加载栅格数据

import os

from PyQt5.QtCore import QSettings, QDir
from PyQt5.QtWidgets import QFileDialog

def select_single_file(weight, suffix_filter: str, last_dir_key: str):
    """
    打开单个文件
    :param weight:
    :param suffix_filter:
    :param last_dir_key:
    :return:
    """
    # 历史目录
    settings = QSettings('PyQgisSEAPP')
    last_dir = settings.value(last_dir_key, QDir().homePath())

    file_dialog = QFileDialog(weight)
    file_dialog.setWindowTitle('文件选择')
    file_dialog.setNameFilter(suffix_filter)
    file_dialog.setDirectory(last_dir)
    file_dialog.setFileMode(QFileDialog.FileMode.ExistingFile)
    file_dialog.setViewMode(QFileDialog.ViewMode.Detail)

    if file_dialog.exec():
        filenames = file_dialog.selectedFiles()
        filepath = filenames[0]
        # 记录历史目录
        settings.setValue(last_dir_key, os.path.dirname(filepath))
        return filepath

    return ''

from os.path import basename

from qgis._core import QgsRasterLayer, QgsProject
from qgis._gui import QgsMapCanvas

import utils.fileUtil as FileUtil


def open_raster_file(main):
    """
    打开栅格文件
    :param main:
    :return:
    """
    # 选择文件
    filepath = FileUtil.select_single_file(main, 'GeoTiff(*.tif;*tiff;*TIF;*TIFF)', 'last_dir_raster')
    if filepath == '':
        return

    canvas: QgsMapCanvas = main.preview_canvas
    # 添加图层
    layer: QgsRasterLayer = QgsRasterLayer(filepath, basename(filepath), 'gdal')
    layer.dataProvider().setNoDataValue(1, 0)
    # 检查图层合法性
    if not layer.isValid():
        return False
    QgsProject.instance().addMapLayer(layer)
    # 渲染栅格图像，渲染到最上层
    is_first_add_layer = len(canvas.layers()) == 0
    canvas.setLayers([layer] + canvas.layers())
    if is_first_add_layer:
        canvas.setExtent(layer.extent())
        canvas.setDestinationCrs(layer.crs())
    canvas.freeze(False)
    canvas.setVisible(True)
    canvas.refresh()

from gui.preview.functions import open_raster_file

def bind_func(main):
    _ui = main.ui
    _ui.button_add_raster.clicked.connect(lambda self: open_raster_file(main))