add examples; do not hard-shutdown when screen is closed - destructors did not run!

crsn_screen/src/exec.rs

@@ -97,9 +97,9 @@ impl OpTrait for ScreenOp {
                 let backend: &mut Backend = state.ext_mut();
 
                 if force != 0 {
-                    blit(backend)
+                    blit(backend)?;
                 } else {
-                    blit_maybe(backend)
+                    blit_maybe(backend)?;
                 }
             }
 
@@ -143,7 +143,7 @@ impl OpTrait for ScreenOp {
                             backend.buffer[index as usize] = color as u32;
 
                             if backend.opts.auto_blit {
-                                blit_maybe(backend);
+                                blit_maybe(backend)?;
                             }
                         }
                     }
@@ -274,29 +274,31 @@ fn init(state: &mut RunState, width: Value, height: Value) -> Result<(), Fault>
 
     backend.window = Some(window);
 
-    blit_maybe(backend);
+    blit_maybe(backend)?;
 
     Ok(())
 }
 
-fn blit_maybe(backend: &mut Backend) {
+fn blit_maybe(backend: &mut Backend) -> Result<(), Fault> {
     if backend.last_render.elapsed() >= backend.opts.frame_rate {
-        blit(backend);
+        blit(backend)
+    } else {
+        Ok(())
     }
 }
 
-fn blit(backend: &mut Backend) {
+fn blit(backend: &mut Backend) -> Result<(), Fault> {
     let w = backend.window.as_mut().unwrap();
 
     if !w.is_open() {
-        // TODO...
-        std::process::exit(0);
+        return Err(Fault::Halt);
     }
 
     w.update_with_buffer(&backend.buffer, backend.width, backend.height)
         .expect("Update screen"); // TODO fault
 
     backend.last_render = Instant::now();
+    Ok(())
 }
 
 fn num2key(num: Value) -> Option<Key> {