From fbedc2e9ab507314cf2d65592d88b094f1bc99cf Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emilernerfeldt@gmail.com>
Date: Sun, 26 Apr 2020 22:30:24 +0200
Subject: [PATCH] Add scroll bars to windows.

Auto-hide scroll bars when not needed

Bug fixes:
 * collapsing headers animation
 * clip rect interactions
 * clip rects for scroll areas
---
 emigui/README.md                           |  8 ++-
 emigui/src/containers/collapsing_header.rs | 18 ++----
 emigui/src/containers/floating.rs          |  3 +-
 emigui/src/containers/resize.rs            |  3 +-
 emigui/src/containers/scroll_area.rs       | 68 ++++++++++++++--------
 emigui/src/containers/window.rs            | 19 ++++--
 emigui/src/context.rs                      | 13 ++++-
 emigui/src/emigui.rs                       |  2 +-
 emigui/src/example_app.rs                  |  1 +
 emigui/src/math.rs                         |  2 +-
 emigui/src/region.rs                       | 20 +++++--
 emigui/src/style.rs                        |  1 +
 12 files changed, 103 insertions(+), 55 deletions(-)

diff --git a/emigui/README.md b/emigui/README.md
index 7c67167f..99a70280 100644
--- a/emigui/README.md
+++ b/emigui/README.md
@@ -13,6 +13,7 @@ This is the core library crate Emigui. It is fully platform independent without
 * [x] Tooltip
 * [x] Movable/resizable windows
     * [ ] Kinetic windows
+    * [ ] BUG FIX: Don't catch clicks on closed windows
 * [ ] Scroll areas
     * [x] Vertical scrolling
     * [ ] Horizontal scrolling
@@ -26,6 +27,10 @@ This is the core library crate Emigui. It is fully platform independent without
 * [ ] Color picker
 * [ ] Style editor
 * [ ] Table with resizable columns
+* [ ] Layout
+    * [ ] Generalize Layout (separate from Region)
+    * [ ] Cascading layout: same lite if it fits, else next line. Like text.
+    * [ ] Grid layout
 
 ### Web version:
 * [x] Scroll input
@@ -38,7 +43,7 @@ Add extremely quick animations for some things, maybe 2-3 frames. For instance:
 ### Clip rects
 * [x] Separate Region::clip_rect from Region::rect
 * [x] Use clip rectangles when painting
-* [ ] Use clip rectangles when interacting
+* [x] Use clip rectangles when interacting
 * [x] Adjust clip rects so edges of child widgets aren't clipped
 
 ### Modularity
@@ -54,7 +59,6 @@ Add extremely quick animations for some things, maybe 2-3 frames. For instance:
 * [ ] Text
 
 ### Other
-* [ ] Generalize Layout so we can create grid layouts etc
 * [ ] Persist UI state in external storage
 * [ ] Pixel-perfect rendering (round positions to nearest pixel).
 * [ ] Build in a profiler which tracks which region in which window takes up CPU.
diff --git a/emigui/src/containers/collapsing_header.rs b/emigui/src/containers/collapsing_header.rs
index 3fe901fd..97c9b4be 100644
--- a/emigui/src/containers/collapsing_header.rs
+++ b/emigui/src/containers/collapsing_header.rs
@@ -92,16 +92,15 @@ impl CollapsingHeader {
 
         let animation_time = region.style().animation_time;
         let time_since_toggle = (region.ctx.input.time - state.toggle_time) as f32;
-        if time_since_toggle < animation_time {
+        let animate = time_since_toggle < animation_time;
+        if animate {
             region.indent(id, |region| {
-                // animation time
-
                 let max_height = if state.open {
                     remap(
                         time_since_toggle,
                         0.0..=animation_time,
                         // Get instant feedback, and we don't expect to get bigger than this
-                        50.0..=1500.0,
+                        100.0..=1500.0,
                     )
                 } else {
                     remap_clamp(
@@ -112,17 +111,12 @@ impl CollapsingHeader {
                     )
                 };
 
-                region
-                    .clip_rect
-                    .set_height(region.clip_rect.height().min(max_height));
+                region.clip_rect.max.y = region.clip_rect.max.y.min(region.cursor.y + max_height);
 
                 add_contents(region);
 
-                region.child_bounds.max.y = region
-                    .child_bounds
-                    .max
-                    .y
-                    .min(region.child_bounds.min.y + max_height);
+                region.child_bounds.max.y =
+                    region.child_bounds.max.y.min(region.cursor.y + max_height);
             });
         } else if state.open {
             region.indent(id, add_contents);
diff --git a/emigui/src/containers/floating.rs b/emigui/src/containers/floating.rs
index aec7ffdc..16575212 100644
--- a/emigui/src/containers/floating.rs
+++ b/emigui/src/containers/floating.rs
@@ -72,7 +72,8 @@ impl Floating {
         state.size = region.bounding_size().ceil();
 
         let rect = Rect::from_min_size(state.pos, state.size);
-        let move_interact = ctx.interact(layer, &rect, Some(id.with("move")));
+        let clip_rect = Rect::everything();
+        let move_interact = ctx.interact(layer, &clip_rect, &rect, Some(id.with("move")));
 
         if move_interact.active {
             state.pos += ctx.input().mouse_move;
diff --git a/emigui/src/containers/resize.rs b/emigui/src/containers/resize.rs
index bb73c18a..bbcc79d7 100644
--- a/emigui/src/containers/resize.rs
+++ b/emigui/src/containers/resize.rs
@@ -172,7 +172,8 @@ impl Resize {
             contents_region.clip_rect.max = contents_region
                 .clip_rect
                 .max
-                .max(contents_region.clip_rect.min + last_frame_size);
+                .max(contents_region.clip_rect.min + last_frame_size)
+                .min(region.clip_rect.max); // Respect parent region
 
             add_contents(&mut contents_region);
             contents_region.bounding_size()
diff --git a/emigui/src/containers/scroll_area.rs b/emigui/src/containers/scroll_area.rs
index f9add704..d72c6292 100644
--- a/emigui/src/containers/scroll_area.rs
+++ b/emigui/src/containers/scroll_area.rs
@@ -4,15 +4,24 @@ use crate::*;
 pub struct State {
     /// Positive offset means scrolling down/right
     pub offset: Vec2,
+
+    pub show_scroll: bool, // TODO: default value?
 }
 
+#[derive(Clone, Debug)]
 pub struct ScrollArea {
     max_height: f32,
+    always_show_scroll: bool,
+    auto_hide_scroll: bool,
 }
 
 impl Default for ScrollArea {
     fn default() -> Self {
-        Self { max_height: 200.0 }
+        Self {
+            max_height: 200.0,
+            always_show_scroll: false,
+            auto_hide_scroll: true,
+        }
     }
 }
 
@@ -21,6 +30,16 @@ impl ScrollArea {
         self.max_height = max_height;
         self
     }
+
+    pub fn always_show_scroll(mut self, always_show_scroll: bool) -> Self {
+        self.always_show_scroll = always_show_scroll;
+        self
+    }
+
+    pub fn auto_hide_scroll(mut self, auto_hide_scroll: bool) -> Self {
+        self.auto_hide_scroll = auto_hide_scroll;
+        self
+    }
 }
 
 impl ScrollArea {
@@ -42,38 +61,40 @@ impl ScrollArea {
 
         let scroll_bar_width = 16.0;
 
-        let outer_size = vec2(outer_region.available_width(), self.max_height);
+        let outer_size = vec2(
+            outer_region.available_width(),
+            outer_region.available_height().min(self.max_height),
+        );
         let outer_rect = Rect::from_min_size(outer_region.cursor, outer_size);
 
-        let inner_size = outer_size - vec2(scroll_bar_width, 0.0);
+        let inner_size = if state.show_scroll || !self.auto_hide_scroll {
+            outer_size - vec2(scroll_bar_width, 0.0) // TODO: animate?
+        } else {
+            outer_size
+        };
         let inner_rect = Rect::from_min_size(outer_region.cursor, inner_size);
 
-        let mut content_region =
-            outer_region.child_region(Rect::from_min_size(outer_region.cursor(), inner_size));
-        content_region.cursor -= state.offset;
-        content_region.desired_rect = content_region.desired_rect.translate(-state.offset);
+        let mut content_region = outer_region.child_region(Rect::from_min_size(
+            outer_region.cursor() - state.offset,
+            vec2(inner_size.x, f32::INFINITY),
+        ));
+        content_region.clip_rect = outer_region.clip_rect().intersect(&inner_rect);
         add_contents(&mut content_region);
         let content_size = content_region.bounding_size();
 
-        let content_interact = ctx.interact(
-            outer_region.layer,
-            &inner_rect,
-            Some(scroll_area_id.with("area")),
-        );
+        let content_interact = outer_region.interact_rect(&inner_rect, scroll_area_id.with("area"));
         if content_interact.active {
             // Dragging scroll area to scroll:
             state.offset.y -= ctx.input.mouse_move.y;
         }
 
         // TODO: check that nothing else is being inteacted with
-        if ctx.contains_mouse_pos(outer_region.layer, &outer_rect)
-            && ctx.memory.lock().active_id.is_none()
-        {
+        if outer_region.contains_mouse(&outer_rect) && ctx.memory.lock().active_id.is_none() {
             state.offset.y -= ctx.input.scroll_delta.y;
         }
 
-        let show_scroll = content_size.y > inner_size.y;
-        if show_scroll {
+        let show_scroll_this_frame = content_size.y > inner_size.y || self.always_show_scroll;
+        if show_scroll_this_frame || state.show_scroll {
             let left = inner_rect.right() + 2.0;
             let right = outer_rect.right();
             let corner_radius = (right - left) / 2.0;
@@ -94,8 +115,8 @@ impl ScrollArea {
             );
 
             // intentionally use same id for inside and outside of handle
-            let interact_id = Some(scroll_area_id.with("vertical"));
-            let handle_interact = ctx.interact(outer_region.layer, &handle_rect, interact_id);
+            let interact_id = scroll_area_id.with("vertical");
+            let handle_interact = outer_region.interact_rect(&handle_rect, interact_id);
 
             if let Some(mouse_pos) = ctx.input.mouse_pos {
                 if handle_interact.active {
@@ -106,7 +127,7 @@ impl ScrollArea {
                 } else {
                     // Check for mouse down outside handle:
                     let scroll_bg_interact =
-                        ctx.interact(outer_region.layer, &outer_scroll_rect, interact_id);
+                        outer_region.interact_rect(&outer_scroll_rect, interact_id);
 
                     if scroll_bg_interact.active {
                         // Center scroll at mouse pos:
@@ -132,7 +153,7 @@ impl ScrollArea {
             outer_region.add_paint_cmd(PaintCmd::Rect {
                 rect: outer_scroll_rect,
                 corner_radius,
-                fill_color: Some(color::BLACK),
+                fill_color: Some(color::gray(0, 196)), // TODO style
                 outline: None,
             });
 
@@ -144,11 +165,12 @@ impl ScrollArea {
             });
         }
 
-        let size = content_size.min(content_region.clip_rect.size());
+        let size = content_size.min(inner_rect.size());
         outer_region.reserve_space_without_padding(size);
 
-        state.offset.y = state.offset.y.max(0.0);
         state.offset.y = state.offset.y.min(content_size.y - inner_rect.height());
+        state.offset.y = state.offset.y.max(0.0);
+        state.show_scroll = show_scroll_this_frame;
 
         outer_region
             .ctx()
diff --git a/emigui/src/containers/window.rs b/emigui/src/containers/window.rs
index 703fa01e..9ef12126 100644
--- a/emigui/src/containers/window.rs
+++ b/emigui/src/containers/window.rs
@@ -4,13 +4,14 @@ use crate::{widgets::*, *};
 
 use super::*;
 
-// TODO: separate out resizing into a contained and reusable Resize-region.
+/// A wrapper around other containers for things you often want in a window
 #[derive(Clone, Debug)]
 pub struct Window {
     title: String,
     floating: Floating,
     frame: Frame,
     resize: Resize,
+    scroll: ScrollArea,
 }
 
 impl Window {
@@ -22,7 +23,11 @@ impl Window {
             frame: Frame::default(),
             resize: Resize::default()
                 .handle_offset(Vec2::splat(4.0))
-                .auto_shrink_height(true),
+                .auto_shrink_height(false)
+                .auto_expand(false),
+            scroll: ScrollArea::default()
+                .always_show_scroll(false)
+                .max_height(f32::INFINITY), // As large as we can be
         }
     }
 
@@ -66,15 +71,17 @@ impl Window {
             floating,
             frame,
             resize,
+            scroll,
         } = self;
+        // TODO: easier way to compose these
         floating.show(ctx, |region| {
             frame.show(region, |region| {
                 resize.show(region, |region| {
                     region.add(Label::new(title).text_style(TextStyle::Heading));
                     region.add(Separator::new().line_width(1.0)); // TODO: nicer way to split window title from contents
-                    add_contents(region);
-                });
-            });
-        });
+                    scroll.show(region, |region| add_contents(region))
+                })
+            })
+        })
     }
 }
diff --git a/emigui/src/context.rs b/emigui/src/context.rs
index c66ae1dc..924f3edb 100644
--- a/emigui/src/context.rs
+++ b/emigui/src/context.rs
@@ -120,7 +120,8 @@ impl Context {
         }
     }
 
-    pub fn contains_mouse_pos(&self, layer: Layer, rect: &Rect) -> bool {
+    pub fn contains_mouse(&self, layer: Layer, clip_rect: &Rect, rect: &Rect) -> bool {
+        let rect = rect.intersect(clip_rect);
         if let Some(mouse_pos) = self.input.mouse_pos {
             rect.contains(mouse_pos) && layer == self.memory.lock().layer_at(mouse_pos)
         } else {
@@ -128,8 +129,14 @@ impl Context {
         }
     }
 
-    pub fn interact(&self, layer: Layer, rect: &Rect, interaction_id: Option<Id>) -> InteractInfo {
-        let hovered = self.contains_mouse_pos(layer, &rect);
+    pub fn interact(
+        &self,
+        layer: Layer,
+        clip_rect: &Rect,
+        rect: &Rect,
+        interaction_id: Option<Id>,
+    ) -> InteractInfo {
+        let hovered = self.contains_mouse(layer, clip_rect, &rect);
 
         let mut memory = self.memory.lock();
         let active = interaction_id.is_some() && memory.active_id == interaction_id;
diff --git a/emigui/src/emigui.rs b/emigui/src/emigui.rs
index f551b243..438d886e 100644
--- a/emigui/src/emigui.rs
+++ b/emigui/src/emigui.rs
@@ -108,7 +108,7 @@ impl Emigui {
                 region.input().pixels_per_point,
             ));
             if let Some(mouse_pos) = region.input().mouse_pos {
-                region.add(label!("mouse_pos: {} x {}", mouse_pos.x, mouse_pos.y,));
+                region.add(label!("mouse_pos: {:.2} x {:.2}", mouse_pos.x, mouse_pos.y,));
             } else {
                 region.add_label("mouse_pos: None");
             }
diff --git a/emigui/src/example_app.rs b/emigui/src/example_app.rs
index 354f6d6b..d1151ff8 100644
--- a/emigui/src/example_app.rs
+++ b/emigui/src/example_app.rs
@@ -156,6 +156,7 @@ impl ExampleApp {
                 Resize::default()
                     .default_height(200.0)
                     // .as_wide_as_possible()
+                    .auto_shrink_height(false)
                     .show(region, |region| {
                         region.add(label!("This region can be resized!"));
                         region.add(label!("Just pull the handle on the bottom right"));
diff --git a/emigui/src/math.rs b/emigui/src/math.rs
index 9e83ebb0..468c8784 100644
--- a/emigui/src/math.rs
+++ b/emigui/src/math.rs
@@ -370,7 +370,7 @@ impl Rect {
     }
 
     #[must_use]
-    pub fn intersect(self, other: Rect) -> Self {
+    pub fn intersect(self, other: &Rect) -> Self {
         Self {
             min: self.min.max(other.min),
             max: self.max.min(other.max),
diff --git a/emigui/src/region.rs b/emigui/src/region.rs
index 3aac818e..fbc6ca85 100644
--- a/emigui/src/region.rs
+++ b/emigui/src/region.rs
@@ -74,7 +74,7 @@ impl Region {
     pub fn child_region(&self, child_rect: Rect) -> Self {
         let clip_rect = self
             .clip_rect
-            .intersect(child_rect.expand(CLIP_RECT_MARGIN));
+            .intersect(&child_rect.expand(CLIP_RECT_MARGIN));
         Region {
             ctx: self.ctx.clone(),
             layer: self.layer,
@@ -339,12 +339,21 @@ impl Region {
 
     /// Check for clicks on this entire region (desired_rect)
     pub fn interact_whole(&self) -> InteractInfo {
-        self.ctx
-            .interact(self.layer, &self.desired_rect, Some(self.id))
+        self.ctx.interact(
+            self.layer,
+            &self.clip_rect,
+            &self.desired_rect,
+            Some(self.id),
+        )
     }
 
     pub fn interact_rect(&self, rect: &Rect, id: Id) -> InteractInfo {
-        self.ctx.interact(self.layer, rect, Some(id))
+        self.ctx
+            .interact(self.layer, &self.clip_rect, rect, Some(id))
+    }
+
+    pub fn contains_mouse(&self, rect: &Rect) -> bool {
+        self.ctx.contains_mouse(self.layer, &self.clip_rect, rect)
     }
 
     // ------------------------------------------------------------------------
@@ -380,7 +389,8 @@ impl Region {
         };
         let pos = self.reserve_space_without_padding(padded_size);
         let rect = Rect::from_min_size(pos, size);
-        self.ctx.interact(self.layer, &rect, interaction_id)
+        self.ctx
+            .interact(self.layer, &self.clip_rect, &rect, interaction_id)
     }
 
     /// Reserve this much space and move the cursor.
diff --git a/emigui/src/style.rs b/emigui/src/style.rs
index 7598f983..660a3346 100644
--- a/emigui/src/style.rs
+++ b/emigui/src/style.rs
@@ -165,5 +165,6 @@ impl Style {
         region.add(Slider::f32(&mut self.clickable_diameter, 0.0..=60.0).text("clickable_diameter").precision(0));
         region.add(Slider::f32(&mut self.start_icon_width, 0.0..=60.0).text("start_icon_width").precision(0));
         region.add(Slider::f32(&mut self.line_width, 0.0..=10.0).text("line_width").precision(0));
+        region.add(Slider::f32(&mut self.animation_time, 0.0..=1.0).text("animation_time").precision(2));
     }
 }