C++ 在C+中选择屏幕创建位图时出现黑色图像+;
我正在尝试获取桌面选定区域的屏幕截图 我遇到的问题是输出(.bmp文件)是黑色的 我获取了createBitMapInfo();和CreateBMPFile();从…起其余的都是我从网上截取的弗兰肯斯坦 下面是我的代码目前的样子:C++ 在C+中选择屏幕创建位图时出现黑色图像+;,c++,winapi,screenshot,bmp,C++,Winapi,Screenshot,Bmp,我正在尝试获取桌面选定区域的屏幕截图 我遇到的问题是输出(.bmp文件)是黑色的 我获取了createBitMapInfo();和CreateBMPFile();从…起其余的都是我从网上截取的弗兰肯斯坦 下面是我的代码目前的样子: #include <windows.h> #include <iostream> #include <fstream> #include <string> using namespace std; PBITMAPINF
#include <windows.h>
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
PBITMAPINFO CreateBitmapInfoStruct(HBITMAP hBmp)
{
BITMAP bmp;
PBITMAPINFO pbmi;
WORD cClrBits;
// Retrieve the bitmap color format, width, and height.
if (!GetObject(hBmp, sizeof(BITMAP), (LPSTR)&bmp))
cout << "ERROR:1";
// Convert the color format to a count of bits.
cClrBits = (WORD)(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;
// Allocate memory for the BITMAPINFO structure. (This structure
// contains a BITMAPINFOHEADER structure and an array of RGBQUAD
// data structures.)
if (cClrBits < 24)
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER) +
sizeof(RGBQUAD) * (1<< cClrBits));
// There is no RGBQUAD array for these formats: 24-bit-per-pixel or 32-bit-per-pixel
else
pbmi = (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.
// The width must be DWORD aligned unless the bitmap is RLE
// compressed.
pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits +31) & ~31) /8
* pbmi->bmiHeader.biHeight;
// Set biClrImportant to 0, indicating that all of the
// device colors are important.
pbmi->bmiHeader.biClrImportant = 0;
return pbmi;
}
void CreateBMPFile(LPTSTR pszFile, PBITMAPINFO pbi,
HBITMAP hBMP, HDC hDC)
{
HANDLE hf; // file handle
BITMAPFILEHEADER hdr; // bitmap file-header
PBITMAPINFOHEADER pbih; // bitmap info-header
LPBYTE lpBits; // memory pointer
DWORD dwTotal; // total count of bytes
DWORD cb; // incremental count of bytes
BYTE *hp; // byte pointer
DWORD dwTmp;
pbih = (PBITMAPINFOHEADER) pbi;
lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbih->biSizeImage);
if (!lpBits)
cout << "ERROR:2";
// Retrieve the color table (RGBQUAD array) and the bits
// (array of palette indices) from the DIB.
GetDIBits(hDC, hBMP, 0, (WORD) pbih->biHeight, lpBits, pbi,
DIB_RGB_COLORS);
// Create the .BMP file.
hf = CreateFile(pszFile,
GENERIC_READ | GENERIC_WRITE,
(DWORD) 0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
(HANDLE) NULL);
if (hf == INVALID_HANDLE_VALUE)
cout << "ERROR:4";
hdr.bfType = 0x4d42; // 0x42 = "B" 0x4d = "M"
// Compute the size of the entire file.
hdr.bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) +
pbih->biSize + pbih->biClrUsed
* sizeof(RGBQUAD) + pbih->biSizeImage);
hdr.bfReserved1 = 0;
hdr.bfReserved2 = 0;
// Compute the offset to the array of color indices.
hdr.bfOffBits = (DWORD) sizeof(BITMAPFILEHEADER) +
pbih->biSize + pbih->biClrUsed
* sizeof (RGBQUAD);
// Copy the BITMAPFILEHEADER into the .BMP file.
if (!WriteFile(hf, (LPVOID) &hdr, sizeof(BITMAPFILEHEADER),
(LPDWORD) &dwTmp, NULL))
{
cout << "ERROR:5";
}
// Copy the BITMAPINFOHEADER and RGBQUAD array into the file.
if (!WriteFile(hf, (LPVOID) pbih, sizeof(BITMAPINFOHEADER)
+ pbih->biClrUsed * sizeof (RGBQUAD),
(LPDWORD) &dwTmp, ( NULL)))
cout << "ERROR:6";
// Copy the array of color indices into the .BMP file.
dwTotal = cb = pbih->biSizeImage;
hp = lpBits;
if (!WriteFile(hf, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp,NULL))
cout << "ERROR:7";
// Close the .BMP file.
if (!CloseHandle(hf))
cout << "ERROR:8";
// Free memory.
GlobalFree((HGLOBAL)lpBits);
}
void getBit(string name) {
int nX = 300;
int nX2 = 600;
int nY = 300;
int nY2 = 700;
HDC hScrDC = GetDC(NULL);
HDC hMemDC = CreateCompatibleDC(hScrDC);
int nWidth = nX2 - nX;
int nHeight = nY2 - nY;
HBITMAP hBitmap = CreateCompatibleBitmap(hScrDC, nWidth, nHeight);
HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);
BitBlt(hMemDC, 0, 0, nWidth, nHeight,
hScrDC, nX, nY, SRCCOPY);
hBitmap = (HBITMAP)SelectObject(hMemDC, hOldBitmap);
DeleteDC(hScrDC);
DeleteDC(hMemDC);
// now your image is held in hBitmap. You can save it or do whatever with it
PBITMAPINFO pbi = CreateBitmapInfoStruct(hBitmap);
//File name
LPTSTR path = L"test.bmp";
CreateBMPFile(path,pbi,hBitmap,hMemDC);
}
void main(void) {
getBit("SAVE");
cout << "Done";
int wait;
cin >> wait;
}
#包括
#包括
#包括
#包括
使用名称空间std;
PBITMAPINFO CreateBitMapInfo结构(HBITMAP hBmp)
{
位图bmp;
PBITMAPINFO pbmi;
字cClrBits;
//检索位图颜色格式、宽度和高度。
if(!GetObject(hBmp、sizeof(位图)、(LPSTR)和bmp))
cout bmiHeader.biclrued=(1bmiHeader.biSizeImage=((pbmi->bmiHeader.biWidth*cClrBits+31)和~31)/8
*pbmi->bmi header.biHeight;
//将biClrImportant设置为0,表示所有
//设备颜色很重要。
pbmi->bmiHeader.biClrImportant=0;
返回pbmi;
}
void CreateBMPFile(LPTSTR pszFile、PBITMAPINFO pbi、,
HBITMAP hBMP,HDC HDC)
{
HANDLE hf;//文件句柄
BITMAPFILEHEADER hdr;//位图文件头
PBITMAPINFOHEADER pbih;//位图信息头
LPBYTE lpBits;//内存指针
DWORD dwTotal;//字节总数
DWORD cb;//字节的增量计数
BYTE*hp;//字节指针
DWORD dwTmp;
pbih=(PBITMAPINFOHEADER)pbi;
lpBits=(LPBYTE)GlobalAlloc(GMEM_固定,pbih->biSizeImage);
if(!lpBits)
cout-biHeight、lpBits、pbi、,
DIB_RGB_颜色);
//创建.BMP文件。
hf=创建文件(pszFile,
一般的读,一般的写,
(德沃德)0,
无效的
永远创造你,
文件\u属性\u正常,
(句柄)NULL);
if(hf==无效的句柄值)
cout biSize+pbih->biClrUsed
*sizeof(RGBQUAD)+pbih->biSizeImage;
hdr.bfReserved1=0;
hdr.bfserved2=0;
//计算颜色索引数组的偏移量。
hdr.bOffBits=(DWORD)大小(BITMAPFILEHEADER)+
pbih->biSize+pbih->BICLRUSE
*sizeof(RGBguad);
//将BITMAPFILEHEADER复制到.BMP文件中。
如果(!WriteFile(hf,(LPVOID)&hdr,sizeof(BITMAPFILEHEADER),
(LPDWORD)和dwTmp,空)
{
cout biClrUsed*sizeof(RGBQUAD),
(LPDWORD)和dwTmp(NULL)))
cout-biSizeImage;
hp=lpbit;
if(!WriteFile(hf,(LPSTR)hp,(int)cb,(LPDWORD)和dwTmp,NULL))
cout最大的问题是,GetDIBits
失败,因为您正在将句柄传递给已删除的内存上下文,而不是传递给有效的设备上下文。如果您解决了这个问题,它就会工作
调试时,最好检查所有返回值
我注意到的其他事情:
您不应该删除hSrcDC,因为您没有创建它。请使用ReleaseDC
,它是GetDC
的配套工具
考虑在BitBlt
调用中使用CAPTUREBLT
如果我在getBit例程结束时移动他的DeleteDC函数,这对我也很有效。我尝试使用ReleaseDC,但这个函数有两个参数:ReleaseDC(u in_opt HWND HWND,u in HDC HDC);但是,在他的代码中,他没有声明任何HWND变量,所以我像那样传递了NULL,结果成功了。ReleaseDC(NULL,hScrDC);ReleaseDC(NULL,hMemDC);在他的情况下使用它是否合适?@ForceMagic:ReleaseDC用于返回您通过GetDC获得的DC。如果您需要整个屏幕的DC,则GetDC接受HWND或NULL。由于他使用NULL调用GetDC,因此调用ReleaseDC(NULL,hSrcDC)是合适的.但hMemDC来自CreateCompatibleDC调用,因此DeleteDC适用于该调用。