vc调用python接口操作mapnik

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0.准备工作

参考文章

1.python支持下的mapnik安装
2.mapnik的demo运行
3.几个shape格式地图免费下载网站
参考文章1、2配置好python和mapnik的环境
设定好系统的PATH、PYTHONPATH
在C:\mapnik-v2.2.0\demo\新建一个map文件夹，并参考文章3下载一个shp地图包到这个文件夹

1.VS工程及配置

新建win32控制台工程
切换到release模式（因为没有debug的mapnik.dll）
.cpp下写入下面的代码

#include "stdafx.h"#include <iostream> #include "python.h"using namespace std;int _tmain(int argc, char* argv[]){    Py_SetProgramName(argv[0]);  /* optional but recommended */     Py_Initialize();    PyRun_SimpleString("execfile('C:\\mapnik-v2.2.0\\demo\\python\\pytest.py')");      //使用execfile来运行python文件    Py_Finalize();    system("pause");    return 0;}

这里有几个注意：

Py_SetProgramName(argv[0]);这句是python官方给的pdf上列出的，推荐使用

PyRun_SimpleString这句原本可以用PyRun_SimpleFile，但发现用这个函数会产生崩溃，具体原因有说法是文件编码方式和c不兼容，这里用execfile来迂回实现

2.python代码

C:\mapnik-v2.2.0\demo\python\文件夹下新建一个pytest.py文件
写入下面代码

import mapnikm = mapnik.Map(800,600)# create a map with a given width and height in pixels# note: m.srs will default to '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs'# the 'map.srs' is the target projection of the map and can be whatever you wish m.background = mapnik.Color('steelblue') # set background colour to 'steelblue'.  s = mapnik.Style() # style object to hold rulesr = mapnik.Rule() # rule object to hold symbolizers# to fill a polygon we create a PolygonSymbolizerpolygon_symbolizer = mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9'))r.symbols.append(polygon_symbolizer) # add the symbolizer to the rule object# to add outlines to a polygon we create a LineSymbolizerline_symbolizer = mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'),0.1)r.symbols.append(line_symbolizer) # add the symbolizer to the rule objects.rules.append(r) # now add the rule to the style and we're donem.append_style('My Style',s) # Styles are given names only as they are applied to the mapds = mapnik.Shapefile(file='C:\mapnik-v2.2.0\demo\map\map.shp')layer = mapnik.Layer('world') # new layer called 'world' (we could name it anything)# note: layer.srs will default to '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs'layer.datasource = dslayer.styles.append('My Style')m.layers.append(layer)m.zoom_all()# Write the data to a png image called world.png the current directorymapnik.render_to_file(m,'china.png', 'png')

3.结果

编译连接运行后，在vs工程目录下得到结果PNG图片

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