如何在窗口上绘制图像？

Question

我在 Windows Vista 上使用 C++ 中的 VS2005 创建了一个带有 createwindow() api 的窗口

我的要求是在该窗口上绘制图像（任何格式）。我没有在此应用程序中使用任何 MFC。

Answer 1

不完全确定您的问题是什么：在表单上绘制位图，或者您想知道如何处理各种图像格式，或两者兼而有之。无论如何，下面是一个如何加载位图并将其绘制在表单上的示例：

HBITMAP hBitmap = NULL;

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;

    switch (message)
    {
<...>

    case WM_CREATE:
        hBitmap = (HBITMAP)LoadImage(hInst, L"c:\\test.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
        break;
    case WM_PAINT:
        PAINTSTRUCT     ps;
        HDC             hdc;
        BITMAP          bitmap;
        HDC             hdcMem;
        HGDIOBJ         oldBitmap;

        hdc = BeginPaint(hWnd, &ps);

        hdcMem = CreateCompatibleDC(hdc);
        oldBitmap = SelectObject(hdcMem, hBitmap);

        GetObject(hBitmap, sizeof(bitmap), &bitmap);
        BitBlt(hdc, 0, 0, bitmap.bmWidth, bitmap.bmHeight, hdcMem, 0, 0, SRCCOPY);

        SelectObject(hdcMem, oldBitmap);
        DeleteDC(hdcMem);

        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        DeleteObject(hBitmap);
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

LoadImage 加载图标、光标、动画光标或位图。详情here

要处理各种图像格式，您可以使用 Windows 映像组件（请参阅 IWICBitmapDecoder）或此处的代码 Loading JPEG and GIF pictures 或 3rd 方工具，如 FreeImage 或 LeadTools

希望这会有所帮助，问候

Answer 2

void LoadScreen(HWND hWnd) {
    RECT rect;
    HDC hdc = GetDC(hWnd);
    HBRUSH brush = CreatePatternBrush((HBITMAP)LoadImage(NULL, L"file.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE));
    GetWindowRect(hWnd, &rect);
    FillRect(hdc, &rect, brush);
    DeleteObject(brush);
    ReleaseDC(hWnd, hdc);
}

Answer 3

#include <windows.h>
#include <string.h>

HBITMAP hBitmap, hOldBitmap;
HDC hdc, hdcMem;
BITMAP bm;
HINSTANCE hI;
PAINTSTRUCT ps;
RECT rect;
RECT rc;

LRESULT CALLBACK WindowProcedure(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch (msg)
    {
    case WM_CREATE:
    hBitmap = (HBITMAP)LoadImage(hI, "1.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
    GetObject(hBitmap, sizeof(BITMAP), &bm);
    hdc = GetDC(hWnd);
    hdcMem = CreateCompatibleDC(hdc);
    hOldBitmap = SelectBitmap(hdcMem, hBitmap);
    ReleaseDC(hWnd, hdc);
    return 0;

    case WM_LBUTTONDOWN:
    //for dragging not only by the title, but also by any part of the window 
    ReleaseCapture();
    SendMessage(hWnd, 0xA1, 2, 0);
    break;
    case WM_PAINT:
    hdc=BeginPaint(hWnd,&ps);
    
    //overlay image with stretching to fit the window 
    GetClientRect(hWnd,&rect);
    SetStretchBltMode(hdc, STRETCH_HALFTONE);
    StretchBlt(hdc,0,0,rect.right,rect.bottom,
    hdcMem,0,0,bm.bmWidth,bm.bmHeight,SRCCOPY);
    
    EndPaint(hWnd,&ps);
    break;      


    case WM_DESTROY:
    PostQuitMessage(0);
      
    DeleteDC(hdcMem);
    DeleteObject(hBitmap);
    DeleteObject(hOldBitmap);
    break;
    }
return DefWindowProc(hWnd, msg, wParam, lParam);
}
 
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPInst, LPSTR lpCmdLine, int nCmdShow)
{
//copying a pointer to a running application instance (module)
hI=hInstance;

WNDCLASS wc;

wc.style         = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc   = WindowProcedure;
wc.hInstance     = hInstance;
wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH) GetStockObject(LTGRAY_BRUSH);
wc.lpszClassName = "test_class";
wc.lpszMenuName  = NULL;
wc.cbClsExtra    = 0;
wc.cbWndExtra    = 0;

RegisterClass(&wc);

HWND hWnd = CreateWindow(wc.lpszClassName, "Image Window", 
//window with title (overlapping window) 
WS_OVERLAPPEDWINDOW,
//window without title
//WS_VISIBLE | WS_POPUP | WS_SYSMENU | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
CW_USEDEFAULT, CW_USEDEFAULT, 500, 500, NULL, NULL, hInstance, NULL);

ShowWindow(hWnd, SW_SHOW);
UpdateWindow(hWnd);

MSG msg;
while(GetMessage (&msg, NULL, 0, 0))
    {
    DispatchMessage (&msg);
    TranslateMessage (&msg);
    }
UnregisterClass(wc.lpszClassName, hInstance);
return (int) msg.wParam;
}