c++ - win32 C++ 在屏幕上放置图像

Question

我正在学习 C++，但我在将图像放到屏幕上时遇到了问题。

我已经在互联网上搜索了帮助，但找不到。

我正在尝试创建一个窗口，并在调用 WM_Paint 消息时在客户区放置一个简单的颜色，但程序像往常一样只显示灰色屏幕。我正在使用 code::blocks 10.05。

    #include <windows.h>
#include <iostream>

using namespace std;

int winx = 500;
int winy = 500;
int winbpp = 24;


     static  char                    m_bibuf[ sizeof(BITMAPINFOHEADER) + 12 ];
     static  BITMAPINFO              &m_bi = *(BITMAPINFO*)&m_bibuf;
     static  BITMAPINFOHEADER        &m_bih = m_bi.bmiHeader;
     int* buffer = new int[winx*winy*winbpp];





 int setbuffer()
 {

  for(int x = 0; x < winx; x++)
                {
                    for(int y=0; y < winy; y++)
                    {
                            for(int z =0; z < winbpp; z++)
                            {
                                buffer[x*y*z] = 1;
                            }
                    }

                }

                return 0;

 }



/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "CodeBlocksWindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           " project 1 ",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           winx,                 /* The programs width */
           winy,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {

        case WM_CREATE:
        {


        m_bih.biWidth = winx;
        m_bih.biHeight = winy;
        m_bih.biBitCount = winbpp;
        m_bih.biSize = sizeof(m_bih);
        m_bih.biPlanes = 1;                     // DIBs are upside down
        m_bih.biCompression = BI_BITFIELDS;
        m_bih.biSizeImage = 0;
        m_bih.biXPelsPerMeter = 0;
        m_bih.biYPelsPerMeter = 0;
        m_bih.biClrUsed = 0;
        m_bih.biClrImportant = 0;

        setbuffer();

        InvalidateRect(hwnd, NULL, TRUE);

        } break;

        case WM_PAINT:

        {


          PAINTSTRUCT ps;
      HDC hDC = BeginPaint(hwnd, &ps);

          RECT client;

          GetClientRect(hwnd, &client);



        StretchDIBits           (      hDC,
                                 0,                 // Destination top left hand
                                                    // corner X Position
                                 0,                 // Destination top left hand
                                                    // corner Y Position
                                 client.right,      // Destinations width
                                 client.bottom,     // Destinations height
                                 0,                 // Source top left hand
                                                    // corner's X Position
                                 0,                 // Source top left hand
                                                    // corner's Y Position
                                 winx,              // Sources width
                                 winy,               // Sources height
                                 buffer,            // Source's data
                                 &m_bi,             // Bitmap Info
                                 DIB_RGB_COLORS,    // operations
                                 SRCCOPY);


          EndPaint(hwnd, &ps);

        } break;



        case WM_DESTROY:

            delete buffer;
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

程序编译正常，但是没有在客户区显示'buffer'的内容，它只是像往常一样显示灰色。

“缓冲区”的格式是否正确？

=下面的更新代码=

#include <windows.h>

int winx = 500;
int winy = 400;

int bpp = 24;
size_t pwidth;


int scanlinewidth = 0;
int numscanlines = 0;

bool setscanline = 1;
bool setbitmap = 1;

BITMAPINFO m_bi;
struct BGR{ char blue; char green; char red;};

BGR* buffer;



void setframebuffer()
{
    m_bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);

    m_bi.bmiHeader.biPlanes = 1;
    m_bi.bmiHeader.biBitCount = bpp;
    m_bi.bmiHeader.biCompression = BI_RGB;
    m_bi.bmiHeader.biSizeImage = 0;
    m_bi.bmiHeader.biXPelsPerMeter = 100;
    m_bi.bmiHeader.biYPelsPerMeter = 100;
    m_bi.bmiHeader.biClrUsed = 0;
    m_bi.bmiHeader.biClrImportant = 0;

    if (setbitmap)
    {
    m_bi.bmiHeader.biWidth = scanlinewidth;
    m_bi.bmiHeader.biHeight = numscanlines;
    setbitmap = 0;


    }



    if (!setbitmap)
    {
    pwidth = (scanlinewidth * 3 + 3) & ~3;
    buffer = new BGR[(scanlinewidth + pwidth)*numscanlines];

    }



    for (int i = 0; i < ((scanlinewidth + pwidth) * numscanlines); i++)
    {
        buffer[i].blue = 0;
        buffer[i].green = 0;
        buffer[i].red = 255;

    }


}




/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "CodeBlocksWindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "framebuffer project for win32",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           winx,                 /* The programs width */
           winy,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    DWORD result;

    switch (message)                  /* handle the messages */
    {
        case WM_CREATE:
        {


        InvalidateRect(hwnd,0,0);

        }break;

        case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hDC = BeginPaint(hwnd, &ps);
            RECT client;
            GetClientRect(hwnd,&client);
            if(setscanline) {
            scanlinewidth = client.right;
            numscanlines = client.bottom;
            setscanline = 0;
            }
            setframebuffer();

             result = StretchDIBits(hDC,
                                   0, 0,
                                   client.right, client.bottom,
                                   0, 0,
                                   scanlinewidth, numscanlines,
                                   buffer, &m_bi, DIB_RGB_COLORS, SRCCOPY);
            if(result != winy)
            {
                //Drawing failed
                DebugBreak();
            }
            EndPaint(hwnd, &ps);




        }break;

        case WM_KEYDOWN:{ int escpressed = GetAsyncKeyState(27); if(escpressed){PostQuitMessage(0);}}break;


        case WM_DESTROY: {
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            }break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

编辑将 int setbuffer 更改为 WM_create 中的 setbuffer

编辑 #2 将 getdc 更改为开始绘制。

编辑 #3 将 bpp 更改为 24，还更改了 WM_Create 以设置所有位图属性

编辑 #4 感谢您的帮助，我找到了解决方案。以前我不明白扫描线填充，但现在我完全理解了。更新后的代码在屏幕上打印出纯色，您可以自己编译并更改颜色。感谢您帮助我解决了我的问题，现在我可以开始使用我自己的代码在屏幕上绘图了。

Answer 1

我不确定所有这些问题是否仍然相关，因为我在您开始编辑之前复制了代码。无论哪种方式，这都有效，您应该能够很容易地看到差异。

BITMAPINFO 结构未正确初始化。

缓冲区创建不正确，它太大并且不一定正确对齐以用作位图。宽度需要填充为 4 的倍数，这对于 500 的宽度是可以的，但对于 499 的宽度则不行。

我还添加了一个检查以确保 StretchDIBits 成功，如果失败，它会将您转储到调试器中。如果愿意，您可以添加更合适的错误检查。

我还删除了一些评论，以尽可能缩短内容。

#include <windows.h>

const int winx = 500;
const int winy = 500;
const int winbpp = 3;

BITMAPINFO m_bi;
char* buffer = 0;

void setbuffer()
{
    m_bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    m_bi.bmiHeader.biWidth = winx;
    m_bi.bmiHeader.biHeight = winy;
    m_bi.bmiHeader.biPlanes = 1;
    m_bi.bmiHeader.biBitCount = 24;
    m_bi.bmiHeader.biCompression = BI_RGB;
    m_bi.bmiHeader.biSizeImage = 0;
    m_bi.bmiHeader.biXPelsPerMeter = 100;
    m_bi.bmiHeader.biYPelsPerMeter = 100;
    m_bi.bmiHeader.biClrUsed = 0;
    m_bi.bmiHeader.biClrImportant = 0;

    size_t paddedWidth = (winx * 3 + 3) & ~3;
    buffer = new char[paddedWidth * winy * winbpp];

    for(int y = 0; y < winy; ++y)
    {
        for(int x = 0; x < winx; ++x)
        {
            for(int z = 0; z < 3; ++z)
            {
                buffer[y * paddedWidth + x * winbpp + z] = z * x;
            }
        }
    }
}

LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);

char szClassName[] = "CodeBlocksWindowsApp";

int WINAPI WinMain(HINSTANCE hThisInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpszArgument,
                   int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);
    wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor(NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    wincl.hbrBackground = (HBRUSH)COLOR_BACKGROUND;

    if(!RegisterClassEx(&wincl))
        return 0;

    hwnd = CreateWindowEx(
        0,                   /* Extended possibilites for variation */
        szClassName,         /* Classname */
        " project 1 ",       /* Title Text */
        WS_OVERLAPPEDWINDOW, /* default window */
        CW_USEDEFAULT,       /* Windows decides the position */
        CW_USEDEFAULT,       /* where the window ends up on the screen */
        winx,                 /* The programs width */
        winy,                 /* and height in pixels */
        HWND_DESKTOP,        /* The window is a child-window to desktop */
        NULL,                /* No menu */
        hThisInstance,       /* Program Instance handler */
        NULL                 /* No Window Creation data */
        );

    ShowWindow(hwnd, nCmdShow);

    while(GetMessage(&messages, NULL, 0, 0))
    {
        TranslateMessage(&messages);
        DispatchMessage(&messages);
    }

    return messages.wParam;
}

LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hDC;
    RECT client;
    DWORD result;

    switch(message)                  /* handle the messages */
    {
        case WM_CREATE:
            setbuffer();
            InvalidateRect(hwnd, NULL, TRUE);
            break;

        case WM_PAINT:
            hDC = BeginPaint(hwnd, &ps);
            GetClientRect(hwnd, &client);
            result = StretchDIBits(hDC,
                                   0, 0,
                                   client.right, client.bottom,
                                   0, 0,
                                   winx, winy,
                                   buffer, &m_bi, DIB_RGB_COLORS, SRCCOPY);
            if(result != winy)
            {
                //Drawing failed
                DebugBreak();
            }
            EndPaint(hwnd, &ps);
            break;

        case WM_DESTROY:
            delete buffer;
            PostQuitMessage(0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc(hwnd, message, wParam, lParam);
    }
    return 0;
}