非活动窗口 PrintWindow + win32gui 的屏幕截图

问题描述：

经过几个小时的谷歌搜索，我设法“写”了这个：

import win32gui
from ctypes import windll

hwnd = win32gui.FindWindow(None, 'Steam')

hdc = win32gui.GetDC(hwnd)
hdcMem = win32gui.CreateCompatibleDC(hdc)
    
hbitmap = win32ui.CreateBitmap()
hbitmap = win32gui.CreateCompatibleBitmap(hdcMem, 500, 500)
    
win32gui.SelectObject(hdcMem, hbitmap)
    
windll.user32.PrintWindow(hwnd, hdcMem, 0)

这是正确的方法吗？我该如何保存图像？

解决方案 1：

经过大量搜索并尝试各种不同的方法后，以下方法对我有用。

import win32gui
import win32ui
from ctypes import windll
from PIL import Image

hwnd = win32gui.FindWindow(None, 'Calculator')

# Uncomment the following line if you use a high DPI display or >100% scaling size
# windll.user32.SetProcessDPIAware()

# Change the line below depending on whether you want the whole window
# or just the client area. 
#left, top, right, bot = win32gui.GetClientRect(hwnd)
left, top, right, bot = win32gui.GetWindowRect(hwnd)
w = right - left
h = bot - top

hwndDC = win32gui.GetWindowDC(hwnd)
mfcDC  = win32ui.CreateDCFromHandle(hwndDC)
saveDC = mfcDC.CreateCompatibleDC()

saveBitMap = win32ui.CreateBitmap()
saveBitMap.CreateCompatibleBitmap(mfcDC, w, h)

saveDC.SelectObject(saveBitMap)

# Change the line below depending on whether you want the whole window
# or just the client area. 
#result = windll.user32.PrintWindow(hwnd, saveDC.GetSafeHdc(), 1)
result = windll.user32.PrintWindow(hwnd, saveDC.GetSafeHdc(), 0)
print result

bmpinfo = saveBitMap.GetInfo()
bmpstr = saveBitMap.GetBitmapBits(True)

im = Image.frombuffer(
    'RGB',
    (bmpinfo['bmWidth'], bmpinfo['bmHeight']),
    bmpstr, 'raw', 'BGRX', 0, 1)

win32gui.DeleteObject(saveBitMap.GetHandle())
saveDC.DeleteDC()
mfcDC.DeleteDC()
win32gui.ReleaseDC(hwnd, hwndDC)

if result == 1:
    #PrintWindow Succeeded
    im.save("test.png")

解决方案 2：

这是我的更完整的脚本，它具有与 相同的效果ALT + PrtSc。

它打印带有 1px 边框的整个窗口。（如果最大化则无边框）

我们可以像组合一样将其复制到剪贴板。

或者我们可以将其转换为 PIL 图像并保存。

import ctypes, win32con, win32gui
import win32clipboard as w32clip
from struct import pack, calcsize
from ctypes import windll, wintypes
from PIL import Image
user32,gdi32 = windll.user32,windll.gdi32
PW_RENDERFULLCONTENT = 2

def getWindowBMAP(hwnd,returnImage=False):
    # get Window size and crop pos/size
    L,T,R,B = win32gui.GetWindowRect(hwnd); W,H = R-L,B-T
    x,y,w,h = (8,8,W-16,H-16) if user32.IsZoomed(hwnd) else (7,0,W-14,H-7)

    # create dc's and bmp's
    dc = user32.GetWindowDC(hwnd)
    dc1,dc2 = gdi32.CreateCompatibleDC(dc),gdi32.CreateCompatibleDC(dc)
    bmp1,bmp2 = gdi32.CreateCompatibleBitmap(dc,W,H),gdi32.CreateCompatibleBitmap(dc,w,h)

    # render dc1 and dc2 (bmp1 and bmp2) (uncropped and cropped)
    obj1,obj2 = gdi32.SelectObject(dc1,bmp1),gdi32.SelectObject(dc2,bmp2) # select bmp's into dc's
    user32.PrintWindow(hwnd,dc1,PW_RENDERFULLCONTENT) # render window to dc1
    gdi32.BitBlt(dc2,0,0,w,h,dc1,x,y,win32con.SRCCOPY) # copy dc1 (x,y,w,h) to dc2 (0,0,w,h)
    gdi32.SelectObject(dc1,obj1); gdi32.SelectObject(dc2,obj2) # restore dc's default obj's

    if returnImage: # create Image from bmp2
        data = ctypes.create_string_buffer((w*4)*h)
        bmi = ctypes.c_buffer(pack("IiiHHIIiiII",calcsize("IiiHHIIiiII"),w,-h,1,32,0,0,0,0,0,0))
        gdi32.GetDIBits(dc2,bmp2,0,h,ctypes.byref(data),ctypes.byref(bmi),win32con.DIB_RGB_COLORS)
        img = Image.frombuffer('RGB',(w,h),data,'raw','BGRX')

    # clean up
    gdi32.DeleteObject(bmp1) # delete bmp1 (uncropped)
    gdi32.DeleteDC(dc1); gdi32.DeleteDC(dc2) # delete created dc's
    user32.ReleaseDC(hwnd,dc) # release retrieved dc

    return (bmp2,w,h,img) if returnImage else (bmp2,w,h)

def copyBitmap(hbmp): # copy HBITMAP to clipboard
    w32clip.OpenClipboard(); w32clip.EmptyClipboard()
    w32clip.SetClipboardData(w32clip.CF_BITMAP,hbmp); w32clip.CloseClipboard()

def copySnapshot(hwnd): # copy Window HBITMAP to clipboard
    hbmp,w,h = getWindowBMAP(hwnd); copyBitmap(hbmp); gdi32.DeleteObject(hbmp)

def getSnapshot(hwnd): # get Window HBITMAP as Image
    hbmp,w,h,img = getWindowBMAP(hwnd,True); gdi32.DeleteObject(hbmp); return img


hwnd = windll.kernel32.GetConsoleWindow()                         # Console
if not hwnd: hwnd = user32.FindWindowW("Notepad",None)            # Notepad
if not hwnd: hwnd = user32.FindWindowW("Chrome_WidgetWin_1",None) # Chrome
if not hwnd: hwnd = user32.FindWindowW("CabinetWClass",None)      # Windows Explorer

if not hwnd: print("Couldn't find Window")
elif user32.IsIconic(hwnd): print("Window is minimized")
else:
    print(win32gui.GetWindowText(hwnd))
    print(win32gui.GetClassName(hwnd))
    copySnapshot(hwnd)
    img = getSnapshot(hwnd)
    img.save("snapshot.png")
    #img.show()
    print("Snapshot Saved!")

解释：

如果我们做了基本的PrintWindow，它会呈现 Windows 7 样式的框架/边框，其左侧/右侧/底部的边框要厚 7 个像素。它也位于顶部，但仅在最大化时才如此。

我们可以使用隐藏标志PW_RENDERFULLCONTENT来正确渲染，但额外的边框空间仍然存在并且保持空白。所以我们的图像被厚厚的黑色边框填充。

所以我们需要裁剪我们的 HBITMAP。

为此，我们可以创建一个新的位图并使用BitBlt第一个位图的DC作为源。

从这里我们可以win32clipboard像 一样复制 HBITMAP ALT + PrtSc。

HBITMAP 到 PIL：

我们可以用来GetDIBits获取大小数组中的原始像素数据w*h*4。

它需要结构来BITMAPINFOHEADER接收width、、、height。planes`bitCount`

一种方法是：

class BITMAPINFOHEADER(ctypes.Structure):
    _fields_ = [
        ("biSize", wintypes.DWORD),
        ("biWidth", ctypes.c_long),
        ("biHeight", ctypes.c_long),
        ("biPlanes", wintypes.WORD),
        ("biBitCount", wintypes.WORD),
        ("biCompression", wintypes.DWORD),
        ("biSizeImage", wintypes.DWORD),
        ("biXPelsPerMeter", ctypes.c_long),
        ("biYPelsPerMeter", ctypes.c_long),
        ("biClrUsed", wintypes.DWORD),
        ("biClrImportant", wintypes.DWORD)
    ]
    def __init__(self,w,h,p=1,b=32):
        self.biSize = ctypes.sizeof(BITMAPINFOHEADER)
        self.biWidth,self.biHeight,self.biPlanes,self.biBitCount = w,h,p,b

bmi = BITMAPINFOHEADER(w,-h) # we use -h to flip the image also

但更紧凑的方式是：

bmi = ctypes.c_buffer(pack("IiiHHIIiiII",calcsize("IiiHHIIiiII"),w,-h,1,32,0,0,0,0,0,0))

我们用来struct将值打包为特定的数据类型。

i = int            (c_long)
I = unsigned int   (DWORD)
H = unsigned short (WORD)

我们用它calcsize("IiiHHIIiiII")来做相当于的事情ctypes.sizeof(BITMAPINFOHEADER)。

以下是如何获取客户端的方法：

PW_CLIENTONLY,PW_RENDERFULLCONTENT = 1,2

def getClientBMAP(hwnd,returnImage=False):
    # get Client size
    L,T,R,B = win32gui.GetClientRect(hwnd); w,h = R-L,B-T

    # create dc's and bmp's
    dc = user32.GetWindowDC(hwnd)
    dc1 = gdi32.CreateCompatibleDC(dc)
    bmp1 = gdi32.CreateCompatibleBitmap(dc,w,h)

    # render dc1 (bmp1)
    obj1 = gdi32.SelectObject(dc1,bmp1) # select bmp into dc
    user32.PrintWindow(hwnd,dc1,PW_CLIENTONLY|PW_RENDERFULLCONTENT) # render window to dc1
    gdi32.SelectObject(dc1,obj1) # restore dc's default obj

    if returnImage: # create Image from bmp1
        data = ctypes.create_string_buffer((w*4)*h)
        bmi = ctypes.c_buffer(pack("IiiHHIIiiII",calcsize("IiiHHIIiiII"),w,-h,1,32,0,0,0,0,0,0))
        gdi32.GetDIBits(dc1,bmp1,0,h,ctypes.byref(data),ctypes.byref(bmi),win32con.DIB_RGB_COLORS)
        img = Image.frombuffer('RGB',(w,h),data,'raw','BGRX')

    # clean up
    gdi32.DeleteDC(dc1) # delete created dc
    user32.ReleaseDC(hwnd,dc) # release retrieved dc

    return (bmp1,w,h,img) if returnImage else (bmp1,w,h)

def getClientSnapshot(hwnd): # get Client HBITMAP as Image
    hbmp,w,h,img = getClientBMAP(hwnd,True); gdi32.DeleteObject(hbmp); return img