Tkinter图像裁剪工具：使用多个矩形裁剪图像，添加滚动条导致矩形位置错误

Question

我只是 Python 和 Tkinter 的初学者，我正在尝试编写一个应用程序来裁剪图像中的多个区域并将它们保存为单独的图像，我可以通过绘制多个矩形来裁剪图像，但是在添加滚动条后使用鼠标指针绘制矩形时，鼠标位置出现错误，由于滚动效果，鼠标指针位置稍远。我还尝试添加放大和缩小功能，您能否建议我如何实现这一目标。import osimport tkinter as tkimport tkinter.filedialog as filedialogfrom PIL import Image, ImageTk, ImageGrabWIDTH, HEIGHT = 1200, 800topx, topy, botx, boty = 0, 0, 0, 0rect_id = Nonepath = "test.jpg"rect_list = list()rect_main_data = list()ImageFilePath = ""ImgOpen = NoneprodDir = ""ImageFound = Falsewindow = tk.Tk()window.title("Image Croping Tool")window.geometry('%sx%s' % (WIDTH, HEIGHT))window.configure(background='grey')ImageFrame = tk.Frame(window, width=WIDTH,height=HEIGHT - 70, borderwidth=1)ImageFrame.pack(expand=True, fill=tk.BOTH)ImageFrame.place(x=0,y=71)rawImage = Image.open("test.jpg")img = ImageTk.PhotoImage(rawImage)canvasWidth, canvasHeight = rawImage.sizecanvas = tk.Canvas(ImageFrame, width=canvasWidth, height=canvasHeight - 70, borderwidth=2, highlightthickness=2,scrollregion=(0,0,canvasWidth,canvasHeight))def get_mouse_posn(event):    global topy, topx    topx, topy = event.x, event.ydef update_sel_rect(event):    global rect_id    global topy, topx, botx, boty    botx, boty = event.x, event.y    canvas.coords(rect_id, topx, topy, botx, boty)  # Update selection rect.def draw_rect(self):    draw_data = canvas.create_rectangle(topx,topy,botx,boty,outline="green", fill="")    rect_list.append((topx,topy,botx,boty))    rect_main_data.append(draw_data)    def GetImageFilePath():    global ImageFilePath    global ImageFound    global img    global canvas    global ImageFrame    test = False    if (ImageFound):        canvas.destroy()        canvas = tk.Canvas(ImageFrame, width=canvasWidth, height=canvasHeight - 70, borderwidth=2, highlightthickness=2,scrollregion=(0,0,canvasWidth,canvasHeight))    

Answer 1

因为event.x和event.y始终相对于画布的左上角。如果画布没有滚动，它们将与真实坐标匹配。但当画布滚动时则不然。

但是，您可以使用canvas.canvasx()和canvas.canvasy()函数将鼠标位置转换为画布中的真实坐标：

def get_mouse_posn(event):

    global topy, topx

    topx, topy = canvas.canvasx(event.x), canvas.canvasy(event.y) # convert to real canvas coordinates

def update_sel_rect(event):

    global botx, boty

    botx, boty = canvas.canvasx(event.x), canvas.canvasy(event.y) # convert to real canvas coordinates

    canvas.coords(rect_id, topx, topy, botx, boty)  # Update selection rect.