HP Prime Programming

https://udel.edu/~mm/hp/primePython/
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Provides guidance and lessons learned for programming the HP Prime calculator, particularly focusing...
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### Call numToAvars function

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

Example of moving a number from the Python app to a variable named 'solution'.

```python
numToAvars('solution', myNumber)
```

--------------------------------

### Main Loop with Soft Menu

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

Demonstrates a main loop that draws a soft menu and handles user selection using mouse coordinates.

```python
  import hpprime as h
  def main():
    while True:
      h.eval('drawmenu("Item0", "Item1", "Item2", "Item3", "Item4", "Item5")')
      m = mousePt()   # Get user screen tap coordinates.
      b = softPick(m) # -1 if not a soft menu tap.
      if b == 0:
        doItem0()
      elif b == 1:
        doItem1()
      elif b == 2:
        doItem2()
      elif b == 3:
        doItem3()
      elif b == 4:
        doItem4()
      elif b == 5:
        doItem5()
```

--------------------------------

### uio.open

Source: https://udel.edu/~mm/hp/primePython/upython.html

Open a file and return a file object.

```APIDOC
## uio.open

### Description
Open a file and return a file object.

```

--------------------------------

### Create a pop-up menu using CHOOSE

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

This snippet demonstrates how to trigger a selection menu on the HP Prime. The variable used in the first parameter must be defined beforehand.

```Python
  import hpprime as h
  c = h.eval('X:=0;choose(X,"Title","Choice 1","Choice 2","Choice 3")')
```

--------------------------------

### uio.FileIO

Source: https://udel.edu/~mm/hp/primePython/upython.html

File object for binary file I/O.

```APIDOC
## uio.FileIO

### Description
File object for binary file I/O.

### Methods
- **close** - Close the file.
- **fileno** - Return the file descriptor.
- **flush** - Flush the file.
- **read** - Read data.
- **readinto** - Read data into a buffer.
- **readline** - Read a line.
- **readlines** - Read all lines.
- **seek** - Change file position.
- **tell** - Return current position.
- **write** - Write data.

```

--------------------------------

### uio.TextIOWrapper

Source: https://udel.edu/~mm/hp/primePython/upython.html

Text I/O wrapper for a binary file.

```APIDOC
## uio.TextIOWrapper

### Description
Text I/O wrapper for a binary file.

### Methods
- **close** - Close the wrapper.
- **fileno** - Return the file descriptor.
- **flush** - Flush the wrapper.
- **read** - Read data.
- **readinto** - Read data into a buffer.
- **readline** - Read a line.
- **readlines** - Read all lines.
- **seek** - Change position.
- **tell** - Return current position.
- **write** - Write data.

```

--------------------------------

### ustruct functions

Source: https://udel.edu/~mm/hp/primePython/upython.html

Pack and unpack binary data according to a format string.

```APIDOC
## ustruct functions

### Description
Pack and unpack binary data according to a format string.

### Functions
- **calcsize** - Return the size of the struct for a given format.
- **pack** - Pack values into a bytes object.
- **pack_into** - Pack values into a buffer at a given offset.
- **unpack** - Unpack bytes according to a format.
- **unpack_from** - Unpack from a buffer at a given offset.

```

--------------------------------

### Demo Python App for HP Prime

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

A demonstration program for an HP Prime Python app that shows how to share variables using AVars and handle user input via keyboard and touch events.

```python
import hpprime as h

def main():
  h.eval('AVars("MyVar"):=1234')
  h.eval('AVars("MyVar2"):=(3,4)')
  h.eval('AVars("MyVar3"):="Mike"')
  n=h.eval('AVars("MyVar")')
  c=h.eval('AVars("MyVar2")')
  s=h.eval('AVars("MyVar3")')
  h.eval('print') # Clear screen.
  print('n=1234 is now type %s' % str(type(n)))
  print('c=(3,4) is now type %s' % str(type(c)))
  print('s="Mike" is now type %s' % str(type(s)))
  print('Press + to end demo.')
  while True:
    h.eval('wait(0.2)') # Throttle i/o loop.

    # Retrieve mouse & keyboard events.
    b=h.eval('getkey') # Keyboard button press, -1 if none since last call.
    f1,f2=h.eval('mouse') # Finger 1, finger 2 touch data.

    if len(f1)>0: # Finger touch sensed.
      # Mouse data: [x,y,xOrig,yOrig,type].
      print('You touched (%d,%d)' % (f1[0],f1[1]), end='')
      if len(f2)>0: # Two finger touch.
        print(' and (%d,%d)' % (f2[0],f2[1]))
      else:
        print()

    if b==-1: # No button pressed.
      continue
    print('You pressed button %d' % b)
    if b==50: # + button exits demo.
      print('Slán!')
      break

main()
```

--------------------------------

### uio.StringIO

Source: https://udel.edu/~mm/hp/primePython/upython.html

In-memory text stream with read/write methods.

```APIDOC
## uio.StringIO

### Description
In-memory text stream.

### Methods
- **close** - Close the stream.
- **flush** - Flush the stream.
- **getvalue** - Return the entire contents.
- **read** - Read data.
- **readinto** - Read data into a buffer.
- **readline** - Read a line.
- **readlines** - Read all lines.
- **seek** - Change stream position.
- **write** - Write data.

```

--------------------------------

### uio.BytesIO

Source: https://udel.edu/~mm/hp/primePython/upython.html

In-memory binary stream with read/write methods.

```APIDOC
## uio.BytesIO

### Description
In-memory binary stream.

### Methods
- **close** - Close the stream.
- **flush** - Flush the stream.
- **getvalue** - Return the entire contents.
- **read** - Read data.
- **readinto** - Read data into a buffer.
- **readline** - Read a line.
- **readlines** - Read all lines.
- **seek** - Change stream position.
- **write** - Write data.

```

--------------------------------

### Display Message Box

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

Constructs and executes a PPL msgbox command using a Python string variable.

```python
  import hpprime as h
  cmd = 'msgbox("%s")' % s
  h.eval(cmd)
```

--------------------------------

### Main SPIRO function

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

The entry point function that displays a splash screen and provides a menu-driven interface for selecting different drawing modes.

```HP PPL
EXPORT SPIRO()
BEGIN
  LOCAL b,c:=0,m;
  // Display splash screen.
  RECT; // Clear screen.
  PRINT; // Clear terminal.
  WHILE 1 DO
    DRAWMENU("Clear","Inner","Outer","Maurer","Color","Exit"); // Soft menu.
    m:=mousePt; // Wait for choice.
    b:=softPick(m);
    CASE
      IF b==1 THEN RECT; END; // Clear drawing.
      IF b==2 THEN inner(c); END; // Inner.
      IF b==3 THEN outer(c); END; // Outer.
      IF b==4 THEN maurer(c); END; // Maurer.
      IF b==5 THEN c:=pen(); RECT; END; // Choose pen color.
      IF b==6 THEN PRINT;RECT;KILL; END; // Exit.
    END;
  END;
END;
```

--------------------------------

### Soft Menu Selection Logic

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

Calculates which soft button was pressed based on screen coordinates, assuming a 320x240 screen and 53x20 pixel buttons.

```python
  def softPick(pt): # pt is [x, y, xOrig, yOrig, type]
    return -1 if pt[1]<220 else pt[0]//53 # Soft button is 53x20 pixels.
```

--------------------------------

### Mouse point utility

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

Utility function to wait for and return the coordinates of a mouse click.

```HP PPL
mousePt()
BEGIN
  LOCAL m,m1;
  WHILE MOUSE(1)≥0 DO END;
  REPEAT
    m := MOUSE;
    m1 := m(1); 
  UNTIL SIZE(m1)>0;
  RETURN m1; // {x, y, xOrig, yOrig, type}
END;
```

--------------------------------

### utimeq.utimeq

Source: https://udel.edu/~mm/hp/primePython/upython.html

A time queue for scheduling events with peektime, pop, and push methods.

```APIDOC
## utimeq.utimeq

### Description
A time queue for scheduling events.

### Methods
- **peektime** - Return the time of the earliest event.
- **pop** - Remove and return the earliest event.
- **push** - Add an event to the queue.

```

--------------------------------

### Handle screen tap events with hpprime

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

These subroutines manage mouse events on the HP Prime screen. mouseClear removes old events, while mousePt waits for a screen touch.

```Python
  import hpprime as h

  def mouseClear(): # Clear out old mouse events like button bounces.
    while h.eval('mouse(1)')>=0:
      pass

  def mousePt(): # Wait forever for a screen touch.
    while True:
      h.eval('wait(0.1)') # Throttle i/o loop.
      f1,f2 = h.eval('mouse') # Touch info for fingers 1 and 2.
      if len(f1) > 0: # Got a finger touch!
        return f1,f2 # [x,y,xOrig,yOrig,type], [x,y,xOrig,yOrig,type]
```

--------------------------------

### Define a Python wrapper for PPL

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

Use this structure to wrap Python code within a PPL program, allowing the Python code to be executed via an EXPORT function.

```PPL
  #PYTHON PPLwrapper
     print('Super complicated python functions go here!')
  #END

  EXPORT myFunc()
  BEGIN
    PYTHON(PPLwrapper);
  END;
```

--------------------------------

### Pen color selection

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

Displays a menu to choose a pen color and returns the corresponding RGB value.

```HP PPL
pen()
BEGIN
  LOCAL c;
  CHOOSE(c,
    "Choose Color",
    "Black","Blue","Green","Orange","Red","Yellow");
  IF c==1 THEN RETURN RGB(0,0,0); END;
  IF c==2 THEN RETURN RGB(0,0,255); END;
  IF c==3 THEN RETURN RGB(0,255,0); END;
  IF c==4 THEN RETURN RGB(255,127,0); END;
  IF c==5 THEN RETURN RGB(255,0,0); END;
  IF c==6 THEN RETURN RGB(255,255,0); END;
END;
```

--------------------------------

### Soft button picker

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

Determines which soft button was clicked based on mouse coordinates.

```HP PPL
softPick(m)
// Determine which soft button was clicked on by user, -1 if none.
BEGIN
  LOCAL x,y;
  x:=m(1); // X coord of mouse click.
  y:=m(2); // Y coord.
  IF y<220 THEN RETURN -1; END; // Not in soft menu region.
  IF x≤52 THEN RETURN 1; END;
  IF x≤105 THEN RETURN 2; END;
  IF x≤158 THEN RETURN 3; END;
  IF x≤211 THEN RETURN 4; END;
  IF x≤264 THEN RETURN 5; END;
  RETURN 6;
END;
```

--------------------------------

### ucollections.namedtuple

Source: https://udel.edu/~mm/hp/primePython/upython.html

Factory function for creating tuple subclasses with named fields.

```APIDOC
## ucollections.namedtuple

### Description
Factory function for creating tuple subclasses with named fields.

```

--------------------------------

### uerrno constants

Source: https://udel.edu/~mm/hp/primePython/upython.html

Error code constants for common system errors.

```APIDOC
## uerrno constants

### Description
Error code constants for common system errors.

### Constants
- **EACCES** - Permission denied.
- **EADDRINUSE** - Address already in use.
- **EAGAIN** - Resource temporarily unavailable.
- **EALREADY** - Operation already in progress.
- **EBADF** - Bad file descriptor.
- **ECONNABORTED** - Connection aborted.
- **ECONNREFUSED** - Connection refused.
- **ECONNRESET** - Connection reset.
- **EEXIST** - File exists.
- **EHOSTUNREACH** - Host unreachable.
- **EINPROGRESS** - Operation in progress.
- **EINVAL** - Invalid argument.
- **EIO** - I/O error.
- **EISDIR** - Is a directory.
- **ENOBUFS** - No buffer space available.
- **ENODEV** - No such device.
- **ENOENT** - No such file or directory.
- **ENOMEM** - Out of memory.
- **ENOTCONN** - Not connected.
- **EOPNOTSUPP** - Operation not supported.
- **EPERM** - Operation not permitted.
- **ETIMEDOUT** - Operation timed out.

```

--------------------------------

### uhashlib.sha256

Source: https://udel.edu/~mm/hp/primePython/upython.html

SHA-256 hash object with digest and update methods.

```APIDOC
## uhashlib.sha256

### Description
SHA-256 hash object.

### Methods
- **digest** - Return the digest of the data hashed so far.
- **update** - Update the hash with additional data.

```

--------------------------------

### urandom functions

Source: https://udel.edu/~mm/hp/primePython/upython.html

Random number generation functions.

```APIDOC
## urandom functions

### Description
Random number generation functions.

### Functions
- **choice** - Return a random element from a sequence.
- **getrandbits** - Return a random integer with the given number of bits.
- **randint** - Return a random integer in a range.
- **random** - Return a random float in [0.0, 1.0).
- **randrange** - Return a random integer from a range.
- **seed** - Initialize the random number generator.
- **uniform** - Return a random float in a range.

```

--------------------------------

### ure functions

Source: https://udel.edu/~mm/hp/primePython/upython.html

Regular expression functions and constants.

```APIDOC
## ure functions

### Description
Regular expression functions and constants.

### Functions
- **compile** - Compile a pattern into a regex object.
- **match** - Match a pattern at the beginning of a string.
- **search** - Search for a pattern anywhere in a string.

### Constants
- **DEBUG** - Debug flag for regex compilation.

```

--------------------------------

### Define numToAvars function

Source: https://udel.edu/~mm/hp/primePython/#:~:text=Since%20official%20Prime%20documentation%20for,App%20needs%20a%20PPL%20wrapper:

Uses cas.caseval() to bypass the PPL parsing bug where exponents with plus signs cause errors in the HOME environment.

```python
import cas
def numToAvars(varName, val):
    cmd = 'AVars("%s"):=%s' % (varName, str(val))
    cas.caseval(cmd)
```

--------------------------------

### ucollections.deque

Source: https://udel.edu/~mm/hp/primePython/upython.html

A double-ended queue that supports appending and popping from both ends. Provides append and popleft methods.

```APIDOC
## ucollections.deque

### Description
A double-ended queue that supports appending and popping from both ends.

### Methods
- **append** - Add an item to the right end.
- **popleft** - Remove and return an item from the left end.

```

--------------------------------

### Maurer rose drawing function

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

Calculates and draws a Maurer rose pattern based on user-defined petals and angular steps.

```HP PPL
maurer(c)
// Calculate and draw a Maurer rose.
// See https://en.wikipedia.org/wiki/Maurer_rose
BEGIN
  LOCAL f:=1,r,t;
  LOCAL x0,y0,x1,y1;
  LOCAL a,p,s,x0p,y0p,x1p,y1p;
  INPUT({p,s},
    "Maurer Rose",
    {"p=","s="},
    {"Number of Petals", "Angular Step"});
  RECT; // Clear screen.
  LOCAL pi=3.1415928, sInc=2*pi/360;
  FOR t FROM 0 TO 2*pi+sInc STEP sInc DO
    x0:=x1; y0:=y1; // Save previous point.
    r:=SIN(p*s*t);
    x1:=r*COS(s*t);
    y1:=r*SIN(s*t);
    IF f==1 THEN // First time through loop.
      f:=0; // Never first time again.
    ELSE
      a:=(110-10); // Scale to plotting area.
      x0p:=160+x0*a; x1p:=160+x1*a; // Center figure.
      y0p:=100+y0*a; y1p:=100+y1*a;
      LINE_P(x0p,y0p,x1p,y1p,c);
    END;
  END;
  FREEZE;
END;
```

--------------------------------

### uerrno.errorcode

Source: https://udel.edu/~mm/hp/primePython/upython.html

A dictionary mapping error numbers to error names.

```APIDOC
## uerrno.errorcode

### Description
A dictionary mapping error numbers to error names.

```

--------------------------------

### ucollections.OrderedDict

Source: https://udel.edu/~mm/hp/primePython/upython.html

A dictionary subclass that remembers the order in which keys were inserted. Provides standard dictionary methods.

```APIDOC
## ucollections.OrderedDict

### Description
A dictionary subclass that remembers the order in which keys were inserted.

### Methods
- **clear** - Remove all items.
- **copy** - Return a shallow copy.
- **fromkeys** - Create a new dictionary with keys from an iterable.
- **get** - Return the value for a key, or a default if missing.
- **items** - Return a view of key-value pairs.
- **keys** - Return a view of keys.
- **pop** - Remove and return a value for a key.
- **popitem** - Remove and return the last inserted key-value pair.
- **setdefault** - Insert a key with a default value if not present.
- **update** - Update the dictionary with key-value pairs.
- **values** - Return a view of values.

```

--------------------------------

### Epitrochoid drawing function

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

Calculates and draws an epitrochoid where a small wheel rolls outside a fixed circle.

```HP PPL
outer(c)
// Calculate an epitrochoid where a small wheel rolls outside a fixed
// circle.  GUI inputs:
//   R: radius in pixels of fixed circle.
//   r: radius in pixels of rolling circle outside fixed circle.
//   d: offset in pixels of pen from center of rolling circle.
// See https://en.wikipedia.org/wiki/Epitrochoid
BEGIN
  LOCAL d,f:=1,R,r,t,tInc,tMax;
  LOCAL x0,y0,x1,y1;
  LOCAL s,x0p,y0p,x1p,y1p;
  INPUT({R,r,d},
    "Epitrochoid",
    {"R=","r=","d="},
    {"Radius (pixels) of Fixed Circle",
     "Radius (pixels) of Outer Rolling Circle",
     "Pen Distance (pixels) from Rolling Center"});
  if R==0 THEN RETURN; END;
  tMax:=CAS.lcm(R, r); // theta maximum.
  tInc:=0.1; // theta increment.
  RECT; // Clear screen.
  FOR t FROM 0 TO tMax+tInc STEP tInc DO
    x0:=x1; y0:=y1; // Save previous point.
    x1:=(R+r)*COS(t) - d*COS(((R+r)/r)*t);
    y1:=(R+r)*SIN(t) - d*SIN(((R+r)/r)*t);
    IF f==1 THEN // First time through loop.
      f:=0; // Never first time again.
    ELSE
      s:=(110-1)/(R+2*r); // Scale to plotting area.
      x0p:=160+x0*s; x1p:=160+x1*s; // Center figure.
      y0p:=110+y0*s; y1p:=110+y1*s;
      LINE_P(x0p,y0p,x1p,y1p,c);
    END;
  END;
  FREEZE;
END;
```

--------------------------------

### Hypotrochoid drawing function

Source: https://udel.edu/~mm/hp/primePython/spiro.ppl

Calculates and draws a hypotrochoid where an inner wheel rolls within a fixed outer circle.

```HP PPL
inner(c)
// Calculate a hypotrochoid where an inner wheel rolls within a fixed, outer
// wheel.  GUI inputs:
//   R: radius in pixels of fixed, larger circle.
//   r: radius in pixels of rolling, smaller circle inside fixed circle.
//   d: offset in pixels of pen from center of rolling circle.
// See https://en.wikipedia.org/wiki/Hypotrochoid
BEGIN
  LOCAL d,f:=1,R,r,t,tInc,tMax;
  LOCAL x0,y0,x1,y1;
  LOCAL s,x0p,y0p,x1p,y1p;
  INPUT({R,r,d},
    "Hypotrochoid",
    {"R=","r=","d="},
    {"Radius (pixels) of Fixed Circle",
     "Radius (pixels) of Inner Rolling Circle",
     "Pen Distance (pixels) from Rolling Center"});
  if R==0 THEN RETURN; END;
  tMax:=CAS.lcm(R, r); // theta maximum.
  tInc:=0.1; // theta increment.
  RECT; // Clear screen.
  FOR t FROM 0 TO tMax+tInc STEP tInc DO
    x0:=x1; y0:=y1; // Save previous point.
    x1:=(R-r)*COS(t) + d*COS(((R-r)/r)*t);
    y1:=(R-r)*SIN(t) - d*SIN(((R-r)/r)*t);
    IF f==1 THEN // First time through loop.
      f:=0; // Never first time again.
    ELSE
      s:=(110-1)/R; // Scale to plotting area.
      x0p:=160+x0*s; x1p:=160+x1*s; // Center figure.
      y0p:=110+y0*s; y1p:=110+y1*s;
      LINE_P(x0p,y0p,x1p,y1p,c);
    END;
  END;
  FREEZE;
END;
```
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