QGIS python 调用GIS功能

QGIS 中文学习手册：https://www.osgeo.cn/qgisdoc/docs/user_manual/index.html
前提：已经下载并安装QGIS
● qgis环境配置：
○ 设置PYTHONPATH为QGIS自带的python路径即可（其他脚本中配置）：
/Applications/QGIS-LTR.app/Contents/MacOS/bin/python3.8
可用以下语句在QGIS软件中查看路径：

QStandardPaths.standardLocations(QStandardPaths.AppDataLocation)

○ 脚本开头需要初始化QGIS资源，以下语句查询路径：

QgsApplication.prefixPath()

○ 按步骤配置依然不成功可以试试重装QGIS（血泪教训）

# @Time : 2023/2/17 15:26
# @Comment : 独立脚本调用GIS功能

# 1. 环境配置
from qgis.core import *
from qgis.PyQt.QtGui import QColor
from PyQt5.QtCore import *
import sys

process_path = '/Applications/QGIS-LTR.app/Contents/Resources/python/plugins'
if process_path not in sys.path:
    sys.path.append(process_path)

QgsApplication.setPrefixPath(r"/Applications/QGIS-LTR.app/Contents/MacOS", True)
qgs = QgsApplication([], False)
qgs.initQgis()

from processing.core.Processing import Processing

Processing.initialize()
import processing

# 2. 加载数据
data_source = r"XX.shp"
data_output = r"XX.shp"
image_output = r"XX.png"
fileInfo = QFileInfo(data_source)
if fileInfo.exists():
    print("File exists; Path is correct")

dlr_layer = QgsVectorLayer(data_source, "dlr_layer", "ogr")
if not dlr_layer.isValid():
    print("Layer failed to load!")
else:
    QgsProject.instance().addMapLayer(dlr_layer)
    print("Layer loaded successfully！")

    # 3. 调用工具箱
parameter_buffer = {
    'INPUT': dlr_layer,
    'DISTANCE': 0.001,
    'SEGMENTS': 5,
    'DISSOLVE': True,
    'OUTPUT': data_output,
    'END_CAP_STYLE': 0,
    'JOIN_STYLE': 0,
    'MITER_LIMIT': 2
}
dlr_buffer = processing.run("native:buffer", parameter_buffer)
print('file save to:', data_output)

# 4. 可视化输出
dlr_buffer_layer = QgsVectorLayer(data_output, "dlr_buffer_layer", "ogr")
if not dlr_buffer_layer.isValid():
    print("Layer failed to load!")
else:
    QgsProject.instance().addMapLayer(dlr_buffer_layer)
    print("Layer loaded successfully！")

settings = QgsMapSettings()
settings.setLayers([dlr_buffer_layer])
settings.setBackgroundColor(QColor(255, 255, 255))
settings.setOutputSize(QSize(1000, 800))
settings.setExtent(dlr_layer.extent())
settings.setOutputDpi(500)

render = QgsMapRendererParallelJob(settings)


def finished():
    img = render.renderedImage()
    img.save(image_output, "png")
    print('image save to:', image_output)


render.finished.connect(finished)
render.start()
render.waitForFinished()

# 5. 退出QGIS
qgs.exitQgis()