Adam Haile edited this page Jun 24, 2017 · 2 revisions

class bibliopixel.POV

POV provides methods to control persistence of vision (POV) displays, which are built from a single, in motion, strip. It inherits from Matrix and provides a logical matrix on which to write pixel data, but then displays that data one vertical column at a time onto the strip. So the display should be built from a strip that contains a number of pixels equal to the vertical height of the desired matrix, while the width is arbitrary and dependent on time and speed. For a great example of a POV display and the usage of this class, check out the POVStick project. POV actually lives at bibliopixel.led.POV but can be accessed at bibiliopixel.POV for convenience.

__init__

(driver, povHeight, width, rotation = Rotation.ROTATE_0, vert_flip = False, masterBrightness=255)

  • driver - A driver class or list of driver classes that inherit from bibliopixel.drivers.DriverBase. See the Drivers page for more info.
  • povHeight - height (y-axis) of the POV display. In this case, this must be the actual pixel count of the attached LED strip.
  • width - logical width (x-axis) of the matrix. Because the display is actually 1 dimensional, this width only exists in memory and can be however wide the desired width of the virtual display is.
  • rotation - Amount to rotate matrix coordinate map by in order for coordinate (0,0) to be the Top-Left corner of the display. See Matrix Orientation for more details.
  • vert_flip - True to flip the matrix coordinate map on the y-axis. See Matrix Orientation for more details.
  • brightness - Default master brightness value, 0-255

All drawing methods from Matrix are available for use with POV. It does however, overwrite the normal update method. Currently none of the animation classes properly handle POV because there is no way to set how long each frame displays for. Because of this, they will simply display each vertical column as fast as possible. BasePOVAnim will likely be created in the near future to fix this. For now, the best way to use POV is to load or generate a single image and then call the update method directly, like this:

from bibliopixel.led import *
import bibliopixel.image as img
from bibliopixel.drivers.serial_driver import *
import bibliopixel.gamma as gamma

i = img.Image.open("povimage.png")

img_width = i.size[0]
totalFrameTime = img_width * col_time

print "Image Display Time: {0:.1f}s".format(totalFrameTime/1000.0)

driver = Serial(LEDTYPE.LPD8806, num = 96)

#automatically configure matrix width to image width.
#change povHeight to match your setup
led = POV(driver, povHeight = 96, width = img_width, rotation=MatrixRotation.ROTATE_0, vert_flip=True)
led.setMasterBrightness(bright)

img.showImage(led, imageObj = i, bgcolor=bgcolor)

try:
    while True:
        led.update(frameTime=totalFrameTime)
except KeyboardInterrupt:
    led.all_off()
    led.update()

update

(frameTime = None):

  • frameTime - The total time (in milliseconds) over which to display the current frame. This time will be divided by the width and each vertical column will be shown for that amount of time. This is great for dialing in the display time with the speed at which the LEDs are moving to generate the desired image size. Also, when taking a long exposure to capture the POV image, the exposure time should be set to some amount of time greater than frameTime.

Properties


All properties from Matrix are available for use with POV:

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