Validations

examples/login.rs

@@ -1,6 +1,6 @@
 use std::process::exit;
 
-use gooey::value::{Dynamic, MapEach};
+use gooey::value::{Dynamic, Validations};
 use gooey::widget::MakeWidget;
 use gooey::widgets::input::{InputValue, MaskedString};
 use gooey::widgets::Expand;
@@ -10,19 +10,42 @@ use kludgine::figures::units::Lp;
 fn main() -> gooey::Result {
     let username = Dynamic::default();
     let password = Dynamic::default();
+    let validations = Validations::default();
 
-    let valid =
+    let username_valid = validations.validate(&username, |u: &String| {
-        (&username, &password).map_each(|(username, password)| validate(username, password));
+        if u.is_empty() {
+            Err("usernames must contain at least one character")
+        } else {
+            Ok(())
+        }
+    });
+
+    let password_valid = validations.validate(&password, |u: &MaskedString| match u.len() {
+        0..=7 => Err("passwords must be at least 8 characters long"),
+        _ => Ok(()),
+    });
 
     // TODO this should be a grid layout to ensure proper visual alignment.
     let username_field = "Username"
         .align_left()
-        .and(username.clone().into_input())
+        .and(
+            username
+                .clone()
+                .into_input()
+                .validation(username_valid)
+                .hint("* required"),
+        )
         .into_rows();
 
     let password_field = "Password"
         .align_left()
-        .and(password.clone().into_input())
+        .and(
+            password
+                .clone()
+                .into_input()
+                .validation(password_valid)
+                .hint("* required, 8 characters min"),
+        )
         .into_rows();
 
     let buttons = "Cancel"
@@ -36,12 +59,11 @@ fn main() -> gooey::Result {
         .and(
             "Log In"
                 .into_button()
-                .on_click(move |_| {
+                .on_click(validations.when_valid(move |()| {
                     println!("Welcome, {}", username.get());
                     exit(0);
-                })
+                }))
-                .into_default()
+                .into_default(),
-                .with_enabled(valid),
         )
         .into_columns();
 
@@ -57,7 +79,3 @@ fn main() -> gooey::Result {
         .expand()
         .run()
 }
-
-fn validate(username: &String, password: &MaskedString) -> bool {
-    !username.is_empty() && !password.is_empty()
-}

examples/validation.rs

@@ -0,0 +1,52 @@
+use gooey::value::{Dynamic, Validations};
+use gooey::widget::MakeWidget;
+use gooey::widgets::input::InputValue;
+use gooey::Run;
+use kludgine::figures::units::Lp;
+
+fn main() -> gooey::Result {
+    let text = Dynamic::default();
+    let validations = Validations::default();
+
+    "Hinted"
+        .and(
+            text.clone()
+                .into_input()
+                .validation(validations.validate(&text, validate_input))
+                .hint("* required"),
+        )
+        .and("Not Hinted")
+        .and(
+            text.clone()
+                .into_input()
+                .validation(validations.validate(&text, validate_input)),
+        )
+        .and(
+            "Submit"
+                .into_button()
+                .on_click(validations.clone().when_valid(move |()| {
+                    println!(
+                    "Success! This callback only happens when all associated validations are valid"
+                );
+                })),
+        )
+        .and("Reset".into_button().on_click(move |()| {
+            let _value = text.take();
+            validations.reset();
+        }))
+        .into_rows()
+        .width(Lp::inches(6))
+        .centered()
+        .expand()
+        .run()
+}
+
+fn validate_input(input: &String) -> Result<(), &'static str> {
+    if input.is_empty() {
+        Err("This field cannot be empty")
+    } else if input.trim().is_empty() {
+        Err("This field must have at least one non-whitespace character")
+    } else {
+        Ok(())
+    }
+}

src/value.rs

@@ -4,7 +4,9 @@ use std::cell::Cell;
 use std::fmt::{Debug, Display};
 use std::future::Future;
 use std::ops::{Deref, DerefMut, Not};
+use std::panic::UnwindSafe;
 use std::str::FromStr;
+use std::sync::atomic::{self, AtomicBool};
 use std::sync::{Arc, Mutex, MutexGuard, TryLockError};
 use std::task::{Poll, Waker};
 use std::thread::ThreadId;
@@ -495,6 +497,28 @@ impl<T> Dynamic<T> {
     {
         Radio::new(widget_value, self.clone(), label)
     }
+
+    /// Validates the contents of this dynamic using the `check` function,
+    /// returning a dynamic that contains the validation status.
+    #[must_use]
+    pub fn validate_with<E, Valid>(&self, mut check: Valid) -> Dynamic<Validation>
+    where
+        T: Send + 'static,
+        Valid: for<'a> FnMut(&'a T) -> Result<(), E> + Send + 'static,
+        E: Display,
+    {
+        let validation = Dynamic::new(Validation::None);
+        self.for_each({
+            let validation = validation.clone();
+            move |value| {
+                validation.set(match check(value) {
+                    Ok(()) => Validation::Valid,
+                    Err(err) => Validation::Invalid(err.to_string()),
+                });
+            }
+        });
+        validation
+    }
 }
 
 impl Dynamic<WidgetInstance> {
@@ -670,7 +694,7 @@ impl<T> DynamicData<T> {
         F: for<'a> FnMut() + Send + 'static,
     {
         let state = self.state().expect("deadlocked");
-        let mut callbacks = state.callbacks.lock().ignore_poison();
+        let mut callbacks = state.callbacks.callbacks.lock().ignore_poison();
         callbacks.push(Box::new(map));
     }
 
@@ -716,7 +740,7 @@ impl Display for DeadlockError {
 
 struct State<T> {
     wrapped: GenerationalValue<T>,
-    callbacks: Arc<Mutex<Vec<Box<dyn ValueCallback>>>>,
+    callbacks: Arc<ChangeCallbacksData>,
     windows: AHashSet<WindowHandle>,
     widgets: AHashSet<(WindowHandle, WidgetId)>,
     wakers: Vec<Waker>,
@@ -753,14 +777,36 @@ where
     }
 }
 
-struct ChangeCallbacks(Arc<Mutex<Vec<Box<dyn ValueCallback>>>>);
+#[derive(Default)]
+struct ChangeCallbacksData {
+    callbacks: Mutex<Vec<Box<dyn ValueCallback>>>,
+    currently_executing: AtomicBool,
+}
+
+struct ChangeCallbacks(Arc<ChangeCallbacksData>);
 
 impl Drop for ChangeCallbacks {
     fn drop(&mut self) {
-        if let Ok(mut callbacks) = self.0.lock() {
+        if self
+            .0
+            .currently_executing
+            .compare_exchange(
+                false,
+                true,
+                atomic::Ordering::Release,
+                atomic::Ordering::Acquire,
+            )
+            .is_ok()
+        {
+            let mut callbacks = self.0.callbacks.lock().ignore_poison();
             for callback in &mut *callbacks {
                 callback.changed();
             }
+            self.0
+                .currently_executing
+                .store(false, atomic::Ordering::Release);
+        } else {
+            tracing::warn!("Could not invoke dynamic callbacks because they are already running on this thread");
         }
     }
 }
@@ -1600,3 +1646,169 @@ macro_rules! impl_tuple_map_each_cloned {
 }
 
 impl_all_tuples!(impl_tuple_map_each_cloned);
+
+/// The status of validating data.
+#[derive(Debug, Default, Clone, Eq, PartialEq)]
+pub enum Validation {
+    /// No validation has been performed yet.
+    ///
+    /// This status represents that the data is still in its initial state, so
+    /// errors should be delayed until it is changed.
+    #[default]
+    None,
+    /// The data is valid.
+    Valid,
+    /// The data is invalid. The string contains a human-readable message.
+    Invalid(String),
+}
+
+impl Validation {
+    /// Returns the effective text to display along side the field.
+    ///
+    /// When there is a validation error, it is returned, otherwise the hint is
+    /// returned.
+    #[must_use]
+    pub fn message<'a>(&'a self, hint: &'a str) -> &'a str {
+        match self {
+            Validation::None | Validation::Valid => hint,
+            Validation::Invalid(err) => err,
+        }
+    }
+
+    /// Returns true if there is a validation error.
+    #[must_use]
+    pub const fn is_error(&self) -> bool {
+        matches!(self, Self::Invalid(_))
+    }
+}
+
+/// A grouping of validations that can be checked simultaneously.
+#[derive(Debug, Default, Clone)]
+pub struct Validations {
+    state: Dynamic<ValidationsState>,
+    invalid: Dynamic<usize>,
+}
+
+#[derive(Default, Debug, Eq, PartialEq, Clone)]
+enum ValidationsState {
+    #[default]
+    Initial,
+    Resetting,
+    Checked,
+}
+
+impl Validations {
+    /// Validates `dynamic`'s contents using `check`, returning a dynamic
+    /// containing the validation status.
+    ///
+    /// The validation is linked with `self` such that checking `self`'s
+    /// validation status will include this validation.
+    #[must_use]
+    pub fn validate<T, E, Valid>(
+        &self,
+        dynamic: &Dynamic<T>,
+        mut check: Valid,
+    ) -> Dynamic<Validation>
+    where
+        T: Send + 'static,
+        Valid: for<'a> FnMut(&'a T) -> Result<(), E> + Send + 'static,
+        E: Display,
+    {
+        let validation = Dynamic::new(Validation::None);
+        self.invalid.map_mut(|invalid| *invalid += 1);
+
+        let error_message = dynamic.map_each(move |value| match check(value) {
+            Ok(()) => None,
+            Err(err) => Some(err.to_string()),
+        });
+
+        (&self.state, &error_message).for_each_cloned({
+            let validation = validation.clone();
+            let invalid_count = self.invalid.clone();
+            let state = self.state.clone();
+            let dynamic = dynamic.clone();
+            let mut initial_generation = dynamic.generation();
+            let mut invalid = true;
+
+            move |(current_state, message)| {
+                let new_status = if let Some(err) = message {
+                    if !invalid {
+                        invalid_count.map_mut(|invalid| *invalid += 1);
+                        invalid = true;
+                    }
+                    Validation::Invalid(err.to_string())
+                } else {
+                    if invalid {
+                        invalid_count.map_mut(|invalid| *invalid -= 1);
+                        invalid = false;
+                    }
+                    Validation::Valid
+                };
+                match current_state {
+                    ValidationsState::Resetting => {
+                        initial_generation = dynamic.generation();
+                        let state = state.clone();
+                        validation.set(Validation::None);
+                        Duration::ZERO
+                            .on_complete(move || {
+                                state.set(ValidationsState::Initial);
+                            })
+                            .launch();
+                    }
+                    ValidationsState::Initial if initial_generation == dynamic.generation() => {}
+                    _ => {
+                        validation.set(new_status);
+                    }
+                }
+            }
+        });
+
+        validation
+    }
+
+    /// Returns true if this set of validations are all valid.
+    #[must_use]
+    pub fn is_valid(&self) -> bool {
+        self.invoke_callback((), &mut |()| true)
+    }
+
+    fn invoke_callback<T, R, F>(&self, t: T, handler: &mut F) -> R
+    where
+        F: FnMut(T) -> R + UnwindSafe + Send + 'static,
+        R: Default,
+    {
+        let mut state = self.state.lock();
+        if let ValidationsState::Initial = &*state {
+            *state = ValidationsState::Checked;
+        }
+        drop(state);
+        if self.invalid.get() == 0 {
+            handler(t)
+        } else {
+            R::default()
+        }
+    }
+
+    /// Returns a function that invokes `handler` only when all tracked
+    /// validations are valid.
+    ///
+    /// The returned function can be use in a
+    /// [`Callback`](crate::widget::Callback).
+    ///
+    /// When the contents are invalid, `R::default()` is returned.
+    pub fn when_valid<T, R, F>(
+        self,
+        mut handler: F,
+    ) -> impl FnMut(T) -> R + UnwindSafe + Send + 'static
+    where
+        F: FnMut(T) -> R + UnwindSafe + Send + 'static,
+        R: Default,
+    {
+        move |t: T| self.invoke_callback(t, &mut handler)
+    }
+
+    /// Resets the validation status for all related validations.
+    pub fn reset(&self) {
+        self.state.set(ValidationsState::Resetting);
+    }
+}

src/widget.rs

@@ -25,11 +25,11 @@ use crate::styles::{
 };
 use crate::tree::Tree;
 use crate::utils::IgnorePoison;
-use crate::value::{IntoDynamic, IntoValue, Value};
+use crate::value::{IntoDynamic, IntoValue, Validation, Value};
 use crate::widgets::checkbox::{Checkable, CheckboxState};
 use crate::widgets::{
     Align, Button, Checkbox, Collapse, Container, Expand, Resize, Scroll, Space, Stack, Style,
-    Themed, ThemedMode,
+    Themed, ThemedMode, Validated,
 };
 use crate::window::{RunningWindow, ThemeMode, Window, WindowBehavior};
 use crate::{ConstraintLimit, Run};
@@ -882,6 +882,11 @@ pub trait MakeWidget: Sized {
     fn collapse_vertically(self, collapse_when: impl IntoDynamic<bool>) -> Collapse {
         Collapse::vertical(collapse_when, self)
     }
+
+    /// Returns a widget that shows validation errors and/or hints.
+    fn validation(self, validation: impl IntoDynamic<Validation>) -> Validated {
+        Validated::new(validation, self)
+    }
 }
 
 /// A type that can create a [`WidgetInstance`] with a preallocated
@@ -921,12 +926,6 @@ impl MakeWidget for Color {
     }
 }
 
-impl MakeWidget for () {
-    fn make_widget(self) -> WidgetInstance {
-        Space::clear().make_widget()
-    }
-}
-
 /// A type that represents whether an event has been handled or ignored.
 pub type EventHandling = ControlFlow<EventHandled, EventIgnored>;
 

src/widgets.rs

@@ -23,6 +23,7 @@ mod style;
 mod switcher;
 mod themed;
 mod tilemap;
+mod validated;
 
 pub use align::Align;
 pub use button::Button;
@@ -47,3 +48,4 @@ pub use style::Style;
 pub use switcher::Switcher;
 pub use themed::Themed;
 pub use tilemap::TileMap;
+pub use validated::Validated;

src/widgets/input.rs

@@ -575,6 +575,7 @@ where
                         }
                     });
 
+                    context.apply_current_font_settings();
                     let mut text = Text::new(text, color);
                     if let Some(width) = width {
                         text = text.wrap_at(width);

src/widgets/validated.rs

@@ -0,0 +1,110 @@
+use std::fmt::Debug;
+
+use kludgine::figures::units::Lp;
+use kludgine::Color;
+
+use crate::styles::components::{LineHeight, OutlineColor, TextColor, TextSize};
+use crate::value::{Dynamic, IntoDynamic, IntoValue, MapEach, Validation, Value};
+use crate::widget::{MakeWidget, WidgetInstance, WidgetRef, WrapperWidget};
+
+/// A widget that displays validation information around another widget.
+///
+/// This widget overrides the outline color of its child to be the theme's error
+/// color.
+///
+/// Additionally, a message may be shown below the content widget. If there is a
+/// validation error, it is shown. Otherwise, an optional hint message is
+/// supported.
+#[derive(Debug)]
+pub struct Validated {
+    hint: Value<String>,
+    validation: Dynamic<Validation>,
+    validated: WidgetInstance,
+}
+
+impl Validated {
+    /// Returns a widget that displays validation information around `validated`
+    /// based on `validation`.
+    #[must_use]
+    pub fn new(validation: impl IntoDynamic<Validation>, validated: impl MakeWidget) -> Self {
+        Self {
+            validation: validation.into_dynamic(),
+            validated: validated.make_widget(),
+            hint: Value::default(),
+        }
+    }
+
+    /// Sets the hint message to be displayed when there is no validation error.
+    #[must_use]
+    pub fn hint(mut self, hint: impl IntoValue<String>) -> Self {
+        self.hint = hint.into_value();
+        self
+    }
+}
+
+impl MakeWidget for Validated {
+    fn make_widget(self) -> WidgetInstance {
+        let message = match self.hint {
+            Value::Constant(hint) => self
+                .validation
+                .map_each(move |validation| validation.message(&hint).to_string()),
+            Value::Dynamic(hint) => (&hint, &self.validation)
+                .map_each(move |(hint, validation)| validation.message(hint).to_string()),
+        };
+        let collapse = message.map_each(String::is_empty);
+
+        let error_color = Dynamic::new(Color::CLEAR_BLACK);
+        let default_color = Dynamic::new(Color::CLEAR_BLACK);
+        let color = (&self.validation, &error_color, &default_color).map_each(
+            |(validation, error, default)| {
+                if validation.is_error() {
+                    *error
+                } else {
+                    *default
+                }
+            },
+        );
+
+        ValidatedWidget {
+            contents: WidgetRef::new(
+                self.validated
+                    .with(&OutlineColor, color.clone())
+                    .and(
+                        message
+                            .with(&TextColor, color)
+                            // TODO these should be components
+                            .with(&TextSize, Lp::points(9))
+                            .with(&LineHeight, Lp::points(13))
+                            .collapse_vertically(collapse)
+                            .align_left(),
+                    )
+                    .into_rows(),
+            ),
+            error_color,
+            default_color,
+        }
+        .make_widget()
+    }
+}
+
+#[derive(Debug)]
+struct ValidatedWidget {
+    contents: WidgetRef,
+    error_color: Dynamic<Color>,
+    default_color: Dynamic<Color>,
+}
+
+impl WrapperWidget for ValidatedWidget {
+    fn child_mut(&mut self) -> &mut WidgetRef {
+        &mut self.contents
+    }
+
+    fn redraw_background(
+        &mut self,
+        context: &mut crate::context::GraphicsContext<'_, '_, '_, '_, '_>,
+    ) {
+        // TODO move these to components.
+        self.error_color.set(context.theme().error.color);
+        self.default_color.set(context.theme().surface.outline);
+    }
+}