self._image_label = QLabel()

这段代码定义了一个名为 _image_label 的实例变量，并将其初始化为一个 QLabel 对象。QLabel 是 Qt 中的一个控件类，用于显示文本或图像。在这个 ImageViewer 类中，_image_label 控件用于显示打开的图像文件。当用户打开一个图像文件后，程序会将该文件显示在 _image_label 控件中。

相关问题

class ImageViewer(QMainWindow): def __init__(self, parent=None): super().__init__(parent) self._scale_factor = 1.0 self._first_file_dialog = True self._image_label = QLabel() self._image_label.setBackgroundRole(QPalette.Base) self._image_label.setSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored) self._image_label.setScaledContents(True) self._scroll_area = QScrollArea() self._scroll_area.setBackgroundRole(QPalette.Dark) self._scroll_area.setWidget(self._image_label) self._scroll_area.setVisible(False) self.setCentralWidget(self._scroll_area) self._create_actions() self.resize(QGuiApplication.primaryScreen().availableSize() * 3 / 5)

这段代码定义了一个名为 ImageViewer 的 QMainWindow 类。在 __init__ 方法中，它创建了一些私有变量用于缩放和文件对话框等操作，并创建了一个 QLabel 对象 _image_label 和一个 QScrollArea 对象 _scroll_area，用于显示和滚动图像。其中，_image_label 的背景角色设置为 QPalette.Base，大小策略为 QSizePolicy.Ignored，设置了其自适应大小为 True；_scroll_area 的背景角色设置为 QPalette.Dark，将 _image_label 设置为其滚动的控件，并将其初始不可见。最后，它设置了该窗口的中央控件为 _scroll_area，并创建了一些操作（_create_actions），并将该窗口的大小设置为主屏幕大小的 3/5。

import os from PyQt5.QtCore import Qt from PyQt5.QtGui import QPixmap, QIcon from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QVBoxLayout, QHBoxLayout, QTreeView, QFileSystemModel class ImageViewer(QWidget): def init(self, folder_path): super().init() self.folder_path = folder_path self.image_dict = {} self.current_image = None self.setWindowTitle("Image Viewer") self.setFixedSize(1000, 600) self.image_label = QLabel(self) self.image_label.setAlignment(Qt.AlignCenter) self.tree_view = QTreeView() self.tree_view.setMinimumWidth(250) self.tree_view.setMaximumWidth(250) self.model = QFileSystemModel() self.model.setRootPath(folder_path) self.tree_view.setModel(self.model) self.tree_view.setRootIndex(self.model.index(folder_path)) self.tree_view.setHeaderHidden(True) self.tree_view.setColumnHidden(1, True) self.tree_view.setColumnHidden(2, True) self.tree_view.setColumnHidden(3, True) self.tree_view.doubleClicked.connect(self.tree_item_double_clicked) self.main_layout = QHBoxLayout(self) self.main_layout.addWidget(self.tree_view) self.main_layout.addWidget(self.image_label) self.load_images() self.update_image() def load_images(self): for file_name in os.listdir(self.folder_path): if file_name.lower().endswith((".jpg", ".jpeg", ".png", ".gif", ".bmp")): file_path = os.path.join(self.folder_path, file_name) self.image_dict[file_name] = file_path current_image = list(self.image_dict.keys())[0] def update_image(self): if self.current_image is not None: pixmap = QPixmap(self.image_dict[self.current_image]) self.image_label.setPixmap(pixmap.scaled(self.width() - self.tree_view.width(), self.height(), Qt.KeepAspectRatio, Qt.SmoothTransformation)) def tree_item_double_clicked(self, index): file_name = self.model.fileName(index) if file_name in self.image_dict: self.current_image = file_name self.update_image() def keyPressEvent(self, event): if event.key() == Qt.Key_A: self.previous_image() elif event.key() == Qt.Key_D: self.next_image() elif event.key() in [Qt.Key_1, Qt.Key_2, Qt.Key_3, Qt.Key_4, Qt.Key_5]: self.save_text_file(event.key() - Qt.Key_0) def previous_image(self): if self.current_image is not None: file_names = list(self.image_dict.keys()) current_index = file_names.index(self.current_image) if current_index > 0: self.current_image = file_names[current_index - 1] else: self.current_image = file_names[-1] self.update_image() def next_image(self): if self.current_image is not None: file_names = list(self.image_dict.keys()) current_index = file_names.index(self.current_image) if current_index < len(file_names) - 1: self.current_image = file_names[current_index + 1] else: self.current_image = file_names[0] self.update_image() def save_text_file(self, number): if self.current_image is not None: file_name = self.current_image txt_file_path = os.path.join(self.folder_path, os.path.splitext(file_name)[0] + ".txt") with open(txt_file_path, "w") as file: file.write(str(number)) if name == "main": import sys app = QApplication(sys.argv) viewer = ImageViewer("D:/图片/wallpaper") viewer.show() sys.exit(app.exec_())这份代码实现不了使用键盘的A键向上翻页以及D键向下翻页，也实现不了键盘数字键生成相应txt文档，帮我分析一下错在哪里

这份代码在实现键盘事件的时候，使用了错误的函数名称。应该使用`keyPressEvent`而不是`key_press_event`函数。另外，在`save_text_file`函数中，应该先判断当前图片是否为`None`，再执行后续的代码。以下是修改后的代码：

import os 
from PyQt5.QtCore import Qt 
from PyQt5.QtGui import QPixmap, QIcon 
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QVBoxLayout, QHBoxLayout, QTreeView, QFileSystemModel 

class ImageViewer(QWidget): 
    def __init__(self, folder_path): 
        super().__init__() 
        self.folder_path = folder_path 
        self.image_dict = {} 
        self.current_image = None 
        self.setWindowTitle("Image Viewer") 
        self.setFixedSize(1000, 600) 
        self.image_label = QLabel(self) 
        self.image_label.setAlignment(Qt.AlignCenter) 
        self.tree_view = QTreeView() 
        self.tree_view.setMinimumWidth(250) 
        self.tree_view.setMaximumWidth(250) 
        self.model = QFileSystemModel() 
        self.model.setRootPath(folder_path) 
        self.tree_view.setModel(self.model) 
        self.tree_view.setRootIndex(self.model.index(folder_path)) 
        self.tree_view.setHeaderHidden(True) 
        self.tree_view.setColumnHidden(1, True) 
        self.tree_view.setColumnHidden(2, True) 
        self.tree_view.setColumnHidden(3, True) 
        self.tree_view.doubleClicked.connect(self.tree_item_double_clicked) 
        self.main_layout = QHBoxLayout(self) 
        self.main_layout.addWidget(self.tree_view) 
        self.main_layout.addWidget(self.image_label) 
        self.load_images() 
        self.update_image() 

    def load_images(self): 
        for file_name in os.listdir(self.folder_path): 
            if file_name.lower().endswith((".jpg", ".jpeg", ".png", ".gif", ".bmp")): 
                file_path = os.path.join(self.folder_path, file_name) 
                self.image_dict[file_name] = file_path 
        self.current_image = list(self.image_dict.keys())[0] 

    def update_image(self): 
        if self.current_image is not None: 
            pixmap = QPixmap(self.image_dict[self.current_image]) 
            self.image_label.setPixmap(pixmap.scaled(self.width() - self.tree_view.width(), self.height(), Qt.KeepAspectRatio, Qt.SmoothTransformation)) 

    def tree_item_double_clicked(self, index): 
        file_name = self.model.fileName(index) 
        if file_name in self.image_dict: 
            self.current_image = file_name 
            self.update_image() 

    def keyPressEvent(self, event): 
        if event.key() == Qt.Key_A: 
            self.previous_image() 
        elif event.key() == Qt.Key_D: 
            self.next_image() 
        elif event.key() in [Qt.Key_1, Qt.Key_2, Qt.Key_3, Qt.Key_4, Qt.Key_5]: 
            self.save_text_file(event.key() - Qt.Key_0) 

    def previous_image(self): 
        if self.current_image is not None: 
            file_names = list(self.image_dict.keys()) 
            current_index = file_names.index(self.current_image) 
            if current_index > 0: 
                self.current_image = file_names[current_index - 1] 
            else: 
                self.current_image = file_names[-1] 
            self.update_image() 

    def next_image(self): 
        if self.current_image is not None: 
            file_names = list(self.image_dict.keys()) 
            current_index = file_names.index(self.current_image) 
            if current_index < len(file_names) - 1: 
                self.current_image = file_names[current_index + 1] 
            else: 
                self.current_image = file_names[0] 
            self.update_image() 

    def save_text_file(self, number): 
        if self.current_image is not None: 
            file_name = self.current_image 
            txt_file_path = os.path.join(self.folder_path, os.path.splitext(file_name)[0] + ".txt") 
            with open(txt_file_path, "w") as file: 
                file.write(str(number)) 

if __name__ == "__main__": 
    import sys 
    app = QApplication(sys.argv) 
    viewer = ImageViewer("D:/图片/wallpaper") 
    viewer.show() 
    sys.exit(app.exec_())