Padding can be constructed with Key<Insets>

Author: cmyr

CHANGELOG.md

@@ -26,6 +26,7 @@ You can find its changes [documented below](#070---2021-01-01).
 - New `TextBox` widget with IME integration ([#1636] by [@cmyr])
 - `Notification`s can be submitted while handling other `Notification`s ([#1640] by [@cmyr])
 - Added ListIter implementations for OrdMap ([#1641] by [@Lejero])
+- `Padding` can now use `Key<Insets>` ([#1662] by [@cmyr])
 
 ### Changed
 
@@ -644,6 +645,7 @@ Last release without a changelog :(
 [#1640]: https://github.com/linebender/druid/pull/1640
 [#1641]: https://github.com/linebender/druid/pull/1641
 [#1647]: https://github.com/linebender/druid/pull/1647
+[#1662]: https://github.com/linebender/druid/pull/1662
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.7.0...master
 [0.7.0]: https://github.com/linebender/druid/compare/v0.6.0...v0.7.0

druid/src/env.rs

@@ -623,6 +623,24 @@ impl<T: ValueType> From<Key<T>> for KeyOrValue<T> {
     }
 }
 
+impl Into<KeyOrValue<Insets>> for f64 {
+    fn into(self) -> KeyOrValue<Insets> {
+        KeyOrValue::Concrete(self.into())
+    }
+}
+
+impl Into<KeyOrValue<Insets>> for (f64, f64) {
+    fn into(self) -> KeyOrValue<Insets> {
+        KeyOrValue::Concrete(self.into())
+    }
+}
+
+impl Into<KeyOrValue<Insets>> for (f64, f64, f64, f64) {
+    fn into(self) -> KeyOrValue<Insets> {
+        KeyOrValue::Concrete(self.into())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

druid/src/widget/padding.rs

@@ -15,24 +15,21 @@
 //! A widget that just adds padding during layout.
 
 use crate::widget::{prelude::*, WidgetWrapper};
-use crate::{Data, Insets, Point, WidgetPod};
+use crate::{Data, Insets, KeyOrValue, Point, WidgetPod};
 
 use tracing::{instrument, trace};
 
 /// A widget that just adds padding around its child.
 pub struct Padding<T, W> {
-    left: f64,
-    right: f64,
-    top: f64,
-    bottom: f64,
-
+    insets: KeyOrValue<Insets>,
     child: WidgetPod<T, W>,
 }
 
 impl<T, W: Widget<T>> Padding<T, W> {
     /// Create a new widget with the specified padding. This can either be an instance
-    /// of [`kurbo::Insets`], a f64 for uniform padding, a 2-tuple for axis-uniform padding
-    /// or 4-tuple with (left, top, right, bottom) values.
+    /// of [`Insets`], a [`Key`] referring to [`Insets`] in the [`Env`],
+    /// an `f64` for uniform padding, a `(f64, f64)` for axis-uniform padding,
+    /// or `(f64, f64, f64, f64)` (left, top, right, bottom) values.
     ///
     /// # Examples
     ///
@@ -58,14 +55,10 @@ impl<T, W: Widget<T>> Padding<T, W> {
     /// let _: Padding<(), _> = Padding::new(Insets::uniform_xy(10.0, 20.0), Label::new("ditto :)"));
     /// ```
     ///
-    /// [`kurbo::Insets`]: https://docs.rs/kurbo/0.5.3/kurbo/struct.Insets.html
-    pub fn new(insets: impl Into<Insets>, child: W) -> Padding<T, W> {
-        let insets = insets.into();
+    /// [`Key`]: crate::Key
+    pub fn new(insets: impl Into<KeyOrValue<Insets>>, child: W) -> Padding<T, W> {
         Padding {
-            left: insets.x0,
-            right: insets.x1,
-            top: insets.y0,
-            bottom: insets.y1,
+            insets: insets.into(),
             child: WidgetPod::new(child),
         }
     }
@@ -86,25 +79,25 @@ impl<T: Data, W: Widget<T>> Widget<T> for Padding<T, W> {
         self.child.lifecycle(ctx, event, data, env)
     }
 
-    #[instrument(
-        name = "Padding",
-        level = "trace",
-        skip(self, ctx, _old_data, data, env)
-    )]
-    fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &T, data: &T, env: &Env) {
+    #[instrument(name = "Padding", level = "trace", skip(self, ctx, _old, data, env))]
+    fn update(&mut self, ctx: &mut UpdateCtx, _old: &T, data: &T, env: &Env) {
+        if ctx.env_key_changed(&self.insets) {
+            ctx.request_layout();
+        }
         self.child.update(ctx, data, env);
     }
 
     #[instrument(name = "Padding", level = "trace", skip(self, ctx, bc, data, env))]
     fn layout(&mut self, ctx: &mut LayoutCtx, bc: &BoxConstraints, data: &T, env: &Env) -> Size {
         bc.debug_check("Padding");
+        let insets = self.insets.resolve(env);
 
-        let hpad = self.left + self.right;
-        let vpad = self.top + self.bottom;
+        let hpad = insets.x0 + insets.x1;
+        let vpad = insets.y0 + insets.y1;
 
         let child_bc = bc.shrink((hpad, vpad));
         let size = self.child.layout(ctx, &child_bc, data, env);
-        let origin = Point::new(self.left, self.top);
+        let origin = Point::new(insets.x0, insets.y0);
         self.child.set_origin(ctx, data, env, origin);
 
         let my_size = Size::new(size.width + hpad, size.height + vpad);

druid/src/widget/widget_ext.rs

@@ -28,9 +28,12 @@ use crate::{
 pub trait WidgetExt<T: Data>: Widget<T> + Sized + 'static {
     /// Wrap this widget in a [`Padding`] widget with the given [`Insets`].
     ///
-    /// [`Padding`]: widget/struct.Padding.html
-    /// [`Insets`]: kurbo/struct.Insets.html
-    fn padding(self, insets: impl Into<Insets>) -> Padding<T, Self> {
+    /// Like [`Padding::new`], this can accept a variety of arguments, including
+    /// a [`Key`] referring to [`Insets`] in the [`Env`].
+    ///
+    /// [`Key`]: crate::Key
+    /// [`Insets`]: crate::Insets
+    fn padding(self, insets: impl Into<KeyOrValue<Insets>>) -> Padding<T, Self> {
         Padding::new(insets, self)
     }