (response, painter) = ui.allocate_painter(size, Sense::click());
+        let code_ref = match &self.code {
-        let w = self.code.width();
+            CodeSrc::Ref(code) => code,
-        let start = response.rect.min;
+            CodeSrc::Owned(q) => q,
+        };
+        let w = code_ref.width();
+        let scale = (size.x.min(size.y) / w as f32).floor();
+        let start = ui.cursor().min;
+        let (response, painter) =
+            ui.allocate_painter(vec2(w as f32 * scale, w as f32 * scale), Sense::click());
+
+        painter.rect(
+            response.rect,
+            Rounding::none(),
+            Color32::WHITE,
+            Stroke::NONE,
+        );
         let mut ctr = 0;
-        let scale = (size.x / w as f32).floor();
+        for c in code_ref.to_colors() {
-        for c in self.code.to_colors() {
             let row = ctr / w;
             let col = ctr % w;
             let c_start = start + vec2(col as f32 * scale, row as f32 * scale);
             let c_end = c_start + vec2(scale, scale);
-            painter.rect(
+            if matches!(c, Color::Dark) {
-                Rect::from_min_max(c_start, c_end),
+                painter.rect(
-                Rounding::none(),
+                    Rect::from_min_max(c_start, c_end),
-                match c {
+                    Rounding::none(),
-                    Color::Light => Color32::WHITE,
+                    match c {
-                    Color::Dark => Color32::BLACK,
+                        Color::Light => Color32::WHITE,
-                },
+                        Color::Dark => Color32::BLACK,
-                Stroke::NONE,
+                    },
-            );
+                    Stroke::NONE,
+                );
+            }
             ctr += 1;
         }
         response