多监视器截屏只有2个监视器在C++与WinApi 我有一个功能，可以在Windows平台上使用WinApi和C++进行截图。它与一个和两个监视器完美配合，但当我在一台有3个或更多监视器的机器上运行时，它只拍摄两个监视器的照片 // Create a normal DC and a memory DC for the entire screen. The normal DC provides a "snapshot" of the screen contents. // The memory DC keeps a copy of this "snapshot" in the associated bitmap. const HDC hdcScr = CreateDCW(TEXT("DISPLAY"), NULL, NULL, NULL); const HDC hdcMem = CreateCompatibleDC(hdcScr); if (!StretchBlt(hdcMem, 0, 0, width, height, hdcScr, 0, 0, width, height, SRCCOPY)) { return; } // Create a compatible bitmap for hdcScreen. const HBITMAP hbmScr = CreateCompatibleBitmap(hdcScr, width, height); if (hbmScr == 0) { return; } if (!BitBlt(hdcMem, 0, 0, width, height, hdcScr, 0, 0, SRCCOPY)) { return; } // Select the bitmaps into the compatible DC. if (!SelectObject(hdcMem, hbmScr)) { DeleteDC(hdcScr); DeleteDC(hdcMem); DeleteObject(hbmScr); return; } // Copy color data for the entire display into a bitmap that is selected into a compatible DC. if (!StretchBlt(hdcMem, 0, 0, width, height, hdcScr, 0, 0, width, height, SRCCOPY)) { DeleteDC(hdcScr); DeleteDC(hdcMem); DeleteObject(hbmScr); return; } BITMAP bmp; // Retrieve the bitmap's color format, width, and height. if (!GetObject(hbmScr, sizeof(BITMAP), reinterpret_cast<LPSTR>(&bmp))) { DeleteDC(hdcScr); DeleteDC(hdcMem); DeleteObject(hbmScr); return; } // Convert the color format to a count of bits. unsigned short cClrBits = bmp.bmPlanes * bmp.bmBitsPixel; if (cClrBits == 1) { cClrBits = 1; } else if (cClrBits <= 4) { cClrBits = 4; } else if (cClrBits <= 8) { cClrBits = 8; } else if (cClrBits <= 16) { cClrBits = 16; } else if (cClrBits <= 24) { cClrBits = 24; } else { cClrBits = 32; } PBITMAPINFO pbmi; // Allocate memory for the BITMAPINFO structure. (This structure contains a BITMAPINFOHEADER structure and an array of RGBQUAD data structures.) if (cClrBits != 24) { pbmi = static_cast<PBITMAPINFO>(LocalAlloc(LPTR, sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * (1 << cClrBits))); } else { // There is no RGBQUAD array for the 24-bit-per-pixel format. pbmi = static_cast<PBITMAPINFO>(LocalAlloc(LPTR, sizeof(BITMAPINFOHEADER))); } // Initialize the fields in the BITMAPINFO structure. pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER); pbmi->bmiHeader.biWidth = bmp.bmWidth; pbmi->bmiHeader.biHeight = bmp.bmHeight; pbmi->bmiHeader.biPlanes = bmp.bmPlanes; pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel; if (cClrBits < 24) { pbmi->bmiHeader.biClrUsed = (1 << cClrBits); } // If the bitmap is not compressed, set the BI_RGB flag. pbmi->bmiHeader.biCompression = BI_RGB; // Compute the number of bytes in the array of color indices and store the result in biSizeImage. pbmi->bmiHeader.biSizeImage = (pbmi->bmiHeader.biWidth + 7) / 8 * pbmi->bmiHeader.biHeight * cClrBits; // Set biClrImportant to 0, indicating that all of the device colors are important. pbmi->bmiHeader.biClrImportant = 0; const PBITMAPINFOHEADER pbih = reinterpret_cast<PBITMAPINFOHEADER>(pbmi); // bitmap info-header const LPBYTE lpBits = static_cast<LPBYTE>(GlobalAlloc(GMEM_FIXED, pbih->biSizeImage)); // memory pointer if (!lpBits) { DeleteDC(hdcScr); DeleteDC(hdcMem); LocalFree(pbmi); GlobalFree(lpBits); DeleteObject(hbmScr); return; } // Retrieve the color table (RGBQUAD array) and the bits (array of palette indices) from the DIB. if (!GetDIBits(hdcMem, hbmScr, 0, pbih->biHeight, lpBits, pbmi, DIB_RGB_COLORS)) { DeleteDC(hdcScr); DeleteDC(hdcMem); LocalFree(pbmi); GlobalFree(lpBits); DeleteObject(hbmScr); return; } BITMAPFILEHEADER hdr; // bitmap file-header hdr.bfType = 0x4d42; // ('M' << 8) + 'B'; // Calculate the size of the entire file. hdr.bfSize = sizeof(BITMAPFILEHEADER) + pbih->biSize + pbih->biClrUsed * sizeof(RGBQUAD) + pbih->biSizeImage; hdr.bfReserved1 = NULL; hdr.bfReserved2 = NULL; // Calculate the offset to the array of color indices. hdr.bfOffBits = sizeof(BITMAPFILEHEADER) + pbih->biSize + pbih->biClrUsed * sizeof(RGBQUAD); const DWORD cb = pbih->biSizeImage; // incremental count of bytes std::stringstream outputBitmap; // Write the BITMAPFILEHEADER into the .BMP file. outputBitmap.write( reinterpret_cast<LPSTR>(&hdr), sizeof(BITMAPFILEHEADER)); // Write the BITMAPINFOHEADER and RGBQUAD array into the file. outputBitmap.write(reinterpret_cast<LPSTR>(pbih), sizeof(BITMAPINFOHEADER) + pbih->biClrUsed * sizeof(RGBQUAD)); // Write the array of color indices outputBitmap.write(reinterpret_cast<LPSTR>(lpBits), cb); // To test the whole thing std::ofstream out("test.bmp", std::ios::out | std::ios::binary); out << outputBitmap.str(); out.close(); // Cleanup DeleteDC(hdcScr); DeleteDC(hdcMem); LocalFree(pbmi); GlobalFree(lpBits); DeleteObject(hbmScr);

我想我的问题是主显示器左边的显示器内容被切掉了。可悲的是，我不知道如何修复它，也不知道我做错了什么

我读过关于BitBlt和StretchBlt的文章，所以我试着和他们一起尝试，但没有成功

这就是我正在做的：

// Get the system metrics
const int width = GetSystemMetrics(SM_CXVIRTUALSCREEN);
const int height = GetSystemMetrics(SM_CYVIRTUALSCREEN);

所有显示器的宽度和高度都经过完美计算

// Create a normal DC and a memory DC for the entire screen. The normal DC provides a "snapshot" of the screen contents.
// The memory DC keeps a copy of this "snapshot" in the associated bitmap.
const HDC hdcScr = CreateDCW(TEXT("DISPLAY"), NULL, NULL, NULL);
const HDC hdcMem = CreateCompatibleDC(hdcScr);



if (!StretchBlt(hdcMem, 0, 0, width, height, hdcScr, 0, 0, width, height, SRCCOPY)) {
    return;
}


// Create a compatible bitmap for hdcScreen.
const HBITMAP hbmScr = CreateCompatibleBitmap(hdcScr, width, height);
if (hbmScr == 0) {
    return;
}

if (!BitBlt(hdcMem, 0, 0, width, height, hdcScr, 0, 0, SRCCOPY)) {
    return;
}



// Select the bitmaps into the compatible DC.
if (!SelectObject(hdcMem, hbmScr)) {
    DeleteDC(hdcScr);
    DeleteDC(hdcMem);
    DeleteObject(hbmScr);
    return;
}

// Copy color data for the entire display into a bitmap that is selected into a compatible DC.
if (!StretchBlt(hdcMem, 0, 0, width, height, hdcScr, 0, 0, width, height, SRCCOPY)) {
    DeleteDC(hdcScr);
    DeleteDC(hdcMem);
    DeleteObject(hbmScr);
    return;
}

BITMAP bmp;

// Retrieve the bitmap's color format, width, and height.
if (!GetObject(hbmScr, sizeof(BITMAP), reinterpret_cast<LPSTR>(&bmp))) {
    DeleteDC(hdcScr);
    DeleteDC(hdcMem);
    DeleteObject(hbmScr);
    return;
}


// Convert the color format to a count of bits.
unsigned short cClrBits = bmp.bmPlanes * bmp.bmBitsPixel;
if (cClrBits == 1) {
    cClrBits = 1;
}
else if (cClrBits <= 4) {
    cClrBits = 4;
}
else if (cClrBits <= 8) {
    cClrBits = 8;
}
else if (cClrBits <= 16) {
    cClrBits = 16;
}
else if (cClrBits <= 24) {
    cClrBits = 24;
}
else {
    cClrBits = 32;
}


PBITMAPINFO pbmi;

// Allocate memory for the BITMAPINFO structure. (This structure contains a BITMAPINFOHEADER structure and an array of RGBQUAD data structures.)
if (cClrBits != 24) {
    pbmi = static_cast<PBITMAPINFO>(LocalAlloc(LPTR, sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * (1 << cClrBits)));
}
else { // There is no RGBQUAD array for the 24-bit-per-pixel format.
    pbmi = static_cast<PBITMAPINFO>(LocalAlloc(LPTR, sizeof(BITMAPINFOHEADER)));
}

// Initialize the fields in the BITMAPINFO structure.
pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel;

if (cClrBits < 24) {
    pbmi->bmiHeader.biClrUsed = (1 << cClrBits);
}

// If the bitmap is not compressed, set the BI_RGB flag.
pbmi->bmiHeader.biCompression = BI_RGB;

// Compute the number of bytes in the array of color indices and store the result in biSizeImage.
pbmi->bmiHeader.biSizeImage = (pbmi->bmiHeader.biWidth + 7) / 8 * pbmi->bmiHeader.biHeight * cClrBits;

// Set biClrImportant to 0, indicating that all of the device colors are important.
pbmi->bmiHeader.biClrImportant = 0;


const PBITMAPINFOHEADER pbih = reinterpret_cast<PBITMAPINFOHEADER>(pbmi);              // bitmap info-header
const LPBYTE lpBits = static_cast<LPBYTE>(GlobalAlloc(GMEM_FIXED, pbih->biSizeImage)); // memory pointer

if (!lpBits) {
    DeleteDC(hdcScr);
    DeleteDC(hdcMem);
    LocalFree(pbmi);
    GlobalFree(lpBits);
    DeleteObject(hbmScr);
    return;
}

// Retrieve the color table (RGBQUAD array) and the bits (array of palette indices) from the DIB.
if (!GetDIBits(hdcMem, hbmScr, 0, pbih->biHeight, lpBits, pbmi, DIB_RGB_COLORS)) {
    DeleteDC(hdcScr);
    DeleteDC(hdcMem);
    LocalFree(pbmi);
    GlobalFree(lpBits);
    DeleteObject(hbmScr);
    return;
}

BITMAPFILEHEADER hdr; // bitmap file-header

hdr.bfType = 0x4d42; // ('M' << 8) + 'B';

// Calculate the size of the entire file.
hdr.bfSize = sizeof(BITMAPFILEHEADER) + pbih->biSize + pbih->biClrUsed * sizeof(RGBQUAD) + pbih->biSizeImage;
hdr.bfReserved1 = NULL;
hdr.bfReserved2 = NULL;

// Calculate the offset to the array of color indices.
hdr.bfOffBits = sizeof(BITMAPFILEHEADER) + pbih->biSize + pbih->biClrUsed * sizeof(RGBQUAD);


const DWORD cb = pbih->biSizeImage; // incremental count of bytes


std::stringstream outputBitmap;

// Write the BITMAPFILEHEADER into the .BMP file.
outputBitmap.write( reinterpret_cast<LPSTR>(&hdr), sizeof(BITMAPFILEHEADER));

// Write the BITMAPINFOHEADER and RGBQUAD array into the file.
outputBitmap.write(reinterpret_cast<LPSTR>(pbih), sizeof(BITMAPINFOHEADER) + pbih->biClrUsed * sizeof(RGBQUAD));

// Write the array of color indices
outputBitmap.write(reinterpret_cast<LPSTR>(lpBits), cb);




// To test the whole thing
std::ofstream out("test.bmp", std::ios::out | std::ios::binary);
out << outputBitmap.str();
out.close();


// Cleanup
DeleteDC(hdcScr);
DeleteDC(hdcMem);
LocalFree(pbmi);
GlobalFree(lpBits);
DeleteObject(hbmScr);

---

监视器可能有负坐标，因此假设0，0是监视器的左上角†是危险的。真实原点x，y由系统度量SM_XVIRTUALSCREEN和SM_YVIRTUALSCREEN给出。然后必须更新所有BLT，以参考正确的源位置。这使函数的第一位：

int x = GetSystemMetrics(SM_XVIRTUALSCREEN);
int y = GetSystemMetrics(SM_YVIRTUALSCREEN);
int w = GetSystemMetrics(SM_CXVIRTUALSCREEN);
int h = GetSystemMetrics(SM_CYVIRTUALSCREEN);

BOOL ok = StretchBlt(hdcMem, 0, 0, w, h, hdcScr, x, y, w, h, SRCCOPY);
// And So On...

或者，由于此类问题经常被问到，您可以使用类似于以下一段不太符合生产质量的代码的内容来获取单个监视器：

#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <iostream>
using std::wcout;
using std::endl;

typedef struct tagMonData
{
    int current;
    MONITORINFOEXW* info;
} MonData;

BOOL EnumProc(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData)
{
    MonData* data = (MonData*)dwData;
    data->info[data->current].cbSize = sizeof(MONITORINFOEXW);
    return GetMonitorInfoW(hMonitor, &(data->info[data->current++]));
}

BOOL GetAllMonitorInfo(MonData* data)
{
    return EnumDisplayMonitors(NULL, NULL, (MONITORENUMPROC)(&EnumProc), (LPARAM)(data));
}

int main()
{
    int cMonitors = GetSystemMetrics(SM_CMONITORS);
    MonData data;
    data.current = 0;
    data.info = (MONITORINFOEXW*)calloc(cMonitors, sizeof(MONITORINFOEXW));

    if (!GetAllMonitorInfo(&data)) return 1;

    for (int i = 0; i < cMonitors; i++)
    {
        wcout << data.info[i].szDevice << "X: " << data.info[i].rcMonitor.left << " Y: " << data.info[i].rcMonitor.top << endl;
    }

    free(data.info);
    return 0;
}

请注意，如果GetMonitorInfo调用因某种原因失败，这将创建快捷方式并留下不完整的信息

---

†Raymond Chen已就Windows坐标系的复杂性撰写了几篇文章，位于

显示器DC（显示器位于原点左侧）是否不需要负片坐标或负片x？肯定有一百万个屏幕截图问题，但它们仍在不断出现。