以鼠标位置进行图像非中心zoom

# 以鼠标位置进行图像非中心zoom
import tkinter as tk
from PIL import Image, ImageTk

image_show_width = 800
image_show_height = 600
window_width = image_show_width
window_height = image_show_height+120

root = tk.Tk()
root.geometry(f"{window_width}x{window_height}+800+50") 

# 创建标签用于显示图片    
label_imgshow = tk.Label(root, text="拖拽图片到这里", width=image_show_width, height=image_show_height, bg="lightgrey") 
label_imgshow.place(x = 0, y=0, width=image_show_width, height=image_show_height, bordermode = 'outside')


original_image = Image.open('test.png')
photo_image = ImageTk.PhotoImage(original_image)

# 更新Label中的图像
label_imgshow.config(image = photo_image)
label_imgshow.image = photo_image

width, height = original_image.size
print(width, height)
imgAdapting_display = original_image.resize((image_show_width, image_show_height), Image.LANCZOS)

zoom_value = 1.0

class Rect:
       def __init__(self, x = 0, y = 0, width = 0, height = 0):
           self.x = x
           self.y = y
           self.width = width
           self.height = height

class Point:
       def __init__(self, x = 0, y = 0):
           self.x = x
           self.y = y
import time
def timebegin():
    # 记录开始时间
    # global start_time
    start_time = time.time()
    return start_time

def timeend(code_blokc, start_time):
    # 记录结束时间
    # global end_time
    end_time = time.time()
    # 计算耗时（单位：秒）
    elapsed_time = end_time - start_time
    # print(code_blokc + f" 代码块耗时: {elapsed_time} 秒")

def zoom(event):
    # 1 imgAdapting_display用于控件显示的1x倍率图像，FOV为原始FOV, 大小与控件大小一致
    # 2 imgZoom是根据当前zoom_value，缩放的图像，FOV为原始FOV
    # 3 cropped_show_image 图像大小控件大小一致， FOV不确定
    start_time = timebegin()

    global zoom_value
    # 鼠标位置在图像显示控件的相对坐标
    # 获取鼠标位置或其他指定的缩放触发点位置
    ptMouse = Point(event.x, event.y)
    print("ptMouse ", ptMouse.x, ptMouse.y)
    scalestep = 1.21

    showRect = Rect(0,0,image_show_width,image_show_height)

    bIsImgSmallToDispCtrl = False
    if (event.delta  > 0):#放大图片
        if (zoom_value > 5):
            return
        else:
            zoom_value = zoom_value * scalestep;
    elif (event.delta < 0): #缩小图片
        zoom_value /= scalestep

    print("zoom_value ", zoom_value)

    zoom_width = int(image_show_width * zoom_value)
    zoom_height = int(image_show_height * zoom_value)

    timeend("mgAdapting_display.resize pre", start_time)

    start_time = timebegin()

    imgZoom = imgAdapting_display.resize((zoom_width, zoom_height), Image.LANCZOS)

    timeend("mgAdapting_display.resize", start_time)

    start_time = timebegin()

    #保持图像放大后，鼠标所指向的像素位置与原始像素位置一致
    showRect.x = zoom_value * ptMouse.x - ptMouse.x
    showRect.y = zoom_value * ptMouse.y - ptMouse.y

    showRect.width = image_show_width
    showRect.height = image_show_height
    
    if showRect.x < 0:
        showRect.x = abs(showRect.x)
        bIsImgSmallToDispCtrl = True
    if showRect.y < 0:
        showRect.y = abs(showRect.y)
        bIsImgSmallToDispCtrl = True

    showRect.x = int(showRect.x)
    showRect.y = int(showRect.y)

    print("bIsImgSmallToDispCtrl ", bIsImgSmallToDispCtrl)

    if bIsImgSmallToDispCtrl == True:
        # imgZoom的图像，此时属于显示图像已经比原始图像小了，然后进行放大，不需要进行crop，直接显示imgZoom
        cropped_show_image = imgZoom
    else:
        #imgZoom的图像比原始图像大，从imgZoom的图像中crop一块区域进行显示，crop的大小为显示控件的size
        left = showRect.x
        top = showRect.y
        width = showRect.width
        height = showRect.height
        crop_rect = (left, top, left + width, top + height)
        cropped_show_image = imgZoom.crop(crop_rect)

    timeend("cropped_show_image ", start_time)

    start_time = timebegin()

    # 更新Label中的图像
    photo_image = ImageTk.PhotoImage(cropped_show_image)
    label_imgshow.config(image = photo_image)
    label_imgshow.image = photo_image

    timeend("更新Label中的图像 ", start_time)


label_imgshow.bind("<MouseWheel>", zoom)
root.mainloop()