1 files changed, 67 insertions, 0 deletions
diff --git a/src/render.rs b/src/render.rs
new file mode 100644
index 0000000..e7ec02d
--- /dev/null
+++ b/src/render.rs
@@ -0,0 +1,67 @@
+/// Tells a window controller whether the previous render state is intact and
+/// can be updated, or was destroyed and needs to be fully redrawn.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum RenderHint {
+    /// The buffer content is unchanged, only updates are required.
+    Update,
+    /// The buffer content has been destroyed, a full redraw is required.
+    Redraw,
+}
+
+impl RenderHint {
+    pub fn is_update(&self) -> bool { *self == RenderHint::Update }
+    pub fn is_redraw(&self) -> bool { *self == RenderHint::Redraw }
+}
+
+impl std::ops::BitAnd for RenderHint {
+    type Output = RenderHint;
+    fn bitand(self, other: RenderHint) -> Self::Output {
+        if self == RenderHint::Redraw || other == RenderHint::Redraw {
+            RenderHint::Redraw
+        } else {
+            RenderHint::Update
+        }
+    }
+}
+
+impl std::ops::BitAndAssign for RenderHint {
+    fn bitand_assign(&mut self, other: RenderHint) {
+        *self = *self & other;
+    }
+}
+
+/// A request to the window manager for a render pass to be run.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum RenderRequest {
+    None,
+    Render(RenderHint),
+}
+
+impl RenderRequest {
+    pub const NONE:   RenderRequest = RenderRequest::None;
+    pub const UPDATE: RenderRequest = RenderRequest::Render(RenderHint::Update);
+    pub const REDRAW: RenderRequest = RenderRequest::Render(RenderHint::Redraw);
+
+    pub fn is_none(&self)   -> bool { *self == RenderRequest::None }
+    pub fn is_some(&self)   -> bool { *self != RenderRequest::None }
+    pub fn is_update(&self) -> bool { *self == RenderRequest::UPDATE }
+    pub fn is_redraw(&self) -> bool { *self == RenderRequest::REDRAW }
+}
+
+impl std::ops::BitAnd for RenderRequest {
+    type Output = RenderRequest;
+    fn bitand(self, other: RenderRequest) -> Self::Output {
+        use RenderRequest::*;
+        match (self, other) {
+            (None, req)  => req,
+            (req, None)  => req,
+            (Render(a), Render(b)) => Render(a & b),
+        }
+    }
+}
+
+impl std::ops::BitAndAssign for RenderRequest {
+    fn bitand_assign(&mut self, other: RenderRequest) {
+        *self = *self & other;
+    }
+}