用自定义消息替换错误

Question

我的程序是关于图像处理的，它会询问用户何时运行以打开图像。但如果用户关闭窗口而不选择任何图像，则会出现以下错误：

Traceback (most recent call last):
  File "<string>", line 420, in run_nodebug
  File "E:\Projet Complet\Test 2.py", line 255, in <module>
    Ima1=Image.open(a)
  File "C:\EduPython\App\lib\site-packages\PIL\Image.py", line 2317, in open
    fp = io.BytesIO(fp.read())
AttributeError: 'str' object has no attribute 'read'

我正在尝试用一个自定义消息替换这个错误，比如打开的消息框中的"You didn't choose any image"。我知道如何打开消息框，但不知道如何用它替换错误消息。 我试过这样做：

main.withdraw()
try:
    a = filedialog.askopenfilename()
    main.deiconify()
except AttributeError:
    tkMessageBox.showinfo( "Image Error", "You didn't choose any image.")
    sys.exit()

但是它给了我上面的错误。 以下是完整代码：

from tkinter import*
import tkinter as Tkinter
from tkinter import filedialog, DISABLED, messagebox as tkMessageBox
import os
import ntpath
from PIL import Image, ImageTk, ImageFilter
import PIL
from collections import Counter
from random import randint
import random
import PIL.ImageOps


def EchelleDeGris():
    Ima2=Image.new("RGB",(z[0],z[1]))
    px=Ima1.load()
    px1=Ima2.load()
    for x in range(z[0]):
        for y in range(z[1]):
            p=px[x,y]
            if type(p)==int:
                p=(p,p,p)
            o=int((p[0]+p[1]+p[2])/3)
            px1[x,y]=(o,o,o)
    Ima2.save(""+dir_path+"\\Requirements\\ImageMod.png")
    im2 = ImageTk.PhotoImage(file=""+dir_path+"\\Requirements\\ImageMod.png")
    main.image = im2
    I2 = Tkinter.Label(main, image=im2)
    I2.grid(row=0, column=4, columnspan =4)

def SupprimerImage():
    I2 = Tkinter.Label(main, image=imt)
    I2.grid(row=0, column=4, columnspan =4)

def Luminosite():
    Ima2=Image.new("RGB",(z[0],z[1]))
    px=Ima1.load()
    px1=Ima2.load()
    for x in range(z[0]):
        for y in range(z[1]):
            p=px[x,y]
            if type(p)==int:
                p=(p,p,p)
            px1[x,y]=(p[0]+S1.get(),p[1]+S1.get(),p[2]+S1.get())
    Ima2.save(""+dir_path+"\\Requirements\\ImageMod.png")
    im2 = ImageTk.PhotoImage(file=""+dir_path+"\\Requirements\\ImageMod.png")
    main.image = im2
    I2 = Tkinter.Label(main, image=im2)
    I2.grid(row=0, column=4, columnspan =4)

def AnnulerModifications():
    I2 = Tkinter.Label(main, image=im1)
    I2.grid(row=0, column=4, columnspan =4)

def get_pixel(pixels, x, y):
    try:
        return pixels[x, y]
    except IndexError:
        return None


def get_neighbors(pixels, x, y):
    neighbors = list()
    neighbors.append(get_pixel(pixels, x, y - 1))
    neighbors.append(get_pixel(pixels, x, y + 1))
    neighbors.append(get_pixel(pixels, x - 1, y))
    neighbors.append(get_pixel(pixels, x + 1, y))
    neighbors.append(get_pixel(pixels, x - 1, y - 1))
    neighbors.append(get_pixel(pixels, x - 1, y + 1))
    neighbors.append(get_pixel(pixels, x + 1, y - 1))
    neighbors.append(get_pixel(pixels, x + 1, y + 1))
    return neighbors


def filter_art(pixels, size):
    indexes = dict()
    for x in range(size[0]):
        for y in range(size[1]):
            color = get_pixel(pixels, x, y)
            neighbors = get_neighbors(pixels, x, y)
            new_color = Counter(neighbors).most_common()[0][0]
            if new_color is not None:
                indexes[x, y] = new_color
    for x, y in indexes:
        pixels[x, y] = indexes[x, y]


def pop_art(path_orig, path_mod, coef):

    s=[]
    for i in range(9):

        r=(randint(0,255), randint(0,255), randint(0,255))
        g=(randint(0,255), randint(0,255), randint(0,255))
        b=(randint(0,255), randint(0,255), randint(0,255))

        image_orig = Image.open(path_orig)
        size = image_orig.size
        image_mod = Image.new("RGB",(size[0],size[1]))
        pixels_orig = image_orig.load()
        pixels_mod = image_mod.load()
        for x in range(size[0]):
            for y in range(size[1]):
                p = pixels_orig[x, y]
                if isinstance(p, int):
                    rgb = (p,p,p)
                elif isinstance(p, tuple) and len(p) in (3, 4):
                    rgb = p[:3]
                else:
                    raise TypeError('Unknown pallete')
                average_color = sum(rgb) / 3
                if average_color <= 85:
                    pixels_mod[x, y] = r
                elif 85 < average_color <= 170:
                    pixels_mod[x, y] = g
                elif average_color > 170:
                    pixels_mod[x, y] = b
        for _ in range(coef):
            filter_art(pixels_mod, size)
        image_mod.save(''+dir_path+'\\PopArt\\Modified Images\\result'+str(i)+'.png')
        Img=[None]*9
    for i in range(9):
        Img[i]=Image.open(""+dir_path+"\\PopArt\\Modified Images\\result"+str(i)+".png")
        basewidth = int(Img[i].size[1]/3)
        wpercent = (basewidth / float(Img[i].size[0]))
        hsize = int((float(Img[i].size[1]) * float(wpercent )))
        Img[i] = Img[i].resize((basewidth , hsize ), PIL.Image.ANTIALIAS)
        Img[i].save(''+dir_path+'\\PopArt\\Resized Images\\resized_image'+str(i)+'.png')


    Img1=[None]*9
    pixels1=[None]*9
    Imaz=Image.new("RGB",(basewidth*3,hsize*3))
    pixels=Imaz.load()
    for i in range(9):
        Img1[i]=Image.open(''+dir_path+'\\PopArt\\Resized Images\\resized_image'+str(i)+'.png')
        pixels1[i]=Img1[i].load()


    for x in range(0,basewidth):
        for y in range(0,hsize):
            pixels[x,y]=pixels1[0][x,y]
        for y in range(hsize,hsize*2):
            pixels[x,y]=pixels1[1][x,y-hsize]
        for y in range(hsize*2,hsize*3):
            pixels[x,y]=pixels1[2][x,y-hsize*2]

    for x in range(basewidth,basewidth*2):
        for y in range(0,hsize):
            pixels[x,y]=pixels1[3][x-basewidth,y]
        for y in range(hsize,hsize*2):
            pixels[x,y]=pixels1[4][x-basewidth,y-hsize]
        for y in range(hsize*2,hsize*3):
            pixels[x,y]=pixels1[5][x-basewidth,y-hsize*2]

    for x in range(basewidth*2,basewidth*3):
        for y in range(0,hsize):
            pixels[x,y]=pixels1[6][x-basewidth*2,y]
        for y in range(hsize,hsize*2):
            pixels[x,y]=pixels1[7][x-basewidth*2,y-hsize]
        for y in range(hsize*2,hsize*3):
            pixels[x,y]=pixels1[8][x-basewidth*2,y-hsize*2]
    Imaz = Imaz.resize((size[0] , size[1] ), PIL.Image.ANTIALIAS)
    Imaz.save(""+dir_path+"\\PopArt\\Result Image\\result.png")


def usepop():
    im2 = ImageTk.PhotoImage(file=""+dir_path+"\\Requirements\\traitement.png")
    main.image = im2
    I2 = Tkinter.Label(main, image=im2)
    I2.grid(row=0, column=4, columnspan =4)
    I2.update_idletasks()
    pop_art(a, None, coef=4)
    im2 = ImageTk.PhotoImage(file=""+dir_path+"\\PopArt\\Result Image\\result.png")
    main.image = im2
    I2 = Tkinter.Label(main, image=im2)
    I2.grid(row=0, column=4, columnspan =4)

def change_contrast(level):

    img = Image.open(a)
    img.load()

    factor = (259 * (level+255)) / (255 * (259-level))
    for x in range(img.size[0]):
        for y in range(img.size[1]):
            color = img.getpixel((x, y))
            if type(color) == int:
                color=(color,color,color)
                new_color = tuple(int(factor * (c-128) + 128) for c in color)
                new_color = new_color[0]
                img.putpixel((x, y), new_color)
            elif type(color) != int:
                new_color = tuple(int(factor * (c-128) + 128) for c in color)
                img.putpixel((x, y), new_color)
    return img

def use_contrast():
    result = change_contrast(S2.get())
    result.save(""+dir_path+"\\Requirements\\ImageMod.png")
    im2 = ImageTk.PhotoImage(file=""+dir_path+"\\Requirements\\ImageMod.png")
    main.image = im2
    I2 = Tkinter.Label(main, image=im2)
    I2.grid(row=0, column=4, columnspan =4)

def recherche_contours():
    Ima2=Image.new("RGB",(z[0],z[1]))
    px=Ima1.load()
    px1=Ima2.load()
    for x in range(z[0]):
        for y in range(z[1]):
            p=px[x,y]
            if type(p)==int:
                p=(p,p,p)
            o=int((p[0]+p[1]+p[2])/3)
            px1[x,y]=(o,o,o)
    Ima2 = Ima2.filter(ImageFilter.FIND_EDGES)
    image = Ima2
    if image.mode == 'RGBA':
        r,g,b,a = image.split()
        rgb_image = Image.merge('RGB', (r,g,b))

        inverted_image = PIL.ImageOps.invert(rgb_image)

        r2,g2,b2 = inverted_image.split()

        final_transparent_image = Image.merge('RGBA', (r2,g2,b2,a))

        final_transparent_image.save(""+dir_path+"\\Requirements\\ImageMod.png")

    else:
        inverted_image = PIL.ImageOps.invert(image)
        inverted_image.save(""+dir_path+"\\Requirements\\ImageMod.png")
    im2 = ImageTk.PhotoImage(file=""+dir_path+"\\Requirements\\ImageMod.png")
    main.image = im2
    I2 = Tkinter.Label(main, image=im2)
    I2.grid(row=0, column=4, columnspan =4)

main=Tk()

main.withdraw()
try:
    a = filedialog.askopenfilename()
    main.deiconify()
except AttributeError:
    tkMessageBox.showinfo( "Resolution Error", "The image is too big, please select a smaller one.")
    sys.exit()


dir_path = os.path.dirname(os.path.realpath("Test2.py"))

main.configure(background="#a1dbcd")
main.title("Photoshop Version.Megzari")
try:
    Ima1=Image.open(a)
    z=Ima1.size
    nux=Image.new("RGB",(z[0],z[1]))
    nuxy=nux.load()
    for x in range(z[0]):
        for y in range(z[1]):
            nuxy[x,y]=(255,255,255)
    nux.save(""+dir_path+"\\Requirements\\Blank.png")


    main.withdraw()
    a = filedialog.askopenfilename()
except AttributeError:
    tkMessageBox.showinfo( "Image Error", "You didn't choose any image.")
    sys.exit()
main.deiconify()

if z>(400,400):
    main.withdraw()
    tkMessageBox.showinfo( "Resolution Error", "The image is too big, please select a smaller one.")
    sys.exit()

elif z<(400,400):
    im1 = ImageTk.PhotoImage(file=a)
    I1 = Tkinter.Label(main, image=im1)
    I1.grid(row=0, column=1, columnspan =3)
    imt = ImageTk.PhotoImage(file=""+dir_path+"\\Requirements\\Blank.png")
    T1 = Tkinter.Label(main, image=imt)
    T1.grid(row=0, column=4, columnspan =4)
    B1 = Tkinter.Button(main, text ="Echelle de gris", command = EchelleDeGris, fg="#a1dbcd", bg="#383a39", state=NORMAL)
    B1.grid(padx=20, pady=20, row=1, column=0)
    B3 = Tkinter.Button(main, text ="Appliquer Luminosité", command = Luminosite, fg="#a1dbcd", bg="#383a39")
    B3.grid(padx=20, pady=20, row=1, column=1)
    S1 = Scale(main, from_=0, to=254, orient=HORIZONTAL, fg="#a1dbcd", bg="#383a39", length = 200)
    S1.grid(row=2, column=1)
    B2 = Tkinter.Button(main, text ="Supprimer Image", command = SupprimerImage, fg="#a1dbcd", bg="#383a39")
    B2.grid(padx=20, pady=20, row=1, column=7)
    B3 = Tkinter.Button(main, text ="Annuler Modifications", command = AnnulerModifications, fg="#a1dbcd", bg="#383a39")
    B3.grid(padx=20, pady=20, row=1, column=6)
    B4 = Tkinter.Button(main, text ="Pop Art", command = usepop, fg="#a1dbcd", bg="#383a39")
    B4.grid(padx=20, pady=20, row=1, column=3)
    S2 = Scale(main, from_=-258, to=258, orient=HORIZONTAL, fg="#a1dbcd", bg="#383a39", length = 200)
    S2.grid(row=2, column=4)
    B4 = Tkinter.Button(main, text ="Appliquer Contraste", command = use_contrast, fg="#a1dbcd", bg="#383a39")
    B4.grid(padx=20, pady=20, row=1, column=4)
    B5 = Tkinter.Button(main, text ="Trouver Contours", command = recherche_contours, fg="#a1dbcd", bg="#383a39")
    B5.grid(padx=20, pady=20, row=1, column=5)

    s=S1.get()
    s2=S2.get()




main.mainloop()

编辑1： 我应用了来自@Juan T的答案，它确实显示了消息，但是它没有关闭窗口，即使我启动了sys.exit()

编辑2： 我发现如何修复它我所要做的就是在sys.exit()之前添加main.destroy()

编辑3： 现在，当我运行代码时，我选择了图像，它再次提示我输入图像。我要它提示它一次。你知道吗

EDIT4：我修复了它，问题是我在代码中隐藏了一个旧的代码片段，导致了问题，现在一切正常。你知道吗

Answer 1

如果将try放在。所以，不是：

Ima1=Image.open(a)
z=Ima1.size
...
nux.save(""+dir_path+"\\Requirements\\Blank.png")


main.withdraw()
try:
    a = filedialog.askopenfilename()
except AttributeError:
    tkMessageBox.showinfo( "Image Error", "You didn't choose any image.")
    sys.exit()
main.deiconify()

考虑：

try:
    Ima1=Image.open(a)
    z=Ima1.size
    ...
    nux.save(""+dir_path+"\\Requirements\\Blank.png")

    main.withdraw()

    a = filedialog.askopenfilename()
except AttributeError:
    tkMessageBox.showinfo( "Image Error", "You didn't choose any image.")
    sys.exit()
main.deiconify()