Python tkinter 画布透明 [英] Python tkinter canvas transparent
问题描述
我想让 tkinter 画布的背景透明，但仍然有画布的鼠标事件，这是我的代码，我在 Windows 10，Python 3.6 上:
I am looking to make the background of the tkinter canvas transparent, but still have Mouse events of the canvas, here is my code, I am on Windows 10, Python 3.6:
from tkinter import *
import time
WIDTH = 500
HEIGHT = 500
LINEWIDTH = 1
TRANSCOLOUR = 'gray'
global old
old = ()
tk = Tk()
tk.title('Virtual whiteboard')
tk.wm_attributes('-transparentcolor', TRANSCOLOUR)
canvas = Canvas(tk, width=WIDTH, height=HEIGHT)
canvas.pack()
canvas.config(cursor='tcross')
canvas.create_rectangle(0, 0, WIDTH, HEIGHT, fill=TRANSCOLOUR, outline=TRANSCOLOUR)
def buttonmotion(evt):
global old
if old == ():
old = (evt.x, evt.y)
return
else:
canvas.create_line(old[0], old[1], evt.x, evt.y, width=LINEWIDTH)
old = (evt.x, evt.y)
def buttonclick(evt):
global old
canvas.create_line(evt.x-1, evt.y-1, evt.x, evt.y, width=LINEWIDTH)
old = (evt.x, evt.y)
canvas.bind('<Button-1>', buttonmotion)
canvas.bind('<B1-Motion>', buttonclick)
while True:
tk.update()
time.sleep(0.01)
当运行代码时，它制作了一个透明的背景，但我选择了下面的东西，而不是画布.
When run the code, it makes a transparent background, but I select the things under, instead of the canvas.
推荐答案
我在 win api 的帮助下构建了一个小解决方法，这是我的建议:
I build a little workaround with the help of the win api, here is my suggestion:
from tkinter import *
import time
import win32gui
import win32api
WIDTH = 500
HEIGHT = 500
LINEWIDTH = 1
TRANSCOLOUR = 'gray'
title = 'Virtual whiteboard'
global old
old = ()
global HWND_t
HWND_t = 0
tk = Tk()
tk.title(title)
tk.lift()
tk.wm_attributes("-topmost", True)
tk.wm_attributes("-transparentcolor", TRANSCOLOUR)
state_left = win32api.GetKeyState(0x01) # Left button down = 0 or 1. Button up = -127 or -128
canvas = Canvas(tk, width=WIDTH, height=HEIGHT)
canvas.pack()
canvas.config(cursor='tcross')
canvas.create_rectangle(0, 0, WIDTH, HEIGHT, fill=TRANSCOLOUR, outline=TRANSCOLOUR)
def putOnTop(event):
event.widget.unbind('<Visibility>')
event.widget.update()
event.widget.lift()
event.widget.bind('<Visibility>', putOnTop)
def drawline(data):
global old
if old !=():
canvas.create_line(old[0], old[1], data[0], data[1], width=LINEWIDTH)
old = (data[0], data[1])
def enumHandler(hwnd, lParam):
global HWND_t
if win32gui.IsWindowVisible(hwnd):
if title in win32gui.GetWindowText(hwnd):
HWND_t = hwnd
win32gui.EnumWindows(enumHandler, None)
tk.bind('<Visibility>', putOnTop)
tk.focus()
running = 1
while running == 1:
try:
tk.update()
time.sleep(0.01)
if HWND_t != 0:
windowborder = win32gui.GetWindowRect(HWND_t)
cur_pos = win32api.GetCursorPos()
state_left_new = win32api.GetKeyState(0x01)
if state_left_new != state_left:
if windowborder[0] < cur_pos[0] and windowborder[2] > cur_pos[0] and windowborder[1] < cur_pos[1] and windowborder[3] > cur_pos[1]:
drawline((cur_pos[0] - windowborder[0] - 5, cur_pos[1] - windowborder[1] - 30))
else:
old = ()
except Exception as e:
running = 0
print("error %r" % (e))
新码位截图说明:
tk.lift()
tk.wm_attributes("-topmost", True)
...
def putOnTop(event):
event.widget.unbind('<Visibility>')
event.widget.update()
event.widget.lift()
event.widget.bind('<Visibility>', putOnTop)
...
tk.bind('<Visibility>', putOnTop)
tk.focus()
这些行确保窗口始终位于所有其他窗口之上.
These lines ensure, that the window will be always be on top of all other windows.
global HWND_t
HWND_t = 0
...
def enumHandler(hwnd, lParam):
global HWND_t
if win32gui.IsWindowVisible(hwnd):
if title in win32gui.GetWindowText(hwnd):
HWND_t = hwnd
win32gui.EnumWindows(enumHandler, None)
此代码位将遍历当前显示的所有窗口并捕获白板窗口的句柄(确保标题唯一，否则可能会捕获错误的句柄).
This code bit will go through all the windows currently displayed and catches the handle of the whiteboard window (make sure the title is unique, or this could capture the wrong handle).
state_left = win32api.GetKeyState(0x01)
...
if HWND_t != 0:
windowborder = win32gui.GetWindowRect(HWND_t)
cur_pos = win32api.GetCursorPos()
state_left_new = win32api.GetKeyState(0x01)
if state_left_new != state_left:
if windowborder[0] < cur_pos[0] and windowborder[2] > cur_pos[0] and windowborder[1] < cur_pos[1] and windowborder[3] > cur_pos[1]:
drawline((cur_pos[0] - windowborder[0] - 5, cur_pos[1] - windowborder[1] - 30))
else:
old = ()
这个
- 检查是否找到句柄
- 检查鼠标按钮 1 是否被点击
- 检查鼠标是否在窗口内
如果全部为真，则获取鼠标数据并绘制线条
if all is true, it takes the mouse data and draws the line
当前的模式是，它在按钮被点击之前不绘制任何东西，然后在按钮被再次点击之前绘制.
the current mode is, that it doesn't draw anything till the button is clicked and then draws until the button is clicked again.
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