(WinApi) ChangeDisplaySettingsEx 不起作用

Question

我正在尝试编写一个 python 脚本来切换主监视器。 我有 3 台显示器（一台插入 i5 的图形芯片，两台插入 ATI HD7870）

我写了以下脚本：

import win32api as w
import win32con as c

i = 0
workingDevices = []

def setPrimary(id):
    global workingDevices
    return w.ChangeDisplaySettingsEx(
        workingDevices[id].DeviceName,
        w.EnumDisplaySettings(
            workingDevices[id].DeviceName,
            c.ENUM_CURRENT_SETTINGS
            ),
        c.CDS_SET_PRIMARY | c.CDS_UPDATEREGISTRY | c.CDS_RESET) \
        == c.DISP_CHANGE_SUCCESSFUL

while True:
    try:
        Device = w.EnumDisplayDevices(None, i, 1)
        if Device.StateFlags & c.DISPLAY_DEVICE_ATTACHED_TO_DESKTOP: #Attached to desktop
            workingDevices.append(Device)

        i += 1
    except:
        break

print("Num Devices: ", len(workingDevices))

for dev in workingDevices:
    print("Name: ", dev.DeviceName)

调用它会导致：

In [192]: %run test.py
Num Devices:  3
Name:  \\.\DISPLAY1
Name:  \\.\DISPLAY2
Name:  \\.\DISPLAY7

In [193]: setPrimary(0)
Out[193]: True

In [194]: setPrimary(1)
Out[194]: True

In [195]: setPrimary(2)
Out[195]: True

到目前为止，它看起来不错，但问题是：没有任何变化。由于 CDS_RESET，我的显示器很快闪烁，但主屏幕没有改变，尽管 ChangeDisplaySettingsEx 返回 DISP_CHANGE_SUCCESSFUL

有人知道为什么吗？ （我使用 Python 3.5.1 和 PyWin32 build 220）

PS 我使用 1 作为 EnumDisplayDevices 的第三个参数，因为 msdn 声明它应该设置为 1，尽管 PyWin 帮助说它应该设置为 0。 但是脚本的行为不会独立于这个值是一或零而改变

Answer 1

好的，我找到了解决方案。 显然，主监视器必须始终位于位置 (0, 0)。 因此，当我尝试将另一台显示器设置为主显示器时，它的位置设置为 (0, 0)，这导致它与旧的主显示器相交。 似乎要走的路是更新所有监视器的位置，并将这些更改写入注册表，然后一旦完成，通过使用默认参数调用 ChangeDisplaySettingsEx() 来应用更改。 这是我的新（正在使用）代码：

import win32api as w
import win32con as c

def load_device_list():
    """loads all Monitor which are plugged into the pc
    The list is needed to use setPrimary
    """
    workingDevices = []
    i = 0
    while True:
        try:
            Device = w.EnumDisplayDevices(None, i, 0)
            if Device.StateFlags & c.DISPLAY_DEVICE_ATTACHED_TO_DESKTOP: #Attached to desktop
                workingDevices.append(Device)

            i += 1
        except:
            return workingDevices


def setPrimary(id, workingDevices, MonitorPositions):
    """
    param id: index in the workingDevices list.
              Designates which display should be the new primary one

    param workingDevices: List of Monitors returned by load_device_list()

    param MonitorPositions: dictionary of form {id: (x_position, y_position)}
                            specifies the monitor positions

    """

    FlagForPrimary = c.CDS_SET_PRIMARY | c.CDS_UPDATEREGISTRY | c.CDS_NORESET
    FlagForSec = c.CDS_UPDATEREGISTRY | c.CDS_NORESET
    offset_X = - MonitorPositions[id][0]
    offset_Y = - MonitorPositions[id][1]
    numDevs = len(workingDevices)

    #get devmodes, correct positions, and update registry
    for i in range(numDevs):
        devmode = w.EnumDisplaySettings(workingDevices[i].DeviceName, c.ENUM_CURRENT_SETTINGS)
        devmode.Position_x = MonitorPositions[i][0] + offset_X
        devmode.Position_y = MonitorPositions[i][1] + offset_Y
        if(w.ChangeDisplaySettingsEx(workingDevices[i].DeviceName, devmode, 
            FlagForSec if i != id else FlagForPrimary) \
            != c.DISP_CHANGE_SUCCESSFUL): return False

    #apply Registry updates once all settings are complete
    return w.ChangeDisplaySettingsEx() == c.DISP_CHANGE_SUCCESSFUL;

if(__name__ == "__main__"):
    devices = load_device_list()
    for dev in devices:
        print("Name: ", dev.DeviceName)

    MonitorPositions = {
        0: (0, -1080),
        1: (0, 0),
        2: (1920, 0)
    }

    setPrimary(0, devices, MonitorPositions)