I gots tachometer :3c

py/hexagram/tacho.py

@@ -0,0 +1,40 @@
+import enum
+import math
+import cairo
+
+from hexagram.dial import Dial
+
+class Tacho(Dial):
+    MIN_ANGLE = 232.0 * (math.pi / 180.0)
+    MAX_ANGLE = 488.0 * (math.pi / 180.0)
+
+    FONT_FACE = "Muli"
+
+    __slots__ = 'units',
+
+    def __init__(self, x: float, y: float, radius: float, max_value: float):
+        super().__init__(x, y, radius, self.MIN_ANGLE, self.MAX_ANGLE, max_value)
+
+    def draw_number(self, cr: cairo.Context, radius: float, value: float, text: str):
+        scale = value / self.max_value
+        angle = self.min_angle + ((self.max_angle - self.min_angle) * scale) - Dial.ANGLE_OFFSET
+
+        cr.set_source_rgb(1, 1, 1)
+        cr.move_to(self.x + radius * self.radius * math.cos(angle) -  8,
+                   self.y + radius * self.radius * math.sin(angle) + 15)
+
+        cr.show_text(text)
+        cr.stroke()
+
+    def draw_bg(self, cr: cairo.Context):
+        super().draw_bg(cr)
+
+        cr.select_font_face(self.FONT_FACE,
+                            cairo.FontSlant.ITALIC,
+                            cairo.FontWeight.BOLD)
+
+        cr.set_font_size(self.radius * 0.15)
+        cr.set_source_rgb(1, 1, 1)
+
+        for speed in range(0, int(self.max_value)+1, 1000):
+            self.draw_number(cr, 0.78, speed, "%d" % int(speed / 1000))