From f1f7e423a241c408f5adf1b2f6cf9a9e5577469b Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Fri, 5 Jan 2024 16:27:57 -0500
Subject: [PATCH] Do not redraw background on every frame

---
 py/hexagram/cluster.pyx | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/py/hexagram/cluster.pyx b/py/hexagram/cluster.pyx
index 6a64cad..6a5948e 100644
--- a/py/hexagram/cluster.pyx
+++ b/py/hexagram/cluster.pyx
@@ -114,8 +114,8 @@ class Clock(TextGauge):
         )
 
 class Cluster():
-    __slots__ = 'gauges', 'speedo', 'fuel', 'tacho', 'thermo', 'odo', \
-                'ambient', 'clock', 'shift_indicator', 'status',
+    __slots__ = '_redraw', 'bg', 'gauges', 'speedo', 'fuel', 'tacho', 'thermo', \
+                'odo', 'ambient', 'clock', 'shift_indicator', 'status',
 
     WIDTH  = 1280
     HEIGHT =  480
@@ -127,6 +127,11 @@ class Cluster():
     SECTION_HEIGHT_BOTTOM = 52
 
     def __init__(self, rpm_min: float, rpm_redline: float, rpm_max: float):
+        self._redraw = True
+        self.bg      = cairo.ImageSurface(cairo.FORMAT_ARGB32,
+                                          self.WIDTH,
+                                          self.HEIGHT)
+
         self.gauges: List[Gauge] = list()
 
         self.speedo = Speedo(self.HEIGHT / 2,
@@ -172,14 +177,14 @@ class Cluster():
         self.gauges.append(self.shift_indicator)
         self.gauges.append(self.status)
 
-    def draw_bg(self, cr: cairo.Context):
+    def _update_bg(self):
+        cr = cairo.Context(self.bg)
         cr.set_source_rgb(0.1, 0.1, 0.1)
         cr.rectangle(0, 0, self.WIDTH, self.HEIGHT)
         cr.fill()
 
-        cr.rectangle(0, 0, self.WIDTH, self.HEIGHT)
-
         pattern = HexagonPattern()
+        cr.rectangle(0, 0, self.WIDTH, self.HEIGHT)
         pattern.fill(cr)
 
         # Top dark area
@@ -207,6 +212,18 @@ class Cluster():
         for gauge in self.gauges:
             gauge.draw_bg(cr)
 
+    def draw_bg(self, cr: cairo.Context):
+        if self._redraw:
+            self._update_bg()
+            self._redraw = False
+
+        op = cr.get_operator()
+        cr.set_source_surface(self.bg, 0, 0)
+        cr.set_operator(cairo.OPERATOR_SOURCE)
+        cr.rectangle(0, 0, self.WIDTH, self.HEIGHT)
+        cr.fill()
+        cr.set_operator(op)
+
     def draw_fg(self, cr: cairo.Context):
         for gauge in self.gauges:
             gauge.draw_fg(cr)