cpython/Lib/idlelib/help.py

""" help.py: Implement the Idle help menu.
Contents are subject to revision at any time, without notice.


Help => About IDLE: diplay About Idle dialog

<to be moved here from aboutDialog.py>


Help => IDLE Help: Display help.html with proper formatting.
Doc/library/idle.rst (Sphinx)=> Doc/build/html/library/idle.html
(help.copy_strip)=> Lib/idlelib/help.html

HelpParser - Parse help.html and and render to tk Text.

HelpText - Display formatted help.html.

HelpFrame - Contain text, scrollbar, and table-of-contents.
(This will be needed for display in a future tabbed window.)

HelpWindow - Display HelpFrame in a standalone window.

copy_strip - Copy idle.html to help.html, rstripping each line.

show_idlehelp - Create HelpWindow.  Called in EditorWindow.help_dialog.
"""
from html.parser import HTMLParser
from os.path import abspath, dirname, isdir, isfile, join
from tkinter import Tk, Toplevel, Frame, Text, Scrollbar, Menu, Menubutton
from tkinter import font as tkfont

use_ttk = False # until available to import
if use_ttk:
    from tkinter.ttk import Menubutton

## About IDLE ##


## IDLE Help ##

class HelpParser(HTMLParser):
    """Render help.html into a text widget.

    The overridden handle_xyz methods handle a subset of html tags.
    The supplied text should have the needed tag configurations.
    The behavior for unsupported tags, such as table, is undefined.
    """
    def __init__(self, text):
        HTMLParser.__init__(self, convert_charrefs=True)
        self.text = text         # text widget we're rendering into
        self.tags = ''           # current text tags to apply
        self.show = False        # used so we exclude page navigation
        self.hdrlink = False     # used so we don't show header links
        self.level = 0           # indentation level
        self.pre = False         # displaying preformatted text
        self.hprefix = ''        # strip e.g. '25.5' from headings
        self.nested_dl = False   # if we're in a nested <dl>
        self.simplelist = False  # simple list (no double spacing)
        self.tocid = 1           # id for table of contents entries
        self.contents = []       # map toc ids to section titles
        self.data = ''           # to record data within header tags for toc

    def indent(self, amt=1):
        self.level += amt
        self.tags = '' if self.level == 0 else 'l'+str(self.level)

    def handle_starttag(self, tag, attrs):
        "Handle starttags in help.html."
        class_ = ''
        for a, v in attrs:
            if a == 'class':
                class_ = v
        s = ''
        if tag == 'div' and class_ == 'section':
            self.show = True    # start of main content
        elif tag == 'div' and class_ == 'sphinxsidebar':
            self.show = False   # end of main content
        elif tag == 'p' and class_ != 'first':
            s = '\n\n'
        elif tag == 'span' and class_ == 'pre':
            self.tags = 'pre'
        elif tag == 'span' and class_ == 'versionmodified':
            self.tags = 'em'
        elif tag == 'em':
            self.tags = 'em'
        elif tag in ['ul', 'ol']:
            if class_.find('simple') != -1:
                s = '\n'
                self.simplelist = True
            else:
                self.simplelist = False
            self.indent()
        elif tag == 'dl':
            if self.level > 0:
                self.nested_dl = True
        elif tag == 'li':
            s = '\n* ' if self.simplelist else '\n\n* '
        elif tag == 'dt':
            s = '\n\n' if not self.nested_dl else '\n'  # avoid extra line
            self.nested_dl = False
        elif tag == 'dd':
            self.indent()
            s = '\n'
        elif tag == 'pre':
            self.pre = True
            if self.show:
                self.text.insert('end', '\n\n')
            self.tags = 'preblock'
        elif tag == 'a' and class_ == 'headerlink':
            self.hdrlink = True
        elif tag == 'h1':
            self.text.mark_set('toc'+str(self.tocid),
                            self.text.index('end-1line'))
            self.tags = tag
        elif tag in ['h2', 'h3']:
            if self.show:
                self.data = ''
                self.text.mark_set('toc'+str(self.tocid),
                                self.text.index('end-1line'))
                self.text.insert('end', '\n\n')
            self.tags = tag
        if self.show:
            self.text.insert('end', s, self.tags)

    def handle_endtag(self, tag):
        "Handle endtags in help.html."
        if tag in ['h1', 'h2', 'h3', 'span', 'em']:
            self.indent(0)  # clear tag, reset indent
            if self.show and tag in ['h1', 'h2', 'h3']:
                title = self.data
                self.contents.append(('toc'+str(self.tocid), title))
                self.tocid += 1
        elif tag == 'a':
            self.hdrlink = False
        elif tag == 'pre':
            self.pre = False
            self.tags = ''
        elif tag in ['ul', 'dd', 'ol']:
            self.indent(amt=-1)

    def handle_data(self, data):
        "Handle date segments in help.html."
        if self.show and not self.hdrlink:
            d = data if self.pre else data.replace('\n', ' ')
            if self.tags == 'h1':
                self.hprefix = d[0:d.index(' ')]
            if self.tags in ['h1', 'h2', 'h3'] and self.hprefix != '':
                if d[0:len(self.hprefix)] == self.hprefix:
                    d = d[len(self.hprefix):].strip()
                self.data += d
            self.text.insert('end', d, self.tags)


class HelpText(Text):
    "Display help.html."
    def __init__(self, parent, filename):
        "Configure tags and feed file to parser."
        Text.__init__(self, parent, wrap='word', highlightthickness=0,
                      padx=5, borderwidth=0)

        normalfont = self.findfont(['TkDefaultFont', 'arial', 'helvetica'])
        fixedfont = self.findfont(['TkFixedFont', 'monaco', 'courier'])
        self['font'] = (normalfont, 12)
        self.tag_configure('em', font=(normalfont, 12, 'italic'))
        self.tag_configure('h1', font=(normalfont, 20, 'bold'))
        self.tag_configure('h2', font=(normalfont, 18, 'bold'))
        self.tag_configure('h3', font=(normalfont, 15, 'bold'))
        self.tag_configure('pre', font=(fixedfont, 12))
        self.tag_configure('preblock', font=(fixedfont, 10), lmargin1=25,
                borderwidth=1, relief='solid', background='#eeffcc')
        self.tag_configure('l1', lmargin1=25, lmargin2=25)
        self.tag_configure('l2', lmargin1=50, lmargin2=50)
        self.tag_configure('l3', lmargin1=75, lmargin2=75)
        self.tag_configure('l4', lmargin1=100, lmargin2=100)

        self.parser = HelpParser(self)
        with open(filename, encoding='utf-8') as f:
            contents = f.read()
        self.parser.feed(contents)
        self['state'] = 'disabled'

    def findfont(self, names):
        "Return name of first font family derived from names."
        for name in names:
            if name.lower() in (x.lower() for x in tkfont.names(root=self)):
                font = tkfont.Font(name=name, exists=True, root=self)
                return font.actual()['family']
            elif name.lower() in (x.lower()
                                  for x in tkfont.families(root=self)):
                return name


class HelpFrame(Frame):
    "Display html text, scrollbar, and toc."
    def __init__(self, parent, filename):
        Frame.__init__(self, parent)
        text = HelpText(self, filename)
        self['background'] = text['background']
        scroll = Scrollbar(self, command=text.yview)
        text['yscrollcommand'] = scroll.set
        text.grid(column=1, row=0, sticky='nsew')
        scroll.grid(column=2, row=0, sticky='ns')
        self.grid_columnconfigure(1, weight=1)
        self.grid_rowconfigure(0, weight=1)
        toc = self.contents_widget(text)
        toc.grid(column=0, row=0, sticky='nw')

    def contents_widget(self, text):
        "Create table of contents."
        toc = Menubutton(self, text='TOC')
        drop = Menu(toc, tearoff=False)
        for tag, lbl in text.parser.contents:
            drop.add_command(label=lbl, command=lambda mark=tag:text.see(mark))
        toc['menu'] = drop
        return toc


class HelpWindow(Toplevel):
    "Display frame with rendered html."
    def __init__(self, parent, filename, title):
        Toplevel.__init__(self, parent)
        self.wm_title(title)
        self.protocol("WM_DELETE_WINDOW", self.destroy)
        HelpFrame(self, filename).grid(column=0, row=0, sticky='nsew')
        self.grid_columnconfigure(0, weight=1)
        self.grid_rowconfigure(0, weight=1)


def copy_strip():
    "Copy idle.html to idlelib/help.html, stripping trailing whitespace."
    src = join(abspath(dirname(dirname(dirname(__file__)))),
               'Doc', 'build', 'html', 'library', 'idle.html')
    dst = join(abspath(dirname(__file__)), 'help.html')
    with open(src, 'rb') as inn,\
         open(dst, 'wb') as out:
        for line in inn:
            out.write(line.rstrip() + b'\n')
    print('idle.html copied to help.html')

def show_idlehelp(parent):
    "Create HelpWindow; called from Idle Help event handler."
    filename = join(abspath(dirname(__file__)), 'help.html')
    if not isfile(filename):
        # try copy_strip, present message
        return
    HelpWindow(parent, filename, 'IDLE Help')

if __name__ == '__main__':
    from idlelib.idle_test.htest import run
    run(show_idlehelp)