HideWindow API Tutorial: Step-by-Step Implementation
This tutorial walks through implementing a HideWindow API to programmatically hide and show application windows. It covers design, platform specifics, a simple cross-platform interface, example implementations for Windows and a Unix/X11-like environment, and usage patterns including safety and accessibility considerations.
Goals and API design
- Goal: Provide a minimal, safe API to hide and show windows owned by an application process.
- Requirements:
- HideWindow(windowHandle): hides the specified window.
- ShowWindow(windowHandle): restores visibility.
- IsWindowHidden(windowHandle): returns boolean.
- Non-destructive: should not destroy window or alter layout/state beyond visibility.
- Accessible: consider screen readers and focus handling.
- Thread-safe for typical GUI thread models (document assumptions).
API signature (pseudo):
c
typedef void* WindowHandle; bool HideWindow(WindowHandle h); bool ShowWindow(WindowHandle h); bool IsWindowHidden(WindowHandle h);
Cross-platform considerations
- Run on the GUI/main thread when required by the platform.
- Respect platform conventions: “hide” may differ from “minimize” or “withdraw”.
- Preserve focus and active-window semantics: if hiding the active window, move focus to a sensible window or none.
- Accessibility: notify assistive technologies about visibility changes if platform supports notifications.
- Security: do not expose handles across privilege boundaries.
Windows implementation (Win32)
Behavior: hide by changing window visibility state; use ShowWindow or SetWindowPos without destroying.
Key functions:
- ShowWindow(hWnd, SW_HIDE / SW_SHOW)
- IsWindowVisible(hWnd)
- GetForegroundWindow / SetFocus for focus handling
- SendMessage with WM_ACTIVATE / WMSHOWWINDOW for notifications
Example (C/C++):
c
#include#include bool HideWindow(HWND hWnd) { if (!IsWindow(hWnd)) return false; // If window is foreground, set focus to another window HWND fg = GetForegroundWindow(); if (fg == hWnd) { // try to set focus to owner or desktop HWND owner = GetWindow(hWnd, GW_OWNER); if (IsWindow(owner)) SetForegroundWindow(owner); else SetForegroundWindow(GetDesktopWindow()); } BOOL res = ShowWindow(hWnd, SW_HIDE); // Notify accessibility frameworks // (Windows will dispatch WM_SHOWWINDOW) return res != 0; } bool ShowWindowEx(HWND hWnd) { if (!IsWindow(hWnd)) return false; BOOL res = ShowWindow(hWnd, SW_SHOW); // Bring to foreground optionally SetForegroundWindow(hWnd); return res != 0; } bool IsWindowHidden(HWND hWnd) { if (!IsWindow(hWnd)) return false; return !IsWindowVisible(hWnd); }
Notes:
- SW_MINIMIZE differs from SW
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