Pierre Raybaut's "formlayout" Python module, with some improvements

formlayout.py

# -*- coding: utf-8 -*-
"""
formlayout
==========

Module creating Qt form dialogs/layouts to edit various type of parameters


formlayout License Agreement (MIT License)
------------------------------------------

Copyright (c) 2009-2013 Pierre Raybaut

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
"""

from __future__ import print_function

# History:
# 1.0.17: (Quint's own) shows all available labels in a list
# 1.0.16: (Quint's own) named buttons
# 1.0.15: added support for multiline strings
# 1.0.14: fixed Python 3 support (regression in 1.0.13)
# 1.0.13: replaced obsolete QColorDialog.getRgba function and fixed other 
#         compatibility issues with PySide (see Issue 8 of formlayout website)
# 1.0.12: added support for Python 3
# 1.0.11: added support for PySide
# 1.0.10: added float validator: disable "OK" and "Apply" button when not valid
# 1.0.7: added support for "Apply" button
# 1.0.6: code cleaning

__version__ = '1.0.17'
__license__ = __doc__

DEBUG_FORMLAYOUT = False

import os
import sys
import datetime

STDERR = sys.stderr

_modname = os.environ.setdefault('QT_API', 'pyqt')
assert _modname in ('pyqt', 'pyside')

if os.environ['QT_API'] == 'pyqt':
    try:
        import PyQt4  # analysis:ignore
    except ImportError:
        # Switching to PySide
        os.environ['QT_API'] = _modname = 'pyside'

if os.environ['QT_API'] == 'pyqt':
    try:
        from PyQt4.QtGui import QFormLayout
    except ImportError:
        raise ImportError("formlayout requires PyQt4 4.4+ (or PySide)")
    from PyQt4.QtGui import (QWidget, QLineEdit, QComboBox, QLabel, QSpinBox,
            QIcon, QStyle, QDialogButtonBox, QHBoxLayout, QVBoxLayout, QDialog,
            QColor, QPushButton, QCheckBox, QColorDialog, QPixmap, QTabWidget,
            QApplication, QStackedWidget, QDateEdit, QDateTimeEdit, QFont,
            QFontComboBox, QFontDatabase, QGridLayout, QTextEdit,
            QDoubleValidator, QListWidget, QAbstractItemView)
    from PyQt4.QtCore import Qt, SIGNAL, SLOT, QSize
    from PyQt4.QtCore import pyqtSlot as Slot
    from PyQt4.QtCore import pyqtProperty as Property

if os.environ['QT_API'] == 'pyside':
    from PySide.QtGui import (QWidget, QLineEdit, QComboBox, QLabel, QSpinBox,
            QIcon, QStyle, QDialogButtonBox, QHBoxLayout, QVBoxLayout, QDialog,
            QColor, QPushButton, QCheckBox, QColorDialog, QPixmap, QTabWidget,
            QApplication, QStackedWidget, QDateEdit, QDateTimeEdit, QFont,
            QFontComboBox, QFontDatabase, QGridLayout, QTextEdit,
            QDoubleValidator, QFormLayout, QListWidget, QAbstractItemView)
    from PySide.QtCore import Qt, SIGNAL, SLOT, QSize, Slot, Property

class FlatList(list):
    '''There's no real difference between this and `list`, but instantiate this
    rather than a vanilla list if you want a flat-style choose-box sort of
    thing.'''
    pass

# ----+- Python 3 compatibility -+----
PY2 = sys.version[0] == '2'

if PY2:
    # Python 2
    import codecs
    def u(obj):
        """Make unicode object"""
        return codecs.unicode_escape_decode(obj)[0]
else:
    # Python 3
    def u(obj):
        """Return string as it is"""
        return obj

def is_text_string(obj):
    """Return True if `obj` is a text string, False if it is anything else,
    like binary data (Python 3) or QString (Python 2, PyQt API #1)"""
    if PY2:
        # Python 2
        return isinstance(obj, basestring)
    else:
        # Python 3
        return isinstance(obj, str)

def is_binary_string(obj):
    """Return True if `obj` is a binary string, False if it is anything else"""
    if PY2:
        # Python 2
        return isinstance(obj, str)
    else:
        # Python 3
        return isinstance(obj, bytes)

def is_string(obj):
    """Return True if `obj` is a text or binary Python string object,
    False if it is anything else, like a QString (Python 2, PyQt API #1)"""
    return is_text_string(obj) or is_binary_string(obj)

def to_text_string(obj, encoding=None):
    """Convert `obj` to (unicode) text string"""
    if PY2:
        # Python 2
        if encoding is None:
            return unicode(obj)
        else:
            return unicode(obj, encoding)
    else:
        # Python 3
        if encoding is None:
            return str(obj)
        elif isinstance(obj, str):
            # In case this function is not used properly, this could happen
            return obj
        else:
            return str(obj, encoding)


class ColorButton(QPushButton):
    """
    Color choosing push button
    """
    __pyqtSignals__ = ("colorChanged(QColor)",)
    
    def __init__(self, parent=None):
        QPushButton.__init__(self, parent)
        self.setFixedSize(20, 20)
        self.setIconSize(QSize(12, 12))
        self.connect(self, SIGNAL("clicked()"), self.choose_color)
        self._color = QColor()
    
    def choose_color(self):
        color = QColorDialog.getColor(self._color, self.parentWidget())
        if color.isValid():
            self.set_color(color)
    
    def get_color(self):
        return self._color
    
    @Slot(QColor)
    def set_color(self, color):
        if color != self._color:
            self._color = color
            self.emit(SIGNAL("colorChanged(QColor)"), self._color)
            pixmap = QPixmap(self.iconSize())
            pixmap.fill(color)
            self.setIcon(QIcon(pixmap))
    
    color = Property("QColor", get_color, set_color)


def text_to_qcolor(text):
    """
    Create a QColor from specified string
    Avoid warning from Qt when an invalid QColor is instantiated
    """
    color = QColor()
    if not is_string(text): # testing for QString (PyQt API#1)
        text = str(text)
    if not is_text_string(text):
        return color
    if text.startswith('#') and len(text)==7:
        correct = '#0123456789abcdef'
        for char in text:
            if char.lower() not in correct:
                return color
    elif text not in list(QColor.colorNames()):
        return color
    color.setNamedColor(text)
    return color


class ColorLayout(QHBoxLayout):
    """Color-specialized QLineEdit layout"""
    def __init__(self, color, parent=None):
        QHBoxLayout.__init__(self)
        assert isinstance(color, QColor)
        self.lineedit = QLineEdit(color.name(), parent)
        self.connect(self.lineedit, SIGNAL("textChanged(QString)"),
                     self.update_color)
        self.addWidget(self.lineedit)
        self.colorbtn = ColorButton(parent)
        self.colorbtn.color = color
        self.connect(self.colorbtn, SIGNAL("colorChanged(QColor)"),
                     self.update_text)
        self.addWidget(self.colorbtn)

    def update_color(self, text):
        color = text_to_qcolor(text)
        if color.isValid():
            self.colorbtn.color = color

    def update_text(self, color):
        self.lineedit.setText(color.name())
        
    def text(self):
        return self.lineedit.text()
    
    
def font_is_installed(font):
    """Check if font is installed"""
    return [fam for fam in QFontDatabase().families()
            if to_text_string(fam) == font]

def tuple_to_qfont(tup):
    """
    Create a QFont from tuple:
        (family [string], size [int], italic [bool], bold [bool])
    """
    if not isinstance(tup, tuple) or len(tup) != 4 \
       or not font_is_installed(tup[0]) \
       or not isinstance(tup[1], int) \
       or not isinstance(tup[2], bool) \
       or not isinstance(tup[3], bool):
        return None
    font = QFont()
    family, size, italic, bold = tup
    font.setFamily(family)
    font.setPointSize(size)
    font.setItalic(italic)
    font.setBold(bold)
    return font

def qfont_to_tuple(font):
    return (to_text_string(font.family()), int(font.pointSize()),
            font.italic(), font.bold())

class FontLayout(QGridLayout):
    """Font selection"""
    def __init__(self, value, parent=None):
        QGridLayout.__init__(self)
        font = tuple_to_qfont(value)
        assert font is not None
        
        # Font family
        self.family = QFontComboBox(parent)
        self.family.setCurrentFont(font)
        self.addWidget(self.family, 0, 0, 1, -1)
        
        # Font size
        self.size = QComboBox(parent)
        self.size.setEditable(True)
        sizelist = list(range(6, 12)) + list(range(12, 30, 2)) + [36, 48, 72]
        size = font.pointSize()
        if size not in sizelist:
            sizelist.append(size)
            sizelist.sort()
        self.size.addItems([str(s) for s in sizelist])
        self.size.setCurrentIndex(sizelist.index(size))
        self.addWidget(self.size, 1, 0)
        
        # Italic or not
        self.italic = QCheckBox(self.tr("Italic"), parent)
        self.italic.setChecked(font.italic())
        self.addWidget(self.italic, 1, 1)
        
        # Bold or not
        self.bold = QCheckBox(self.tr("Bold"), parent)
        self.bold.setChecked(font.bold())
        self.addWidget(self.bold, 1, 2)
        
    def get_font(self):
        font = self.family.currentFont()
        font.setItalic(self.italic.isChecked())
        font.setBold(self.bold.isChecked())
        font.setPointSize(int(self.size.currentText()))
        return qfont_to_tuple(font)


def is_edit_valid(edit):
    text = edit.text()
    state, _t = edit.validator().validate(text, 0)
    return state == QDoubleValidator.Acceptable

class FormWidget(QWidget):
    def __init__(self, data, comment="", parent=None):
        QWidget.__init__(self, parent)
        from copy import deepcopy
        self.data = deepcopy(data)
        self.widgets = []
        self.formlayout = QFormLayout(self)
        if comment:
            self.formlayout.addRow(QLabel(comment))
            self.formlayout.addRow(QLabel(" "))
        if DEBUG_FORMLAYOUT:
            print("\n"+("*"*80))
            print("DATA:", self.data)
            print("*"*80)
            print("COMMENT:", comment)
            print("*"*80)
            
    def get_dialog(self):
        """Return FormDialog instance"""
        dialog = self.parent()
        while not isinstance(dialog, QDialog):
            dialog = dialog.parent()
        return dialog

    def setup(self):
        for label, value in self.data:
            if DEBUG_FORMLAYOUT:
                print("value:", value)
            if label is None and value is None:
                # Separator: (None, None)
                self.formlayout.addRow(QLabel(" "), QLabel(" "))
                self.widgets.append(None)
                continue
            elif label is None:
                # Comment
                self.formlayout.addRow(QLabel(value))
                self.widgets.append(None)
                continue
            elif tuple_to_qfont(value) is not None:
                field = FontLayout(value, self)
            elif text_to_qcolor(value).isValid():
                field = ColorLayout(QColor(value), self)
            elif is_text_string(value):
                if '\n' in value:
                    for linesep in (os.linesep, '\n'):
                        if linesep in value:
                            value = value.replace(linesep, u("\u2029"))
                    field = QTextEdit(value, self)
                else:
                    field = QLineEdit(value, self)

            elif isinstance(value, (list, tuple)):
                flat = isinstance(value, FlatList)
                value = list(value)  # in case this is a tuple

                selindex = value.pop(0)
                field = QListWidget(self) if flat else QComboBox(self)

                if isinstance(value[0], (list, tuple)):
                    keys =  [ key for key, _val in value ]
                    value = [ val for _key, val in value ]
                else:
                    keys = value

                field.addItems(value)

                if selindex in value:
                    selindex = value.index(selindex)
                elif selindex in keys:
                    selindex = keys.index(selindex)
                elif not isinstance(selindex, int):
                    print("Warning: '%s' index is invalid (label: "\
                          "%s, value: %s)" % (selindex, label, value),
                          file=STDERR)
                    selindex = 0

                if flat:
                    field.setCurrentRow(selindex)
                else:
                    field.setCurrentIndex(selindex)

            elif isinstance(value, bool):
                field = QCheckBox(self)
                field.setCheckState(Qt.Checked if value else Qt.Unchecked)
            elif isinstance(value, float):
                field = QLineEdit(repr(value), self)
                field.setValidator(QDoubleValidator(field))
                dialog = self.get_dialog()
                dialog.register_float_field(field)
                self.connect(field, SIGNAL('textChanged(QString)'),
                             lambda text: dialog.update_buttons())
            elif isinstance(value, int):
                field = QSpinBox(self)
                field.setRange(-1e9, 1e9)
                field.setValue(value)
            elif isinstance(value, datetime.datetime):
                field = QDateTimeEdit(self)
                field.setDateTime(value)
            elif isinstance(value, datetime.date):
                field = QDateEdit(self)
                field.setDate(value)
            else:
                field = QLineEdit(repr(value), self)
            self.formlayout.addRow(label, field)
            self.widgets.append(field)
            
    def get(self):
        valuelist = []
        for index, (label, value) in enumerate(self.data):
            field = self.widgets[index]
            if label is None:
                # Separator / Comment
                continue
            elif tuple_to_qfont(value) is not None:
                value = field.get_font()
            elif is_text_string(value):
                if isinstance(field, QTextEdit):
                    value = to_text_string(field.toPlainText()
                                           ).replace(u("\u2029"), os.linesep)
                else:
                    value = to_text_string(field.text())
            elif isinstance(value, (list, tuple)):

                if isinstance(value, FlatList):
                    # TODO: multiple selections
                    index = int(field.currentRow())
                else:
                    index = int(field.currentIndex())

                if isinstance(value[0], int):
                    # Return an int index, if initialization was an int
                    # n.b. the call to pop earlier operated on a copy, so the
                    # initializing selindex is still around
                    value = index
                else:
                    value = value[index+1]
                    if isinstance(value, (list, tuple)):
                        value = value[0]
            elif isinstance(value, bool):
                value = field.checkState() == Qt.Checked
            elif isinstance(value, float):
                value = float(field.text())
            elif isinstance(value, int):
                value = int(field.value())
            elif isinstance(value, datetime.datetime):
                value = field.dateTime()
                try:
                    value = value.toPyDateTime()  # PyQt
                except AttributeError:
                    value = value.toPython()  # PySide
            elif isinstance(value, datetime.date):
                value = field.date()
                try:
                    value = value.toPyDate()  # PyQt
                except AttributeError:
                    value = value.toPython()  # PySide
            else:
                value = eval(str(field.text()))
            valuelist.append(value)
        return valuelist


class FormComboWidget(QWidget):
    def __init__(self, datalist, comment="", parent=None):
        QWidget.__init__(self, parent)
        layout = QVBoxLayout()
        self.setLayout(layout)
        self.combobox = QComboBox()
        layout.addWidget(self.combobox)
        
        self.stackwidget = QStackedWidget(self)
        layout.addWidget(self.stackwidget)
        self.connect(self.combobox, SIGNAL("currentIndexChanged(int)"),
                     self.stackwidget, SLOT("setCurrentIndex(int)"))
        
        self.widgetlist = []
        for data, title, comment in datalist:
            self.combobox.addItem(title)
            widget = FormWidget(data, comment=comment, parent=self)
            self.stackwidget.addWidget(widget)
            self.widgetlist.append(widget)
            
    def setup(self):
        for widget in self.widgetlist:
            widget.setup()

    def get(self):
        return [ widget.get() for widget in self.widgetlist]
        

class FormTabWidget(QWidget):
    def __init__(self, datalist, comment="", parent=None):
        QWidget.__init__(self, parent)
        layout = QVBoxLayout()
        self.tabwidget = QTabWidget()
        layout.addWidget(self.tabwidget)
        self.setLayout(layout)
        self.widgetlist = []
        for data, title, comment in datalist:
            if len(data[0])==3:
                widget = FormComboWidget(data, comment=comment, parent=self)
            else:
                widget = FormWidget(data, comment=comment, parent=self)
            index = self.tabwidget.addTab(widget, title)
            self.tabwidget.setTabToolTip(index, comment)
            self.widgetlist.append(widget)
            
    def setup(self):
        for widget in self.widgetlist:
            widget.setup()
            
    def get(self):
        return [ widget.get() for widget in self.widgetlist]


class FormDialog(QDialog):
    """Form Dialog"""
    def __init__(self, data, title="", comment="",
                 icon=None, parent=None, apply=None, ok="OK",
                 cancel="Cancel"):

        QDialog.__init__(self, parent)
        
        # Destroying the C++ object right after closing the dialog box,
        # otherwise it may be garbage-collected in another QThread
        # (e.g. the editor's analysis thread in Spyder), thus leading to
        # a segmentation fault on UNIX or an application crash on Windows
        self.setAttribute(Qt.WA_DeleteOnClose)

        self.apply_callback = apply
        
        # Form
        if isinstance(data[0][0], (list, tuple)):
            self.formwidget = FormTabWidget(data, comment=comment,
                                            parent=self)
        elif len(data[0])==3:
            self.formwidget = FormComboWidget(data, comment=comment,
                                              parent=self)
        else:
            self.formwidget = FormWidget(data, comment=comment, 
                                         parent=self)
        layout = QVBoxLayout()
        layout.addWidget(self.formwidget)
        
        self.float_fields = []
        self.formwidget.setup()
        
        # Button box
        self.bbox = bbox = QDialogButtonBox()
        bbox.addButton(ok, QDialogButtonBox.AcceptRole)
        if cancel:
            bbox.addButton(cancel, QDialogButtonBox.RejectRole)

        self.connect(self.formwidget, SIGNAL('update_buttons()'),
                     self.update_buttons)
        if self.apply_callback is not None:
            apply_btn = bbox.addButton(QDialogButtonBox.Apply)
            self.connect(apply_btn, SIGNAL("clicked()"), self.apply)
        self.connect(bbox, SIGNAL("accepted()"), SLOT("accept()"))
        self.connect(bbox, SIGNAL("rejected()"), SLOT("reject()"))
        layout.addWidget(bbox)

        self.setLayout(layout)
        
        self.setWindowTitle(title)
        if not isinstance(icon, QIcon):
            icon = QWidget().style().standardIcon(QStyle.SP_MessageBoxQuestion)
        self.setWindowIcon(icon)
        
    def register_float_field(self, field):
        self.float_fields.append(field)
        
    def update_buttons(self):
        valid = True
        for field in self.float_fields:
            if not is_edit_valid(field):
                valid = False
        for btn_type in (QDialogButtonBox.Ok, QDialogButtonBox.Apply):
            btn = self.bbox.button(btn_type)
            if btn is not None:
                btn.setEnabled(valid)
        
    def accept(self):
        self.data = self.formwidget.get()
        QDialog.accept(self)
        
    def reject(self):
        self.data = None
        QDialog.reject(self)
        
    def apply(self):
        self.apply_callback(self.formwidget.get())
        
    def get(self):
        """Return form result"""
        # It is import to avoid accessing Qt C++ object as it has probably
        # already been destroyed, due to the Qt.WA_DeleteOnClose attribute
        return self.data


def fedit(data, title="", comment="", icon=None, parent=None, apply=None,
        ok="OK", cancel="Cancel"):
    """
    Create form dialog and return result
    (if Cancel button is pressed, return None)
    
    data: datalist, datagroup
    title: string
    comment: string
    icon: QIcon instance
    parent: parent QWidget
    apply: apply callback (function)
    
    datalist: list/tuple of (field_name, field_value)
    datagroup: list/tuple of (datalist *or* datagroup, title, comment)
    
    -> one field for each member of a datalist
    -> one tab for each member of a top-level datagroup
    -> one page (of a multipage widget, each page can be selected with a combo
       box) for each member of a datagroup inside a datagroup
       
    Supported types for field_value:
      - int, float, str, unicode, bool
      - colors: in Qt-compatible text form, i.e. in hex format or name (red,...)
                (automatically detected from a string)
      - list/tuple:
          * the first element will be the selected index (or value)
          * the other elements can be couples (key, value) or only values
    """
    # Create a QApplication instance if no instance currently exists
    # (e.g. if the module is used directly from the interpreter)
    if QApplication.startingUp():
        _app = QApplication([])
        
    dialog = FormDialog(data, title, comment, icon, parent, apply, ok, cancel)
    if dialog.exec_():
        return dialog.get()