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如何在OpenCV中捕獲桌面（即，將位圖轉(zhuǎn)換為Mat）？

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慕妹3242003 2019-11-12 10:33:18

我想使用OpenCV處理桌面，就好像它是視頻流一樣。我熟悉OpenCV。我不熟悉Windows API。我意識(shí)到還有其他捕獲屏幕的方法，但是出于我的問題，我需要使用OpenCV來完成。這是我的（超級(jí)天真）代碼：HWND hDesktopWnd;HDC hDesktopDC;hDesktopWnd=GetDesktopWindow();hDesktopDC=GetDC(hDesktopWnd);// get the height and width of the screenint height = GetSystemMetrics(SM_CYVIRTUALSCREEN);int width = GetSystemMetrics(SM_CXVIRTUALSCREEN);// create a bitmapHBITMAP hbDesktop = CreateCompatibleBitmap( hDesktopDC, width, height);Mat src(height,width,CV_8UC4);src.data = (uchar*)hbDesktop;imshow("output",src); //fails :(在StackOverflow上也有類似的問題，但這些問題要么針對(duì)舊式OpenCV，要么針對(duì)Android操作系統(tǒng)。我在Windows 7 64xOpencv 2.4.3上感謝任何可以回答這個(gè)問題的人。

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3 回答

Helenr

TA貢獻(xiàn)1780條經(jīng)驗(yàn) 獲得超4個(gè)贊

一種更好的方法是在將內(nèi)存分配給像素一次的同時(shí)執(zhí)行此操作。所以這里唯一要做的就是BitBlt制作的副本

int main()

{

int x_size = 800, y_size = 600; // <-- Your res for the image

HBITMAP hBitmap; // <-- The image represented by hBitmap

Mat matBitmap; // <-- The image represented by mat

// Initialize DCs

HDC hdcSys = GetDC(NULL); // Get DC of the target capture..

HDC hdcMem = CreateCompatibleDC(hdcSys); // Create compatible DC

void *ptrBitmapPixels; // <-- Pointer variable that will contain the potinter for the pixels

// Create hBitmap with Pointer to the pixels of the Bitmap

BITMAPINFO bi; HDC hdc;

ZeroMemory(&bi, sizeof(BITMAPINFO));

bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);

bi.bmiHeader.biWidth = x_size;

bi.bmiHeader.biHeight = -y_size; //negative so (0,0) is at top left

bi.bmiHeader.biPlanes = 1;

bi.bmiHeader.biBitCount = 32;

hdc = GetDC(NULL);

hBitmap = CreateDIBSection(hdc, &bi, DIB_RGB_COLORS, &ptrBitmapPixels, NULL, 0);

// ^^ The output: hBitmap & ptrBitmapPixels

// Set hBitmap in the hdcMem

SelectObject(hdcMem, hBitmap);

// Set matBitmap to point to the pixels of the hBitmap

matBitmap = Mat(y_size, x_size, CV_8UC4, ptrBitmapPixels, 0);

// ^^ note: first it is y, then it is x. very confusing

// * SETUP DONE *

// Now update the pixels using BitBlt

BitBlt(hdcMem, 0, 0, x_size, y_size, hdcSys, 0, 0, SRCCOPY);

// Just to do some image processing on the pixels.. (Dont have to to this)

Mat matRef = matBitmap(Range(100, 200), Range(100, 200));

// y1 y2 x1 x2

bitwise_not(matRef, matRef); // Invert the colors in this x1,x2,y1,y2

// Display the results through Mat

imshow("Title", matBitmap);

// Wait until some key is pressed

waitKey(0);

return 0;

}

請(qǐng)注意，這里沒有進(jìn)行錯(cuò)誤處理以使其易于理解，但是您必須在代碼中進(jìn)行錯(cuò)誤處理！

希望這可以幫助

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叮當(dāng)貓咪

TA貢獻(xiàn)1776條經(jīng)驗(yàn) 獲得超12個(gè)贊

值得注意的是，如果上面的代碼在可重復(fù)使用的場景（例如循環(huán)）中使用，從長遠(yuǎn)來看，將導(dǎo)致內(nèi)存泄漏并泛濫您的堆內(nèi)存/崩潰應(yīng)用程序。您必須調(diào)用DeleteObject（hBitmap）; 和matBitmap.release（）處理完圖像后。

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