Add padding support

src/engine.rs

@@ -139,7 +139,16 @@ impl LayoutEngine {
             };
 
             // Recursively layout the child node
-            self.layout_node(tree, child, (width, height), child_x, child_y);
+            self.layout_node(
+                tree,
+                child,
+                (
+                    width - (style.padding.left + style.padding.right),
+                    height - (style.padding.top + style.padding.bottom),
+                ),
+                child_x + style.padding.left,
+                child_y + style.padding.top,
+            );
 
             // Update cursor position based on the direction
             cursor += match style.direction {

src/lib.rs

@@ -36,6 +36,10 @@ mod tests {
                 width: Units::Pixels(30.0),
                 height: Units::Pixels(0.0),
             },
+            padding: Padding {
+                top: 20.0,
+                ..Default::default()
+            },
             direction: Direction::Row,
             ..Default::default()
         });
@@ -84,11 +88,11 @@ mod tests {
         assert_eq!(engine.computed[1].height, 300.0);
         assert_eq!(engine.computed[1].width, 450.0);
         assert_eq!(engine.computed[1].x, 0.0);
-        assert_eq!(engine.computed[1].y, 0.0);
+        assert_eq!(engine.computed[1].y, 20.0);
 
         assert_eq!(engine.computed[2].height, 300.0);
         assert_eq!(engine.computed[2].width, 200.0);
-        assert_eq!(engine.computed[2].y, 95.0);
+        assert_eq!(engine.computed[2].y, 105.0);
         assert_eq!(engine.computed[2].x, 500.0);
     }
 }

src/style.rs

@@ -1,4 +1,4 @@
-use crate::{Direction, HorizontalAlign, Margin, Size, VerticalAlign};
+use crate::{Direction, HorizontalAlign, Margin, Padding, Size, VerticalAlign};
 
 /// Style of Node
 #[derive(Default, Clone, Debug)]
@@ -9,6 +9,7 @@ pub struct Style {
     pub gap: Size,
     pub direction: Direction,
     pub margin: Margin,
+    pub padding: Padding,
     pub vertical_align: VerticalAlign,
     pub horizontal_align: HorizontalAlign,
 }

src/styles/mod.rs

@@ -8,3 +8,5 @@ mod vertical_align;
 pub use vertical_align::*;
 mod horizontal_align;
 pub use horizontal_align::*;
+mod padding;
+pub use padding::*;

src/styles/padding.rs

@@ -0,0 +1,19 @@
+#[derive(Clone, Copy, Debug)]
+/// Space inside an node
+pub struct Padding {
+    pub top: f32,
+    pub left: f32,
+    pub right: f32,
+    pub bottom: f32,
+}
+
+impl Default for Padding {
+    fn default() -> Self {
+        Padding {
+            top: 0.0,
+            left: 0.0,
+            right: 0.0,
+            bottom: 0.0,
+        }
+    }
+}