Scroll

src/elements/div.rs

@@ -84,5 +84,6 @@ impl ElementRenderer for DivRenderer<'_> {
         self.0.height = self.0.height.max(t.height + (t.py * 2));
         t.x += self.0.x + self.0.px;
         t.y += self.0.y + self.0.py;
+        t.offset_y = self.0.offset_y;
     }
 }

src/elements/flex.rs

@@ -170,6 +170,7 @@ impl ElementRenderer for RowRenderer<'_> {
         t.py += self.0.py;
 
         self.0.height += t.height + (t.py * 2) + self.1;
+        t.offset_y = self.0.offset_y;
     }
 }
 
@@ -187,5 +188,6 @@ impl ElementRenderer for ColumnRenderer<'_> {
         t.py += self.0.py;
 
         self.0.width += t.width + (t.px * 2) + self.1;
+        t.offset_y = self.0.offset_y;
     }
 }

src/elements/mod.rs

@@ -3,12 +3,14 @@ pub mod flex;
 pub mod heading;
 pub mod input;
 pub mod paginator;
+pub mod scroll;
 
 pub use div::*;
 pub use flex::*;
 pub use heading::*;
 pub use input::*;
 pub use paginator::*;
+pub use scroll::*;
 
 use crate::Element;
 

src/elements/scroll.rs

@@ -0,0 +1,120 @@
+use std::sync::Arc;
+
+use crossterm::event::Event;
+
+use crate::{
+    prelude::ElementRenderer,
+    style::RawTransform,
+    widget::{Element, Widget},
+    NoRenderRoot,
+};
+
+pub struct ScrollRenderer<'a>(&'a mut RawTransform);
+
+pub struct Scroll {
+    pub scroll_offset: u16,
+    children: Vec<Arc<Widget>>,
+    render: (u16, u16),
+}
+
+impl Scroll {
+    pub fn new() -> Self {
+        Self {
+            scroll_offset: 0,
+            children: Vec::new(),
+            render: (0, 0),
+        }
+    }
+}
+
+impl Element for Scroll {
+    fn render(
+        &mut self,
+        scope: &mut crate::prelude::RenderScope,
+        _: &crate::render_scope::RenderContext,
+    ) {
+        scope.use_area(self.render.0, self.render.1);
+    }
+
+    fn after_render(
+        &mut self,
+        parent_scope: &mut crate::render_scope::RenderScope,
+        render_context: &crate::render_scope::RenderContext,
+    ) {
+        let mut transform = {
+            let (width, height) = parent_scope.get_size_or_parent();
+            let mut t = parent_scope.get_transform().clone();
+            t.width = width;
+            t.height = height;
+            t.transform_parent(parent_scope.get_parent_transform());
+            t
+        };
+
+        transform.offset_y = self.scroll_offset;
+
+        let mut scope = crate::render_scope::RenderScope::new();
+        scope.set_parent_transform(transform.clone());
+
+        transform.width = 0;
+        transform.height = 0;
+        let mut renderer = ScrollRenderer(&mut transform);
+        for widget in &self.children {
+            scope.render_widget(&mut renderer, render_context.get_context(), widget);
+        }
+
+        self.render = (transform.width, transform.height);
+    }
+
+    fn draw_child(&mut self, element: &Arc<Widget>) {
+        self.children.push(element.clone());
+        element.inject(|w| w.component(NoRenderRoot));
+    }
+
+    fn undraw_child(&mut self, element: &Arc<Widget>) {
+        if let Some(i) = self.children.iter().position(|v| Arc::ptr_eq(v, element)) {
+            self.children.remove(i);
+        }
+    }
+
+    fn event(&mut self, event: &dyn crate::prelude::Event) {
+        if let Some(e) = event.get::<crossterm::event::Event>() {
+            match e {
+                Event::Key(k) => match k.code {
+                    crossterm::event::KeyCode::Up => {
+                        self.scroll_offset = self.scroll_offset.saturating_sub(1)
+                    }
+                    crossterm::event::KeyCode::Down => {
+                        if self.scroll_offset + 1 < self.render.1 {
+                            self.scroll_offset += 1;
+                        }
+                    }
+                    _ => {}
+                },
+                _ => {}
+            }
+        }
+    }
+
+    fn is_ghost(&mut self) -> bool {
+        true
+    }
+
+    fn as_any(&self) -> &dyn std::any::Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
+        self
+    }
+}
+
+impl ElementRenderer for ScrollRenderer<'_> {
+    fn before_draw(&mut self, scope: &mut crate::prelude::RenderScope, _widget: &Arc<Widget>) {
+        let t = scope.get_transform_mut();
+        self.0.width = self.0.width.max(t.width + (t.px * 2));
+        self.0.height = self.0.height.max(t.height + (t.py * 2));
+        t.x += self.0.x + self.0.px;
+        t.y += self.0.y + self.0.py;
+        t.offset_y = self.0.offset_y;
+    }
+}