Add SCROLLBAR_MIN_SIZE to env, and use Entry (#1661)

* Add SCROLLBAR_MIN_SIZE to env, and  use Entry

* cargo fmt

* Update druid/src/scroll_component.rs

Co-authored-by: Manmeet Maan <[email protected]>

* Update druid/src/env.rs

Co-authored-by: Manmeet Maan <[email protected]>

* Update druid/src/env.rs

Co-authored-by: Manmeet Maan <[email protected]>

* Some adjustments

* Move SCROLLBAR_MIN_SIZE to module theme

* fmt

Co-authored-by: Manmeet Maan <[email protected]>

* cargo fmt

* cargo fmt

* fmt

* Update theme.rs

Co-authored-by: Downtime <[email protected]>
Co-authored-by: Manmeet Maan <[email protected]>

Author: Cupnfish

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

@@ -22,11 +22,6 @@ use crate::theme;
 use crate::widget::{Axis, Viewport};
 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 {
@@ -187,12 +182,13 @@ impl ScrollComponent {
 
         let bar_width = env.get(theme::SCROLLBAR_WIDTH);
         let bar_pad = env.get(theme::SCROLLBAR_PAD);
+        let bar_min_size = env.get(theme::SCROLLBAR_MIN_SIZE);
 
         let percent_visible = viewport_size.height / content_size.height;
         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(bar_min_size);
 
         let vertical_padding = bar_pad + bar_pad + bar_width;
 
@@ -222,12 +218,13 @@ impl ScrollComponent {
 
         let bar_width = env.get(theme::SCROLLBAR_WIDTH);
         let bar_pad = env.get(theme::SCROLLBAR_PAD);
+        let bar_min_size = env.get(theme::SCROLLBAR_MIN_SIZE);
 
         let percent_visible = viewport_size.width / content_size.width;
         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(bar_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 {
@@ -140,6 +143,7 @@ pub(crate) fn add_to_env(env: Env) -> Env {
         .adding(SCROLLBAR_FADE_DELAY, 1500u64)
         .adding(SCROLLBAR_WIDTH, 8.)
         .adding(SCROLLBAR_PAD, 2.)
+        .adding(SCROLLBAR_MIN_SIZE, 45.)
         .adding(SCROLLBAR_RADIUS, 5.)
         .adding(SCROLLBAR_EDGE_WIDTH, 1.)
         .adding(WIDGET_PADDING_VERTICAL, 10.0)