From 3690e7b093975d49eaa3339e2db9209ec595f9c5 Mon Sep 17 00:00:00 2001
From: rdagger <rdagger68@gmail.com>
Date: Thu, 4 May 2023 15:14:52 -0700
Subject: [PATCH] Modify clear code for memory allocation.

---
 demo_clear.py | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++
 ili9341.py    | 22 ++++++++++++++-----
 2 files changed, 77 insertions(+), 6 deletions(-)
 create mode 100644 demo_clear.py

diff --git a/demo_clear.py b/demo_clear.py
new file mode 100644
index 0000000..2d4b21a
--- /dev/null
+++ b/demo_clear.py
@@ -0,0 +1,61 @@
+"""ILI9341 demo (clear)."""
+from time import sleep, ticks_ms
+from ili9341 import Display, color565
+from machine import Pin, SPI
+import gc
+
+valid_hlines = [1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160]
+
+colors = {
+    "RED": (255, 0, 0),
+    "GREEN": (0, 255, 0),
+    "BLUE": (0, 0, 255),
+    "YELLOW": (255, 255, 0),
+    "AQUA": (0, 255, 255),
+    "MAROON": (128, 0, 0),
+    "DARKGREEN": (0, 128, 0),
+    "NAVY": (0, 0, 128),
+    "TEAL": (0, 128, 128),
+    "PURPLE": (128, 0, 128),
+    "ORANGE": (255, 128, 0),
+    "DEEP_PINK": (255, 0, 128),
+    "CYAN": (128, 255, 255),
+}
+
+def test():
+    """Test code."""
+    # Baud rate of 40000000 seems about the max
+    spi = SPI(1, baudrate=40000000, sck=Pin(14), mosi=Pin(13))
+    display = Display(spi, dc=Pin(4), cs=Pin(16), rst=Pin(17))
+
+    print('Clearing to black...')
+    start = ticks_ms()
+    display.clear()
+    end = ticks_ms()
+    print(f'Display cleared in {end - start} ms.')
+    sleep(2)
+
+    print('Clearing to white...')
+    start = ticks_ms()
+    display.clear(color565(255, 255, 255))
+    end = ticks_ms()
+    print(f'Display cleared in {end - start} ms.')
+    sleep(2)
+
+    for hlines, (color, rgb) in zip(valid_hlines, colors.items()):
+        gc.collect()
+        print(f'Clearing display to {color}, hlines={hlines}')
+        try:
+            start = ticks_ms()
+            display.clear(hlines=hlines, color=color565(*rgb))
+            end = ticks_ms()
+            print(f'Display cleared in {end - start} ms.')
+        except Exception as e:
+            print(e)
+        sleep(1)
+
+    sleep(5)
+    display.cleanup()
+
+
+test()
diff --git a/ili9341.py b/ili9341.py
index e9a504d..b81dd37 100644
--- a/ili9341.py
+++ b/ili9341.py
@@ -182,21 +182,31 @@ class Display(object):
         self.spi.deinit()
         print('display off')
 
-    def clear(self, color=0):
+    def clear(self, color=0, hlines=8):
         """Clear display.
 
         Args:
             color (Optional int): RGB565 color value (Default: 0 = Black).
+            hlines (Optional int): # of horizontal lines per chunk (Default: 8)
+        Note:
+            hlines was introduced to deal with memory allocation on some
+            boards.  Smaller values allocate less memory but take longer
+            to execute.  hlines must be a factor of the display height.
+            For example, for a 240 pixel height, valid values for hline
+            would be 1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160.
+            Higher values may result in memory allocation errors.
         """
         w = self.width
         h = self.height
-        # Clear display in 1024 byte blocks
+        assert hlines > 0 and h % hlines == 0, (
+            "hlines must be a non-zero factor of height.")
+        # Clear display
         if color:
-            line = color.to_bytes(2, 'big') * (w * 8)
+            line = color.to_bytes(2, 'big') * (w * hlines)
         else:
-            line = bytearray(w * 16)
-        for y in range(0, h, 8):
-            self.block(0, y, w - 1, y + 7, line)
+            line = bytearray(w * 2 * hlines)
+        for y in range(0, h, hlines):
+            self.block(0, y, w - 1, y + hlines - 1, line)
 
     def display_off(self):
         """Turn display off."""