updating apps to work with new API, working on new terminal app. a lot of stuff is broken rn :/

src/system/kernel/render.rs

@@ -1,3 +1,4 @@
+use alloc::string::String;
 use core::fmt;
 use lazy_static::lazy_static;
 use spin::Mutex;
@@ -5,6 +6,7 @@ use volatile::Volatile;
 
 use alloc::vec;
 use alloc::vec::Vec;
+use crate::serial_println;
 
 #[allow(dead_code)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -62,6 +64,14 @@ impl ScreenChar {
             colour: ColorCode::new(Color::White, Color::Black),
         }
     }
+    
+    pub fn blank() -> ScreenChar {
+        ScreenChar {
+            character: ' ' as u8,
+            colour: ColorCode::new(Color::White, Color::Black), 
+        }
+    }
+    
     pub fn white(mut character: u8) -> ScreenChar {
         if let Some(c) = special_char(character as char) {
             character = c;
@@ -113,15 +123,17 @@ lazy_static! {
 impl Renderer {
     // EXTERNAL API : for use by standard library and other parts of the kernel
     pub fn render_frame(&mut self, mut frame: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT]) { // renders the given frame to the app buffer
+
         for (i, row) in frame.iter_mut().enumerate() {
             for (j, col) in row.iter_mut().enumerate() {
+                if col.character == 0u8 { continue; }
                 if let Some(c) = special_char(col.character as char) {
                     col.character = c as u8;
                 }
+
+                self.app_buffer[i][j] = *col;
             }
         }
-
-        self.app_buffer = frame;
         self.internal_render();
     }
 
@@ -361,4 +373,4 @@ pub fn write(args: fmt::Arguments, cols: (Color, Color)) {
         writer.write_fmt(args).unwrap();
         writer.reset_colour();
     })
-}
+}