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◆ rrdc-perf enhanced-x16-emulator / src / video_win32.c
4.5 KiB · C · last changed chore(): initial commit 25 days ago source blame history raw
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// All rights reserved. License: 2-clause BSD
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#include <SDL.h>
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#include <SDL_syswm.h>
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#include <windows.h>
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#include <dwmapi.h>
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#include "glue.h"
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void video_win32_set_rounded_corners(SDL_Window *window)
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{
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	SDL_SysWMinfo wmInfo;
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	SDL_VERSION(&wmInfo.version);
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	SDL_GetWindowWMInfo(window, &wmInfo);
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	HWND hwnd = wmInfo.info.win.window;
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	DWM_WINDOW_CORNER_PREFERENCE preference = DWMWCP_ROUNDSMALL;
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	DwmSetWindowAttribute(hwnd, DWMWA_WINDOW_CORNER_PREFERENCE, &preference, sizeof(preference));
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}
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// --- Keep the emulator running while the window is dragged/resized ----------
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//
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// Moving or resizing a window on Windows spins the OS in a modal message loop
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// (WM_ENTERSIZEMOVE..WM_EXITSIZEMOVE) that never returns to our main loop, so
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// emulation and painting would otherwise freeze until the drag ends.
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//
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// SDL2's SDL_SetWindowsMessageHook is invoked from WIN_PumpEvents (SDL's own
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// PeekMessage loop). That loop does NOT run while the OS owns the thread inside
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// the modal move/resize loop, so the hook never sees WM_ENTERSIZEMOVE/WM_TIMER
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// and cannot drive stepping. Instead we subclass the window procedure directly
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// (SetWindowLongPtrW / GWLP_WNDPROC): the OS dispatches messages straight to our
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// proc even inside the modal loop. We arm a WM_TIMER for the duration of that
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// loop and advance the emulator one frame per tick, chaining every other message
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// to SDL's original proc so SDL keeps working exactly as before.
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#define X16_MOVE_TIMER_ID 0xB16
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static WNDPROC video_win32_orig_wndproc = NULL;
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static bool    win32_in_modal_move      = false;
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static LRESULT CALLBACK
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video_win32_subclass_proc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
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{
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	switch (message) {
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		case WM_ENTERSIZEMOVE:
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			win32_in_modal_move = true;
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			// The timer covers the case the messages below cannot: a drag that
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			// is held perfectly still still needs the machine to keep running.
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			// 10 ms is the shortest interval Windows honours.
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			SetTimer(hWnd, X16_MOVE_TIMER_ID, 10, NULL);
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			break;
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		case WM_EXITSIZEMOVE:
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			if (win32_in_modal_move) {
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				KillTimer(hWnd, X16_MOVE_TIMER_ID);
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				win32_in_modal_move = false;
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			}
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			break;
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		case WM_TIMER:
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			if (win32_in_modal_move && wParam == X16_MOVE_TIMER_ID) {
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				emulator_step_during_move();
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				return 0; // handled; don't hand our private timer to SDL
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			}
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			break;
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		// WM_TIMER is the lowest-priority message there is: Windows only
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		// synthesises it when the queue has nothing else waiting. Drag the
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		// window quickly and the queue never empties, so the timer stops firing
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		// and the machine appears to pause -- the very case this is meant to
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		// fix. Drive emulation from the messages a drag actually produces as
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		// well; between the two, the machine keeps running whether the pointer
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		// is flying or sitting still. emulator_step_during_move() paces itself,
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		// so being called far more often than 100 Hz costs almost nothing.
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		case WM_MOVING:
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		case WM_SIZING:
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		case WM_WINDOWPOSCHANGED:
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		case WM_NCMOUSEMOVE:
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		case WM_MOUSEMOVE:
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			if (win32_in_modal_move) {
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				emulator_step_during_move();
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			}
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			break; // still needs its normal handling below
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	}
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	if (video_win32_orig_wndproc) {
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		return CallWindowProcW(video_win32_orig_wndproc, hWnd, message, wParam, lParam);
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	}
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	return DefWindowProcW(hWnd, message, wParam, lParam);
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}
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static HWND
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video_win32_hwnd(SDL_Window *window)
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{
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	SDL_SysWMinfo wmInfo;
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	SDL_VERSION(&wmInfo.version);
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	if (!SDL_GetWindowWMInfo(window, &wmInfo)) {
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		return NULL;
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	}
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	return wmInfo.info.win.window;
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}
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void video_win32_install_move_hook(SDL_Window *window)
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{
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	HWND hwnd = video_win32_hwnd(window);
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	if (hwnd == NULL) {
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		return;
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	}
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	// Don't double-subclass the same window (our proc would chain to itself).
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	// All SDL windows share the same WIN_WindowProc, so one saved original is
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	// enough for chaining regardless of how many windows we subclass.
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	WNDPROC prev = (WNDPROC)(LONG_PTR)GetWindowLongPtrW(hwnd, GWLP_WNDPROC);
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	if (prev == video_win32_subclass_proc) {
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		return; // already installed on this window
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	}
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	SetWindowLongPtrW(hwnd, GWLP_WNDPROC, (LONG_PTR)video_win32_subclass_proc);
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	if (video_win32_orig_wndproc == NULL) {
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		video_win32_orig_wndproc = prev;
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	}
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}
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void video_win32_remove_move_hook(SDL_Window *window)
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{
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	if (video_win32_orig_wndproc == NULL) {
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		return;
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	}
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	HWND hwnd = video_win32_hwnd(window);
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	if (hwnd == NULL) {
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		return;
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	}
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	WNDPROC cur = (WNDPROC)(LONG_PTR)GetWindowLongPtrW(hwnd, GWLP_WNDPROC);
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	if (cur == video_win32_subclass_proc) {
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		SetWindowLongPtrW(hwnd, GWLP_WNDPROC, (LONG_PTR)video_win32_orig_wndproc);
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	}
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}
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