Python使用PIL构建图片裁剪工具的实现步骤

import wx
import os
from PIL import Image
 
class ImageCropperFrame(wx.Frame):
    def __init__(self):
        super().__init__(parent=None, title='图片裁剪工具', size=(800, 600))
        self.init_ui()
        
    def init_ui(self):
        # 创建菜单栏
        menubar = wx.MenuBar()
        file_menu = wx.Menu()
        open_item = file_menu.Append(wx.ID_OPEN, '打开图片', '打开一个图片文件')
        menubar.Append(file_menu, '文件')
        self.SetMenuBar(menubar)
        
        # 创建面板和图片显示控件
        self.panel = wx.Panel(self)
        self.image_panel = wx.Panel(self.panel)
        self.image_panel.SetBackgroundColour(wx.Colour(200, 200, 200))
        
        # 初始化变量
        self.image = None
        self.bitmap = None
        self.start_pos = None
        self.current_pos = None
        self.is_drawing = False
        
        # 设置布局
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.image_panel, 1, wx.EXPAND)
        self.panel.SetSizer(sizer)
        
        # 绑定事件
        self.Bind(wx.EVT_MENU, self.on_open, open_item)
        self.image_panel.Bind(wx.EVT_PAINT, self.on_paint)
        self.image_panel.Bind(wx.EVT_LEFT_DOWN, self.on_left_down)
        self.image_panel.Bind(wx.EVT_LEFT_UP, self.on_left_up)
        self.image_panel.Bind(wx.EVT_MOTION, self.on_motion)
        
    def on_open(self, event):
        # 打开文件对话框
        with wx.FileDialog(self, "选择图片文件", 
                          wildcard="图片文件 (*.jpg;*.jpeg;*.png)|*.jpg;*.jpeg;*.png",
                          style=wx.FD_OPEN | wx.FD_FILE_MUST_EXIST) as fileDialog:
            
            if fileDialog.ShowModal() == wx.ID_CANCEL:
                return
            
            # 加载图片
            pathname = fileDialog.GetPath()
            self.load_image(pathname)
            self.image_path = pathname
    
    def load_image(self, path):
        # 使用PIL加载图片
        self.pil_image = Image.open(path)
        # 转换为wx.Bitmap
        self.image = wx.Image(path, wx.BITMAP_TYPE_ANY)
        # 调整图片大小以适应窗口
        self.scale_image()
        self.Refresh()
    
    def scale_image(self):
        # 获取面板大小
        panel_size = self.image_panel.GetSize()
        # 计算缩放比例
        width_ratio = panel_size.width / self.image.GetWidth()
        height_ratio = panel_size.height / self.image.GetHeight()
        scale = min(width_ratio, height_ratio)
        
        # 缩放图片
        new_width = int(self.image.GetWidth() * scale)
        new_height = int(self.image.GetHeight() * scale)
        self.image = self.image.Scale(new_width, new_height)
        self.bitmap = wx.Bitmap(self.image)
        
        # 保存缩放比例用于裁剪
        self.scale_factor = scale
    
    def on_paint(self, event):
        dc = wx.PaintDC(self.image_panel)
        if self.bitmap:
            dc.DrawBitmap(self.bitmap, 0, 0)
        
        # 绘制选择框
        if self.start_pos and self.current_pos:
            dc.SetPen(wx.Pen(wx.RED, 1, wx.PENSTYLE_DOT))
            dc.SetBrush(wx.TRANSPARENT_BRUSH)
            x = min(self.start_pos[0], self.current_pos[0])
            y = min(self.start_pos[1], self.current_pos[1])
            w = abs(self.current_pos[0] - self.start_pos[0])
            h = abs(self.current_pos[1] - self.start_pos[1])
            dc.DrawRectangle(x, y, w, h)
    
    def on_left_down(self, event):
        self.start_pos = event.GetPosition()
        self.current_pos = self.start_pos
        self.is_drawing = True
    
    def on_motion(self, event):
        if self.is_drawing:
            self.current_pos = event.GetPosition()
            self.Refresh()
    
    def on_left_up(self, event):
        if self.is_drawing:
            self.is_drawing = False
            # 获取选择区域
            x1 = min(self.start_pos[0], self.current_pos[0])
            y1 = min(self.start_pos[1], self.current_pos[1])
            x2 = max(self.start_pos[0], self.current_pos[0])
            y2 = max(self.start_pos[1], self.current_pos[1])
            
            # 转换回原始图片坐标
            orig_x1 = int(x1 / self.scale_factor)
            orig_y1 = int(y1 / self.scale_factor)
            orig_x2 = int(x2 / self.scale_factor)
            orig_y2 = int(y2 / self.scale_factor)
            
            # 裁剪图片
            cropped = self.pil_image.crop((orig_x1, orig_y1, orig_x2, orig_y2))
            
            # 生成保存路径
            directory = os.path.dirname(self.image_path)
            filename = os.path.splitext(os.path.basename(self.image_path))[0]
            save_path = os.path.join(directory, f"{filename}_cropped.png")
            
            # 保存裁剪后的图片
            cropped.save(save_path)
            
            # 显示成功消息
            wx.MessageBox(f"裁剪后的图片已保存至:\n{save_path}", 
                         "保存成功", 
                         wx.OK | wx.ICON_INFORMATION)
            
            # 重置选择区域
            self.start_pos = None
            self.current_pos = None
            self.Refresh()
 
if __name__ == '__main__':
    app = wx.App()
    frame = ImageCropperFrame()
    frame.Show()
    app.MainLoop()