pyqt5 addLegend使用例子

以下是一个使用pyqt5中QgsMapCanvas和QgsLayerTreeView添加图例的例子：

from PyQt5.QtWidgets import QMainWindow, QToolBar, QDockWidget, QVBoxLayout, QWidget
from qgis.gui import QgsMapCanvas, QgsLayerTreeView
from qgis.core import QgsProject, QgsLayerDefinition

class MainWindow(QMainWindow):

    def __init__(self):
        super().__init__()
        self.setWindowTitle('Add Legend')
        self.setGeometry(100, 100, 800, 600)

        # 创建图层
        self.layer = QgsLayerDefinition()
        self.layer.setType(QgsMapLayerType.RasterLayer)
        self.layer.setProviderType('gdal')
        self.layer.setDataSource('path/to/your/raster/image')
        QgsProject.instance().addMapLayer(self.layer)

        # 创建地图画布
        self.canvas = QgsMapCanvas()
        self.canvas.setLayers([self.layer])
        self.setCentralWidget(self.canvas)

        # 创建图层树窗口
        tree_widget = QWidget()
        tree_layout = QVBoxLayout()
        tree_widget.setLayout(tree_layout)
        self.tree_view = QgsLayerTreeView()
        tree_layout.addWidget(self.tree_view)
        dock = QDockWidget()
        dock.setWindowTitle('Layer Tree')
        dock.setWidget(tree_widget)
        self.addDockWidget(1, dock)

        # 添加工具栏
        toolbar = QToolBar()
        self.addToolBar(toolbar)

        # 创建图例并添加到工具栏
        legend = self.canvas.layerTreeCanvasBridge().legendInterface()
        toolbar.addWidget(legend)

        # 更新界面
        self.show()
        self.tree_view.setCanvas(self.canvas)