Add SCROLLBAR_MIN_SIZE to env, and use Entry

druid/src/env.rs

@@ -16,7 +16,7 @@
 
 use std::any;
 use std::borrow::Borrow;
-use std::collections::HashMap;
+use std::collections::{hash_map::Entry, HashMap};
 use std::fmt::{Debug, Formatter};
 use std::marker::PhantomData;
 use std::ops::Deref;
@@ -342,13 +342,18 @@ impl Env {
     ) -> Result<(), ValueTypeError> {
         let env = Arc::make_mut(&mut self.0);
         let key = key.into();
-        // TODO: use of Entry might be more efficient
-        if let Some(existing) = env.map.get(&key) {
-            if !existing.is_same_type(&raw) {
-                return Err(ValueTypeError::new(any::type_name::<V>(), raw));
+        match env.map.entry(key) {
+            Entry::Occupied(mut e) => {
+                let existing = e.get_mut();
+                if !existing.is_same_type(&raw) {
+                    return Err(ValueTypeError::new(any::type_name::<V>(), raw));
+                }
+                *existing = raw;
+            }
+            Entry::Vacant(e) => {
+                e.insert(raw);
             }
         }
-        env.map.insert(key, raw);
         Ok(())
     }
 

druid/src/scroll_component.rs

@@ -17,16 +17,14 @@
 
 use std::time::Duration;
 
-use crate::kurbo::{Point, Rect, Vec2};
 use crate::theme;
 use crate::widget::{Axis, Viewport};
+use crate::{
+    kurbo::{Point, Rect, Vec2},
+    theme::SCROLLBAR_MIN_SIZE,
+};
 use crate::{Env, Event, EventCtx, LifeCycle, LifeCycleCtx, PaintCtx, RenderContext, TimerToken};
 
-//TODO: Add this to env
-/// Minimum length for any scrollbar to be when measured on that
-/// scrollbar's primary axis.
-pub const SCROLLBAR_MIN_SIZE: f64 = 45.0;
-
 #[derive(Debug, Copy, Clone)]
 /// Which scroll bars of a scroll area are currently enabled.
 pub enum ScrollbarsEnabled {
@@ -192,7 +190,7 @@ impl ScrollComponent {
         let percent_scrolled = scroll_offset.y / (content_size.height - viewport_size.height);
 
         let length = (percent_visible * viewport_size.height).ceil();
-        let length = length.max(SCROLLBAR_MIN_SIZE);
+        let length = length.max(env.get(SCROLLBAR_MIN_SIZE));
 
         let vertical_padding = bar_pad + bar_pad + bar_width;
 
@@ -227,7 +225,7 @@ impl ScrollComponent {
         let percent_scrolled = scroll_offset.x / (content_size.width - viewport_size.width);
 
         let length = (percent_visible * viewport_size.width).ceil();
-        let length = length.max(SCROLLBAR_MIN_SIZE);
+        let length = length.max(env.get(SCROLLBAR_MIN_SIZE));
 
         let horizontal_padding = bar_pad + bar_pad + bar_width;
 

druid/src/theme.rs

@@ -100,6 +100,9 @@ pub const SCROLLBAR_PAD: Key<f64> = Key::new("org.linebender.druid.theme.scrollb
 pub const SCROLLBAR_RADIUS: Key<f64> = Key::new("org.linebender.druid.theme.scrollbar_radius");
 pub const SCROLLBAR_EDGE_WIDTH: Key<f64> =
     Key::new("org.linebender.druid.theme.scrollbar_edge_width");
+/// Minimum length for any scrollbar to be when measured on that
+/// scrollbar's primary axis.
+pub const SCROLLBAR_MIN_SIZE: Key<f64> = Key::new("org.linebender.theme.scrollbar_min_size");
 
 /// An initial theme.
 pub(crate) fn add_to_env(env: Env) -> Env {
@@ -161,6 +164,7 @@ pub(crate) fn add_to_env(env: Env) -> Env {
                 .with_style(FontStyle::Italic)
                 .with_size(15.0),
         )
+        .adding(SCROLLBAR_MIN_SIZE, 45.0)
 }
 
 #[deprecated(since = "0.7.0", note = "use Env::default() instead")]