knobs/knob1.py

   1 #!/usr/bin/env python
   2
   3 import cairo
   4 from math import pi, cos, sin
   5
   6 WIDTH, HEIGHT = 20, 20
   7 background = "knob1_bg.png"
   8 output = "knob1.png"
   9 x, y = WIDTH / 2, HEIGHT / 2
  10 lwidth = WIDTH / 10
  11 radius = WIDTH / 2 - lwidth
  12 radiusplus = radius + lwidth / 2
  13 radiusminus = radius - lwidth / 2
  14 radiusminus2 = radius - lwidth
  15 radiusminus3 = radius - lwidth * 3 / 2
  16 radiusint = (radius - lwidth / 2) * 0.25
  17 value = 0.7
  18 arrow = WIDTH / 10
  19 phases = 65
  20
  21 # Setup Cairo
  22 surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, phases * WIDTH, HEIGHT * 4)
  23 ctx = cairo.Context(surface)
  24 ctx.set_source_rgba(0.75, 0.75, 0.75, 0)
  25 ctx.rectangle(0, 0, phases * WIDTH, 4 * HEIGHT)
  26 ctx.fill()
  27
  28 for variant in range(0, 4):
  29     x = WIDTH / 2
  30     y = HEIGHT * (variant + 0.5)
  31     for phase in range(0, phases):
  32         # Draw background image
  33         bgimage = cairo.ImageSurface.create_from_png(background)
  34         ctx.set_source_surface(bgimage, x - WIDTH / 2, y - HEIGHT / 2);
  35         ctx.rectangle(phase * WIDTH, variant * HEIGHT, WIDTH, HEIGHT)
  36         ctx.fill ();
  37
  38         # Draw out the triangle using absolute coordinates
  39         value = phase * 1.0 / (phases - 1)
  40         if variant != 3:
  41             sangle = (180 - 45)*pi/180
  42             eangle = (360 + 45)*pi/180
  43             nleds = 31
  44         else:
  45             sangle = (270)*pi/180
  46             eangle = (270 + 360)*pi/180
  47             nleds = 32
  48         vangle = sangle + value * (eangle - sangle)
  49         c, s = cos(vangle), sin(vangle)
  50
  51         midled = (nleds - 1) / 2
  52         midphase = (phases - 1) / 2
  53         thresholdP = midled + 1 + ((phase - midphase - 1) * 1.0 * (nleds - midled - 2) / (phases - midphase - 2))
  54         thresholdN = midled - 1 - ((midphase - 1 - phase) * 1.0 * (nleds - midled - 2) / (midphase - 1))
  55
  56         spacing = pi / nleds
  57         for led in range(0, nleds):
  58             if variant == 3:
  59                 adelta = (eangle - sangle) / (nleds)
  60             else:
  61                 adelta = (eangle - sangle - spacing) / (nleds - 1)
  62             lit = False
  63             glowlit = False
  64             glowval = 0.5
  65             hilite = False
  66             lvalue = led * 1.0 / (nleds - 1)
  67             pvalue = phase * 1.0 / (phases - 1)
  68             if variant == 3:
  69                 # XXXKF works only for phases = 2 * leds
  70                 exled = phase / 2.0
  71                 lit = led == exled or (phase == phases - 1 and led == 0)
  72                 glowlit = led == (exled + 0.5) or led == (exled - 0.5)
  73                 glowval = 0.8
  74                 hilite = (phase % ((phases - 1) / 4)) == 0
  75             if variant == 0: lit = (pvalue == 1.0) or pvalue > lvalue
  76             if variant == 1:
  77                 if led == midled:
  78                     lit = (phase == midphase)
  79                     #glowlit = (phase < midphase and thresholdN >= midled - 1) or (phase > midphase and thresholdP <= midled + 1)
  80                     glowlit = False
  81                     hilite = True
  82                 elif led > midled and phase > midphase:
  83                     # led = [midled + 1, nleds - 1]
  84                     # phase = [midphase + 1, phases - 1]
  85                     lit = led <= thresholdP
  86                     glowlit = led <= thresholdP + 1
  87                     glowval = 0.4
  88                 elif led < midled and phase < midphase:
  89                     lit = led >= thresholdN
  90                     glowlit = led >= thresholdN - 1
  91                     glowval = 0.4
  92                 else:
  93                     lit = False
  94             if variant == 2: lit = pvalue == 0 or pvalue < lvalue
  95             if not lit:
  96                 if not glowlit:
  97                     ctx.set_source_rgb(0.0, 0.1, 0.1)
  98                 else:
  99                     ctx.set_source_rgb(0.0 * glowval, 0.75 * glowval, 1.0 * glowval)
 100             else:
 101                 if hilite:
 102                     ctx.set_source_rgb(0.3, 1.0, 1.0)
 103                 else:
 104                     ctx.set_source_rgb(0.0, 0.75, 1.0)
 105             ctx.set_line_width(2)
 106             if hilite:
 107                 ctx.set_line_width(3)
 108             ctx.arc(x, y, radius, sangle + adelta * led, sangle + adelta * led + spacing)
 109             ctx.stroke()
 110
 111         ctx.set_source_rgba(0, 0, 0, 1)
 112         ctx.set_line_width(1.5)
 113         mtx = ctx.get_matrix()
 114         ctx.translate(x + radiusminus2 * c, y + radiusminus2 * s)
 115         ctx.rotate(vangle)
 116         ctx.move_to(0, 0)
 117         ctx.line_to(-radius/5, 0)
 118         ctx.stroke()
 119         ctx.set_matrix(mtx)
 120         x += WIDTH
 121
 122 # Output a PNG file
 123 surface.write_to_png(output)