Windows: create a window which fits selected resolution better

[danie1kr]

try to get a window which is closer to the selected resolution. Still 2 pixels off horizontally, but better than what windows creates.

[kisvegabor]

As it might affect existing projects I wouldn't touch this part.
However I would be happy to merge lvgl/lvgl#5639 if it's approved by @MouriNaruto.

[danie1kr]

Sure, I understand. Actually, I moved from lv_drivers to pure lvgl when I fixed this.

[MouriNaruto]

I don't think you have read the implementation carefully. The current 8.x implementation will apply the real size in WM_CREATE message.

lv_drivers/win32drv/win32drv.c

Lines 905 to 941 in 451e659

	RECT calculated_window_size;
	calculated_window_size.left = 0;
	calculated_window_size.right = MulDiv(
	context->display_hor_res * WIN32DRV_MONITOR_ZOOM,
	context->display_dpi,
	USER_DEFAULT_SCREEN_DPI);
	calculated_window_size.top = 0;
	calculated_window_size.bottom = MulDiv(
	context->display_ver_res * WIN32DRV_MONITOR_ZOOM,
	context->display_dpi,
	USER_DEFAULT_SCREEN_DPI);
	AdjustWindowRectEx(
	&calculated_window_size,
	WINDOW_STYLE,
	FALSE,
	WINDOW_EX_STYLE);
	OffsetRect(
	&calculated_window_size,
	-calculated_window_size.left,
	-calculated_window_size.top);
	SetWindowPos(
	hWnd,
	NULL,
	0,
	0,
	calculated_window_size.right,
	calculated_window_size.bottom,
	SWP_NOZORDER | SWP_NOACTIVATE | SWP_NOMOVE);
	lv_win32_register_touch_window(hWnd, 0);
	lv_win32_enable_child_window_dpi_message(hWnd);
	break;

I don't use AdjustWindowRect when creating window because it's not reliable.

First, AdjustWindowRect document said that to specify an extended window style, use the AdjustWindowRectEx function.

Second, AdjustWindowRectEx document said that this API is not DPI aware, and should not be used if the calling thread is per-monitor DPI aware. For the DPI-aware version of this API, see AdjustWindowsRectExForDPI.

Also, AdjustWindowsRectExForDPI is not reliable for enabling the DWM composition which is forced beginning with Windows 8. Especially the Windows 10 frameless-style window which is the DWM hacking.

So, this is why I chose only to pass the raw window size before. Because we need to let WM_CREATE message know the raw value for postprocessing. But for 8.x implementation is simplified because 8.x's driver only provides the simulator mode.

Kenji Mouri