internal void DrawScroller(Graphics g)
{
if ((leftRightImages == null) || (leftRightImages.Images.Count != 4))
return;
Rectangle clientArea = this.ClientRectangle;
Win32.RECT r0 = new Win32.RECT();
Win32.GetClientRect(scroller.Handle, ref r0);
// Fill background of the scroller. Decrease width and height by 1 to
// account for right and bottom borders which should not be used in drawing.
r0.Right--;
r0.Bottom--;
Rectangle scrollerRect = new Rectangle(r0.Location, r0.Size);
using (Brush br = new SolidBrush(SystemColors.Control))
g.FillRectangle(br, scrollerRect);
// Make a small outer border.
using (Pen border = new Pen(SystemColors.ControlDark))
{
Rectangle rborder = scrollerRect;
rborder.Inflate(-1, -1);
g.DrawRectangle(border, rborder);
}
int nMiddle = (r0.Width / 2);
int nTop = (r0.Height - leftRightImages.ImageSize.Height) / 2 + 1;
int nLeft = (nMiddle - leftRightImages.ImageSize.Width) / 2;
Rectangle r1 = new Rectangle(new Point(nLeft, nTop), leftRightImages.ImageSize);
Rectangle r2 = new Rectangle(new Point(nMiddle + nLeft, nTop), leftRightImages.ImageSize);
// Finally draw the buttons.
Image img = leftRightImages.Images[1];
if (img != null)
{
if (TabCount > 0)
{
Rectangle r3 = this.GetTabRect(0);
if (r3.Left < clientArea.Left)
g.DrawImage(img, r1);
else
{
img = leftRightImages.Images[3];
if (img != null)
g.DrawImage(img, r1);
}
}
}
img = leftRightImages.Images[0];
if (img != null)
{
if (this.TabCount > 0)
{
Rectangle r3 = this.GetTabRect(this.TabCount - 1);
if (r3.Right > (clientArea.Width - r0.Width))
g.DrawImage(img, r2);
else
{
img = leftRightImages.Images[2];
if (img != null)
g.DrawImage(img, r2);
}
}
}
}
/// <summary>
/// Adjusts the scroll offset so that the given tab is in the visible area.
/// </summary>
/// <param name="index">The index of the tab to make visible.</param>
/// <returns>True if an adjustment was necessary, otherwise False.</returns>
public bool ScrollIntoView(int index)
{
bool result = false;
if (index < 0 || index >= TabCount)
return result;
// If our bounds are empty then the application is likely minimized and we delay setting
// the horizontal offset until we are restored.
if (Width == 0 && Height == 0)
{
pendingScrollIntoViewIndex = index;
return result;
}
Rectangle area = GetTabRect(index);
if (area.Left < 0)
{
scrollOffset -= area.Left;
result = true;
}
else
{
Win32.RECT rect = new Win32.RECT();
if (scroller != null)
Win32.GetClientRect(scroller.Handle, ref rect);
int rightBorder = ClientSize.Width - Margin.Right - rect.Width - scrollerSpacing;
if (area.Right > rightBorder)
{
scrollOffset -= area.Right - rightBorder;
result = true;
}
}
if (result && scroller != null)
Win32.SendMessage(scroller.Handle, (int)UDM.SETPOS32, IntPtr.Zero, new IntPtr(-scrollOffset / scrollScaleFactor));
return result;
}
private int ScrollerWndProc(ref Message m)
{
switch ((WM) m.Msg)
{
case WM.ERASEBKGND:
m.Result = new IntPtr(1);
break;
case WM.PAINT:
{
IntPtr hDC = Win32.GetDC(m.HWnd);
Graphics g = Graphics.FromHdc(hDC);
DrawScroller(g);
g.Dispose();
Win32.ReleaseDC(m.HWnd, hDC);
Win32.RECT clientArea = new Win32.RECT();
Win32.GetClientRect(m.HWnd, ref clientArea);
Win32.ValidateRect(m.HWnd, ref clientArea);
// return 0 (processed)
m.Result = IntPtr.Zero;
}
return 1;
case (WM) UDM.SETRANGE:
// The systab control sends this message when it wants to update the scroller, however
// that works diametrically opposed to our own intents, so it is simply switched off here.
// Our implementation uses UDM_SETRANGE32.
m.Result = new IntPtr(1);
return 1;
}
return 0;
}
private void UpdateScroller()
{
// Seems the scroll is sometimes re-created, so also check for a 0 handle.
if (scroller == null || scroller.Handle == IntPtr.Zero)
FindScroller();
if (scroller != null)
{
if (tabStyle == TabStyleType.NoTabs)
{
scrollOffset = 0;
Win32.ShowWindow(scroller.Handle, (int)SW.HIDE);
return;
}
Win32.RECT rect = new Win32.RECT();
Win32.GetClientRect(scroller.Handle, ref rect);
int totalTabWidth = GetTotalTabWidth();
int availableWidth = ClientSize.Width - Margin.Horizontal;
if (totalTabWidth > availableWidth)
{
// Decrease available space also by that used of the scroller now.
availableWidth -= rect.Width;
Win32.ShowWindow(scroller.Handle, (int)SW.SHOWNOACTIVATE);
// The scroll range is the number of steps (scaled pixels) we need to scroll over the full tab space.
int scrollRange = (int) Math.Ceiling((totalTabWidth - availableWidth) / (float) scrollScaleFactor) +
(int) ((scrollerSpacing / (float) scrollScaleFactor));
Win32.SendMessage(scroller.Handle, (int) UDM.SETRANGE32, IntPtr.Zero, new IntPtr(scrollRange));
// Make sure the scroll position is still ok before setting it in the scroller.
// Always scroll so that the right border stays close to the scroller.
Rectangle bounds = GetTabRect(TabCount - 1);
if (bounds.Right < ClientSize.Width - Margin.Right - scrollerSpacing - rect.Width)
scrollOffset += ClientSize.Width - Margin.Right - scrollerSpacing - rect.Width - bounds.Right;
Win32.SendMessage(scroller.Handle, (int)UDM.SETPOS32, IntPtr.Zero, new IntPtr(-scrollOffset / scrollScaleFactor));
// Disable scroll acceleration by setting a single scroll increment.
Win32.UDACCEL acceleration = new Win32.UDACCEL();
acceleration.nInc = 5;
acceleration.nSec = 0;
IntPtr parameter = Marshal.AllocHGlobal(Marshal.SizeOf(acceleration));
Marshal.StructureToPtr(acceleration, parameter, true);
Win32.SendMessage(scroller.Handle, (int)UDM.SETACCEL, new IntPtr(1), parameter);
Marshal.FreeHGlobal(parameter);
}
else
{
scrollOffset = 0;
Win32.ShowWindow(scroller.Handle, (int)SW.HIDE);
}
Win32.InvalidateRect(scroller.Handle, ref rect, true);
int scrollerWidth = rect.Width;
rect.Left = Width - scrollerWidth - Margin.Right;
rect.Right = rect.Left + scrollerWidth;
if (tabStyle == TabStyleType.BottomNormal)
rect.Top = ClientSize.Height - ItemSize.Height - Margin.Bottom;
else
rect.Top = Margin.Top;
rect.Bottom = rect.Top + ItemSize.Height;
Win32.MoveWindow(scroller.Handle, rect.Left, rect.Top, rect.Width, rect.Height, true);
}
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
base.OnSelectedIndexChanged(e);
ScrollIntoView(SelectedIndex);
if (scroller != null)
{
Win32.RECT clientArea = new Win32.RECT();
Win32.GetClientRect(scroller.Handle, ref clientArea);
Win32.InvalidateRect(scroller.Handle, ref clientArea, false);
}
Invalidate(); // We need to update border and background colors.
}