internal static Native.SCROLLINFO GetCurrentScrollInfo(IntPtr handle, int direction)
{
var si = new Native.SCROLLINFO();
si.cbSize = (uint)Marshal.SizeOf(si);
si.fMask = (uint)Native.ScrollInfoMask.SIF_ALL;
Native.GetScrollInfo(handle, direction, ref si);
return(si);
}
private void ResetScrollInfo()
{
var si = new Native.SCROLLINFO();
si.cbSize = (uint)Marshal.SizeOf(si);
si.fMask = (uint)Native.ScrollInfoMask.SIF_ALL;
si.nPos = 0;
_scrollInfo = si;
ControlUtils.RepositionScroll(Handle, si, Native.SB_VERT);
}
private static void BetterScroll(IntPtr handle, int pixels)
{
if (pixels == 0)
{
return;
}
Native.SCROLLINFO si = ControlUtils.GetCurrentScrollInfo(handle, Native.SB_VERT);
si.nPos += pixels;
ControlUtils.RepositionScroll(handle, si, Native.SB_VERT);
}
internal static void RepositionScroll(IntPtr handle, Native.SCROLLINFO si, int direction)
{
// Reposition scroll
Native.SetScrollInfo(handle, direction, ref si, true);
// Send a WM_*SCROLL scroll message using SB_THUMBTRACK as wParam
// SB_THUMBTRACK: low-order word of wParam, si.nPos high-order word of wParam
IntPtr ptrWParam = new IntPtr(Native.SB_THUMBTRACK + (0x10000 * si.nPos));
IntPtr ptrLParam = new IntPtr(0);
IntPtr wp = (long)ptrWParam >= 0 ? ptrWParam : (IntPtr)Native.SB_THUMBTRACK;
Native.SendMessage(handle, direction == Native.SB_VERT ? Native.WM_VSCROLL : Native.WM_HSCROLL, wp, ptrLParam);
}
private async Task SetScrollPositionToCorrect()
{
Native.SCROLLINFO si = _scrollInfo;
this.SuspendDrawing();
try
{
await Task.Delay(20);
_scrollInfo = si;
ControlUtils.RepositionScroll(Handle, si, Native.SB_VERT);
}
finally
{
this.ResumeDrawing();
}
}
private void rich_TextChanged(object sender, EventArgs e)
{
if (m_busy)
return;
m_busy = true;
m_buffer.Text = m_active.Text;
m_buffer.SelectAll();
m_buffer.SelectionColor = m_defaultColor;
ControlEventArgs args = new ControlEventArgs(m_buffer);
OnHighlight(args);
m_buffer.SelectionStart = m_active.SelectionStart;
m_buffer.SelectionLength = m_active.SelectionLength;
Native.SCROLLINFO si = new Native.SCROLLINFO();
si.Size = (uint)Marshal.SizeOf(typeof(Native.SCROLLINFO));
si.Mask = Native.SIF_POS;
Native.GetScrollInfo(m_active.Handle, (int)Native.SB_VERT, ref si);
Native.SetScrollInfo(m_buffer.Handle, (int)Native.SB_VERT, ref si, true);
uint wparam = ((uint)si.Pos << 16) + Native.SB_THUMBPOSITION;
Native.SendMessage(m_buffer.Handle, Native.WM_VSCROLL, wparam, 0);
Native.SendMessage(m_buffer.Handle, Native.WM_VSCROLL, Native.SB_ENDSCROLL, 0);
m_busy = false;
RichTextBox temp = m_active;
m_active = m_buffer;
m_buffer = temp;
m_active.BringToFront();
m_active.Show();
m_buffer.Hide();
m_active.Focus();
}
/*
* When the rtfbox is first focused after content load, it will scroll to the top automatically (or more
* specifically to the cursor location, which will always be at the top after content load and before focus).
* Any subsequent de-focus and refocus will not cause this behavior, even if the cursor is still at the top,
* until the next content load.
* This auto-scroll-to-the-top behavior doesn't align with any events, and in fact seems to just happen in
* the background as soon as it feels like it. Hence this filthy hack where we keep track of the scroll
* position, and then on focus we do a brief async delay to let the auto-scroll happen, then set correct
* scroll position again. I don't like the "wait-and-hope" method at all, but hey... worst case, the auto-
* top-scroll will still happen, and that's no worse than it was before.
*/
private void Workarounds_OnVScroll()
{
_scrollInfo = ControlUtils.GetCurrentScrollInfo(Handle, Native.SB_VERT);
}
