在Python中读取屏幕像素的方法比PIL更快？

Question

目前我正在通过AutoItv3使用像素阅读器在运行直接X的程序中执行某些操作; 一个游戏.现在该程序工作正常,但作为一个练习我一直在python中重写它.现在我可以这样做:

import ImageGrab  # Part of PIL
    image = ImageGrab.grab() #Define an area to capture.
    rgb = image.getpixel((1, 90)) #What pixel do we want?

并且我抓住了我想要的像素信息,但我很快就完成了这项工作(需要每秒3次或更快),但结果是它主要影响这款基于DirectX的游戏的帧速率.

Python中有没有更快的方法来读取特定的屏幕像素？即使将此限制为每0.3秒运行一次也会造成比实际应用更多的压力(我实际上认为python会比AutoIt 更快用于此特定目的,因此我正在尝试它的原因)

Answer 1

这是PIL的抓取源,它不接受任何参数,它抓住整个屏幕并将其转换为位图.

PyImaging_GrabScreenWin32(PyObject* self, PyObject* args)
{
    int width, height;
    HBITMAP bitmap;
    BITMAPCOREHEADER core;
    HDC screen, screen_copy;
    PyObject* buffer;

    /* step 1: create a memory DC large enough to hold the
       entire screen */

    screen = CreateDC(";DISPLAY", NULL, NULL, NULL); 
    screen_copy = CreateCompatibleDC(screen); 

    width = GetDeviceCaps(screen, HORZRES);
    height = GetDeviceCaps(screen, VERTRES);

    bitmap = CreateCompatibleBitmap(screen, width, height);
    if (!bitmap)
        goto error;

    if (!SelectObject(screen_copy, bitmap))
        goto error;

    /* step 2: copy bits into memory DC bitmap */

    if (!BitBlt(screen_copy, 0, 0, width, height, screen, 0, 0, SRCCOPY))
        goto error;

    /* step 3: extract bits from bitmap */

    buffer = PyString_FromStringAndSize(NULL, height * ((width*3 + 3) & -4));
    if (!buffer)
        return NULL;

    core.bcSize = sizeof(core);
    core.bcWidth = width;
    core.bcHeight = height;
    core.bcPlanes = 1;
    core.bcBitCount = 24;
    if (!GetDIBits(screen_copy, bitmap, 0, height, PyString_AS_STRING(buffer),
                   (BITMAPINFO*) &core, DIB_RGB_COLORS))
        goto error;

    DeleteObject(bitmap);
    DeleteDC(screen_copy);
    DeleteDC(screen);

    return Py_BuildValue("(ii)N", width, height, buffer);

error:
    PyErr_SetString(PyExc_IOError, "screen grab failed");

    DeleteDC(screen_copy);
    DeleteDC(screen);

    return NULL;
}

所以,当我深入一点时,发现C方法很好

http://msdn.microsoft.com/en-us/library/dd144909(VS.85).aspx

Python有ctypes,所以这里是我使用ctypes的方法(在Windows 10中,winnt已被替换Windows):

>>> from ctypes import *
>>> user= windll.LoadLibrary("c:\\winnt\\system32\\user32.dll") #I am in windows 2000, may be yours will be windows
>>> h = user.GetDC(0)
>>> gdi= windll.LoadLibrary("c:\\winnt\\system32\\gdi32.dll")
>>> gdi.GetPixel(h,1023,767)
16777215 #I believe its white color of RGB or BGR value, #FFFFFF (according to msdn it should be RGB)
>>> gdi.GetPixel(h,1024,767)
-1 #because my screen is only 1024x768

您可以像这样编写函数GetPixel的包装器

from ctypes import windll
dc= windll.user32.GetDC(0)

def getpixel(x,y):
    return windll.gdi32.GetPixel(dc,x,y)

然后你可以使用像getpixel(0,0),getpixel(100,0)等...

PS:我的是Windows 2000,所以我放入winnt路径,您可能需要将其更改为windows或者您可以完全删除路径,只需使用user32.dll并且也gdi32.dll应该工作.

Answer 2

评论S.Mark的解决方案:user32库已经被windll加载到windll.user32中,所以你可以这样做而不是dc = ...行:

def getpixel(x,y):
    return gdi.GetPixel(windll.user32.GetDC(0),x,y)

...或者最好:

dc= windll.user32.GetDC(0)