To address the problem of placing windows below icons and creating background windows using window handles in Windows programming, we can follow a structured approach. Here’s a detailed explanation:
1. Understanding Window Handles (HWND)
- ** HWND** is a unique identifier for each window created in a Windows application. It allows us to manipulate and control the properties of a window programmatically.
- To work with window handles, you need to obtain them using functions like FindWindow, CreateWindowEx, or by receiving them through window messages.
2. Placing Windows Below Taskbar Icons
To place a window below the taskbar icons, follow these steps:
a. Determine Taskbar Height:
- Use the GetWindowMetrics function to retrieve the height of the taskbar.
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[DllImport(“shell32.dll”)] static extern int GetWindowMetrics(out int dwWidth, out int dwHeight); |
b. Create or Move Window Below Taskbar:
- When creating a new window, set its Y-coordinate to negative value equal to the taskbar height.
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int taskBarHeight = 0; GetWindowMetrics(out _, out taskBarHeight); HWND hwnd = CreateWindowEx(..., XPOS: 0, YPOS: –taskBarHeight, ...); |
c. Ensure Window is Always Below:
- Use SetWindowPos to adjust the window’s position periodically if it moves.
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SetWindowPos(hwnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOZORDER); |
3. Creating Background Windows
To create a background window that stays behind other windows:
a. Use Extended Window Styles:
- Set the extended window style to make it transparent or always stay behind.
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DWORD dwExStyle = WS_EX_TRANSPARENT; HWND hwndBg = CreateWindowEx(dwExStyle, ..., ...); |
b. Adjust Z-Order:
- Place the background window at the bottom of the z-order using SetWindowPos.
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SetWindowPos(hwndBg, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOACTIVATE); |
4. Handling Window Messages and Notifications
- If your window needs to react to events like clicking on taskbar icons, handle relevant messages such as WM_NOTIFY.
5. Example Code Implementation:
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#include <windows.h> using namespace std; int main() { HWND hwndMain = GetForegroundWindow(); int taskBarHeight; GetWindowMetrics(0, &taskBarHeight); // Create window below taskbar HWND hwndBelow = CreateWindowEx( WS_EX_TRANSPARENT, “YourClass”, “Window Below Taskbar”, WS_POPUP, 0, –taskBarHeight, 100, 100, hwndMain, NULL, GetModuleHandle(NULL), NULL ); ShowWindow(hwndBelow, SW_SHOW); UpdateWindow(hwndBelow); // Create background window HWND hwndBg = CreateWindowEx( WS_EX_TRANSPARENT, “YourClass”, “Background Window”, WS_POPUP, 100, –taskBarHeight*2, 200, 150, NULL, NULL, GetModuleHandle(NULL), NULL ); ShowWindow(hwndBg, SW_SHOW); UpdateWindow(hwndBg); MSG msg; while (GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg); DispatchMessage(&msg); } return 0; } |
Conclusion
By utilizing window handles and adjusting their positions and styles appropriately, you can control where windows are displayed relative to taskbar icons and other windows. This approach ensures that your windows behave as intended, whether they need to be background elements or positioned below existing UI components.