Do a static buffer allocation for the Canvas

pico-st7789/src/drawing.rs

@@ -10,16 +10,18 @@
 
 use alloc::{boxed::Box, vec::Vec};
 
-pub struct Canvas<'a> {
-    pub buf: &'a mut [u8],
+static mut BUF: [u8; 163200] = [0; 163200];
+
+pub struct Canvas {
+    pub buf: &'static mut [u8; 163200],
     pub width: usize,
 }
 
-impl<'a>  Canvas<'a> {
-    pub fn new(buf: &'a mut [u8], columns: usize) -> Self {
+impl Canvas {
+    pub fn new() -> Self {
         Self {
-            buf,
-            width: columns,
+            buf: unsafe { &mut BUF },
+            width: 170,
         }
     }
 

pico-st7789/src/main.rs

@@ -119,15 +119,18 @@ unsafe fn main() -> ! {
 
     timer.delay_ms(1000);
 
+    /*
     let mut framebuf = [0; FRAMEBUF];
     let mut canvas = Canvas::new(&mut framebuf, COLUMNS);
+    */
+    let mut canvas = Canvas::new();
 
     loop {
         {
             let display = display.acquire();
             let _ = led.set_high();
             timer.delay_ms(100);
-            display.send_buf(&canvas.buf);
+            display.send_buf(canvas.buf);
             let _ = led.set_low();
         }