数组缓冲区与winapi 背景： 视窗10 WinAPI与C代码 问题:

我有一个像素缓冲区，表示为uint8_t buffer[width*height*pixel_SIZE]，我希望定期修改内容数据并将缓冲区重新绘制到窗口中

我在winapi中遇到了两个问题，其中一个问题我不知道：

如何在窗口上打印像素缓冲区？ 我以后如何在dame修改缓冲区的代码中重新绘制？ 我做了很多研究，但没有一个代码片段能够成功地帮助我解决我的问题

下面是一个不起作用的代码示例，以显示我想用我拥有的代码元素归档的内容：

新图片 main.c 这是新的图片

函数new_image，返回像素缓冲区上的指针

一个函数，用于将图像放入显示窗口上像素缓冲区的窗口

sizeof运算符的用法不正确。位图可以是1、4、8、16、24或32位。32位位图每像素有4个字节。如果像素大小声明为int32\t，那么碰巧您得到了正确的大小。否则，请使用正确的公式计算尺寸

此外，将缓冲区复制到位也没有意义。您可以直接使用bits。只要没有破坏hDib，位就有效

对GetDC的调用应该以ReleaseDC结束，否则可能导致资源泄漏。Windows设备上下文不应存储为常量。将其用作临时值

您还将HDC context\u HDC声明为全局变量。这对于内存设备上下文来说是可以的，但不是必需的。您需要的唯一全局变量是hDib，可能还有buffer

解决方案 感谢@RemyLebeau@IInspectable@Raymond Chen和@BarmakShemirani answers的回答，这里有一个解决方案

现在，我根据CreateDIBSection函数获得的缓冲区成功地更新了窗口，而没有通过WM_PAINT事件

我使用UpdateLayeredWindow函数来更新窗口的像素

以下是解决方案代码：

新图片 main.c 以下是@IInspectable为像我这样的WinAPI初学者提供的必读资料：

---

在提问之前应该阅读此内容…

如果UpdateWindow不起作用，您可能会触发重画，如果您的WM\u PAINT处理程序可以使用它，那么您可以详细说明更改的位。您在WM\u PAINT处理程序外部绘制，因此您绘制的任何内容都将在下次绘制请求时被覆盖。您的WM_绘制处理程序不会绘制任何内容，因此它只会绘制您的wc.hbrBackground.Mandatory读数：。确保阅读所有内容。无论如何，你必须能够在WM_PAINT内完成所有绘图，因为如果用户最小化窗口，然后恢复窗口，你需要重新生成内容。如果你在WM_PAINT之外画画，你需要记住足够的信息，以便WM_PAINT可以复制你所做的。大多数人只是让WM_画画。避免代码重复。有两种方法可以处理这种情况：1是处理WM_PAINT的旧方法，即在每次接收WM_PAINT时，将像素放入HBITMAP，然后重新绘制到窗口的HDC上；2使用WS_EX_分层窗口样式和UpdateLayeredWindow函数的新方法。将像素放入HBITMAP并创建一个内存中的HDC以将其选中，然后将该HDC传递给UpdateLayeredWindow，并且根本不处理WM_绘制。每当像素改变时，只需再次调用UpdateLayeredWindow即可。感谢您的回复。我试着从你的例子中写入BYTE*image=new_image500500；就在调用之后，按这种方式：对于大小\u t i=0；i<500*500；i++{uint32_t*image[i]=0xF0；}但实际上它正在失败。字节*图像似乎没有被CreateDIBSection分配大小为500*500

// Global variables
static HDC      hdc;
static HDC      context_hdc;
static HBITMAP  hDib;
static HGDIOBJ  obj;

static void     set_bmi_object(BITMAPINFO *bmi, int width, int height) {
    memset(bmi, 0, sizeof(BITMAPINFO));

    bmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmi->bmiHeader.biWidth = width;
    bmi->bmiHeader.biHeight = -height;
    bmi->bmiHeader.biPlanes = 1;
    bmi->bmiHeader.biBitCount = 32;
    bmi->bmiHeader.biCompression = BI_RGB;
}

// Allocate a new image buffer
void             *new_image(HWND hwnd, int width, int height)
{
    BITMAPINFO  bmi;
    BYTE        *bits = NULL;
    void        *buffer;

    if (NULL == (buffer = (char*)malloc(width * height * PIXEL_SIZE)))
        return (NULL);

    set_bmi_object(&bmi, width, height);

    hdc = GetDC(hwnd);

    hDib = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void**)(&bits), 
                            NULL, 0);

    if (hDib != NULL) {
        context_hdc = CreateCompatibleDC(hdc);
        if (context_hdc == NULL) {
            DeleteObject(hDib);
        } else {
            obj = SelectObject(context_hdc, hDib);
            CopyMemory(bits, buffer, width * height * sizeof(PIXEL_SIZE));
        }
    }

    return (newimg);
}

// Print the buffer of pixel on the window
void             put_image_to_window(HWND hwnd, void *buffer, int x, int y)
{
    (void)hwnd;

    // Void buffer because i should use directly HDCcontext_hdc linked to HGDIOBJ   obj ?
    (void)buffer;

    BitBlt(hdc, // destination
        x,
        y,
        500, // width of the region
        500, // height
        context_hdc, // source
        0,   // x
        0,   // y
        SRCCOPY);

    UpdateWindow(hwnd);
}

static const char g_szClassName[] = "myWindowClass";

static void paint(HWND hwnd) {
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);
    EndPaint(hwnd, &ps);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    case WM_PAINT:
        paint(hwnd);
    return DefWindowProc(hwnd, msg, wParam, lParam);
}

int main(void) {
    MSG             Msg;
    HINSTANCE       hInstance;
    HWND            hwnd;
    STARTUPINFOA    startup_info;
    WNDCLASSEX      wc;
    HWND            hwnd;

    GetStartupInfoA(&startup_info);

    hInstance = GetModuleHandle(NULL);

    memset(&wc, 0, sizeof(wc));

    // Registering the Window Class
    wc.cbSize = sizeof(WNDCLASSEX);
    // ... etc
    wc.lpszClassName = TEXT(g_szClassName);

    if (!RegisterClassEx(&wc)) {
        return (-1);
    }

    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "Title,
        WS_OVERLAPPEDWINDOW | WS_VISIBLE,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        500, 
        500,
        NULL,
        NULL,
        hInstance,
        NULL);

    if (hwnd == NULL) {
        return (-1);
    }

    ShowWindow(hwnd, startup_info.wShowWindow);


    image = new_image(hwnd, 500, 500);

    put_image_to_window(hwnd, image, 0, 0);

    UpdateWindow(hwnd);

    // The Message Loop
    while (GetMessage(&Msg, NULL, 0, 0)) {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    return (Msg.wParam);
}

CopyMemory(bits, buffer, width * height * sizeof(PIXEL_SIZE));

hdc = GetDC(hwnd);

#include <windows.h>

static const char g_szClassName[] = "myWindowClass";
static HBITMAP  hDib;

BYTE *new_image(int width, int height)
{
    BITMAPINFO bmi;
    memset(&bmi, 0, sizeof(BITMAPINFO));
    bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmi.bmiHeader.biWidth = width;
    bmi.bmiHeader.biHeight = -height;
    bmi.bmiHeader.biPlanes = 1;
    bmi.bmiHeader.biBitCount = 32;
    bmi.bmiHeader.biCompression = BI_RGB;

    BYTE *buffer;
    HDC hdc = GetDC(HWND_DESKTOP);
    hDib = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void**)(&buffer), NULL, 0);
    ReleaseDC(HWND_DESKTOP, hdc);
    return buffer;
}

static void paint(HWND hwnd) 
{
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);

    if(hDib)
    {
        HDC context_hdc = CreateCompatibleDC(hdc);
        HGDIOBJ old_obj = SelectObject(context_hdc, hDib);
        BitBlt(hdc, 0, 0, 500, 500, context_hdc, 0, 0, SRCCOPY);
        SelectObject(context_hdc, old_obj);
        DeleteDC(context_hdc);
    }

    EndPaint(hwnd, &ps);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    case WM_PAINT:
        paint(hwnd);
        break;
    case WM_MOUSEMOVE:
    {
        if(hDib)
        {
            //draw something
            HDC context_hdc = CreateCompatibleDC(NULL);
            HGDIOBJ old_obj = SelectObject(context_hdc, hDib);

            SetDCBrushColor(context_hdc, RGB(255, 0, 0));
            int x = (int)(short)LOWORD(lParam);
            int y = (int)(short)HIWORD(lParam);
            RECT rc = { x, y, x + 10, y + 10};
            FillRect(context_hdc, &rc, (HBRUSH)GetStockObject(DC_BRUSH));

            SelectObject(context_hdc, old_obj);
            DeleteDC(context_hdc);

            InvalidateRect(hwnd, NULL, FALSE);
        }
        break;
    }
    }
    return DefWindowProc(hwnd, msg, wParam, lParam);
}

int main(void) {
    MSG             Msg;
    HINSTANCE       hInstance;
    HWND            hwnd;
    STARTUPINFOA    startup_info;
    WNDCLASSEX      wc;

    GetStartupInfoA(&startup_info);
    hInstance = GetModuleHandle(NULL);
    memset(&wc, 0, sizeof(wc));
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszClassName = TEXT(g_szClassName);
    RegisterClassEx(&wc);

    hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, g_szClassName, "Title",
        WS_OVERLAPPEDWINDOW | WS_VISIBLE,
        CW_USEDEFAULT, CW_USEDEFAULT,
        500, 500, NULL, NULL, hInstance, NULL);

    BYTE* image = new_image(500, 500);

    ShowWindow(hwnd, SW_SHOW);//startup_info.wShowWindow);
    UpdateWindow(hwnd);
    while(GetMessage(&Msg, NULL, 0, 0)) 
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    if (hDib)
        DeleteObject(hDib);

    return (Msg.wParam);
}

// global variables
static HBITMAP hDib;

static void     set_bmi_object(BITMAPINFO *bmi, int width, int height) {
    memset(bmi, 0, sizeof(BITMAPINFO));

    bmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmi->bmiHeader.biWidth = width;
    bmi->bmiHeader.biHeight = -height;
    bmi->bmiHeader.biPlanes = 1;
    bmi->bmiHeader.biBitCount = 32;
    bmi->bmiHeader.biCompression = BI_RGB;
}

// Allocate a new image buffer
void             *new_image(HWND hwnd, int width, int height)
{
    BITMAPINFO  bmi;
    void        *buffer;
    HDC         hdc;

    set_bmi_object(&bmi, width, height);

    hdc = GetDC(hwnd);

    hDib = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void**)(&buffer), NULL, 0);

    ReleaseDC(instance->win_list->hwnd, hdc);

    return (buffer);
}

// Print the buffer of pixel on the window
void             put_image_to_window(HWND hwnd, void *buffer, int x, int y)
{
    HDC                     hdc;
    HDC                     context_hdc;
    HGDIOBJ                 old_obj;

    hdc = GetDC(hwnd);

    context_hdc = CreateCompatibleDC(hdc);

    old_obj = SelectObject(context_hdc, hDib);

    BitBlt(hdc,
        0,
        0,
       500,
       500,
       context_hdc,
       0,
       0,
       SRCCOPY);

    SelectObject(context_hdc, old_obj);

    DeleteDC(context_hdc);
    ReleaseDC(hwnd, hdc);

    // Call UpdateLayeredWindow
    BLENDFUNCTION blend = {0};
    blend.BlendOp = AC_SRC_OVER;
    blend.SourceConstantAlpha = 128;// half transparent
    blend.AlphaFormat = AC_SRC_ALPHA;
    POINT ptLocation = {x, y};
    SIZE szWnd = {500, 500};
    POINT ptSrc = {0, 0};
    UpdateLayeredWindow(hwnd, hdc, &ptLocation, &szWnd, context_hdc, &ptSrc, 0, &blend, ULW_ALPHA);
}

static const char g_szClassName[] = "myWindowClass";

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
    }
    return DefWindowProc(hwnd, msg, wParam, lParam);
}

int main(void) {
    MSG             Msg;
    HINSTANCE       hInstance;
    HWND            hwnd;
    STARTUPINFOA    startup_info;
    WNDCLASSEX      wc;
    HWND            hwnd;

    GetStartupInfoA(&startup_info);

    hInstance = GetModuleHandle(NULL);

    memset(&wc, 0, sizeof(wc));

    // Registering the Window Class
    wc.cbSize = sizeof(WNDCLASSEX);
    // ... etc
    wc.lpszClassName = TEXT(g_szClassName);

    if (!RegisterClassEx(&wc)) {
        return (-1);
    }

    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "Title,
        WS_OVERLAPPEDWINDOW | WS_VISIBLE,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        500, 
        500,
        NULL,
        NULL,
        hInstance,
        NULL);

    if (hwnd == NULL) {
        return (-1);
    }

    ShowWindow(hwnd, startup_info.wShowWindow);

    image = new_image(hwnd, 500, 500);

    put_image_to_window(hwnd, image, 0, 0);

    // The Message Loop
    while (GetMessage(&Msg, NULL, 0, 0)) {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    return (Msg.wParam);
}