我正在學習如何在 C 中為視窗設定背景影像。這是我的代碼：
#include <stdio.h>
#include <windows.h>
char* window_name = "Window";
char* window_title = "Window Title";
char* background_name = "test.bmp";
int window_width = 600;
int window_height = 400;
HBITMAP hbackground_image;
WNDCLASSEX wc;
HWND hwnd, hbackground;
MSG msg;
LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp)
{
switch (msg)
{
case WM_CREATE:
hbackground = CreateWindow("STATIC", "background", SS_BITMAP | WS_CHILD | WS_VISIBLE, 0, 0, 300, 300, hwnd,
NULL, NULL, NULL);
hbackground_image = (HBITMAP)LoadImage(NULL, background_name, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
SendMessage(hbackground, STM_SETIMAGE, (WPARAM)IMAGE_BITMAP, (LPARAM)hbackground_image);
break;
default:
return DefWindowProc(hwnd, msg, wp, lp);
}
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = DefWindowProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(hInstance, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW 1);
wc.lpszMenuName = NULL;
wc.hIconSm = LoadIcon(hInstance, IDI_APPLICATION);
wc.lpszClassName = window_name;
if (!RegisterClassEx(&wc))
{
MessageBox(NULL, "Windows registration failure", NULL, MB_RETRYCANCEL);
return 1;
}
hwnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW, window_name, window_title, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT,
CW_USEDEFAULT, window_width, window_height, NULL, NULL, hInstance, NULL);
// hwnd = CreateWindow("test", "test title", WS_OVERLAPPED | WS_VISIBLE, 100, 100, 500, 500, NULL, NULL, NULL, NULL); // This fails
if (!hwnd) // If fails
{
MessageBox(NULL, "Window creation failed :(", NULL, MB_RETRYCANCEL);
return 2;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&msg, NULL, 0, 0) > 0)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
但是，即使在與 .exe 相同的檔案夾中有位圖，也不會設定背景影像。我還嘗試了來自互聯網的不同位圖，其中一個是我用顏料制作的。任何幫助，將不勝感激。
uj5u.com熱心網友回復：
這一行是錯誤的：
wc.lpfnWndProc = DefWindowProc;
您沒有看到背景影像，因為您沒有使用WindowProcedure()window 類，因此永遠不會呼叫它來加載/顯示位圖。
該行需要改為：
wc.lpfnWndProc = WindowProcedure;
此外，在處理時WM_CREATE，您沒有return任何值，因此結果是不確定的，這是未定義的行為。return 0;對于該訊息，您需要：
LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp)
{
switch (msg)
{
case WM_CREATE:
...
return 0;
}
return DefWindowProc(hwnd, msg, wp, lp);
}
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