Python键盘库方向键问题答案

【问题标题】：Python keyboard library arrow keys problemPython键盘库方向键问题
【发布时间】：2019-03-03 20:55:47
【问题描述】：

我正在编写一个脚本，它会截取屏幕截图并解码以图像名称命名的特定按键，如下所示。我的问题是，当我按下左键盘箭头时，也按下了数字 4。我在谷歌或键盘库的文档中找不到任何东西。我正在使用 Windows 和 Python 3.6.5

(75,)
left arrow pressed
(5, 75)
4 pressed

向下箭头也会发生同样的事情，但数字 3 是这样的。

(80,)
down arrow pressed
(3, 80)
2 pressed

代码：

from PIL import ImageGrab
import keyboard  # using module keyboard
import time

keys = [
    "down arrow",
    "up arrow",
    "left arrow",
    "right arrow",
    "w",
    "s",
    "a",
    "d",
    "1",
    "2",
    "3",
    "4",
    "q",

"e", “F” ]

if __name__ == "__main__":
    while True:
        code = []
        try:
            for key in keys:
                if keyboard.is_pressed(key):
                    print(keyboard.key_to_scan_codes(key))
                    print(f"{key} pressed")
                    code.append(1)
                else:
                    code.append(0)
                    
            if keyboard.is_pressed('esc'):
                print(key + " pressed")
                break
                
            c = "".join(map(str, code))
            snapshot = ImageGrab.grab()
            save_path = str(int(time.time()*1000)) + "-" + c + ".jpg"
            snapshot.save("tmp\\" + save_path)

        except:
            break

【问题讨论】：

标签： python keyboard

【解决方案1】：

keyboard 模块为此类实例提供了简单的解决方案，它们使用event-triggered 激活而不是您尝试使用的polling。

示例代码：

import keyboard

def handleLeftKey(e):
    if keyboard.is_pressed("4"):
        print("left arrow was pressed w/ key 4")
        # work your magic

keyboard.on_press_key("left", handleLeftKey)
# self-explanitory: when the left key is pressed down then do something

keyboard.on_release_key("left", handleLeftKey02)
# also self-explanitory: when the left key is released then do something

# don't use both ...on_release & ...on_press or it will be
# triggered twice per key-use (1 up, 1 down)

替换下面的代码并根据您的需要进行更改。

if __name__ == "__main__":
    while True:
        code = []
        try:
            for key in keys:
                if keyboard.is_pressed(key):
                    print(keyboard.key_to_scan_codes(key))
                    print(f"{key} pressed")
                    code.append(1)
                else:
                    code.append(0)

另一种更动态的方法如下所示：

import keyboard

keys = [
    "down",
    "up",
    "left",
    "right",
    "w",
    "s",
    "a",
    "d",
    "1",
    "2",
    "3",
    "4",
    "q",
    "e",
    "f"
]

def kbdCallback(e):
    found = False
    for key in keys:
        if key == keyboard.normalize_name(e.name):
            print(f"{key} was pressed")
            found = True
            # work your magic

    if found == True:
        if e.name == "left":
            if keyboard.is_pressed("4"):
                print("4 & left arrow were pressed together!")
                # work your magic

keyboard.on_press(kbdCallback)
# same as keyboard.on_press_key, but it does this for EVERY key

我注意到的另一个问题是您使用"left arrow"，而实际上它被识别为"left"（至少在我的系统上，它可能在您的系统上有所不同，但我假设您希望它在所有系统上都能正常工作，所以改用"left" 会更安全）

您可以使用的最后一种方法是非常静态类型的并且没有动态功能，但可以在 "4+left" 或 "left+4" 的情况下使用

import keyboard

def left4trigger:
    print("the keys were pressed")

keyboard.add_hotkey("4+left", left4trigger)
# works as 4+left or left+4 (all of the examples do)

你看起来很聪明，可以从那里弄清楚其余的事情。

【讨论】：

在ImportError: You must be root to use this library on linux.之前看起来是一个很棒的解决方案

【解决方案2】：

您可能需要先停用 NumLock 按钮。当 NumLock 处于活动状态时，我在按 Shift 键时遇到一些问题。

【讨论】：

很遗憾，一切都没有改变

【解决方案3】：

当心，语言可能会起作用！在我的情况下，“向上”箭头已翻译为我的本地语言，您可以运行以下代码来获取您计算机的键值：

import keyboard    
def onkeypress(event):
    print(event.name)

keyboard.on_press(onkeypress)

#Use ctrl+c to stop
while True:
    pass

【讨论】：