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"""Cell renderer for directed graph.
This module contains the implementation of a custom GtkCellRenderer that
draws part of the directed graph based on the lines suggested by the code
in graph.py.
Because we're shiny, we use Cairo to do this, and because we're naughty
we cheat and draw over the bits of the TreeViewColumn that are supposed to
just be for the background.
"""
__copyright__ = "Copyright 2005 Canonical Ltd."
__author__ = "Scott James Remnant <scott@ubuntu.com>"
import math
import gtk
import gobject
import pango
import cairo
class CellRendererGraph(gtk.GenericCellRenderer):
"""Cell renderer for directed graph.
Properties:
node (column, colour) tuple to draw revision node,
in_lines (start, end, colour) tuple list to draw inward lines,
out_lines (start, end, colour) tuple list to draw outward lines.
"""
columns_len = 0
__gproperties__ = {
"node": ( gobject.TYPE_PYOBJECT, "node",
"revision node instruction",
gobject.PARAM_WRITABLE
),
"in-lines": ( gobject.TYPE_PYOBJECT, "in-lines",
"instructions to draw lines into the cell",
gobject.PARAM_WRITABLE
),
"out-lines": ( gobject.TYPE_PYOBJECT, "out-lines",
"instructions to draw lines out of the cell",
gobject.PARAM_WRITABLE
),
}
def do_set_property(self, property, value):
"""Set properties from GObject properties."""
if property.name == "node":
self.node = value
elif property.name == "in-lines":
self.in_lines = value
elif property.name == "out-lines":
self.out_lines = value
else:
raise AttributeError, "no such property: '%s'" % property.name
def box_size(self, widget):
"""Calculate box size based on widget's font.
Cache this as it's probably expensive to get. It ensures that we
draw the graph at least as large as the text.
"""
try:
return self._box_size
except AttributeError:
pango_ctx = widget.get_pango_context()
font_desc = widget.get_style().font_desc
metrics = pango_ctx.get_metrics(font_desc)
ascent = pango.PIXELS(metrics.get_ascent())
descent = pango.PIXELS(metrics.get_descent())
self._box_size = ascent + descent
return self._box_size
def set_colour(self, ctx, colour, bg, fg):
"""Set the context source colour.
Picks a distinct colour based on an internal wheel; the bg
parameter provides the value that should be assigned to the 'zero'
colours and the fg parameter provides the multiplier that should be
applied to the foreground colours.
"""
mainline_color = ( 0.0, 0.0, 0.0 )
colours = [
( 1.0, 0.0, 0.0 ),
( 1.0, 1.0, 0.0 ),
( 0.0, 1.0, 0.0 ),
( 0.0, 1.0, 1.0 ),
( 0.0, 0.0, 1.0 ),
( 1.0, 0.0, 1.0 ),
]
if colour == 0:
colour_rgb = mainline_color
else:
colour_rgb = colours[colour % len(colours)]
red = (colour_rgb[0] * fg) or bg
green = (colour_rgb[1] * fg) or bg
blue = (colour_rgb[2] * fg) or bg
ctx.set_source_rgb(red, green, blue)
def on_get_size(self, widget, cell_area):
"""Return the size we need for this cell.
Each cell is drawn individually and is only as wide as it needs
to be, we let the TreeViewColumn take care of making them all
line up.
"""
box_size = self.box_size(widget) + 1
width = box_size * (self.columns_len + 1)
height = box_size
# FIXME I have no idea how to use cell_area properly
return (0, 0, width, height)
def on_render(self, window, widget, bg_area, cell_area, exp_area, flags):
"""Render an individual cell.
Draws the cell contents using cairo, taking care to clip what we
do to within the background area so we don't draw over other cells.
Note that we're a bit naughty there and should really be drawing
in the cell_area (or even the exposed area), but we explicitly don't
want any gutter.
We try and be a little clever, if the line we need to draw is going
to cross other columns we actually draw it as in the .---' style
instead of a pure diagonal ... this reduces confusion by an
incredible amount.
"""
ctx = window.cairo_create()
ctx.rectangle(bg_area.x, bg_area.y, bg_area.width, bg_area.height)
ctx.clip()
box_size = self.box_size(widget)
ctx.set_line_width(box_size / 8)
ctx.set_line_cap(cairo.LINE_CAP_ROUND)
# Draw lines into the cell
for start, end, colour in self.in_lines:
self.render_line (ctx, cell_area, box_size,
bg_area.y, bg_area.height,
start, end, colour)
# Draw lines out of the cell
for start, end, colour in self.out_lines:
self.render_line (ctx, cell_area, box_size,
bg_area.y + bg_area.height, bg_area.height,
start, end, colour)
# Draw the revision node in the right column
(column, colour) = self.node
ctx.arc(cell_area.x + box_size * column + box_size / 2,
cell_area.y + cell_area.height / 2,
box_size / 5, 0, 2 * math.pi)
self.set_colour(ctx, colour, 0.0, 0.5)
ctx.stroke_preserve()
self.set_colour(ctx, colour, 0.5, 1.0)
ctx.fill()
def render_line (self, ctx, cell_area, box_size, mid,
height, start, end, colour):
if start is None:
x = cell_area.x + box_size * end + box_size / 2
ctx.move_to(x, mid + height / 3)
ctx.line_to(x, mid + height / 3)
ctx.move_to(x, mid + height / 6)
ctx.line_to(x, mid + height / 6)
elif end is None:
x = cell_area.x + box_size * start + box_size / 2
ctx.move_to(x, mid - height / 3)
ctx.line_to(x, mid - height / 3)
ctx.move_to(x, mid - height / 6)
ctx.line_to(x, mid - height / 6)
else:
startx = cell_area.x + box_size * start + box_size / 2
endx = cell_area.x + box_size * end + box_size / 2
ctx.move_to(startx, mid - height / 2)
if start - end == 0 :
ctx.line_to(endx, mid + height / 2)
else:
ctx.curve_to(startx, mid - height / 5,
startx, mid - height / 5,
startx + (endx - startx) / 2, mid)
ctx.curve_to(endx, mid + height / 5,
endx, mid + height / 5 ,
endx, mid + height / 2)
self.set_colour(ctx, colour, 0.0, 0.65)
ctx.stroke()
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