render: add opacity to surfaces

src/buffers.rs

@@ -12,7 +12,8 @@ use std::sync::{Arc, Mutex};
 #[derive(Debug)]
 pub struct ShaderBinding {
     shader: Option<Box<dyn Shader>>,
-    rect: Rectangle<u8, Virtual>
+    rect: Rectangle<u8, Virtual>,
+    opacity: u8
 }
 
 #[derive(Clone)]
@@ -24,6 +25,7 @@ impl Debug for BoundSurface<Rc<RefCell<ShaderBinding>>> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("BoundSurface")
         .field("shader", &self.binding.borrow().shader)
+        .field("opacity", &self.binding.borrow().opacity)
         .finish()
     }
 }
@@ -35,7 +37,8 @@ impl Default for BoundSurface<Rc<RefCell<ShaderBinding>>>{
         Self {
             binding: Rc::new(RefCell::new(ShaderBinding {
                 shader: None,
-                rect: Rectangle::everything()
+                rect: Rectangle::everything(),
+                opacity: 255
             })),
         }
     }
@@ -63,6 +66,14 @@ impl Surface for BoundSurface<Rc<RefCell<ShaderBinding>>> {
     fn set_rect(&mut self, rect: &Rectangle<u8, Virtual>) {
         self.binding.borrow_mut().rect = rect.clone();
     }
+
+    fn opacity(&self) -> u8 {
+        self.binding.borrow().opacity
+    }
+
+    fn set_opacity(&mut self, opacity: u8) {
+        self.binding.borrow_mut().opacity = opacity
+    }
 }
 
 #[cfg(feature="threads")]

src/render.rs

@@ -23,6 +23,8 @@ pub trait Surface: Default + Clone + Debug {
 
     fn rect(&self) -> Rectangle<u8, Virtual>;
     fn set_rect(&mut self, rect: &Rectangle<u8, Virtual>);
+    fn opacity(&self) -> u8;
+    fn set_opacity(&mut self, opacity: u8);
 }
 
 pub trait Framed {