libui/windows/areaevents.cpp

// 8 september 2015
#include "uipriv_windows.hpp"
#include "area.hpp"

static uiModifiers getModifiers(void)
{
	uiModifiers m = 0;

	if ((GetKeyState(VK_CONTROL) & 0x80) != 0)
		m |= uiModifierCtrl;
	if ((GetKeyState(VK_MENU) & 0x80) != 0)
		m |= uiModifierAlt;
	if ((GetKeyState(VK_SHIFT) & 0x80) != 0)
		m |= uiModifierShift;
	if ((GetKeyState(VK_LWIN) & 0x80) != 0)
		m |= uiModifierSuper;
	if ((GetKeyState(VK_RWIN) & 0x80) != 0)
		m |= uiModifierSuper;
	return m;
}

/*
Windows doesn't natively support mouse crossing events.

TrackMouseEvent() (and its comctl32.dll wrapper _TrackMouseEvent()) both allow for a window to receive the WM_MOUSELEAVE message when the mouse leaves the client area. There's no equivalent WM_MOUSEENTER because it can be simulated (https://blogs.msdn.microsoft.com/oldnewthing/20031013-00/?p=42193).

Unfortunately, WM_MOUSELEAVE does not get generated while the mouse is captured. We need to capture for drag behavior to work properly, so this isn't going to mix well.

So what we do:
- on WM_MOUSEMOVE, if we don't have the capture, start tracking
	- this will handle the case of the capture being released while still in the area
- on WM_MOUSELEAVE, mark that we are no longer tracking
	- Windows has already done the work of that for us; it's just a flag we use for the next part
- when starting capture, stop tracking if we are tracking
- if capturing, manually check if the pointer is in the client rect on each area event
*/
static void track(uiArea *a, BOOL tracking)
{
	TRACKMOUSEEVENT tm;

	// do nothing if there's no change
	if (a->tracking && tracking)
		return;
	if (!a->tracking && !tracking)
		return;

	a->tracking = tracking;
	ZeroMemory(&tm, sizeof (TRACKMOUSEEVENT));
	tm.cbSize = sizeof (TRACKMOUSEEVENT);
	tm.dwFlags = TME_LEAVE;
	if (!a->tracking)
		tm.dwFlags |= TME_CANCEL;
	tm.hwndTrack = a->hwnd;
	if (_TrackMouseEvent(&tm) == 0)
		logLastError(L"error setting up mouse tracking");
}

static void capture(uiArea *a, BOOL capturing)
{
	// do nothing if there's no change
	if (a->capturing && capturing)
		return;
	if (!a->capturing && !capturing)
		return;

	// change flag first as ReleaseCapture() sends WM_CAPTURECHANGED
	a->capturing = capturing;
	if (a->capturing) {
		track(a, FALSE);
		SetCapture(a->hwnd);
	} else
		if (ReleaseCapture() == 0)
			logLastError(L"error releasing capture on drag");
}

static void areaMouseEvent(uiArea *a, int down, int  up, WPARAM wParam, LPARAM lParam)
{
	uiAreaMouseEvent me;
	int button;
	POINT clientpt;
	RECT client;
	BOOL inClient;
	double xpix, ypix;

	if (a->capturing) {
		clientpt.x = GET_X_LPARAM(lParam);
		clientpt.y = GET_Y_LPARAM(lParam);
		uiWindowsEnsureGetClientRect(a->hwnd, &client);
		inClient = PtInRect(&client, clientpt);
		if (inClient && !a->inside) {
			a->inside = TRUE;
			(*(a->ah->MouseCrossed))(a->ah, a, 0);
			clickCounterReset(&(a->cc));
		} else if (!inClient && a->inside) {
			a->inside = FALSE;
			(*(a->ah->MouseCrossed))(a->ah, a, 1);
			clickCounterReset(&(a->cc));
		}
	}

	xpix = (double) GET_X_LPARAM(lParam);
	ypix = (double) GET_Y_LPARAM(lParam);
	// these are in pixels; we need points
	pixelsToDIP(a, &xpix, &ypix);
	me.X = xpix;
	me.Y = ypix;
	if (a->scrolling) {
		me.X += a->hscrollpos;
		me.Y += a->vscrollpos;
	}

	loadAreaSize(a, NULL, &(me.AreaWidth), &(me.AreaHeight));

	me.Down = down;
	me.Up = up;
	me.Count = 0;
	if (me.Down != 0)
		// GetMessageTime() returns LONG and GetDoubleClckTime() returns UINT, which are int32 and uint32, respectively, but we don't need to worry about the signedness because for the same bit widths and two's complement arithmetic, s1-s2 == u1-u2 if bits(s1)==bits(s2) and bits(u1)==bits(u2) (and Windows requires two's complement: http://blogs.msdn.com/b/oldnewthing/archive/2005/05/27/422551.aspx)
		// signedness isn't much of an issue for these calls anyway because http://stackoverflow.com/questions/24022225/what-are-the-sign-extension-rules-for-calling-windows-api-functions-stdcall-t and that we're only using unsigned values (think back to how you (didn't) handle signedness in assembly language) AND because of the above AND because the statistics below (time interval and width/height) really don't make sense if negative
		// GetSystemMetrics() returns int, which is int32
		me.Count = clickCounterClick(&(a->cc), me.Down,
			me.X, me.Y,
			GetMessageTime(), GetDoubleClickTime(),
			GetSystemMetrics(SM_CXDOUBLECLK) / 2,
			GetSystemMetrics(SM_CYDOUBLECLK) / 2);

	// though wparam will contain control and shift state, let's just one function to get modifiers for both keyboard and mouse events; it'll work the same anyway since we have to do this for alt and windows key (super)
	me.Modifiers = getModifiers();

	button = me.Down;
	if (button == 0)
		button = me.Up;
	me.Held1To64 = 0;
	if (button != 1 && (wParam & MK_LBUTTON) != 0)
		me.Held1To64 |= 1 << 0;
	if (button != 2 && (wParam & MK_MBUTTON) != 0)
		me.Held1To64 |= 1 << 1;
	if (button != 3 && (wParam & MK_RBUTTON) != 0)
		me.Held1To64 |= 1 << 2;
	if (button != 4 && (wParam & MK_XBUTTON1) != 0)
		me.Held1To64 |= 1 << 3;
	if (button != 5 && (wParam & MK_XBUTTON2) != 0)
		me.Held1To64 |= 1 << 4;

	// on Windows, we have to capture on drag ourselves
	if (me.Down != 0)
		capture(a, TRUE);
	// only release capture when all buttons released
	if (me.Up != 0 && me.Held1To64 == 0)
		capture(a, FALSE);

	(*(a->ah->MouseEvent))(a->ah, a, &me);
}

// TODO genericize this so it can be called above
static void onMouseEntered(uiArea *a)
{
	if (a->inside)
		return;
	if (a->capturing)		// we handle mouse crossing in areaMouseEvent()
		return;
	track(a, TRUE);
	(*(a->ah->MouseCrossed))(a->ah, a, 0);
	// TODO figure out why we did this to begin with; either we do it on both GTK+ and Windows or not at all
	clickCounterReset(&(a->cc));
}

// TODO genericize it so that it can be called above
static void onMouseLeft(uiArea *a)
{
	a->tracking = FALSE;
	a->inside = FALSE;
	(*(a->ah->MouseCrossed))(a->ah, a, 1);
	// TODO figure out why we did this to begin with; either we do it on both GTK+ and Windows or not at all
	clickCounterReset(&(a->cc));
}

// we use VK_SNAPSHOT as a sentinel because libui will never support the print screen key; that key belongs to the user
struct extkeymap {
	WPARAM vk;
	uiExtKey extkey;
};

// all mappings come from GLFW - https://github.com/glfw/glfw/blob/master/src/win32_window.c#L152
static const struct extkeymap numpadExtKeys[] = {
	{ VK_HOME, uiExtKeyN7 },
	{ VK_UP, uiExtKeyN8 },
	{ VK_PRIOR, uiExtKeyN9 },
	{ VK_LEFT, uiExtKeyN4 },
	{ VK_CLEAR, uiExtKeyN5 },
	{ VK_RIGHT, uiExtKeyN6 },
	{ VK_END, uiExtKeyN1 },
	{ VK_DOWN, uiExtKeyN2 },
	{ VK_NEXT, uiExtKeyN3 },
	{ VK_INSERT, uiExtKeyN0 },
	{ VK_DELETE, uiExtKeyNDot },
	{ VK_SNAPSHOT, 0 },
};

static const struct extkeymap extKeys[] = {
	{ VK_ESCAPE, uiExtKeyEscape },
	{ VK_INSERT, uiExtKeyInsert },
	{ VK_DELETE, uiExtKeyDelete },
	{ VK_HOME, uiExtKeyHome },
	{ VK_END, uiExtKeyEnd },
	{ VK_PRIOR, uiExtKeyPageUp },
	{ VK_NEXT, uiExtKeyPageDown },
	{ VK_UP, uiExtKeyUp },
	{ VK_DOWN, uiExtKeyDown },
	{ VK_LEFT, uiExtKeyLeft },
	{ VK_RIGHT, uiExtKeyRight },
	{ VK_F1, uiExtKeyF1 },
	{ VK_F2, uiExtKeyF2 },
	{ VK_F3, uiExtKeyF3 },
	{ VK_F4, uiExtKeyF4 },
	{ VK_F5, uiExtKeyF5 },
	{ VK_F6, uiExtKeyF6 },
	{ VK_F7, uiExtKeyF7 },
	{ VK_F8, uiExtKeyF8 },
	{ VK_F9, uiExtKeyF9 },
	{ VK_F10, uiExtKeyF10 },
	{ VK_F11, uiExtKeyF11 },
	{ VK_F12, uiExtKeyF12 },
	// numpad numeric keys and . are handled in common/areaevents.c
	// numpad enter is handled in code below
	{ VK_ADD, uiExtKeyNAdd },
	{ VK_SUBTRACT, uiExtKeyNSubtract },
	{ VK_MULTIPLY, uiExtKeyNMultiply },
	{ VK_DIVIDE, uiExtKeyNDivide },
	{ VK_SNAPSHOT, 0 },
};

static const struct {
	WPARAM vk;
	uiModifiers mod;
} modKeys[] = {
	// even if the separate left/right aren't necessary, have them here anyway, just to be safe
	{ VK_CONTROL, uiModifierCtrl },
	{ VK_LCONTROL, uiModifierCtrl },
	{ VK_RCONTROL, uiModifierCtrl },
	{ VK_MENU, uiModifierAlt },
	{ VK_LMENU, uiModifierAlt },
	{ VK_RMENU, uiModifierAlt },
	{ VK_SHIFT, uiModifierShift },
	{ VK_LSHIFT, uiModifierShift },
	{ VK_RSHIFT, uiModifierShift },
	// there's no combined Windows key virtual-key code as there is with the others
	{ VK_LWIN, uiModifierSuper },
	{ VK_RWIN, uiModifierSuper },
	{ VK_SNAPSHOT, 0 },
};

static int areaKeyEvent(uiArea *a, int up, WPARAM wParam, LPARAM lParam)
{
	uiAreaKeyEvent ke;
	int righthand;
	int i;

	ke.Key = 0;
	ke.ExtKey = 0;
	ke.Modifier = 0;

	ke.Modifiers = getModifiers();

	ke.Up = up;

	// the numeric keypad keys when Num Lock is off are considered left-hand keys as the separate navigation buttons were added later
	// the numeric keypad Enter, however, is a right-hand key because it has the same virtual-key code as the typewriter Enter
	righthand = (lParam & 0x01000000) != 0;
	if (righthand) {
		if (wParam == VK_RETURN) {
			ke.ExtKey = uiExtKeyNEnter;
			goto keyFound;
		}
	} else
		// this is special handling for numpad keys to ignore the state of Num Lock and Shift; see http://blogs.msdn.com/b/oldnewthing/archive/2004/09/06/226045.aspx and https://github.com/glfw/glfw/blob/master/src/win32_window.c#L152
		for (i = 0; numpadExtKeys[i].vk != VK_SNAPSHOT; i++)
			if (numpadExtKeys[i].vk == wParam) {
				ke.ExtKey = numpadExtKeys[i].extkey;
				goto keyFound;
			}

	// okay, those above cases didn't match anything
	// first try the extended keys
	for (i = 0; extKeys[i].vk != VK_SNAPSHOT; i++)
		if (extKeys[i].vk == wParam) {
			ke.ExtKey = extKeys[i].extkey;
			goto keyFound;
		}

	// then try modifier keys
	for (i = 0; modKeys[i].vk != VK_SNAPSHOT; i++)
		if (modKeys[i].vk == wParam) {
			ke.Modifier = modKeys[i].mod;
			// and don't include the key in Modifiers
			ke.Modifiers &= ~ke.Modifier;
			goto keyFound;
		}

	// and finally everything else
	if (fromScancode((lParam >> 16) & 0xFF, &ke))
		goto keyFound;

	// not a supported key, assume unhandled
	// TODO the original code only did this if ke.Modifiers == 0 - why?
	return 0;

keyFound:
	return (*(a->ah->KeyEvent))(a->ah, a, &ke);
}

// We don't handle the standard Windows keyboard messages directly, to avoid both the dialog manager and TranslateMessage().
// Instead, we set up a message filter and do things there.
// That stuff is later in this file.
enum {
	// start at 0x40 to avoid clobbering dialog messages
	msgAreaKeyDown = WM_USER + 0x40,
	msgAreaKeyUp,
};

BOOL areaDoEvents(uiArea *a, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT *lResult)
{
	switch (uMsg) {
	case WM_ACTIVATE:
		// don't keep the double-click timer running if the user switched programs in between clicks
		clickCounterReset(&(a->cc));
		*lResult = 0;
		return TRUE;
	case WM_MOUSEMOVE:
		onMouseEntered(a);
		areaMouseEvent(a, 0, 0, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_MOUSELEAVE:
		onMouseLeft(a);
		*lResult = 0;
		return TRUE;
	case WM_LBUTTONDOWN:
		SetFocus(a->hwnd);
		areaMouseEvent(a, 1, 0, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_LBUTTONUP:
		areaMouseEvent(a, 0, 1, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_MBUTTONDOWN:
		SetFocus(a->hwnd);
		areaMouseEvent(a, 2, 0, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_MBUTTONUP:
		areaMouseEvent(a, 0, 2, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_RBUTTONDOWN:
		SetFocus(a->hwnd);
		areaMouseEvent(a, 3, 0, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_RBUTTONUP:
		areaMouseEvent(a, 0, 3, wParam, lParam);
		*lResult = 0;
		return TRUE;
	case WM_XBUTTONDOWN:
		SetFocus(a->hwnd);
		// values start at 1; we want them to start at 4
		areaMouseEvent(a,
			GET_XBUTTON_WPARAM(wParam) + 3, 0,
			GET_KEYSTATE_WPARAM(wParam), lParam);
		*lResult = TRUE;	// XBUTTON messages are different!
		return TRUE;
	case WM_XBUTTONUP:
		areaMouseEvent(a,
			0, GET_XBUTTON_WPARAM(wParam) + 3,
			GET_KEYSTATE_WPARAM(wParam), lParam);
		*lResult = TRUE;	// XBUTTON messages are different!
		return TRUE;
	case WM_CAPTURECHANGED:
		if (a->capturing) {
			a->capturing = FALSE;
			(*(a->ah->DragBroken))(a->ah, a);
		}
		*lResult = 0;
		return TRUE;
	case msgAreaKeyDown:
		*lResult = (LRESULT) areaKeyEvent(a, 0, wParam, lParam);
		return TRUE;
	case msgAreaKeyUp:
		*lResult = (LRESULT) areaKeyEvent(a, 1, wParam, lParam);
		return TRUE;
	}
	return FALSE;
}

// TODO affect visibility properly
// TODO what did this mean
BOOL areaFilter(MSG *msg)
{
	LRESULT handled;

	// is the recipient an area?
	if (msg->hwnd == NULL)		// this can happen; for example, WM_TIMER
		return FALSE;
	if (windowClassOf(msg->hwnd, areaClass, NULL) != 0)
		return FALSE;			// nope

	handled = 0;
	switch (msg->message) {
	case WM_KEYDOWN:
	case WM_SYSKEYDOWN:
		handled = SendMessageW(msg->hwnd, msgAreaKeyDown, msg->wParam, msg->lParam);
		break;
	case WM_KEYUP:
	case WM_SYSKEYUP:
		handled = SendMessageW(msg->hwnd, msgAreaKeyUp, msg->wParam, msg->lParam);
		break;
	// otherwise handled remains 0, as we didn't handle this
	}
	return (BOOL) handled;
}