vc调用python接口操作mapnik

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

[code]#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

[code]import mapnik
m = 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 rules
r = mapnik.Rule() # rule object to hold symbolizers
# to fill a polygon we create a PolygonSymbolizer
polygon_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 LineSymbolizer
line_symbolizer = mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'),0.1)
r.symbols.append(line_symbolizer) # add the symbolizer to the rule object
s.rules.append(r) # now add the rule to the style and we're done
m.append_style('My Style',s) # Styles are given names only as they are applied to the map
ds = 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 = ds
layer.styles.append('My Style')
m.layers.append(layer)
m.zoom_all()
# Write the data to a png image called world.png the current directory
mapnik.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