From 3cb5017b35154237ea862d3856ef945eb7790005 Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Fri, 7 Nov 2014 10:12:06 -0500
Subject: [PATCH] Implemented horizontal scrolling. Horizontally scrolled
 drawing not yet implemented.

---
 wintable/main.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 82 insertions(+), 3 deletions(-)

diff --git a/wintable/main.c b/wintable/main.c
index 0b5e210..74d1a0b 100644
--- a/wintable/main.c
+++ b/wintable/main.c
@@ -46,7 +46,7 @@ struct table {
 	HIMAGELIST imagelist;
 	int imagelistHeight;
 	intptr_t width;
-	intptr_t hpageSize;
+	intptr_t hpagesize;
 	intptr_t hpos;
 };
 
@@ -94,6 +94,82 @@ static RECT realClientRect(struct table *t)
 	return r;
 }
 
+static void hscrollto(struct table *t, intptr_t newpos)
+{
+	SCROLLINFO si;
+
+	if (newpos < 0)
+		newpos = 0;
+	if (newpos > (t->width - t->hpagesize))
+		newpos = (t->width - t->hpagesize);
+
+	// negative because ScrollWindowEx() is "backwards"
+	if (ScrollWindowEx(t->hwnd, -(newpos - t->hpos), 0,
+		NULL, NULL, NULL, NULL,
+		SW_ERASE | SW_INVALIDATE) == ERROR)
+		abort();
+	t->hpos = newpos;
+	// TODO text in header controls doesn't redraw?
+
+	// TODO put this in a separate function? same for vscroll?
+	ZeroMemory(&si, sizeof (SCROLLINFO));
+	si.cbSize = sizeof (SCROLLINFO);
+	si.fMask = SIF_PAGE | SIF_POS | SIF_RANGE;
+	si.nPage = t->hpagesize;
+	si.nMin = 0;
+	si.nMax = t->width - 1;		// nMax is inclusive
+	si.nPos = t->hpos;
+	SetScrollInfo(t->hwnd, SB_HORZ, &si, TRUE);
+}
+
+static void hscrollby(struct table *t, intptr_t n)
+{
+	hscrollto(t, t->hpos + n);
+}
+
+// unfortunately horizontal wheel scrolling was only added in Vista
+
+static void hscroll(struct table *t, WPARAM wParam)
+{
+	SCROLLINFO si;
+	intptr_t newpos;
+
+	ZeroMemory(&si, sizeof (SCROLLINFO));
+	si.cbSize = sizeof (SCROLLINFO);
+	si.fMask = SIF_POS | SIF_TRACKPOS;
+	if (GetScrollInfo(t->hwnd, SB_HORZ, &si) == 0)
+		abort();
+
+	newpos = t->hpos;
+	switch (LOWORD(wParam)) {
+	case SB_LEFT:
+		newpos = 0;
+		break;
+	case SB_RIGHT:
+		newpos = t->width - t->hpagesize;
+		break;
+	case SB_LINELEFT:
+		newpos--;
+		break;
+	case SB_LINERIGHT:
+		newpos++;
+		break;
+	case SB_PAGELEFT:
+		newpos -= t->hpagesize;
+		break;
+	case SB_PAGERIGHT:
+		newpos += t->hpagesize;
+		break;
+	case SB_THUMBPOSITION:
+		newpos = (intptr_t) (si.nPos);
+		break;
+	case SB_THUMBTRACK:
+		newpos = (intptr_t) (si.nTrackPos);
+	}
+
+	hscrollto(t, newpos);
+}
+
 static void recomputeHScroll(struct table *t)
 {
 	HDITEMW item;
@@ -114,12 +190,12 @@ static void recomputeHScroll(struct table *t)
 
 	if (GetClientRect(t->hwnd, &r) == 0)
 		abort();
-	t->hpageSize = r.right - r.left;
+	t->hpagesize = r.right - r.left;
 
 	ZeroMemory(&si, sizeof (SCROLLINFO));
 	si.cbSize = sizeof (SCROLLINFO);
 	si.fMask = SIF_PAGE | SIF_RANGE;
-	si.nPage = t->hpageSize;
+	si.nPage = t->hpagesize;
 	si.nMin = 0;
 	si.nMax = t->width - 1;			// - 1 because endpoints inclusive
 	SetScrollInfo(t->hwnd, SB_HORZ, &si, TRUE);
@@ -533,6 +609,9 @@ if (ImageList_GetIconSize(t->imagelist, &unused, &(t->imagelistHeight)) == 0)abo
 	case WM_MOUSEWHEEL:
 		wheelscroll(t, wParam);
 		return 0;
+	case WM_HSCROLL:
+		hscroll(t, wParam);
+		return 0;
 	case WM_SIZE:
 		resize(t);
 		return 0;