PyQt5-创建绘画应用 - Python技术站

下面是关于“PyQt5--创建绘画应用”的完整使用攻略。

1. 准备工作

在开始创建绘画应用之前，需要进行一些准备工作，分别是安装PyQt5和导入相关模块。

1.1 安装PyQt5

可以使用pip命令来安装PyQt5，具体命令如下：

pip install PyQt5

1.2 导入相关模块

在创建绘画应用时，需要使用到以下几个模块：

import sys
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtGui import QImage, QPainter, QPen
from PyQt5.QtWidgets import QApplication, QMainWindow, QAction, QFileDialog

2. 创建绘画应用

在准备工作完成之后，就可以创建绘画应用了，主要分为以下几个部分。

2.1 继承QMainWindow类

需要从QMainWindow类继承一个新类DrawingApp，继承过程中需要重写初始化方法和重载绘图事件方法。

class DrawingApp(QMainWindow):

    def __init__(self):
        super().__init__()

        self.setWindowTitle("绘画应用")
        self.setGeometry(100, 100, 800, 600)

        # 初始化画布，填充为白色
        self.image = QImage(self.size(), QImage.Format_RGB32)
        self.image.fill(Qt.white)

        # 记录画笔位置和画笔状态
        self.last_point = QPoint()
        self.drawing = False

        # 初始化画笔样式
        self.pen = QPen(Qt.black)
        self.pen.setWidth(2)

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawImage(self.rect(), self.image, self.image.rect())

2.2 创建菜单栏和工具栏

需要在创建的类中添加菜单栏和工具栏，分别添加文件菜单和画笔颜色工具。

class DrawingApp(QMainWindow):

    def __init__(self):
        super().__init__()

        # ...

        # 创建菜单栏
        main_menu = self.menuBar()
        file_menu = main_menu.addMenu("文件")

        # 添加菜单项
        open_file_action = QAction("打开", self)
        open_file_action.setShortcut("Ctrl+O")
        open_file_action.triggered.connect(self.open_file_dialog)

        save_file_action = QAction("保存", self)
        save_file_action.setShortcut("Ctrl+S")
        save_file_action.triggered.connect(self.save_file_dialog)

        file_menu.addAction(open_file_action)
        file_menu.addAction(save_file_action)

        # 创建工具栏
        toolbar = self.addToolBar("画笔颜色")
        toolbar.setMovable(False)

        # 添加工具项
        color_action = QAction("画笔颜色", self)
        color_action.triggered.connect(self.color_picker)

        toolbar.addAction(color_action)

2.3 添加绘图事件处理函数

当鼠标按下并移动时，需要记录鼠标位置，以此来进行绘图。

class DrawingApp(QMainWindow):
    # ...

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.last_point = event.pos()
            self.drawing = True

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = False

    def mouseMoveEvent(self, event):
        if event.buttons() & Qt.LeftButton and self.drawing:
            painter = QPainter(self.image)
            painter.setPen(self.pen)
            painter.drawLine(self.last_point, event.pos())
            self.last_point = event.pos()
            self.update()

2.4 添加文件读写和画笔颜色选择函数

class DrawingApp(QMainWindow):
    # ...

    def open_file_dialog(self):
        file_path, _ = QFileDialog.getOpenFileName(self,
            "请选择一个图像文件", ".", "图像文件 (*.jpg *.png *.bmp *.gif)")
        if file_path:
            self.image.load(file_path)
            self.update()

    def save_file_dialog(self):
        file_path, _ = QFileDialog.getSaveFileName(self,
            "请选择一个图像文件", ".", "图像文件 (*.jpg *.png *.bmp *.gif)")
        if file_path:
            self.image.save(file_path)

    def color_picker(self):
        chosen_color = QColorDialog.getColor()
        if chosen_color.isValid():
            self.pen.setColor(chosen_color)

3. 示例说明

下面给出两个完整的示例，分别展示如何打开图片和如何使用不同颜色的画笔绘图。

3.1 打开图片

import sys
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtGui import QImage, QPainter, QPen
from PyQt5.QtWidgets import QApplication, QMainWindow, QAction, QFileDialog

class DrawingApp(QMainWindow):

    def __init__(self):
        super().__init__()

        self.setWindowTitle("绘画应用")
        self.setGeometry(100, 100, 800, 600)

        self.image = QImage(self.size(), QImage.Format_RGB32)
        self.image.fill(Qt.white)

        self.last_point = QPoint()
        self.drawing = False

        self.pen = QPen(Qt.black)
        self.pen.setWidth(2)

        main_menu = self.menuBar()
        file_menu = main_menu.addMenu("文件")

        open_file_action = QAction("打开", self)
        open_file_action.setShortcut("Ctrl+O")
        open_file_action.triggered.connect(self.open_file_dialog)

        save_file_action = QAction("保存", self)
        save_file_action.setShortcut("Ctrl+S")
        save_file_action.triggered.connect(self.save_file_dialog)

        file_menu.addAction(open_file_action)
        file_menu.addAction(save_file_action)

    def open_file_dialog(self):
        file_path, _ = QFileDialog.getOpenFileName(self,
            "请选择一个图像文件", ".", "图像文件 (*.jpg *.png *.bmp *.gif)")
        if file_path:
            self.image.load(file_path)
            self.update()

    def save_file_dialog(self):
        file_path, _ = QFileDialog.getSaveFileName(self,
            "请选择一个图像文件", ".", "图像文件 (*.jpg *.png *.bmp *.gif)")
        if file_path:
            self.image.save(file_path)

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawImage(self.rect(), self.image, self.image.rect())

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.last_point = event.pos()
            self.drawing = True

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = False

    def mouseMoveEvent(self, event):
        if event.buttons() & Qt.LeftButton and self.drawing:
            painter = QPainter(self.image)
            painter.setPen(self.pen)
            painter.drawLine(self.last_point, event.pos())
            self.last_point = event.pos()
            self.update()

app = QApplication(sys.argv)
window = DrawingApp()
window.show()
sys.exit(app.exec_())

在菜单栏中选择“文件”-“打开”菜单项，即可打开本地的jpg、png、bmp、gif等格式的图片。

3.2 使用不同颜色的画笔绘图

import sys
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtGui import QImage, QPainter, QPen, QColor
from PyQt5.QtWidgets import QApplication, QMainWindow, QAction, QFileDialog, QColorDialog

class DrawingApp(QMainWindow):

    def __init__(self):
        super().__init__()

        self.setWindowTitle("绘画应用")
        self.setGeometry(100, 100, 800, 600)

        self.image = QImage(self.size(), QImage.Format_RGB32)
        self.image.fill(Qt.white)

        self.last_point = QPoint()
        self.drawing = False

        self.pen = QPen(Qt.black)
        self.pen.setWidth(2)

        main_menu = self.menuBar()
        file_menu = main_menu.addMenu("文件")

        open_file_action = QAction("打开", self)
        open_file_action.setShortcut("Ctrl+O")
        open_file_action.triggered.connect(self.open_file_dialog)

        save_file_action = QAction("保存", self)
        save_file_action.setShortcut("Ctrl+S")
        save_file_action.triggered.connect(self.save_file_dialog)

        file_menu.addAction(open_file_action)
        file_menu.addAction(save_file_action)

        toolbar = self.addToolBar("画笔颜色")
        toolbar.setMovable(False)

        color_action = QAction("画笔颜色", self)
        color_action.triggered.connect(self.color_picker)

        toolbar.addAction(color_action)

    def open_file_dialog(self):
        file_path, _ = QFileDialog.getOpenFileName(self,
            "请选择一个图像文件", ".", "图像文件 (*.jpg *.png *.bmp *.gif)")
        if file_path:
            self.image.load(file_path)
            self.update()

    def save_file_dialog(self):
        file_path, _ = QFileDialog.getSaveFileName(self,
            "请选择一个图像文件", ".", "图像文件 (*.jpg *.png *.bmp *.gif)")
        if file_path:
            self.image.save(file_path)

    def color_picker(self):
        chosen_color = QColorDialog.getColor()
        if chosen_color.isValid():
            new_pen = QPen(chosen_color)
            new_pen.setWidth(2)
            self.pen = new_pen

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawImage(self.rect(), self.image, self.image.rect())

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.last_point = event.pos()
            self.drawing = True

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = False

    def mouseMoveEvent(self, event):
        if event.buttons() & Qt.LeftButton and self.drawing:
            painter = QPainter(self.image)
            painter.setPen(self.pen)
            painter.drawLine(self.last_point, event.pos())
            self.last_point = event.pos()
            self.update()

app = QApplication(sys.argv)
window = DrawingApp()
window.show()
sys.exit(app.exec_())

在工具栏中选择“画笔颜色”按钮，即可选择不同的画笔颜色。

至此，关于“PyQt5--创建绘画应用”的完整使用攻略已经介绍完毕，希望能对你有所帮助。

本站文章如无特殊说明，均为本站原创，如若转载，请注明出处：PyQt5–创建绘画应用 - Python技术站

PyQt5–创建绘画应用