src/pgu/gui/layout.py

   1 """document layout engine."""
   2 class Layout:
   3     """the document layout engine
   4
   5     .widgets -- elements are kept in this list.  read-only, use add to add items to it.
   6     """
   7
   8     def __init__(self,rect=None):
   9         """initialize the object with the size of the box."""
  10         self._widgets = []
  11         self.rect = rect
  12
  13     def add(self,e):
  14         """add a document element to the layout.
  15
  16         a document element may be
  17         - a tuple (w,h) if it is a whitespace element
  18         - a tuple (0,h) if it is a linebreak element
  19         - an integer -1,0,1 if it is a command to start a new block of elements that are aligned either left,center, or right.
  20         - an object with a .rect (for size) -- such as a word element
  21         - an object with a .rect (for size) and .align -- such as an image element
  22         """
  23
  24         self._widgets.append(e)
  25
  26
  27     def resize(self):
  28         """resize the layout
  29         this method recalculates the position of all document elements
  30         after they have been added to the document.  .rect.x,y will be updated for all
  31         objects.
  32         """
  33         self.init()
  34         self.widgets = []
  35         for e in self._widgets:
  36             if type(e) is tuple and e[0] != 0:
  37                 self.do_space(e)
  38             elif type(e) is tuple and e[0] == 0:
  39                 self.do_br(e[1])
  40             elif type(e) is int:
  41                 self.do_block(align=e)
  42             elif hasattr(e,'align'):
  43                 self.do_align(e)
  44             else:
  45                 self.do_item(e)
  46         self.line()
  47         self.rect.h = max(self.y,self.left_bottom,self.right_bottom)
  48
  49     def init(self):
  50         self.x,self.y = self.rect.x,self.rect.y
  51         self.left = self.rect.left
  52         self.right = self.rect.right
  53         self.left_bottom = 0
  54         self.right_bottom = 0
  55         self.y = self.rect.y
  56         self.x = self.rect.x
  57         self.h = 0
  58
  59         self.items = []
  60         self.align = -1
  61
  62     def getleft(self):
  63         if self.y > self.left_bottom:
  64             self.left = self.rect.left
  65         return self.left
  66
  67     def getright(self):
  68         if self.y > self.right_bottom:
  69             self.right = self.rect.right
  70         return self.right
  71
  72     def do_br(self,h):
  73         self.line()
  74         self.h = h
  75
  76     def do_block(self,align=-1):
  77         self.line()
  78         self.align = align
  79
  80     def do_align(self,e):
  81         align = e.align
  82         ox,oy,oh = self.x,self.y,self.h
  83         w,h = e.rect.w,e.rect.h
  84
  85         if align == 0:
  86             self.line()
  87             self.x = self.rect.left + (self.rect.width-w)/2
  88             self.fit = 0
  89         elif align == -1:
  90             self.line()
  91             self.y = max(self.left_bottom,self.y + self.h)
  92             self.h = 0
  93             self.x = self.rect.left
  94         elif align == 1:
  95             self.line()
  96             self.y = max(self.right_bottom,self.y + self.h)
  97             self.h = 0
  98             self.x = self.rect.left + (self.rect.width-w)
  99
 100         e.rect.x,e.rect.y = self.x,self.y
 101
 102         self.x = self.x + w
 103         self.y = self.y
 104
 105         if align == 0:
 106             self.h = max(self.h,h)
 107             self.y = self.y + self.h
 108             self.x = self.getleft()
 109             self.h = 0
 110         elif align == -1:
 111             self.left = self.x
 112             self.left_bottom = self.y + h
 113             self.x,self.y,self.h = ox + w,oy,oh
 114         elif align == 1:
 115             self.right = self.x - w
 116             self.right_bottom = self.y + h
 117             self.x,self.y,self.h = ox,oy,oh
 118
 119         self.widgets.append(e)
 120
 121     def do_space(self,e):
 122         w,h = e
 123         if self.x+w >= self.getright():
 124             self.line()
 125         else:
 126             self.items.append(e)
 127             self.h = max(self.h,h)
 128             self.x += w
 129
 130     def do_item(self,e):
 131         w,h = e.rect.w,e.rect.h
 132         if self.x+w >= self.getright():
 133             self.line()
 134         self.items.append(e)
 135         self.h = max(self.h,h)
 136         self.x += w
 137
 138     def line(self):
 139         x1 = self.getleft()
 140         x2 = self.getright()
 141         align = self.align
 142         y = self.y
 143
 144         if len(self.items) != 0 and type(self.items[-1]) == tuple:
 145             del self.items[-1]
 146
 147         w = 0
 148         for e in self.items:
 149             if type(e) == tuple: w += e[0]
 150             else: w += e.rect.w
 151
 152         if align == -1: x = x1
 153         elif align == 0:
 154             x = x1 + ((x2-x1)-w)/2
 155             self.fit = 0
 156         elif align == 1: x = x2 - w
 157
 158         for e in self.items:
 159             if type(e) == tuple: x += e[0]
 160             else:
 161                 e.rect.x,e.rect.y = x,y
 162                 self.widgets.append(e)
 163                 x += e.rect.w
 164
 165         self.items = []
 166         self.y = self.y + self.h
 167         self.x = self.getleft()
 168         self.h = 0
 169
 170
 171
 172 # vim: set filetype=python sts=4 sw=4 noet si :