Better handling of full-width widgets inside of Ui:s with inf max size

emigui/src/containers/collapsing_header.rs

@@ -54,14 +54,14 @@ impl CollapsingHeader {
             default_open,
         } = self;
 
-        // TODO: horizontal layout, with icon and text as labels. Inser background behind using Frame.
+        // TODO: horizontal layout, with icon and text as labels. Insert background behind using Frame.
 
         let title = &label.text; // TODO: not this
         let id = ui.make_unique_id(title);
         let text_pos = ui.cursor() + vec2(ui.style().indent, 0.0);
         let (title, text_size) = label.layout(text_pos, ui);
         let text_max_x = text_pos.x + text_size.x;
-        let desired_width = ui.available_width().max(text_max_x - ui.cursor().x);
+        let desired_width = ui.available_space_min().x.max(text_max_x - ui.cursor().x);
 
         let interact = ui.reserve_space(
             vec2(

emigui/src/ui.rs

@@ -28,6 +28,8 @@ pub struct Ui {
     /// The widgets will TRY to fit within the rect,
     /// but may overflow (which you will see in child_bounds).
     /// Some widgets (like separator lines) will try to fill the full desired width of the ui.
+    /// If the desired size is zero, it is a signal that child widgets should be as small as possible.
+    /// If the desired size is initie, it is a signal that child widgets should take up as much room as they want.
     desired_rect: Rect, // TODO: rename as max_rect ?
 
     /// Bounding box of all children.
@@ -161,11 +163,24 @@ impl Ui {
 
     /// Screen-space position of the current bottom right corner of this Ui.
     /// This may move when we add children that overflow our desired rectangle bounds.
+    /// This position may be at inifnity if the desired rect is initinite,
+    /// which mappens when a parent widget says "be as big as you want to be".
     pub fn bottom_right(&self) -> Pos2 {
         // If a child doesn't fit in desired_rect, we have effectively expanded:
         self.desired_rect.max.max(self.child_bounds.max)
     }
 
+    pub fn finite_bottom_right(&self) -> Pos2 {
+        let mut bottom_right = self.child_bounds.max;
+        if self.desired_rect.max.x.is_finite() {
+            bottom_right.x = bottom_right.x.max(self.desired_rect.max.x);
+        }
+        if self.desired_rect.max.y.is_finite() {
+            bottom_right.y = bottom_right.y.max(self.desired_rect.max.y);
+        }
+        bottom_right
+    }
+
     /// Position and current size of the ui.
     /// The size is the maximum of the origional (minimum/desired) size and
     /// the size of the containted children.
@@ -216,20 +231,31 @@ impl Ui {
     // ------------------------------------------------------------------------
     // Layout related measures:
 
+    /// A zero should be intepreted as "as little as possible".
+    /// An infinite value should be intereted as "as much as you want"
     pub fn available_width(&self) -> f32 {
         self.available_space().x
     }
 
+    /// A zero should be intepreted as "as little as possible".
+    /// An infinite value should be intereted as "as much as you want"
     pub fn available_height(&self) -> f32 {
         self.available_space().y
     }
 
     /// This how much more space we can take up without overflowing our parent.
     /// Shrinks as cursor increments.
+    /// A zero size should be intepreted as "as little as possible".
+    /// An infinite size should be intereted as "as much as you want"
     pub fn available_space(&self) -> Vec2 {
         self.bottom_right() - self.cursor
     }
 
+    /// Use this for components that want to grow witout bounds.
+    pub fn available_space_min(&self) -> Vec2 {
+        self.finite_bottom_right() - self.cursor
+    }
+
     pub fn direction(&self) -> Direction {
         self.dir
     }

emigui/src/widgets.rs

@@ -23,6 +23,7 @@ pub struct Label {
     // TODO: not pub
     pub(crate) text: String,
     pub(crate) multiline: bool,
+    auto_shrink: bool,
     pub(crate) text_style: TextStyle, // TODO: Option<TextStyle>, where None means "use the default for the ui"
     pub(crate) text_color: Option<Color>,
 }
@@ -32,6 +33,7 @@ impl Label {
         Self {
             text: text.into(),
             multiline: true,
+            auto_shrink: false,
             text_style: TextStyle::Body,
             text_color: None,
         }
@@ -46,6 +48,13 @@ impl Label {
         self
     }
 
+    /// If true, will word wrap to the width of the current child_bounds.
+    /// If false (defailt), will word wrap to the available width
+    pub fn auto_shrink(mut self) -> Self {
+        self.auto_shrink = true;
+        self
+    }
+
     pub fn text_style(mut self, text_style: TextStyle) -> Self {
         self.text_style = text_style;
         self
@@ -58,7 +67,13 @@ impl Label {
 
     pub fn layout(&self, pos: Pos2, ui: &Ui) -> (Vec<font::TextFragment>, Vec2) {
         let font = &ui.fonts()[self.text_style];
-        let max_width = ui.rect().right() - pos.x;
+
+        let max_width = if self.auto_shrink {
+            ui.child_bounds().right() - pos.x
+        } else {
+            ui.rect().right() - pos.x
+        };
+
         if self.multiline {
             font.layout_multiline(&self.text, max_width)
         } else {
@@ -389,7 +404,8 @@ impl Separator {
 
 impl Widget for Separator {
     fn ui(self, ui: &mut Ui) -> GuiResponse {
-        let available_space = ui.available_space();
+        let available_space = ui.available_space_min();
+
         let extra = self.extra;
         let (points, interact) = match ui.direction() {
             Direction::Horizontal => {