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如何获取截图并更改剪贴板上的DPI?

win32gui dpi screenshot python-imaging-library python-3.x

1

theozh · 技术社区 · 6 年前

在Win7下,我想获取剪贴板上窗口的内容,设置/调整剪贴板上的DPI设置并将其复制到最终应用程序。

下面的MCVE尚未按预期工作。有时很明显窗口还没有设置为前景,并且 ImageGrab.grab(bbox)

代码如下:

from io import BytesIO
from PIL import Image,ImageGrab
import win32gui, win32clipboard
import time

def get_screenshot(window_name, dpi):
    hwnd = win32gui.FindWindow(None, window_name)
    if hwnd != 0:
        win32gui.SetForegroundWindow(hwnd)
        time.sleep(2)  ### sometimes window is not yet in foreground. delay/timing problem???
        bbox = win32gui.GetWindowRect(hwnd)
        screenshot = ImageGrab.grab(bbox)
        width, height = screenshot.size
        lmargin = 9
        tmargin = 70
        rmargin = 9
        bmargin = 36
        screenshot = screenshot.crop(box = (lmargin,tmargin,width-rmargin,height-bmargin))
        win32clipboard.OpenClipboard()
        win32clipboard.EmptyClipboard()
        output = BytesIO()
        screenshot.convert("RGB").save(output, "BMP", dpi=(dpi,dpi))
        data = output.getvalue()[14:]
        output.close()
        win32clipboard.SetClipboardData(win32clipboard.CF_DIB, data)
        win32clipboard.CloseClipboard()
        print("Screenshot taken...")
    else:
        print("No window found named:", window_name)

window_name = "Gnuplot (window id : 0)"
get_screenshot(window_name,200)

编辑:

而且这种改进的尝试有时还是会得到错误的内容。也许有人能解释为什么?

win32gui.SetForegroundWindow(hwnd)
for i in range(1000):
    print(i)
    time.sleep(0.01)
    if win32gui.GetForegroundWindow() == hwnd:
        break
bbox = win32gui.GetWindowRect(hwnd)

增加:

这就是我(通常)在延迟时间移除线路时得到的结果 time.sleep(2)

左: 想要的内容, 收到的内容。我怎样才能在所需的窗口中可靠地捕获内容?密码怎么了?设置的延迟时间越大,获得所需内容的概率就越高。但我不想等几秒钟才确定。如何检查系统是否已准备好进行屏幕截图?

0 回复 | 直到 5 年前

1

0

theozh 5 年前

感谢@Tarun Lalwani指出 this answer ,我终于有了一个暂时为我工作的代码。然而,在我看来,这是相当长的与许多不同的模块。也许它仍然可以简化。欢迎提出建议。

代码:

### get the content of a window and crop it
import win32gui, win32ui, win32clipboard
from io import BytesIO
from ctypes import windll
from PIL import Image

# user input
window_name = 'Gnuplot (window id : 0)'
margins = [8,63,8,31]    # left, top, right, bottom
dpi = 96

hwnd = win32gui.FindWindow(None, window_name)
left, top, right, bottom = win32gui.GetWindowRect(hwnd)
width = right - left 
height = bottom - top
crop_box = (margins[0],margins[1],width-margins[2],height-margins[3])

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

saveBitMap = win32ui.CreateBitmap()
saveBitMap.CreateCompatibleBitmap(mfcDC, width, height)
saveDC.SelectObject(saveBitMap)
result = windll.user32.PrintWindow(hwnd, saveDC.GetSafeHdc(), 0)
bmpinfo = saveBitMap.GetInfo()
bmpstr = saveBitMap.GetBitmapBits(True)

im = Image.frombuffer( 'RGB', (bmpinfo['bmWidth'], bmpinfo['bmHeight']),
    bmpstr, 'raw', 'BGRX', 0, 1).crop(crop_box)
win32clipboard.OpenClipboard()
win32clipboard.EmptyClipboard()
output = BytesIO()
im.convert("RGB").save(output, "BMP", dpi=(dpi,dpi))
data = output.getvalue()[14:]
output.close()
win32clipboard.SetClipboardData(win32clipboard.CF_DIB, data)
win32clipboard.CloseClipboard()

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

print('"'+window_name+'"', "is now on the clipboard with", dpi, "dpi.")
### end of code

2

0

Tarun Lalwani 5 年前

如前所述,您可以使用下面讨论的方法

Python Screenshot of inactive window PrintWindow + win32gui

import win32gui
import win32ui
from ctypes import windll
import Image

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

# 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")