1 files changed, 97 insertions, 0 deletions
diff --git a/wintable/vscroll.h b/wintable/vscroll.h
new file mode 100644
index 0000000..7f2d912
--- /dev/null
+++ b/wintable/vscroll.h
@@ -0,0 +1,97 @@
+// 29 november 2014
+
+static void vscrollto(struct table *t, intptr_t newpos)
+{
+	SCROLLINFO si;
+	RECT scrollArea;
+
+	if (newpos < 0)
+		newpos = 0;
+	if (newpos > (t->count - t->pagesize))
+		newpos = (t->count - t->pagesize);
+
+	scrollArea = realClientRect(t);
+
+	// negative because ScrollWindowEx() is "backwards"
+	if (ScrollWindowEx(t->hwnd, 0, (-(newpos - t->firstVisible)) * rowHeight(t),
+		&scrollArea, &scrollArea, NULL, NULL,
+		SW_ERASE | SW_INVALIDATE) == ERROR)
+		abort();
+	t->firstVisible = newpos;
+
+	ZeroMemory(&si, sizeof (SCROLLINFO));
+	si.cbSize = sizeof (SCROLLINFO);
+	si.fMask = SIF_PAGE | SIF_POS | SIF_RANGE;
+	si.nPage = t->pagesize;
+	si.nMin = 0;
+	si.nMax = t->count - 1;		// nMax is inclusive
+	si.nPos = t->firstVisible;
+	SetScrollInfo(t->hwnd, SB_VERT, &si, TRUE);
+}
+
+static void vscrollby(struct table *t, intptr_t n)
+{
+	vscrollto(t, t->firstVisible + n);
+}
+
+static void wheelscroll(struct table *t, WPARAM wParam)
+{
+	int delta;
+	int lines;
+	UINT scrollAmount;
+
+	delta = GET_WHEEL_DELTA_WPARAM(wParam);
+	if (SystemParametersInfoW(SPI_GETWHEELSCROLLLINES, 0, &scrollAmount, 0) == 0)
+		abort();
+	if (scrollAmount == WHEEL_PAGESCROLL)
+		scrollAmount = t->pagesize;
+	if (scrollAmount == 0)		// no mouse wheel scrolling (or t->pagesize == 0)
+		return;
+	// the rest of this is basically http://blogs.msdn.com/b/oldnewthing/archive/2003/08/07/54615.aspx and http://blogs.msdn.com/b/oldnewthing/archive/2003/08/11/54624.aspx
+	// see those pages for information on subtleties
+	delta += t->wheelCarry;
+	lines = delta * ((int) scrollAmount) / WHEEL_DELTA;
+	t->wheelCarry = delta - lines * WHEEL_DELTA / ((int) scrollAmount);
+	vscrollby(t, -lines);
+}
+
+static void vscroll(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_VERT, &si) == 0)
+		abort();
+
+	newpos = t->firstVisible;
+	switch (LOWORD(wParam)) {
+	case SB_TOP:
+		newpos = 0;
+		break;
+	case SB_BOTTOM:
+		newpos = t->count - t->pagesize;
+		break;
+	case SB_LINEUP:
+		newpos--;
+		break;
+	case SB_LINEDOWN:
+		newpos++;
+		break;
+	case SB_PAGEUP:
+		newpos -= t->pagesize;
+		break;
+	case SB_PAGEDOWN:
+		newpos += t->pagesize;
+		break;
+	case SB_THUMBPOSITION:
+		newpos = (intptr_t) (si.nPos);
+		break;
+	case SB_THUMBTRACK:
+		newpos = (intptr_t) (si.nTrackPos);
+	}
+
+	vscrollto(t, newpos);
+}