将图像保存到内存

Question

我有一个dev-c++应用程序，它可以制作屏幕截图并将其写入文件。现在我想将图像写入变量/流。最初我使用了三个Writefile函数，它们将标头，信息和hbitmap写入一个文件。现在，我想将数据保存到流中，而不是保存到文件中，以便我可以使用它进行进一步处理。我使用的代码是这样的：

/* <Include> */
#include <windows.h>
#include <iostream>
#include <sstream>
/* </Include> */
/* <Const> */
const char *AppName="Yeah";
using namespace std;
/* </Const> */
/* <Function> */
void SaveScreen(HWND pScreen, stringstream Path)
{
    int     Width  = GetSystemMetrics(SM_CXSCREEN);//1280;
    int     Height = GetSystemMetrics(SM_CYSCREEN);//1024;
    HDC hdcScreen;
    HBITMAP hbmScreen;

    //---------------Bitmap Informationen
    BITMAPINFO infobmp;
    infobmp.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    infobmp.bmiHeader.biWidth = Width;
    infobmp.bmiHeader.biHeight = Height;
    infobmp.bmiHeader.biPlanes = 1;
    infobmp.bmiHeader.biBitCount = 24;
    infobmp.bmiHeader.biCompression = 0;
    infobmp.bmiHeader.biSizeImage = 0;
    infobmp.bmiHeader.biXPelsPerMeter = 0;
    infobmp.bmiHeader.biYPelsPerMeter = 0;
    infobmp.bmiHeader.biClrUsed = 0;
    infobmp.bmiHeader.biClrImportant = 0;
    int* bitmap = new int[Width*Height*3];
    BITMAPFILEHEADER bfheader;
    bfheader.bfType = 19778;
    bfheader.bfSize = sizeof(BITMAPFILEHEADER) + Width*Height*3 + sizeof(BITMAPINFOHEADER);
    bfheader.bfReserved1 = 0;
    bfheader.bfReserved2 = 0;
    bfheader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
    //Bitmap -----------------------      Informationen

    hdcScreen = GetWindowDC(pScreen);
    hbmScreen = CreateCompatibleBitmap(hdcScreen, Width, Height);
    // tempor?rer DC
    HDC hdcTemp = CreateCompatibleDC(hdcScreen);
    // Bitmap reinselektieren
    HBITMAP hbmOld = (HBITMAP)SelectObject(hdcTemp, hbmScreen);
    // Inhalt von Desktop ?bertragen
    BitBlt(hdcTemp, 0, 0, Width, Height, hdcScreen, 0, 0, SRCCOPY);
    int iResult = GetDIBits(hdcTemp, hbmScreen, 0, Height, bitmap, &infobmp, DIB_RGB_COLORS);
    // aufr?umen
    SelectObject(hdcTemp, hbmOld);
    DeleteObject(hbmScreen);
    DeleteDC(hdcTemp);
   // HANDLE hfile = CreateFile(Path, GENERIC_WRITE, 0, 0, OPEN_ALWAYS, 0, 0);
    //Datei Schreiben
    DWORD word;
    WriteFile(Path, &bfheader, 14, &word, NULL);
    WriteFile(Path, &infobmp, 40,& word, NULL);
    WriteFile(Path, bitmap, Width*Height*3, &word,NULL);
//    Path = &bfheader & &infobmp & bitmap;
    ReleaseDC(pScreen, hdcScreen);
//    CloseHandle(hfile);
    delete[] bitmap;
}
/* </Function> */
int WINAPI WinMain(      
    HINSTANCE hInstance,
    HINSTANCE hPrevInstance,
    LPSTR lpCmdLine,
    int nCmdShow)
{   
    HWND hWnd = FindWindow(NULL, AppName);

    stringstream ms;
    SaveScreen(hWnd, ms);
    return 0;
}

有人可以告诉我我做错了什么吗？

Answer 1

您可以创建如下结构：

struct ScreenShotBuffer
{
BITMAPFILEHEADER bfheader;
BITMAPINFO infobmp;
int* bitmap;
};

然后使用该结构创建一个全局变量。

struct ScreenShotBuffer myScreenShot;

无论如何，您正在使用malloc分配"内存"来保存数据。所以你可以只用这三行而不是WriteBuffer()：

myScreenShot.bfheader=bfheader;
myScreenShot.infobmp=infobmp;
myScreenShot.bitmap=bitmap;