Thuban/UI/baserenderer.py

# Copyright (c) 2001, 2002, 2003 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 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


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.
        """
        # Whether the raster layer has already been drawn. See below for
        # the optimization this is used for
        seenRaster = True

        #
        # This is only a good optimization if there is only one
        # raster layer and the image covers the entire window (as
        # it currently does). We note if there is a raster layer
        # and only begin drawing layers once we have drawn it.
        # That way we avoid drawing layers that won't be seen.
        #
        if Thuban.Model.resource.has_gdal_support():
            for layer in self.map.Layers():
                if isinstance(layer, RasterLayer) and layer.Visible():
                    seenRaster = False
                    break

        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) and seenRaster:
                    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)
                    seenRaster = True
                    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()
            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.
        """
        points = self.projected_points(layer, points)

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

            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):
        """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 = self.resolution * 5
        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 = layer.GetProjection()
        if proj is not None:
            for p in proj.GetAllParameters():
                in_proj += "+" + p + " "

        out_proj = ""
        proj = self.map.GetProjection()
        if proj is not None:
            for p in proj.GetAllParameters():
                out_proj += "+" + p + " "

        xmin = (0 - offx) / self.scale
        ymin = (offy - height) / self.scale
        xmax = (width - offx) / self.scale
        ymax = (offy - 0) / self.scale

        try:
            data = ProjectRasterFile(layer.GetImageFilename(),
                                     in_proj, out_proj,
                                     (xmin, ymin, xmax, ymax), "",
                                     (width, height))
        except (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(data)

    def draw_raster_data(self, data):
        """Draw the raster image in data onto the DC

        The raster image data is a string holding the data in BMP
        format. The data is exactly the size of the dc and covers it
        completely.

        This method has to be implemented by derived classes.
        """
        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 = x * scale + offx
            y = -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 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 traceback
24
25	from Thuban.Model.layer import Layer, RasterLayer
26	from Thuban.Model.data import SHAPETYPE_ARC, SHAPETYPE_POINT
27	from Thuban.Model.label import ALIGN_CENTER, ALIGN_TOP, ALIGN_BOTTOM, \
28	ALIGN_LEFT, ALIGN_RIGHT
29
30	import Thuban.Model.resource
31
32	if Thuban.Model.resource.has_gdal_support():
33	from gdalwarp import ProjectRasterFile
34
35
36	class BaseRenderer:
37
38	"""Basic Renderer Infrastructure for Thuban Maps
39
40	This class can't be used directly to render because it doesn't know
41	anything about real DCs such as how to create pens or brushes. That
42	functionality has to be provided by derived classes. The reason for
43	this is that it makes the BaseRenderer completely independend of wx
44	and thus it's quite easy to write test cases for it.
45	"""
46	# If true the render honors the visibility flag of the layers
47	honor_visibility = 1
48
49	# Transparent brushes and pens. Derived classes should define these
50	# as appropriate.
51	TRANSPARENT_PEN = None
52	TRANSPARENT_BRUSH = None
53
54	def __init__(self, dc, map, scale, offset, region = None,
55	resolution = 72.0, honor_visibility = None):
56	"""Inititalize the renderer.
57
58	dc -- the device context to render on.
59
60	scale, offset -- the scale factor and translation to convert
61	between projected coordinates and the DC coordinates
62
63	region -- The region to draw as a (x, y, width, height) tuple in
64	the map's coordinate system. Default is None meaning
65	to draw everything.
66
67	resolution -- the assumed resolution of the DC. Used to convert
68	absolute lengths like font sizes to DC coordinates. The
69	default is 72.0. If given, this parameter must be
70	provided as a keyword argument.
71
72	honor_visibility -- boolean. If true, honor the visibility flag
73	of the layers, otherwise draw all layers. If None (the
74	default), use the renderer's default. If given, this
75	parameter must be provided as a keyword argument.
76	"""
77	# resolution in pixel/inch
78	self.dc = dc
79	self.map = map
80	self.scale = scale
81	self.offset = offset
82	self.region = region
83	if honor_visibility is not None:
84	self.honor_visibility = honor_visibility
85	# store the resolution in pixel/point because it's more useful
86	# later.
87	self.resolution = resolution / 72.0
88
89	def tools_for_property(self, prop):
90	"""Return a suitable pen and brush for the property
91
92	This method must be implemented in derived classes. The return
93	value should be a tuple (pen, brush).
94	"""
95	raise NotImplementedError
96
97	def render_map(self):
98	"""Render the map onto the DC.
99
100	Both map and DC are the ones the renderer was instantiated with.
101
102	This method is just a front-end for render_map_incrementally
103	which does all rendering in one go. It also calls the dc's
104	BeginDrawing and EndDrawing methods before and after calling
105	render_map_incrementally.
106	"""
107
108	self.dc.BeginDrawing()
109	try:
110	for cont in self.render_map_incrementally():
111	pass
112	finally:
113	self.dc.EndDrawing()
114
115	def render_map_incrementally(self):
116	"""Render the map incrementally.
117
118	Return an iterator whose next method should be called until it
119	returns False. After returning False it will raise StopIteration
120	so that you could also use it in a for loop (implementation
121	detail: this method is implemented as a generator).
122
123	Iterate through all layers and draw them. Layers containing
124	vector data are drawn with the draw_shape_layer method, raster
125	layers are drawn with draw_raster_layer. The label layer is
126	drawn last with draw_label_layer.
127
128	During execution of this method, the map is bound to self.map so
129	that methods especially in derived classes have access to the
130	map if necessary.
131	"""
132	# Whether the raster layer has already been drawn. See below for
133	# the optimization this is used for
134	seenRaster = True
135
136	#
137	# This is only a good optimization if there is only one
138	# raster layer and the image covers the entire window (as
139	# it currently does). We note if there is a raster layer
140	# and only begin drawing layers once we have drawn it.
141	# That way we avoid drawing layers that won't be seen.
142	#
143	if Thuban.Model.resource.has_gdal_support():
144	for layer in self.map.Layers():
145	if isinstance(layer, RasterLayer) and layer.Visible():
146	seenRaster = False
147	break
148
149	for layer in self.map.Layers():
150	# if honor_visibility is true, only draw visible layers,
151	# otherwise draw all layers
152	if not self.honor_visibility or layer.Visible():
153	if isinstance(layer, Layer) and seenRaster:
154	for i in self.draw_shape_layer_incrementally(layer):
155	yield True
156	elif isinstance(layer, RasterLayer) \
157	and Thuban.Model.resource.has_gdal_support():
158	self.draw_raster_layer(layer)
159	seenRaster = True
160	yield True
161
162	self.draw_label_layer(self.map.LabelLayer())
163	yield False
164
165	def draw_shape_layer_incrementally(self, layer):
166	"""Draw the shape layer layer onto the map incrementally.
167
168	This method is a generator which yields True after every 500
169	shapes.
170	"""
171	scale = self.scale
172	offx, offy = self.offset
173
174	map_proj = self.map.projection
175	layer_proj = layer.projection
176
177	brush = self.TRANSPARENT_BRUSH
178	pen = self.TRANSPARENT_PEN
179
180	old_prop = None
181	old_group = None
182	lc = layer.GetClassification()
183	field = layer.GetClassificationColumn()
184	defaultGroup = lc.GetDefaultGroup()
185	table = layer.ShapeStore().Table()
186
187	if lc.GetNumGroups() == 0:
188	# There's only the default group, so we can pretend that
189	# there is no field to classifiy on which makes things
190	# faster since we don't need the attribute information at
191	# all.
192	field = None
193
194	# Determine which render function to use.
195	useraw, draw_func, draw_func_param = self.low_level_renderer(layer)
196
197	#
198	# Iterate through all shapes that have to be drawn.
199	#
200
201	# Count the shapes drawn so that we can yield every few hundred
202	# shapes
203	count = 0
204
205	# Cache the tools (pens and brushes) for the classification
206	# groups. This is a mapping from the group's ids to the a tuple
207	# (pen, brush)
208	tool_cache = {}
209
210	for shape in self.layer_shapes(layer):
211	count += 1
212	if field is None:
213	group = defaultGroup
214	else:
215	value = table.ReadValue(shape.ShapeID(), field)
216	group = lc.FindGroup(value)
217
218	if not group.IsVisible():
219	continue
220
221	try:
222	pen, brush = tool_cache[id(group)]
223	except KeyError:
224	pen, brush = tool_cache[id(group)] \
225	= self.tools_for_property(group.GetProperties())
226
227	if useraw:
228	data = shape.RawData()
229	else:
230	data = shape.Points()
231	draw_func(draw_func_param, data, pen, brush)
232	if count % 500 == 0:
233	yield True
234
235	def layer_shapes(self, layer):
236	"""Return an iterable over the shapes to be drawn from the given layer.
237
238	The default implementation simply returns all ids in the layer.
239	Override in derived classes to be more precise.
240	"""
241	return layer.ShapeStore().AllShapes()
242
243	def low_level_renderer(self, layer):
244	"""Return the low-level renderer for the layer for draw_shape_layer
245
246	The low level renderer to be returned by this method is a tuple
247	(useraw, func, param) where useraw is a boolean indicating
248	whether the function uses the raw shape data, func is a callable
249	object and param is passed as the first parameter to func. The
250	draw_shape_layer method will call func like this:
251
252	func(param, shapedata, pen, brush)
253
254	where shapedata is the return value of the RawData method of the
255	shape object if useraw is true or the return value of the Points
256	method if it's false. pen and brush are the pen and brush to use
257	to draw the shape on the dc.
258
259	The default implementation returns one of
260	self.draw_polygon_shape, self.draw_arc_shape or
261	self.draw_point_shape as func and layer as param. None of the
262	method use the raw shape data. Derived classes can override this
263	method to return more efficient low level renderers.
264	"""
265	shapetype = layer.ShapeType()
266	if shapetype == SHAPETYPE_POINT:
267	func = self.draw_point_shape
268	elif shapetype == SHAPETYPE_ARC:
269	func = self.draw_arc_shape
270	else:
271	func = self.draw_polygon_shape
272	return False, func, layer
273
274	def make_point(self, x, y):
275	"""Convert (x, y) to a point object.
276
277	Derived classes must override this method.
278	"""
279	raise NotImplementedError
280
281	def projected_points(self, layer, points):
282	"""Return the projected coordinates of the points taken from layer.
283
284	Transform all the points in the list of lists of coordinate
285	pairs in points.
286
287	The transformation applies the inverse of the layer's projection
288	if any, then the map's projection if any and finally applies
289	self.scale and self.offset.
290
291	The returned list has the same structure as the one returned the
292	shape's Points method.
293	"""
294	proj = self.map.GetProjection()
295	if proj is not None:
296	forward = proj.Forward
297	else:
298	forward = None
299	proj = layer.GetProjection()
300	if proj is not None:
301	inverse = proj.Inverse
302	else:
303	inverse = None
304	result = []
305	scale = self.scale
306	offx, offy = self.offset
307	make_point = self.make_point
308	for part in points:
309	result.append([])
310	for x, y in part:
311	if inverse:
312	x, y = inverse(x, y)
313	if forward:
314	x, y = forward(x, y)
315	result[-1].append(make_point(x * scale + offx,
316	-y * scale + offy))
317	return result
318
319	def draw_polygon_shape(self, layer, points, pen, brush):
320	"""Draw a polygon shape from layer with the given brush and pen
321
322	The shape is given by points argument which is a the return
323	value of the shape's Points() method. The coordinates in the
324	DC's coordinate system are determined with
325	self.projected_points.
326	"""
327	points = self.projected_points(layer, points)
328
329	if brush is not self.TRANSPARENT_BRUSH:
330	polygon = []
331	for part in points:
332	polygon.extend(part)
333
334	insert_index = len(polygon)
335	for part in points[:-1]:
336	polygon.insert(insert_index, part[0])
337
338	self.dc.SetBrush(brush)
339	self.dc.SetPen(self.TRANSPARENT_PEN)
340	self.dc.DrawPolygon(polygon)
341
342	if pen is not self.TRANSPARENT_PEN:
343	# At last draw the boundarys of the simple polygons
344	self.dc.SetBrush(self.TRANSPARENT_BRUSH)
345	self.dc.SetPen(pen)
346	for part in points:
347	self.dc.DrawLines(part)
348
349	def draw_arc_shape(self, layer, points, pen, brush):
350	"""Draw an arc shape from layer with the given brush and pen
351
352	The shape is given by points argument which is a the return
353	value of the shape's Points() method. The coordinates in the
354	DC's coordinate system are determined with
355	self.projected_points.
356	"""
357	points = self.projected_points(layer, points)
358	self.dc.SetBrush(brush)
359	self.dc.SetPen(pen)
360	for part in points:
361	self.dc.DrawLines(part)
362
363	def draw_point_shape(self, layer, points, pen, brush):
364	"""Draw a point shape from layer with the given brush and pen
365
366	The shape is given by points argument which is a the return
367	value of the shape's Points() method. The coordinates in the
368	DC's coordinate system are determined with
369	self.projected_points.
370
371	The point is drawn as a circle centered on the point.
372	"""
373	points = self.projected_points(layer, points)
374	if not points:
375	return
376
377	radius = self.resolution * 5
378	self.dc.SetBrush(brush)
379	self.dc.SetPen(pen)
380	for part in points:
381	for p in part:
382	self.dc.DrawEllipse(p.x - radius, p.y - radius,
383	2 * radius, 2 * radius)
384
385	def draw_raster_layer(self, layer):
386	"""Draw the raster layer
387
388	This implementation does the projection and scaling of the data
389	as required by the layer's and map's projections and the scale
390	and offset of the renderer and then hands the transformed data
391	to self.draw_raster_data() which has to be implemented in
392	derived classes.
393	"""
394	offx, offy = self.offset
395	width, height = self.dc.GetSizeTuple()
396
397	in_proj = ""
398	proj = layer.GetProjection()
399	if proj is not None:
400	for p in proj.GetAllParameters():
401	in_proj += "+" + p + " "
402
403	out_proj = ""
404	proj = self.map.GetProjection()
405	if proj is not None:
406	for p in proj.GetAllParameters():
407	out_proj += "+" + p + " "
408
409	xmin = (0 - offx) / self.scale
410	ymin = (offy - height) / self.scale
411	xmax = (width - offx) / self.scale
412	ymax = (offy - 0) / self.scale
413
414	try:
415	data = ProjectRasterFile(layer.GetImageFilename(),
416	in_proj, out_proj,
417	(xmin, ymin, xmax, ymax), "",
418	(width, height))
419	except (IOError, AttributeError, ValueError):
420	# Why does this catch AttributeError and ValueError?
421	# FIXME: The exception should be communicated to the user
422	# better.
423	traceback.print_exc()
424	else:
425	self.draw_raster_data(data)
426
427	def draw_raster_data(self, data):
428	"""Draw the raster image in data onto the DC
429
430	The raster image data is a string holding the data in BMP
431	format. The data is exactly the size of the dc and covers it
432	completely.
433
434	This method has to be implemented by derived classes.
435	"""
436	raise NotImplementedError
437
438	def label_font(self):
439	"""Return the font object for the label layer"""
440	raise NotImplementedError
441
442	def draw_label_layer(self, layer):
443	"""Draw the label layer
444
445	All labels are draw in the font returned by self.label_font().
446	"""
447	scale = self.scale
448	offx, offy = self.offset
449
450	self.dc.SetFont(self.label_font())
451
452	map_proj = self.map.projection
453	if map_proj is not None:
454	forward = map_proj.Forward
455	else:
456	forward = None
457
458	for label in layer.Labels():
459	x = label.x
460	y = label.y
461	text = label.text
462	if forward:
463	x, y = forward(x, y)
464	x = x * scale + offx
465	y = -y * scale + offy
466	width, height = self.dc.GetTextExtent(text)
467	if label.halign == ALIGN_LEFT:
468	# nothing to be done
469	pass
470	elif label.halign == ALIGN_RIGHT:
471	x = x - width
472	elif label.halign == ALIGN_CENTER:
473	x = x - width/2
474	if label.valign == ALIGN_TOP:
475	# nothing to be done
476	pass
477	elif label.valign == ALIGN_BOTTOM:
478	y = y - height
479	elif label.valign == ALIGN_CENTER:
480	y = y - height/2
481	self.dc.DrawText(text, x, y)
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