appypod-rattail/gen/layout.py

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'''This module contains classes used for layouting graphical elements
(fields, widgets, groups, ...).'''
# A layout defines how a given field is rendered in a given context. Several
# contexts exist:
# "view" represents a given page for a given Appy class, in read-only mode.
# "edit" represents a given page for a given Appy class, in edit mode.
# "cell" represents a cell in a table, like when we need to render a field
# value in a query result or in a reference table.
# Layout elements for a class or page ------------------------------------------
# s - The page summary, containing summarized information about the page or
# class, workflow information and object history.
# w - The widgets of the current page/class
# n - The navigation panel (inter-objects navigation)
# b - The range of buttons (intra-object navigation, save, edit, delete...)
# m - The global status message sometimes shown. If you specify this in a
# layout, ensure that you have hidden the global_statusmessage zone as
# proposed by Plone. Else, the message will appear twice.
# Layout elements for a field --------------------------------------------------
# l - "label" The field label
# d - "description" The field description (a description is always visible)
# h - "help" Help for the field (typically rendered as an icon,
# clicking on it shows a popup with online help
# v - "validation" The icon that is shown when a validation error occurs
# (typically only used on "edit" layouts)
# r - "required" The icon that specified that the field is required (if
# relevant; typically only used on "edit" layouts)
# f - "field" The field value, or input for entering a value.
# For every field of a Appy class, you can define, for every layout context,
# what field-related information will appear, and how it will be rendered.
# Variables defaultPageLayouts and defaultFieldLayouts defined below give the
# default layouts for pages and fields respectively.
#
# How to express a layout? You simply define a string that is made of the
# letters corresponding to the field elements you want to render. The order of
# elements correspond to the order into which they will be rendered.
# ------------------------------------------------------------------------------
rowDelimiters = {'-':'middle', '=':'top', '_':'bottom'}
rowDelms = ''.join(rowDelimiters.keys())
cellDelimiters = {'|': 'center', ';': 'left', '!': 'right'}
cellDelms = ''.join(cellDelimiters.keys())
macroDict = {
# Page-related elements
's': ('page', 'header'), 'w': ('page', 'widgets'),
'n': ('navigate', 'objectNavigate'), 'b': ('page', 'buttons'),
'm': ('page', 'message'),
# Field-related elements
'l': ('show', 'label'), 'd': ('show', 'description'),
'h': ('show', 'help'), 'v': ('show', 'validation'),
'r': ('show', 'required')
}
# ------------------------------------------------------------------------------
class LayoutElement:
'''Abstract base class for any layout element.'''
def get(self): return self.__dict__
class Cell(LayoutElement):
'''Represents a cell in a row in a table.'''
def __init__(self, content, align, isHeader=False):
self.align = align
self.width = None
self.content = None
self.colspan = 1
if isHeader:
self.width = content
else:
self.content = [] # The list of widgets to render in the cell
self.decodeContent(content)
def decodeContent(self, content):
digits = '' # We collect the digits that will give the colspan
for char in content:
if char.isdigit():
digits += char
else:
# It is a letter corresponding to a macro
if char in macroDict:
self.content.append(macroDict[char])
elif char == 'f':
# The exact macro to call will be known at render-time
self.content.append('?')
# Manage the colspan
if digits:
self.colspan = int(digits)
# ------------------------------------------------------------------------------
class Row(LayoutElement):
'''Represents a row in a table.'''
def __init__(self, content, valign, isHeader=False):
self.valign = valign
self.cells = []
self.decodeCells(content, isHeader)
# Compute the row length
length = 0
for cell in self.cells:
length += cell['colspan']
self.length = length
def decodeCells(self, content, isHeader):
'''Decodes the given chunk of layout string p_content containing
column-related information (if p_isHeader is True) or cell content
(if p_isHeader is False) and produces a list of Cell instances.'''
cellContent = ''
for char in content:
if char in cellDelimiters:
align = cellDelimiters[char]
self.cells.append(Cell(cellContent, align, isHeader).get())
cellContent = ''
else:
cellContent += char
# Manage the last cell if any
if cellContent:
self.cells.append(Cell(cellContent, 'left', isHeader).get())
# ------------------------------------------------------------------------------
class Table(LayoutElement):
'''Represents a table where to dispose graphical elements.'''
simpleParams = ('style', 'css_class', 'cellpadding', 'cellspacing', 'width',
'align')
derivedRepls = {'view': 'hrvd', 'cell': 'ld'}
def __init__(self, layoutString=None, style=None, css_class='',
cellpadding=0, cellspacing=0, width='100%', align='left',
other=None, derivedType=None):
if other:
# We need to create a Table instance from another Table instance,
# given in p_other. In this case, we ignore previous params.
if derivedType != None:
# We will not simply clone p_other. If p_derivedType is:
# - "view", p_derivedFrom is an "edit" layout, and we must
# create the corresponding "view" layout;
# - "cell", p_derivedFrom is a "view" layout, and we must
# create the corresponding "cell" layout;
self.layoutString = Table.deriveLayout(other.layoutString,
derivedType)
else:
self.layoutString = other.layoutString
source = 'other.'
else:
source = ''
self.layoutString = layoutString
# Initialise simple params, either from the true params, either from
# the p_other Table instance.
for param in Table.simpleParams:
exec 'self.%s = %s%s' % (param, source, param)
# The following attribute will store a special Row instance used for
# defining column properties.
self.headerRow = None
# The content rows will be stored hereafter.
self.rows = []
self.decodeRows(self.layoutString)
@staticmethod
def deriveLayout(layout, derivedType):
'''Returns a layout derived from p_layout.'''
res = layout
for letter in Table.derivedRepls[derivedType]:
res = res.replace(letter, '')
# Strip the derived layout
res = res.lstrip(rowDelms); res = res.lstrip(cellDelms)
if derivedType == 'cell':
res = res.rstrip(rowDelms); res = res.rstrip(cellDelms)
return res
def addCssClasses(self, css_class):
'''Adds a single or a group of p_css_class.'''
classes = self.css_class
if classes == None:
classes = ''
if not classes:
self.css_class = css_class
else:
self.css_class += ' ' + css_classes
# Ensures that every class appears once
self.css_class = ' '.join(set(self.css_class.split()))
def isHeaderRow(self, rowContent):
'''Determines if p_rowContent specified the table header row or a
content row.'''
# Find the first char that is a number or a letter
for char in rowContent:
if char not in cellDelimiters:
if char.isdigit(): return True
else: return False
return True
def decodeRows(self, layoutString):
'''Decodes the given p_layoutString and produces a list of Row
instances.'''
# Split the p_layoutString with the row delimiters
rowContent = ''
for char in layoutString:
if char in rowDelimiters:
valign = rowDelimiters[char]
if self.isHeaderRow(rowContent):
if not self.headerRow:
self.headerRow = Row(rowContent, valign,
isHeader=True).get()
else:
self.rows.append(Row(rowContent, valign).get())
rowContent = ''
else:
rowContent += char
# Manage the last row if any
if rowContent:
self.rows.append(Row(rowContent, 'middle').get())
def removeElement(self, elem):
'''Removes given p_elem from myself.'''
macroToRemove = macroDict[elem]
for row in self.rows:
for cell in row['cells']:
if macroToRemove in cell['content']:
cell['content'].remove(macroToRemove)
# ------------------------------------------------------------------------------
defaultPageLayouts = {
'view': Table('m;-s|-n!-w|-b|'), 'edit': Table('m;-w|-b|')}
defaultFieldLayouts = {'edit': 'lrv;f!'}
# ------------------------------------------------------------------------------