From 8b1e0f1ec2cd95986e0a09b6ec74ebc3891829c2 Mon Sep 17 00:00:00 2001
From: Benjamin Saunders <ben.e.saunders@gmail.com>
Date: Mon, 13 Nov 2023 17:44:30 -0800
Subject: [PATCH] Introduce viewport widget

---
 crates/yakui-widgets/src/widgets/mod.rs      |  2 +
 crates/yakui-widgets/src/widgets/viewport.rs | 44 ++++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 crates/yakui-widgets/src/widgets/viewport.rs

diff --git a/crates/yakui-widgets/src/widgets/mod.rs b/crates/yakui-widgets/src/widgets/mod.rs
index f359ea13..a6759927 100644
--- a/crates/yakui-widgets/src/widgets/mod.rs
+++ b/crates/yakui-widgets/src/widgets/mod.rs
@@ -27,6 +27,7 @@ mod state;
 mod text;
 mod textbox;
 mod unconstrained_box;
+mod viewport;
 mod window;
 
 pub use self::align::*;
@@ -58,4 +59,5 @@ pub use self::state::*;
 pub use self::text::*;
 pub use self::textbox::*;
 pub use self::unconstrained_box::*;
+pub use self::viewport::*;
 pub use self::window::*;
diff --git a/crates/yakui-widgets/src/widgets/viewport.rs b/crates/yakui-widgets/src/widgets/viewport.rs
new file mode 100644
index 00000000..fda9d2c7
--- /dev/null
+++ b/crates/yakui-widgets/src/widgets/viewport.rs
@@ -0,0 +1,44 @@
+use yakui_core::{
+    geometry::{Constraints, FlexFit, Vec2},
+    widget::{LayoutContext, Widget},
+    Response,
+};
+
+/// Occupies the largest possible space, draws nothing, and consumes no inputs
+///
+/// Capture `Viewport.show().id`, then look it up in the final `LayoutDom` to find its
+/// dimensions. Useful identifying a viewport for non-GUI rendering.
+#[derive(Debug, Default)]
+pub struct Viewport;
+
+impl Viewport {
+    pub fn show(&self) -> Response<Self> {
+        crate::util::widget::<Self>(())
+    }
+}
+
+impl Widget for Viewport {
+    type Props = ();
+    type Response = ();
+
+    fn new() -> Self {
+        Self
+    }
+
+    fn update(&mut self, (): ()) {}
+
+    fn layout(&self, _: LayoutContext<'_>, constraints: Constraints) -> Vec2 {
+        constraints
+            .max
+            .as_ref()
+            .map(|x| match x.is_infinite() {
+                true => 0.0,
+                false => x,
+            })
+            .into()
+    }
+
+    fn flex(&self) -> (u32, FlexFit) {
+        (1, FlexFit::Tight)
+    }
+}