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""" Defines the Label class.
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from __future__ import with_statement
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# Major library imports
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from math import cos, sin, pi
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from numpy import array, dot
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# Enthought library imports
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from enthought.enable.api import black_color_trait, transparent_color_trait
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from enthought.kiva.traits.kiva_font_trait import KivaFont
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from enthought.traits.api import Any, Bool, Enum, Float, HasTraits, Int, \
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List, Str, on_trait_change
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class Label(HasTraits):
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""" A label used by overlays.
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Label is not a Component; it's just an object encapsulating text settings
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and appearance attributes. It can be used by components that need text
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labels to store state, perform layout, and render the text.
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# The anchor point is the position on the label that is placed at the
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# label's position. The label is also rotated relative to this point.
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# "Left" refers to the left edge of the text's bounding box (including
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# margin), while "center" refers to the horizontal and vertical center
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# of the bounding box.
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# TODO: Implement this and test thoroughly
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#anchor = Enum("left", "right", "top", "bottom", "center",
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# "top left", "top right", "bottom left", "bottom right")
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# The label text. Carriage returns (\n) are always connverted into
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# The angle of rotation of the label.
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rotate_angle = Float(0)
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# The color of the label text.
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color = black_color_trait
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# The background color of the label.
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bgcolor = transparent_color_trait
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# The width of the label border. If it is 0, then it is not shown.
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# The color of the border.
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border_color = black_color_trait
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# Whether or not the border is visible
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border_visible = Bool(True)
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# The font of the label text.
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font = KivaFont("modern 10")
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# Number of pixels of margin around the label, for both X and Y dimensions.
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# Number of pixels of spacing between lines of text.
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#------------------------------------------------------------------------
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#------------------------------------------------------------------------
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_bounding_box = List()
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_position_cache_valid = Bool(False)
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def __init__(self, **traits):
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HasTraits.__init__(self, **traits)
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self._bounding_box = [0,0]
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def _calc_line_positions(self, gc):
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if not self._position_cache_valid:
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gc.set_font(self.font)
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# The bottommost line starts at postion (0,0).
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self._bounding_box = [0,0]
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prev_y_height = -self.line_spacing
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for line in self.text.split("\n")[::-1]:
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(width, height, descent, leading) = gc.get_full_text_extent(line)
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ascent = height - abs(descent)
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new_y_pos = prev_y_pos + prev_y_height + self.line_spacing
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# For blank lines, we use the height of the previous line, if there
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# is one. The width is 0.
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if prev_y_height != -self.line_spacing:
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new_y_pos = prev_y_pos + prev_y_height + self.line_spacing
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ascent = prev_y_height
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new_y_pos = prev_y_pos
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x_pos.append(-leading + margin)
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y_pos.append(new_y_pos)
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prev_y_pos = new_y_pos
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prev_y_height = ascent
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self._line_xpos = x_pos[::-1]
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self._line_ypos = y_pos[::-1]
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border_width = self.border_width if self.border_visible else 0
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self._bounding_box[0] = max_width + 2*margin + 2*border_width
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self._bounding_box[1] = prev_y_pos + prev_y_height + margin + 2*border_width
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self._position_cache_valid = True
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def get_width_height(self, gc):
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""" Returns the width and height of the label, in the rotated frame of
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self._calc_line_positions(gc)
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width, height = self._bounding_box
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def get_bounding_box(self, gc):
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""" Returns a rectangular bounding box for the Label as (width,height).
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width, height = self.get_width_height(gc)
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if self.rotate_angle in (90.0, 270.0):
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return (height, width)
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elif self.rotate_angle in (0.0, 180.0):
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return (width, height)
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angle = self.rotate_angle
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return (abs(width*cos(angle))+abs(height*sin(angle)),
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abs(height*sin(angle))+abs(width*cos(angle)))
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def get_bounding_poly(self, gc):
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Returns a list [(x0,y0), (x1,y1),...] of tuples representing a polygon
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that bounds the label.
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width, height = self.get_width_height(gc)
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offset = array(self.get_bounding_box(gc))/2.
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# unrotated points relative to centre
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array([[-width/2.], [-height/2.]]),
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array([[-width/2.], [height/2.]]),
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array([[width/2.], [height/2.]]),
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array([[width/2.], [-height/2.]]),
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array([[-width/2.], [-height/2.]]),
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# rotate about centre, and offset to bounding box coords
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points = [dot(self.get_rotation_matrix(), point).transpose()[0]+offset
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for point in base_points]
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def get_rotation_matrix(self):
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return array([[cos(self.rotate_angle), -sin(self.rotate_angle)],
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[sin(self.rotate_angle), cos(self.rotate_angle)]])
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This method assumes the graphics context has been translated to the
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correct position such that the origin is at the lower left-hand corner
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of this text label's box.
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# For this version we're not supporting rotated text.
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self._calc_line_positions(gc)
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bb_width, bb_height = self.get_bounding_box(gc)
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# Rotate label about center of bounding box
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width, height = self._bounding_box
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gc.translate_ctm(bb_width/2.0, bb_height/2.0)
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gc.rotate_ctm(pi/180.0*self.rotate_angle)
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gc.translate_ctm(-width/2.0, -height/2.0)
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# Draw border and fill background
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if self.bgcolor != "transparent":
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gc.set_fill_color(self.bgcolor_)
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gc.rect(0, 0, width, height)
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if self.border_visible and self.border_width > 0:
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gc.set_stroke_color(self.border_color_)
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gc.set_line_width(self.border_width)
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border_offset = (self.border_width-1)/2.0
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gc.rect(border_offset, border_offset, width-2*border_offset, height-2*border_offset)
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gc.set_fill_color(self.color_)
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gc.set_stroke_color(self.color_)
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gc.set_font(self.font)
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if self.font.size<=8.0:
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lines = self.text.split("\n")
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if self.border_visible:
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gc.translate_ctm(self.border_width, self.border_width)
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width, height = self.get_width_height(gc)
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for i, line in enumerate(lines):
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x_offset = round(self._line_xpos[i])
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y_offset = round(self._line_ypos[i])
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gc.set_text_position(x_offset, y_offset)
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@on_trait_change("font,margin,text,rotate_angle")
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def _invalidate_position_cache(self):
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self._position_cache_valid = False
added
removed
enthought/chaco/label.py
