From 960533ab1f3cc701e7e9991ec65478785918a193 Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Fri, 22 Apr 2016 14:36:21 -0400
Subject: [PATCH] Abstracted out the message filter stuff so we can add a
 dialog message filter to allow tab navigation anywhere next.

---
 windows/areaevents.c           | 36 ++++-----------------------------
 windows/init.cpp               |  6 ++++--
 windows/main.cpp               | 37 ++++++++++++++++++++++++++++++++++
 windows/uipriv_windows_new.hpp |  4 ++++
 4 files changed, 49 insertions(+), 34 deletions(-)

diff --git a/windows/areaevents.c b/windows/areaevents.c
index 42e001bf..8913d223 100644
--- a/windows/areaevents.c
+++ b/windows/areaevents.c
@@ -393,23 +393,17 @@ BOOL areaDoEvents(uiArea *a, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT *l
 	return FALSE;
 }
 
-static HHOOK areaFilter;
-
 // TODO affect visibility properly
 // TODO what did this mean
-static LRESULT CALLBACK areaFilterProc(int code, WPARAM wParam, LPARAM lParam)
+static BOOL areaFilter(MSG *msg)
 {
-	MSG *msg = (MSG *) lParam;
 	LRESULT handled;
 
-	if (code < 0)
-		goto callNext;
-
 	// is the recipient an area?
 	if (msg->hwnd == NULL)		// this can happen; for example, WM_TIMER
-		goto callNext;
+		return FALSE;
 	if (windowClassOf(msg->hwnd, areaClass, NULL) != 0)
-		goto callNext;		// nope
+		return FALSE;			// nope
 
 	handled = 0;
 	switch (msg->message) {
@@ -423,27 +417,5 @@ static LRESULT CALLBACK areaFilterProc(int code, WPARAM wParam, LPARAM lParam)
 		break;
 	// otherwise handled remains 0, as we didn't handle this
 	}
-	if (!handled)
-		goto callNext;
-
-	// we handled it; discard the message so the dialog manager doesn't see it
-	return 1;
-
-callNext:
-	return CallNextHookEx(areaFilter, code, wParam, lParam);
-}
-
-int registerAreaFilter(void)
-{
-	areaFilter = SetWindowsHookExW(WH_MSGFILTER,
-		areaFilterProc,
-		hInstance,
-		GetCurrentThreadId());
-	return areaFilter != NULL;
-}
-
-void unregisterAreaFilter(void)
-{
-	if (UnhookWindowsHookEx(areaFilter) == 0)
-		logLastError("error unregistering uiArea message filter in unregisterAreaFilter()");
+	return (BOOL) handled;
 }
diff --git a/windows/init.cpp b/windows/init.cpp
index 22e33986..a2492e0d 100644
--- a/windows/init.cpp
+++ b/windows/init.cpp
@@ -126,8 +126,9 @@ const char *uiInit(uiInitOptions *o)
 
 	if (registerAreaClass(hDefaultIcon, hDefaultCursor) == 0)
 		return ieLastErr("registering uiArea window class");
-	if (registerAreaFilter() == 0)
-		return ieLastErr("registering uiArea message filter");
+
+	if (registerMessageFilter() == 0)
+		return ieLastErr("registering libui message filter");
 
 	if (registerD2DScratchClass(hDefaultIcon, hDefaultCursor) == 0)
 		return ieLastErr("initializing D2D scratch window class");
@@ -139,6 +140,7 @@ void uiUninit(void)
 {
 	uninitMenus();
 	unregisterD2DScratchClass();
+	unregisterMessageFilter();
 	unregisterArea();
 	uninitDrawText();
 	uninitDraw();
diff --git a/windows/main.cpp b/windows/main.cpp
index ed7102ca..6d4054a5 100644
--- a/windows/main.cpp
+++ b/windows/main.cpp
@@ -1,6 +1,43 @@
 // 6 april 2015
 #include "uipriv_windows.hpp"
 
+static HHOOK filter;
+
+static LRESULT CALLBACK filterProc(int code, WPARAM wParam, LPARAM lParam)
+{
+	MSG *msg = (MSG *) lParam;
+	BOOL discard;
+
+	if (code < 0)
+		goto callNext;
+
+	discard = !areaFilter(msg);
+
+	if (discard)
+		goto callNext;
+
+	// we handled it; discard the message so the dialog manager doesn't see it
+	return 1;
+
+callNext:
+	return CallNextHookEx(areaFilter, code, wParam, lParam);
+}
+
+int registerMessageFilter(void)
+{
+	filter = SetWindowsHookExW(WH_MSGFILTER,
+		filterProc,
+		hInstance,
+		GetCurrentThreadId());
+	return filter != NULL;
+}
+
+void unregisterMessageFilter(void)
+{
+	if (UnhookWindowsHookEx(areaFilter) == 0)
+		logLastError(L"error unregistering libui message filter");
+}
+
 // TODO http://blogs.msdn.com/b/oldnewthing/archive/2005/04/08/406509.aspx when adding accelerators, TranslateAccelerators() before IsDialogMessage()
 
 void uiMain(void)
diff --git a/windows/uipriv_windows_new.hpp b/windows/uipriv_windows_new.hpp
index f8797dad..c52768a7 100644
--- a/windows/uipriv_windows_new.hpp
+++ b/windows/uipriv_windows_new.hpp
@@ -59,3 +59,7 @@ extern uiInitOptions options;
 extern HWND utilWindow;
 extern const char *initUtilWindow(HICON hDefaultIcon, HCURSOR hDefaultCursor);
 extern void uninitUtilWindow(void);
+
+// main.cpp
+extern void registerMessageFilter(void);
+extern void unregisterMessageFilter(void);