UAHMenuBar.h

#pragma once

// MIT license, see LICENSE
// Copyright(c) 2021 adzm / Adam D. Walling

// processes messages related to UAH / custom menubar drawing.
// return true if handled, false to continue with normal processing in your wndproc
bool UAHDarkModeWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam, LRESULT* lr);

// window messages related to menu bar drawing
#define WM_UAHDESTROYWINDOW    0x0090	// handled by DefWindowProc
#define WM_UAHDRAWMENU         0x0091	// lParam is UAHMENU
#define WM_UAHDRAWMENUITEM     0x0092	// lParam is UAHDRAWMENUITEM
#define WM_UAHINITMENU         0x0093	// handled by DefWindowProc
#define WM_UAHMEASUREMENUITEM  0x0094	// lParam is UAHMEASUREMENUITEM
#define WM_UAHNCPAINTMENUPOPUP 0x0095	// handled by DefWindowProc

// describes the sizes of the menu bar or menu item
typedef union tagUAHMENUITEMMETRICS
{
	// cx appears to be 14 / 0xE less than rcItem's width!
	// cy 0x14 seems stable, i wonder if it is 4 less than rcItem's height which is always 24 atm
	struct {
		DWORD cx;
		DWORD cy;
	} rgsizeBar[2];
	struct {
		DWORD cx;
		DWORD cy;
	} rgsizePopup[4];
} UAHMENUITEMMETRICS;

// not really used in our case but part of the other structures
typedef struct tagUAHMENUPOPUPMETRICS
{
	DWORD rgcx[4];
	DWORD fUpdateMaxWidths : 2; // from kernel symbols, padded to full dword
} UAHMENUPOPUPMETRICS;

// hmenu is the main window menu; hdc is the context to draw in
typedef struct tagUAHMENU
{
	HMENU hmenu;
	HDC hdc;
	DWORD dwFlags; // no idea what these mean, in my testing it's either 0x00000a00 or sometimes 0x00000a10
} UAHMENU;

// menu items are always referred to by iPosition here
typedef struct tagUAHMENUITEM
{
	int iPosition; // 0-based position of menu item in menubar
	UAHMENUITEMMETRICS umim;
	UAHMENUPOPUPMETRICS umpm;
} UAHMENUITEM;

// the DRAWITEMSTRUCT contains the states of the menu items, as well as
// the position index of the item in the menu, which is duplicated in
// the UAHMENUITEM's iPosition as well
typedef struct UAHDRAWMENUITEM
{
	DRAWITEMSTRUCT dis; // itemID looks uninitialized
	UAHMENU um;
	UAHMENUITEM umi;
} UAHDRAWMENUITEM;

// the MEASUREITEMSTRUCT is intended to be filled with the size of the item
// height appears to be ignored, but width can be modified
typedef struct tagUAHMEASUREMENUITEM
{
	MEASUREITEMSTRUCT mis;
	UAHMENU um;
	UAHMENUITEM umi;
} UAHMEASUREMENUITEM;