Thuban/UI/baserenderer.py

# Copyright (c) 2001, 2002, 2003, 2004 by Intevation GmbH
# Authors:
# Bernhard Herzog <[email protected]>
# Jonathan Coles <[email protected]>
# Frank Koormann <[email protected]>
#
# This program is free software under the GPL (>=v2)
# Read the file COPYING coming with Thuban for details.

"""Basic rendering logic for Thuban maps

The code in this module is completely independend of wx so that it can
be tested reasonably easily and it could make it easier to write non-wx
renderers.
"""

from __future__ import generators

__version__ = "$Revision$"
# $Source$
# $Id$

import sys
import traceback

from Thuban.Model.layer import Layer, RasterLayer
from Thuban.Model.data import SHAPETYPE_ARC, SHAPETYPE_POINT
from Thuban.Model.label import ALIGN_CENTER, ALIGN_TOP, ALIGN_BOTTOM, \
     ALIGN_LEFT, ALIGN_RIGHT

import Thuban.Model.resource

if Thuban.Model.resource.has_gdal_support():
    from gdalwarp import ProjectRasterFile


#
#       Renderer Extensions
#
# The renderer extensions provide a way to render layer types defined in
# Thuban extensions. The renderer extensions are stored as a list with
# (layer_class, draw_function) pairs. If the renderer has to draw a
# non-builtin layer type, i.e. a layer that is not a subclass of Layer
# or RasterLayer, it iterates through that list, tests whether the layer
# to be drawn is an instance of layer_class and if so calls
# draw_function with the renderer and the layer as arguments. Since
# drawing is done incrementally, the draw_function should return an
# iterable. The easiest way is to simply implement the draw_function as
# a generator and to yield in suitable places, or to return the empty
# tuple.
#
# New renderer extensions should be added with add_renderer_extension().
# If necessary the extensions list can be reset with
# init_renderer_extensions().

_renderer_extensions = []

def add_renderer_extension(layer_class, function):
    """Add a renderer extension for the layer class layer_class

    When an instance of layer_class is to be drawn by the renderer the
    renderer will call function with the renderer and the layer_class
    instance as arguments. Since drawing is done incrementally, the
    function should return an iterable. The easiest way is to simply
    implement the draw_function as a generator and to yield True in
    suitable places, or to return the empty tuple if it's not possible
    to do the rendering incrementally.
    """
    _renderer_extensions.append((layer_class, function))

def init_renderer_extensions():
    """(Re)initialize the list of renderer extensions

    Calling this function outside of the test suite is probably not
    useful.
    """
    del _renderer_extensions[:]

def proj_params_to_str(proj):
    "Build a string suitable for GDAL describing the given projection"
    str = ""
    if proj is not None:
        for p in proj.GetAllParameters():
            str += "+" + p + " "
    return str

#
#       Base Renderer
#

class BaseRenderer:

    """Basic Renderer Infrastructure for Thuban Maps

    This class can't be used directly to render because it doesn't know
    anything about real DCs such as how to create pens or brushes. That
    functionality has to be provided by derived classes. The reason for
    this is that it makes the BaseRenderer completely independend of wx
    and thus it's quite easy to write test cases for it.
    """
    # If true the render honors the visibility flag of the layers
    honor_visibility = 1

    # Transparent brushes and pens. Derived classes should define these
    # as appropriate.
    TRANSPARENT_PEN = None
    TRANSPARENT_BRUSH = None

    def __init__(self, dc, map, scale, offset, region = None,
                 resolution = 72.0, honor_visibility = None):
        """Inititalize the renderer.

        dc -- the device context to render on.

        scale, offset -- the scale factor and translation to convert
                between projected coordinates and the DC coordinates

        region -- The region to draw as a (x, y, width, height) tuple in
                  the map's coordinate system. Default is None meaning
                  to draw everything.

        resolution -- the assumed resolution of the DC. Used to convert
                absolute lengths like font sizes to DC coordinates. The
                default is 72.0. If given, this parameter must be
                provided as a keyword argument.

        honor_visibility -- boolean. If true, honor the visibility flag
                of the layers, otherwise draw all layers. If None (the
                default), use the renderer's default. If given, this
                parameter must be provided as a keyword argument.
        """
        # resolution in pixel/inch
        self.dc = dc
        self.map = map
        self.scale = scale
        self.offset = offset
        self.region = region
        if honor_visibility is not None:
            self.honor_visibility = honor_visibility
        # store the resolution in pixel/point because it's more useful
        # later.
        self.resolution = resolution / 72.0

    def tools_for_property(self, prop):
        """Return a suitable pen and brush for the property

        This method must be implemented in derived classes. The return
        value should be a tuple (pen, brush).
        """
        raise NotImplementedError

    def render_map(self):
        """Render the map onto the DC.

        Both map and DC are the ones the renderer was instantiated with.

        This method is just a front-end for render_map_incrementally
        which does all rendering in one go. It also calls the dc's
        BeginDrawing and EndDrawing methods before and after calling
        render_map_incrementally.
        """

        self.dc.BeginDrawing()
        try:
            for cont in self.render_map_incrementally():
                pass
        finally:
            self.dc.EndDrawing()

    def render_map_incrementally(self):
        """Render the map incrementally.

        Return an iterator whose next method should be called until it
        returns False. After returning False it will raise StopIteration
        so that you could also use it in a for loop (implementation
        detail: this method is implemented as a generator).

        Iterate through all layers and draw them. Layers containing
        vector data are drawn with the draw_shape_layer method, raster
        layers are drawn with draw_raster_layer. The label layer is
        drawn last with draw_label_layer.

        During execution of this method, the map is bound to self.map so
        that methods especially in derived classes have access to the
        map if necessary.
        """

        for layer in self.map.Layers():
            # if honor_visibility is true, only draw visible layers,
            # otherwise draw all layers
            if not self.honor_visibility or layer.Visible():
                if isinstance(layer, Layer):
                    for i in self.draw_shape_layer_incrementally(layer):
                        yield True
                elif isinstance(layer, RasterLayer) \
                    and Thuban.Model.resource.has_gdal_support():
                    self.draw_raster_layer(layer)
                    yield True
                else:
                    # look it up in the renderer extensions
                    for cls, func in _renderer_extensions:
                        if isinstance(layer, cls):
                            for i in func(self, layer):
                                yield True
                            break
                    else:
                        # No renderer found. Print a message about it
                        print >>sys.stderr, ("Drawing layer %r not supported"
                                             % layer)
            yield True

        self.draw_label_layer(self.map.LabelLayer())
        yield False

    def draw_shape_layer_incrementally(self, layer):
        """Draw the shape layer layer onto the map incrementally.

        This method is a generator which yields True after every 500
        shapes.
        """
        scale = self.scale
        offx, offy = self.offset

        map_proj = self.map.projection
        layer_proj = layer.projection

        brush = self.TRANSPARENT_BRUSH
        pen   = self.TRANSPARENT_PEN

        old_prop = None
        old_group = None
        lc = layer.GetClassification()
        field = layer.GetClassificationColumn()
        defaultGroup = lc.GetDefaultGroup()
        table = layer.ShapeStore().Table()

        if lc.GetNumGroups() == 0:
            # There's only the default group, so we can pretend that
            # there is no field to classifiy on which makes things
            # faster since we don't need the attribute information at
            # all.
            field = None

        # Determine which render function to use.
        useraw, draw_func, draw_func_param = self.low_level_renderer(layer)

        #
        # Iterate through all shapes that have to be drawn.
        #

        # Count the shapes drawn so that we can yield every few hundred
        # shapes
        count = 0

        # Cache the tools (pens and brushes) for the classification
        # groups. This is a mapping from the group's ids to the a tuple
        # (pen, brush)
        tool_cache = {}

        for shape in self.layer_shapes(layer):
            count += 1
            if field is None:
                group = defaultGroup
            else:
                value = table.ReadValue(shape.ShapeID(), field)
                group = lc.FindGroup(value)

            if not group.IsVisible():
                continue

            try:
                pen, brush = tool_cache[id(group)]
            except KeyError:
                pen, brush = tool_cache[id(group)] \
                             = self.tools_for_property(group.GetProperties())

            if useraw:
                data = shape.RawData()
            else:
                data = shape.Points()
            if draw_func == self.draw_point_shape:
                 draw_func(draw_func_param, data, pen, brush,
                           size = group.GetProperties().GetSize())
            else:
                 draw_func(draw_func_param, data, pen, brush)
            if count % 500 == 0:
                yield True

    def layer_shapes(self, layer):
        """Return an iterable over the shapes to be drawn from the given layer.

        The default implementation simply returns all ids in the layer.
        Override in derived classes to be more precise.
        """
        return layer.ShapeStore().AllShapes()

    def low_level_renderer(self, layer):
        """Return the low-level renderer for the layer for draw_shape_layer

        The low level renderer to be returned by this method is a tuple
        (useraw, func, param) where useraw is a boolean indicating
        whether the function uses the raw shape data, func is a callable
        object and param is passed as the first parameter to func. The
        draw_shape_layer method will call func like this:

            func(param, shapedata, pen, brush)

        where shapedata is the return value of the RawData method of the
        shape object if useraw is true or the return value of the Points
        method if it's false. pen and brush are the pen and brush to use
        to draw the shape on the dc.

        The default implementation returns one of
        self.draw_polygon_shape, self.draw_arc_shape or
        self.draw_point_shape as func and layer as param. None of the
        method use the raw shape data. Derived classes can override this
        method to return more efficient low level renderers.
        """
        shapetype = layer.ShapeType()
        if shapetype == SHAPETYPE_POINT:
            func = self.draw_point_shape
        elif shapetype == SHAPETYPE_ARC:
            func = self.draw_arc_shape
        else:
            func = self.draw_polygon_shape
        return False, func, layer

    def make_point(self, x, y):
        """Convert (x, y) to a point object.

        Derived classes must override this method.
        """
        raise NotImplementedError

    def projected_points(self, layer, points):
        """Return the projected coordinates of the points taken from layer.

        Transform all the points in the list of lists of coordinate
        pairs in points.

        The transformation applies the inverse of the layer's projection
        if any, then the map's projection if any and finally applies
        self.scale and self.offset.

        The returned list has the same structure as the one returned the
        shape's Points method.
        """
        proj = self.map.GetProjection()
        if proj is not None:
            forward = proj.Forward
        else:
            forward = None
        proj = layer.GetProjection()
        if proj is not None:
            inverse = proj.Inverse
        else:
            inverse = None
        result = []
        scale = self.scale
        offx, offy = self.offset
        make_point = self.make_point

        for part in points:
            result.append([])
            for x, y in part:
                if inverse:
                    x, y = inverse(x, y)
                if forward:
                    x, y = forward(x, y)
                result[-1].append(make_point(x * scale + offx,
                                             -y * scale + offy))
        return result

    def draw_polygon_shape(self, layer, points, pen, brush):
        """Draw a polygon shape from layer with the given brush and pen

        The shape is given by points argument which is a the return
        value of the shape's Points() method. The coordinates in the
        DC's coordinate system are determined with
        self.projected_points.

        For a description of the algorithm look in wxproj.cpp.
        """
        points = self.projected_points(layer, points)

        if brush is not self.TRANSPARENT_BRUSH:
            polygon = []
            for part in points:
                polygon.extend(part)

            # missing back vertices for correct filling.
            insert_index = len(polygon)
            for part in points[:-1]:
                polygon.insert(insert_index, part[0])

            self.dc.SetBrush(brush)
            self.dc.SetPen(self.TRANSPARENT_PEN)
            self.dc.DrawPolygon(polygon)

        if pen is not self.TRANSPARENT_PEN:
            # At last draw the boundarys of the simple polygons
            self.dc.SetBrush(self.TRANSPARENT_BRUSH)
            self.dc.SetPen(pen)
            for part in points:
                self.dc.DrawLines(part)

    def draw_arc_shape(self, layer, points, pen, brush):
        """Draw an arc shape from layer with the given brush and pen

        The shape is given by points argument which is a the return
        value of the shape's Points() method. The coordinates in the
        DC's coordinate system are determined with
        self.projected_points.
        """
        points = self.projected_points(layer, points)
        self.dc.SetBrush(brush)
        self.dc.SetPen(pen)
        for part in points:
            self.dc.DrawLines(part)

    def draw_point_shape(self, layer, points, pen, brush, size = 5):
        """Draw a point shape from layer with the given brush and pen

        The shape is given by points argument which is a the return
        value of the shape's Points() method. The coordinates in the
        DC's coordinate system are determined with
        self.projected_points.

        The point is drawn as a circle centered on the point.
        """
        points = self.projected_points(layer, points)
        if not points:
            return

        radius = int(round(self.resolution * size))
        self.dc.SetBrush(brush)
        self.dc.SetPen(pen)
        for part in points:
            for p in part:
                self.dc.DrawEllipse(p.x - radius, p.y - radius,
                                    2 * radius, 2 * radius)

    def draw_raster_layer(self, layer):
        """Draw the raster layer

        This implementation does the projection and scaling of the data
        as required by the layer's and map's projections and the scale
        and offset of the renderer and then hands the transformed data
        to self.draw_raster_data() which has to be implemented in
        derived classes.
        """
        offx, offy = self.offset
        width, height = self.dc.GetSizeTuple()

        in_proj  = proj_params_to_str(layer.GetProjection())
        out_proj = proj_params_to_str(self.map.GetProjection())

        # True  -- warp the image to the size of the whole screen
        # False -- only use the bound box of the layer (currently inaccurate)
        if True: 
        #if False: 
            pmin = [0,height]
            pmax = [width, 0]
        else:
            bb = layer.LatLongBoundingBox()
            bb = [[[bb[0], bb[1]], [bb[2], bb[3]],],]
            pmin, pmax = self.projected_points(layer, bb)[0]

        #print bb
        #print pmin, pmax

        fmin = [max(0, min(pmin[0], pmax[0])) - offx, 
                offy - min(height, max(pmin[1], pmax[1]))]

        fmax = [min(width, max(pmin[0], pmax[0])) - offx, 
                offy - max(0, min(pmin[1], pmax[1]))]

        xmin = fmin[0]/self.scale
        ymin = fmin[1]/self.scale
        xmax = fmax[0]/self.scale
        ymax = fmax[1]/self.scale

        width  = int(min(width,  round(fmax[0] - fmin[0] + 1)))
        height = int(min(height, round(fmax[1] - fmin[1] + 1)))

        try:
            options = 0
            options = options | layer.MaskType()

            project_params = (layer.GetImageFilename(), in_proj, out_proj, 
                              (xmin, ymin, xmax, ymax), "", (width, height),
                              options)

            data = (width, height, apply(ProjectRasterFile, project_params))

        except (MemoryError, IOError, AttributeError, ValueError):
            # Why does this catch AttributeError and ValueError?
            # FIXME: The exception should be communicated to the user
            # better.
            traceback.print_exc()
        else:
            self.draw_raster_data(fmin[0]+offx, offy-fmax[1], data, "RAW")
            data = None

    def draw_raster_data(self, x, y, data, format="BMP"):
        """Draw the raster image in data onto the DC with the top
        left corner at (x,y)

        The raster image data is a tuple of the form
            (width, height, (image_data, mask_data, alpha_data))
        
        holding the image width, height, image data, mask data, and alpha data.
        mask_data may be None if a mask should not be used. alpha_data may
        also be None. If both are not None mask overrides alpha. If 
        format is 'RAW' the data will be RGB values and the mask
        will be in XMB format. Otherwise, both kinds 
        of data are assumed to be in the format specified in format.

        The format parameter is a string with the name of the format.
        The following format names should be used:

          'RAW'  -- an array of RGB values (len=3*width*height)
          'BMP'  -- Windows Bitmap
          'JPEG' -- JPEG Image

        The default format is 'BMP'.

        This method has to be implemented by derived classes. The
        implementation in the derived class should try to support at
        least the formats specified above and may support more.
        """
        raise NotImplementedError

    def label_font(self):
        """Return the font object for the label layer"""
        raise NotImplementedError

    def draw_label_layer(self, layer):
        """Draw the label layer

        All labels are draw in the font returned by self.label_font().
        """
        scale = self.scale
        offx, offy = self.offset

        self.dc.SetFont(self.label_font())

        map_proj = self.map.projection
        if map_proj is not None:
            forward = map_proj.Forward
        else:
            forward = None

        for label in layer.Labels():
            x = label.x
            y = label.y
            text = label.text
            if forward:
                x, y = forward(x, y)
            x = int(round(x * scale + offx))
            y = int(round(-y * scale + offy))
            width, height = self.dc.GetTextExtent(text)
            if label.halign == ALIGN_LEFT:
                # nothing to be done
                pass
            elif label.halign == ALIGN_RIGHT:
                x = x - width
            elif label.halign == ALIGN_CENTER:
                x = x - width/2
            if label.valign == ALIGN_TOP:
                # nothing to be done
                pass
            elif label.valign == ALIGN_BOTTOM:
                y = y - height
            elif label.valign == ALIGN_CENTER:
                y = y - height/2
            self.dc.DrawText(text, x, y)
1	# Copyright (c) 2001, 2002, 2003, 2004 by Intevation GmbH
2	# Authors:
3	# Bernhard Herzog <[email protected]>
4	# Jonathan Coles <[email protected]>
5	# Frank Koormann <[email protected]>
6	#
7	# This program is free software under the GPL (>=v2)
8	# Read the file COPYING coming with Thuban for details.
9
10	"""Basic rendering logic for Thuban maps
11
12	The code in this module is completely independend of wx so that it can
13	be tested reasonably easily and it could make it easier to write non-wx
14	renderers.
15	"""
16
17	from __future__ import generators
18
19	__version__ = "$Revision$"
20	# $Source$
21	# $Id$
22
23	import sys
24	import traceback
25
26	from Thuban.Model.layer import Layer, RasterLayer
27	from Thuban.Model.data import SHAPETYPE_ARC, SHAPETYPE_POINT
28	from Thuban.Model.label import ALIGN_CENTER, ALIGN_TOP, ALIGN_BOTTOM, \
29	ALIGN_LEFT, ALIGN_RIGHT
30
31	import Thuban.Model.resource
32
33	if Thuban.Model.resource.has_gdal_support():
34	from gdalwarp import ProjectRasterFile
35
36
37	#
38	# Renderer Extensions
39	#
40	# The renderer extensions provide a way to render layer types defined in
41	# Thuban extensions. The renderer extensions are stored as a list with
42	# (layer_class, draw_function) pairs. If the renderer has to draw a
43	# non-builtin layer type, i.e. a layer that is not a subclass of Layer
44	# or RasterLayer, it iterates through that list, tests whether the layer
45	# to be drawn is an instance of layer_class and if so calls
46	# draw_function with the renderer and the layer as arguments. Since
47	# drawing is done incrementally, the draw_function should return an
48	# iterable. The easiest way is to simply implement the draw_function as
49	# a generator and to yield in suitable places, or to return the empty
50	# tuple.
51	#
52	# New renderer extensions should be added with add_renderer_extension().
53	# If necessary the extensions list can be reset with
54	# init_renderer_extensions().
55
56	_renderer_extensions = []
57
58	def add_renderer_extension(layer_class, function):
59	"""Add a renderer extension for the layer class layer_class
60
61	When an instance of layer_class is to be drawn by the renderer the
62	renderer will call function with the renderer and the layer_class
63	instance as arguments. Since drawing is done incrementally, the
64	function should return an iterable. The easiest way is to simply
65	implement the draw_function as a generator and to yield True in
66	suitable places, or to return the empty tuple if it's not possible
67	to do the rendering incrementally.
68	"""
69	_renderer_extensions.append((layer_class, function))
70
71	def init_renderer_extensions():
72	"""(Re)initialize the list of renderer extensions
73
74	Calling this function outside of the test suite is probably not
75	useful.
76	"""
77	del _renderer_extensions[:]
78
79	def proj_params_to_str(proj):
80	"Build a string suitable for GDAL describing the given projection"
81	str = ""
82	if proj is not None:
83	for p in proj.GetAllParameters():
84	str += "+" + p + " "
85	return str
86
87	#
88	# Base Renderer
89	#
90
91	class BaseRenderer:
92
93	"""Basic Renderer Infrastructure for Thuban Maps
94
95	This class can't be used directly to render because it doesn't know
96	anything about real DCs such as how to create pens or brushes. That
97	functionality has to be provided by derived classes. The reason for
98	this is that it makes the BaseRenderer completely independend of wx
99	and thus it's quite easy to write test cases for it.
100	"""
101	# If true the render honors the visibility flag of the layers
102	honor_visibility = 1
103
104	# Transparent brushes and pens. Derived classes should define these
105	# as appropriate.
106	TRANSPARENT_PEN = None
107	TRANSPARENT_BRUSH = None
108
109	def __init__(self, dc, map, scale, offset, region = None,
110	resolution = 72.0, honor_visibility = None):
111	"""Inititalize the renderer.
112
113	dc -- the device context to render on.
114
115	scale, offset -- the scale factor and translation to convert
116	between projected coordinates and the DC coordinates
117
118	region -- The region to draw as a (x, y, width, height) tuple in
119	the map's coordinate system. Default is None meaning
120	to draw everything.
121
122	resolution -- the assumed resolution of the DC. Used to convert
123	absolute lengths like font sizes to DC coordinates. The
124	default is 72.0. If given, this parameter must be
125	provided as a keyword argument.
126
127	honor_visibility -- boolean. If true, honor the visibility flag
128	of the layers, otherwise draw all layers. If None (the
129	default), use the renderer's default. If given, this
130	parameter must be provided as a keyword argument.
131	"""
132	# resolution in pixel/inch
133	self.dc = dc
134	self.map = map
135	self.scale = scale
136	self.offset = offset
137	self.region = region
138	if honor_visibility is not None:
139	self.honor_visibility = honor_visibility
140	# store the resolution in pixel/point because it's more useful
141	# later.
142	self.resolution = resolution / 72.0
143
144	def tools_for_property(self, prop):
145	"""Return a suitable pen and brush for the property
146
147	This method must be implemented in derived classes. The return
148	value should be a tuple (pen, brush).
149	"""
150	raise NotImplementedError
151
152	def render_map(self):
153	"""Render the map onto the DC.
154
155	Both map and DC are the ones the renderer was instantiated with.
156
157	This method is just a front-end for render_map_incrementally
158	which does all rendering in one go. It also calls the dc's
159	BeginDrawing and EndDrawing methods before and after calling
160	render_map_incrementally.
161	"""
162
163	self.dc.BeginDrawing()
164	try:
165	for cont in self.render_map_incrementally():
166	pass
167	finally:
168	self.dc.EndDrawing()
169
170	def render_map_incrementally(self):
171	"""Render the map incrementally.
172
173	Return an iterator whose next method should be called until it
174	returns False. After returning False it will raise StopIteration
175	so that you could also use it in a for loop (implementation
176	detail: this method is implemented as a generator).
177
178	Iterate through all layers and draw them. Layers containing
179	vector data are drawn with the draw_shape_layer method, raster
180	layers are drawn with draw_raster_layer. The label layer is
181	drawn last with draw_label_layer.
182
183	During execution of this method, the map is bound to self.map so
184	that methods especially in derived classes have access to the
185	map if necessary.
186	"""
187
188	for layer in self.map.Layers():
189	# if honor_visibility is true, only draw visible layers,
190	# otherwise draw all layers
191	if not self.honor_visibility or layer.Visible():
192	if isinstance(layer, Layer):
193	for i in self.draw_shape_layer_incrementally(layer):
194	yield True
195	elif isinstance(layer, RasterLayer) \
196	and Thuban.Model.resource.has_gdal_support():
197	self.draw_raster_layer(layer)
198	yield True
199	else:
200	# look it up in the renderer extensions
201	for cls, func in _renderer_extensions:
202	if isinstance(layer, cls):
203	for i in func(self, layer):
204	yield True
205	break
206	else:
207	# No renderer found. Print a message about it
208	print >>sys.stderr, ("Drawing layer %r not supported"
209	% layer)
210	yield True
211
212	self.draw_label_layer(self.map.LabelLayer())
213	yield False
214
215	def draw_shape_layer_incrementally(self, layer):
216	"""Draw the shape layer layer onto the map incrementally.
217
218	This method is a generator which yields True after every 500
219	shapes.
220	"""
221	scale = self.scale
222	offx, offy = self.offset
223
224	map_proj = self.map.projection
225	layer_proj = layer.projection
226
227	brush = self.TRANSPARENT_BRUSH
228	pen = self.TRANSPARENT_PEN
229
230	old_prop = None
231	old_group = None
232	lc = layer.GetClassification()
233	field = layer.GetClassificationColumn()
234	defaultGroup = lc.GetDefaultGroup()
235	table = layer.ShapeStore().Table()
236
237	if lc.GetNumGroups() == 0:
238	# There's only the default group, so we can pretend that
239	# there is no field to classifiy on which makes things
240	# faster since we don't need the attribute information at
241	# all.
242	field = None
243
244	# Determine which render function to use.
245	useraw, draw_func, draw_func_param = self.low_level_renderer(layer)
246
247	#
248	# Iterate through all shapes that have to be drawn.
249	#
250
251	# Count the shapes drawn so that we can yield every few hundred
252	# shapes
253	count = 0
254
255	# Cache the tools (pens and brushes) for the classification
256	# groups. This is a mapping from the group's ids to the a tuple
257	# (pen, brush)
258	tool_cache = {}
259
260	for shape in self.layer_shapes(layer):
261	count += 1
262	if field is None:
263	group = defaultGroup
264	else:
265	value = table.ReadValue(shape.ShapeID(), field)
266	group = lc.FindGroup(value)
267
268	if not group.IsVisible():
269	continue
270
271	try:
272	pen, brush = tool_cache[id(group)]
273	except KeyError:
274	pen, brush = tool_cache[id(group)] \
275	= self.tools_for_property(group.GetProperties())
276
277	if useraw:
278	data = shape.RawData()
279	else:
280	data = shape.Points()
281	if draw_func == self.draw_point_shape:
282	draw_func(draw_func_param, data, pen, brush,
283	size = group.GetProperties().GetSize())
284	else:
285	draw_func(draw_func_param, data, pen, brush)
286	if count % 500 == 0:
287	yield True
288
289	def layer_shapes(self, layer):
290	"""Return an iterable over the shapes to be drawn from the given layer.
291
292	The default implementation simply returns all ids in the layer.
293	Override in derived classes to be more precise.
294	"""
295	return layer.ShapeStore().AllShapes()
296
297	def low_level_renderer(self, layer):
298	"""Return the low-level renderer for the layer for draw_shape_layer
299
300	The low level renderer to be returned by this method is a tuple
301	(useraw, func, param) where useraw is a boolean indicating
302	whether the function uses the raw shape data, func is a callable
303	object and param is passed as the first parameter to func. The
304	draw_shape_layer method will call func like this:
305
306	func(param, shapedata, pen, brush)
307
308	where shapedata is the return value of the RawData method of the
309	shape object if useraw is true or the return value of the Points
310	method if it's false. pen and brush are the pen and brush to use
311	to draw the shape on the dc.
312
313	The default implementation returns one of
314	self.draw_polygon_shape, self.draw_arc_shape or
315	self.draw_point_shape as func and layer as param. None of the
316	method use the raw shape data. Derived classes can override this
317	method to return more efficient low level renderers.
318	"""
319	shapetype = layer.ShapeType()
320	if shapetype == SHAPETYPE_POINT:
321	func = self.draw_point_shape
322	elif shapetype == SHAPETYPE_ARC:
323	func = self.draw_arc_shape
324	else:
325	func = self.draw_polygon_shape
326	return False, func, layer
327
328	def make_point(self, x, y):
329	"""Convert (x, y) to a point object.
330
331	Derived classes must override this method.
332	"""
333	raise NotImplementedError
334
335	def projected_points(self, layer, points):
336	"""Return the projected coordinates of the points taken from layer.
337
338	Transform all the points in the list of lists of coordinate
339	pairs in points.
340
341	The transformation applies the inverse of the layer's projection
342	if any, then the map's projection if any and finally applies
343	self.scale and self.offset.
344
345	The returned list has the same structure as the one returned the
346	shape's Points method.
347	"""
348	proj = self.map.GetProjection()
349	if proj is not None:
350	forward = proj.Forward
351	else:
352	forward = None
353	proj = layer.GetProjection()
354	if proj is not None:
355	inverse = proj.Inverse
356	else:
357	inverse = None
358	result = []
359	scale = self.scale
360	offx, offy = self.offset
361	make_point = self.make_point
362
363	for part in points:
364	result.append([])
365	for x, y in part:
366	if inverse:
367	x, y = inverse(x, y)
368	if forward:
369	x, y = forward(x, y)
370	result[-1].append(make_point(x * scale + offx,
371	-y * scale + offy))
372	return result
373
374	def draw_polygon_shape(self, layer, points, pen, brush):
375	"""Draw a polygon shape from layer with the given brush and pen
376
377	The shape is given by points argument which is a the return
378	value of the shape's Points() method. The coordinates in the
379	DC's coordinate system are determined with
380	self.projected_points.
381
382	For a description of the algorithm look in wxproj.cpp.
383	"""
384	points = self.projected_points(layer, points)
385
386	if brush is not self.TRANSPARENT_BRUSH:
387	polygon = []
388	for part in points:
389	polygon.extend(part)
390
391	# missing back vertices for correct filling.
392	insert_index = len(polygon)
393	for part in points[:-1]:
394	polygon.insert(insert_index, part[0])
395
396	self.dc.SetBrush(brush)
397	self.dc.SetPen(self.TRANSPARENT_PEN)
398	self.dc.DrawPolygon(polygon)
399
400	if pen is not self.TRANSPARENT_PEN:
401	# At last draw the boundarys of the simple polygons
402	self.dc.SetBrush(self.TRANSPARENT_BRUSH)
403	self.dc.SetPen(pen)
404	for part in points:
405	self.dc.DrawLines(part)
406
407	def draw_arc_shape(self, layer, points, pen, brush):
408	"""Draw an arc shape from layer with the given brush and pen
409
410	The shape is given by points argument which is a the return
411	value of the shape's Points() method. The coordinates in the
412	DC's coordinate system are determined with
413	self.projected_points.
414	"""
415	points = self.projected_points(layer, points)
416	self.dc.SetBrush(brush)
417	self.dc.SetPen(pen)
418	for part in points:
419	self.dc.DrawLines(part)
420
421	def draw_point_shape(self, layer, points, pen, brush, size = 5):
422	"""Draw a point shape from layer with the given brush and pen
423
424	The shape is given by points argument which is a the return
425	value of the shape's Points() method. The coordinates in the
426	DC's coordinate system are determined with
427	self.projected_points.
428
429	The point is drawn as a circle centered on the point.
430	"""
431	points = self.projected_points(layer, points)
432	if not points:
433	return
434
435	radius = int(round(self.resolution * size))
436	self.dc.SetBrush(brush)
437	self.dc.SetPen(pen)
438	for part in points:
439	for p in part:
440	self.dc.DrawEllipse(p.x - radius, p.y - radius,
441	2 * radius, 2 * radius)
442
443	def draw_raster_layer(self, layer):
444	"""Draw the raster layer
445
446	This implementation does the projection and scaling of the data
447	as required by the layer's and map's projections and the scale
448	and offset of the renderer and then hands the transformed data
449	to self.draw_raster_data() which has to be implemented in
450	derived classes.
451	"""
452	offx, offy = self.offset
453	width, height = self.dc.GetSizeTuple()
454
455	in_proj = proj_params_to_str(layer.GetProjection())
456	out_proj = proj_params_to_str(self.map.GetProjection())
457
458	# True -- warp the image to the size of the whole screen
459	# False -- only use the bound box of the layer (currently inaccurate)
460	if True:
461	#if False:
462	pmin = [0,height]
463	pmax = [width, 0]
464	else:
465	bb = layer.LatLongBoundingBox()
466	bb = [[[bb[0], bb[1]], [bb[2], bb[3]],],]
467	pmin, pmax = self.projected_points(layer, bb)[0]
468
469	#print bb
470	#print pmin, pmax
471
472	fmin = [max(0, min(pmin[0], pmax[0])) - offx,
473	offy - min(height, max(pmin[1], pmax[1]))]
474
475	fmax = [min(width, max(pmin[0], pmax[0])) - offx,
476	offy - max(0, min(pmin[1], pmax[1]))]
477
478	xmin = fmin[0]/self.scale
479	ymin = fmin[1]/self.scale
480	xmax = fmax[0]/self.scale
481	ymax = fmax[1]/self.scale
482
483	width = int(min(width, round(fmax[0] - fmin[0] + 1)))
484	height = int(min(height, round(fmax[1] - fmin[1] + 1)))
485
486	try:
487	options = 0
488	options = options \| layer.MaskType()
489
490	project_params = (layer.GetImageFilename(), in_proj, out_proj,
491	(xmin, ymin, xmax, ymax), "", (width, height),
492	options)
493
494	data = (width, height, apply(ProjectRasterFile, project_params))
495
496	except (MemoryError, IOError, AttributeError, ValueError):
497	# Why does this catch AttributeError and ValueError?
498	# FIXME: The exception should be communicated to the user
499	# better.
500	traceback.print_exc()
501	else:
502	self.draw_raster_data(fmin[0]+offx, offy-fmax[1], data, "RAW")
503	data = None
504
505	def draw_raster_data(self, x, y, data, format="BMP"):
506	"""Draw the raster image in data onto the DC with the top
507	left corner at (x,y)
508
509	The raster image data is a tuple of the form
510	(width, height, (image_data, mask_data, alpha_data))
511
512	holding the image width, height, image data, mask data, and alpha data.
513	mask_data may be None if a mask should not be used. alpha_data may
514	also be None. If both are not None mask overrides alpha. If
515	format is 'RAW' the data will be RGB values and the mask
516	will be in XMB format. Otherwise, both kinds
517	of data are assumed to be in the format specified in format.
518
519	The format parameter is a string with the name of the format.
520	The following format names should be used:
521
522	'RAW' -- an array of RGB values (len=3widthheight)
523	'BMP' -- Windows Bitmap
524	'JPEG' -- JPEG Image
525
526	The default format is 'BMP'.
527
528	This method has to be implemented by derived classes. The
529	implementation in the derived class should try to support at
530	least the formats specified above and may support more.
531	"""
532	raise NotImplementedError
533
534	def label_font(self):
535	"""Return the font object for the label layer"""
536	raise NotImplementedError
537
538	def draw_label_layer(self, layer):
539	"""Draw the label layer
540
541	All labels are draw in the font returned by self.label_font().
542	"""
543	scale = self.scale
544	offx, offy = self.offset
545
546	self.dc.SetFont(self.label_font())
547
548	map_proj = self.map.projection
549	if map_proj is not None:
550	forward = map_proj.Forward
551	else:
552	forward = None
553
554	for label in layer.Labels():
555	x = label.x
556	y = label.y
557	text = label.text
558	if forward:
559	x, y = forward(x, y)
560	x = int(round(x * scale + offx))
561	y = int(round(-y * scale + offy))
562	width, height = self.dc.GetTextExtent(text)
563	if label.halign == ALIGN_LEFT:
564	# nothing to be done
565	pass
566	elif label.halign == ALIGN_RIGHT:
567	x = x - width
568	elif label.halign == ALIGN_CENTER:
569	x = x - width/2
570	if label.valign == ALIGN_TOP:
571	# nothing to be done
572	pass
573	elif label.valign == ALIGN_BOTTOM:
574	y = y - height
575	elif label.valign == ALIGN_CENTER:
576	y = y - height/2
577	self.dc.DrawText(text, x, y)
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