Wednesday, April 10, 2013

Resistor Calculator wxPython

So recently I decided to take a serious attempt at programming with using a GUI. While it has not been easy, the results are very satisfying. This program was entirely from scratch to get my feet wet, but I think my next project will be converting an already existing program to a GUI.

I chose wx over Tkinter for a couple reasons. The first was wx looks native while Tkinter looks like a Java application. Also, much like a Java application, however the windows are made with Tkinter, they have a bad habit of glitching out and making pieces illegible. The downside to wx is that it is not included with Python, however the wx packages are easy enough to get a hold of (in many different languages) and easy to install.

I'm happy with the end result, both the GUI and the code. I spent some extra time afterwards cleaning up the code, expanding variable names and commenting. This proved useful since I deleted a bunch of code that didn't do anything. Granted it's not perfect, I'm happy that overall it works.

You can check it out on my site here, or just copy/paste the source code.

#!/usr/bin/env python
# Author: Matthew DeSantis
#
# Resistor Calc

import wx

# Colors aranged by value (index=value)
COLOR = [
    'black',
    'brown',
    'red',
    'orange',
    'yellow',
    'green',
    'blue',
    'violet',
    'grey',
    'white']

# Colors because the default ones suck
COLORCODE = {
    "black":    "#000000",
    "brown":    "#a52a2a",
    "red":      "#ff0000",
    "orange":   "#ffa500",
    "yellow":   "#ffff00",
    "green":    "#008000",
    "blue":     "#0000ff",
    "violet":   "#800080",
    "grey":     "#808080",
    "white":    "#ffffff",
    "silver":   "#c0c0c0",
    "gold":     "#d4a017"}

# Multipliers in a dictionary, organized by value for ease of reading
MULTIPLIER = {
    1e-2:   'silver',
    1e-1:   'gold',
    1e0:    'black',
    1e1:    'brown',
    1e2:    'red',
    1e3:    'orange',
    1e4:    'yellow',
    1e5:    'green',
    1e6:    'blue',
    1e7:    'violet',}

# Converts a number to a list of resistor colors of equivalent value
def getColors(num):
    # To-be return value
    returnVals = []
    failReturnVals = [COLOR[0], COLOR[0], MULTIPLIER[1e0]]
    # Process the number
    indexPlaceholder = 0
    numStr = str(num)
    bandValues = ""

    # For anything smaller than 0
    if num < 1 and num >= 0.01:
        while indexPlaceholder < len(numStr):
            # Discard leading 0's and decimal
            if numStr[indexPlaceholder] == "0" or numStr[indexPlaceholder] == ".":
                indexPlaceholder += 1
            else:
                break

        # It's all zeroes, time to leave
        else:
            return failReturnVals

        bandValues = numStr[indexPlaceholder:]

        # Short a value, needs a black band
        if len(bandValues) < 2:
            bandValues = bandValues + "0"

        # Ready return color values
        before = True

        for value in bandValues:
            if len(returnVals) < 2:
                returnVals.append(COLOR[int(value)])
            elif value != "0":
                ret.append(COLOR[int(value)])
            else:
                break

    # And everything else
    elif num >= 1 and num <= 9990000000:
        indexPlaceholder = 2
        bandValues = numStr[:indexPlaceholder]

        # If there's 4 stripes
        if (num / float(bandValues)) % 10:
            indexPlaceholder = 3
            bandValues = numStr[:indexPlaceholder]

        # If there's a third band to add
        if len(numStr) > indexPlaceholder:
            if numStr[indexPlaceholder] != "0":
                bandValues = numStr[:indexPlaceholder + 1]

        # Needs another black band
        if len(bandValues) < 2:
            bandValues = bandValues + "0"

        for value in bandValues:
            if value == ".":
                continue

            returnVals.append(COLOR[int(value)])

    # Outside the limit
    else:
        return failReturnVals

    # Get the multiplier
    returnVals.append(MULTIPLIER[round(num / float(bandValues.replace(".", "")), 2)])

    return returnVals

#List of colors to Ohms
def getOhms(colors):
    bandValues = ""
    # Key storage
    multiply = 0

    # Get the index numbers of the colors
    while len(colors) > 1:
        bandValues = bandValues + str(COLOR.index(colors.pop(0)))

    # Find the key (multiplier) based on color (no easy way to do this)
    for key, value in MULTIPLIER.items():
        if value == colors[0]:
            multiply = key
            break

    # Color value * multiplier
    return float(bandValues) * multiply

def main():
    # Initialize app
    app = wx.App()
    frame = Window(None, "Resistor Calc")
    frame.display()
    app.MainLoop()

# The GUI class setup
class Window(wx.Frame):
    def __init__(self, parent, title):
        # Initialize the frame
        super(Window, self).__init__(
            parent,
            title=title,
            style=wx.DEFAULT_FRAME_STYLE,
            size=(550, 200))

        # UI setup
        self.uiInit()
        self.evtInit()
        self.colorSet()

        # Control variables
        self.lock = False
        self.prvs = self.ohmstxt.GetValue()

    def uiInit(self):
        # Third band list (needs optional added)
        self.r3colors = COLOR[:]
        self.r3colors.insert(0, "-")

        # Fourth band has some extra as well (organize by values)
        self.r4colors = COLOR[:-2]
        self.r4colors.insert(0, "gold")
        self.r4colors.insert(0, "silver")

        # Create panel and sub panels for colored boxes
        self.panel = wx.Panel(self)

        self.pr1 = wx.Panel(self.panel)
        self.pr2 = wx.Panel(self.panel)
        self.pr3 = wx.Panel(self.panel)
        self.pr4 = wx.Panel(self.panel)

        # Initialize font
        font = wx.SystemSettings_GetFont(wx.SYS_SYSTEM_FONT)
        font.SetPointSize(12)

        # Boxes for resizing and aligning
        # 3 tall
        self.vbox = wx.BoxSizer(wx.VERTICAL)
        hbox1 = wx.BoxSizer(wx.HORIZONTAL)
        hbox2 = wx.BoxSizer(wx.HORIZONTAL)
        hbox3 = wx.BoxSizer(wx.HORIZONTAL)

        # First row
        lblohms = wx.StaticText(self.panel, label="Ohms:")
        lblohms.SetFont(font)

        self.ohmstxt = wx.TextCtrl(self.panel, value="0.0")

        # Second row
        lblcolor = wx.StaticText(self.panel, label="Colors:")
        lblcolor.SetFont(font)

        self.r1 = wx.ComboBox(
            self.panel,
            choices=COLOR,
            style=wx.CB_READONLY)

        self.r2 = wx.ComboBox(
            self.panel,
            choices=COLOR,
            style=wx.CB_READONLY)

        self.r3 = wx.ComboBox(
            self.panel,
            choices=self.r3colors,
            style=wx.CB_READONLY)

        self.r4 = wx.ComboBox(
            self.panel,
            choices=self.r4colors,
            style=wx.CB_READONLY)

        # Create first row
        hbox1.Add(lblohms, flag=wx.RIGHT, border=8)
        hbox1.Add(self.ohmstxt, proportion=1)

        # Create second row
        hbox2.AddMany([
            (lblcolor, wx.RIGHT, 8),
            (self.r1,),
            (self.r2,),
            (self.r3,),
            (self.r4,)])

        # Create third row
        hbox3.AddMany([
            (self.pr1, 1, wx.EXPAND),
            (self.pr2, 1, wx.EXPAND),
            (self.pr3, 1, wx.EXPAND),
            (self.pr4, 1, wx.EXPAND)])

        # Insert rows with padding
        self.vbox.Add(hbox1, flag=wx.EXPAND|wx.LEFT|wx.RIGHT|wx.TOP, border=10)
        self.vbox.Add((-1, 10))
        self.vbox.Add(hbox2, flag=wx.EXPAND|wx.LEFT|wx.RIGHT, border=10)
        self.vbox.Add((-1, 10))
        self.vbox.Add(hbox3, 1, flag=wx.EXPAND|wx.LEFT|wx.RIGHT, border=10)
        self.vbox.Add((-1, 10))

        # Sets everything in place on the window
        self.panel.SetSizer(self.vbox)

        # Set combobox selections (not intialized by default
        self.r1.SetSelection(0)
        self.r2.SetSelection(0)
        self.r3.SetSelection(0)
        self.r4.SetSelection(2)

    # Initialize events
    def evtInit(self):
        self.Bind(wx.EVT_COMBOBOX, self.onCBChange)
        self.Bind(wx.EVT_TEXT, self.onTextChange)

    # Combobox was changed
    def onCBChange(self, e):
        self.lock = True

        bandColors = []
        thirdBand = self.r3.GetValue()

        bandColors.append(self.r1.GetValue())
        bandColors.append(self.r2.GetValue())

        # Third band is optional, check to see if it's actually used
        if thirdBand != "-":
            bandColors.append(thirdBand)

        bandColors.append(self.r4.GetValue())

        self.ohmstxt.SetValue(str(getOhms(bandColors)))
        self.colorSet()

    # Text change
    def onTextChange(self, e):
        ohms = self.ohmstxt.GetValue()

        # This is because event fires twice for some unknown reason
        if self.lock or ohms == self.prvs:
            self.prvs = ohms
            self.lock = False
            return None

        # If no value given, default to zero
        if not ohms:
            ohms = "0"

        try:
            bandColors = getColors(float(ohms))
            self.r1.SetSelection(COLOR.index(bandColors[0]))
            self.r2.SetSelection(COLOR.index(bandColors[1]))

            # All 4 bands are present
            if len(bandColors) > 3:
                self.r3.SetSelection(self.r3colors.index(bandColors[2]))
                self.r4.SetSelection(self.r4colors.index(bandColors[3]))
            # Third band is not present
            else:
                self.r3.SetSelection(0)
                self.r4.SetSelection(self.r4colors.index(bandColors[2]))

            self.colorSet()

        # Not a valid number or possible value
        except (ValueError, KeyError):
            pass

    # Display the colors for the bands
    def colorSet(self):
        self.pr1.SetBackgroundColour(COLORCODE[self.r1.GetValue()])
        self.pr2.SetBackgroundColour(COLORCODE[self.r2.GetValue()])

        # If band 3 isn't used, don't show it
        if self.r3.GetValue() == "-":
            self.pr3.SetBackgroundColour(wx.NullColour)
        else:
            self.pr3.SetBackgroundColour(COLORCODE[self.r3.GetValue()])

        self.pr4.SetBackgroundColour(COLORCODE[self.r4.GetValue()])

    def display(self):
        self.Centre
        self.Show()

if __name__ == '__main__':
    main()

Sunday, April 7, 2013

Shared Object with GHC 7

I was hitting my face on my desk for a few hours today trying to work this out. So here's my post to hopefully save anyone else who ended up stuck on this. I made a bash script to do it all, so here's the script. Note that this makes dynamic shared objects (.so files), still trying to figure out how to do it statically.

#!/bin/bash

TMPHELP="module_init.c"
FILENAME=${1%.*}
declare -i EXITCODE

cat <<TMPHELPER > $TMPHELP
#define CAT(a,b) XCAT(a,b)
#define XCAT(a,b) a ## b
#define STR(a) XSTR(a)
#define XSTR(a) #a

#include <HsFFI.h>

extern void CAT(__stginit_, MODULE)(void);

static void library_init(void) __attribute__((constructor));
static void library_init(void) {
    /* This seems to be a no-op, but it makes the GHCRTS envvar work. */
    static char *argv[] = { STR(MODULE) ".so", 0 }, **argv_ = argv;
    static int argc = 1;

    hs_init(&argc, &argv_);
    hs_add_root(CAT(__stginit_, MODULE));
}

static void library_exit(void) __attribute__((destructor));
static void library_exit(void) {
    hs_exit();
}
TMPHELPER

ghc -O2 --make -dynamic -shared -fPIC $2 -o "${FILENAME}.so" -optl-Wl,-rpath,/usr/lib/ghc/ -lHSrts_debug-ghc7.4.1 $1 $TMPHELP  >&1

EXITCODE=$?

set -x

if [[ $EXITCODE -eq 0 ]] ; then
    rm "${FILENAME}.hi"
    rm "${FILENAME}.o"
fi

if [[ -f ${FILENAME}_stub.h ]] ; then
    rm "${FILENAME}_stub.h"
fi

rm $TMPHELP
exit $EXITCODE

I'm honestly not 100% sure how everything works, but my main goal was to create shared objects so I could use them in Python. One thing to note if you are loading a shared object into Python made with Haskell, the IO functions don't seem to display on IDLE (works fine on the terminal).

Tuesday, April 2, 2013

Arduino Wii Nunchuck on Linux

I came across a DIY project over on the website for Maker magazine to connected a Wii Nunchuck to your computer as a mouse using an Arduino board and Python. Problem was, they only made it for Windows (they also suck at Python programming, but whatever). So after quite a bit of work over the past three days, I finally got it working.

The problem is Windows is not very secure and anything running on it can really do whatever it pleases, like say move the mouse around or click on things, without much effort. Linux has a bit more to it.

I went in originally planning on using libX11.so through ctypes.cdll, but setting up an event on that was not only pure hell, I don't even know if it is possible. Plan B presented itself as Xlib. The documents are not that complete, examples seem to be scarce and I don't have much in the way of patience.

You can check everything out here, I'm going to skim over the details and then show the Python code, all commented.

First thing first, get the library for interfacing the Nunchuck here. The readme there should tell you how to use it.

Next you want to jam some wires into your Nunchuck (the jumper wires from the starter kit fit fine without breaking anything) like so and connect it to your board to the corresponding holes.


From there you want to upload the example code for the Wii Nunchuck library so we can just process the data as a string rather than a bytestream.

Now we just need to run some Python code and you get all the mouse control I could jam into the thing (two buttons, joystick and accelerometer gave me just enough room for everything a standard modern day mouse has).

#!/usr/bin/env python
import serial, sys, Xlib, Xlib.display, Xlib.ext.xtest

# This will be later on, setting it now
global d, root

# The port to which your Arduino board is connected
# Change for your system and board
port = '/dev/serial/by-id/usb-Arduino__www.arduino.cc__0043_64131383331351306291-if00'

# The baudrate of the Arduino program
baudrate = 19200

# Variables indicating the center position (no movement) of the controller
# Increase the amount of play if to sensitive, decrease if not sensitive enough
# Increase speed to cut it down, decrease to raise it (1 is the highest)
midAccelX   = 515 # Accelerometer X
midAccelY   = 590 # Accelerometer Y
midAccelZ   = 710 # Accelerometer Z (not used)
midAnalogY  = 134 # Analog Y
midAnalogX  = 127 # Analog X
tollerance  = 5   # Amount of play
accelToll   = 80  # Amout of accelerometer play
speed       = 4   # difference / speed = movement

# Generic mouse movement
def move_mouse(x,y):
    x = int((x - midAnalogX) / speed)
    y = int((midAnalogY - y) / speed)

    # Make sure it's not just white noise
    if abs(x) < tollerance:
        x = 0
    # Move in the right direction the right amount
    else:
        if x < 0:
            x += tollerance
        else:
            x -= tollerance

    # Same deal, filtering white noise
    if abs(y) < tollerance:
        y = 0
    # Move in the right direction the right amount
    else:
        if y < 0:
            y += tollerance
        else:
            y -= tollerance

    # Save the Xorg processing if we're not moving
    if x != 0 or y != 0:
        d.warp_pointer(x, y, src_window = root)
        d.flush()

# Simulated button down
def mouse_down(button):
    Xlib.ext.xtest.fake_input(d, Xlib.X.ButtonPress, button)
    d.sync()

#simulated button up
def mouse_up(button):
    Xlib.ext.xtest.fake_input(d, Xlib.X.ButtonRelease, button)
    d.sync()

def main():
    # Connect to the serial port
    try:
        ser = serial.Serial(port, baudrate)
    except Exception as err:
        sys.stderr.write(str(err) + "\n")
        return 0

    # Mouse buttons
    leftDown = False
    rightDown = False
    middleDown = False

    # While the serial port is open
    while ser.isOpen():
        # Read and process the line
        line = ser.readline()
        line = line.strip('\r\n')
        line = line.split(' ')

        # Not sane yet, nothing to see here
        if len(line) != 7:
            continue

        # Alias the info so we can make sense of the rest
        try:
            analogX = int(line[0])
            analogY = int(line[1])
            accelX  = int(line[2])
            accelY  = int(line[3])
            accelZ  = int(line[4])
            zButton = int(line[5])
            cButton = int(line[6])

        # It hiccuped, ignore and move on
        except ValueError:
            continue

        # Left Mouse Button (Z)
        # Button down, don't need to press again if it's already down
        if zButton and not leftDown:
            leftDown = True
            mouse_down(Xlib.X.Button1)
        # Release the button
        elif leftDown and not zButton:
            leftDown = False
            mouse_up(Xlib.X.Button1)

        # Gestures to map more buttons since we only have two
        # It's the C button
        if cButton:
            # Tilt right, right click
            if (not rightDown) and accelX - midAccelX > accelToll:
                rightDown = True
                mouse_down(Xlib.X.Button3)
            elif rightDown and accelX - midAccelX <= accelToll:
                rightDown = False
                mouse_up(Xlib.X.Button3)

            # Tilt left, middle click
            if (not middleDown) and midAccelX - accelX > accelToll:
                middleDown = True
                mouse_down(Xlib.X.Button2)
            elif rightDown and accelX - midAccelX <= accelToll:
                middleDown = False
                mouse_up(Xlib.X.Button2)

            # Tilt forward, scroll up
            if accelY - midAccelY > accelToll:
                mouse_down(Xlib.X.Button4)
                mouse_up(Xlib.X.Button4)
            # Tilt back, scroll down
            elif midAccelY - accelY > accelToll:
                mouse_down(Xlib.X.Button5)
                mouse_up(Xlib.X.Button5)
        # Cleanup any buttons down when gesture stops
        else:
            if rightDown:
                rightDown = False
                mouse_up(Xlib.X.Button3)

            if middleDown:
                middleDown = False
                mouse_up(Xlib.X.Button2)

        # Move the mouse
        move_mouse(analogX, analogY)

    # After the program is over, close the serial port connection
    ser.close()

if __name__ == '__main__':
    # Create display and get the root
    d = Xlib.display.Display(None)
    root = d.screen().root
    try:
        main()

    except KeyboardInterrupt:
        print ""

    except Exception as err:
        sys.stderr.write(str(err) + "\n")

    # Regardless of what happens, close the display
    finally:
        d.close()

Remember to change your port for your board and system and adjust any values to adjust to your sensitivity and any excess give or lack there of that it may have.

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