/// <summary>
/// Draw the text supporting clipping according to ClipRegion.
/// </summary>
/// <param name="g"></param>
/// <param name="color"></param>
/// <param name="rect"></param>
/// <param name="topOffset"></param>
/// <param name="orientation"></param>
/// <param name="fontDescription"></param>
/// <param name="text"></param>
/// <param name="contentAlignment"></param>
/// <param name="flags"></param>
public static void ClipSupportingDrawText(Graphics g, Color color, Rectangle rect, int topOffset, int orientation, FontDescription fontDescription, String text,
ContentAlignment contentAlignment, int flags, bool rightToLeft)
{
IntPtr region = IntPtr.Zero;
IntPtr currentclippedRegion = g.Clip.GetHrgn(g);
bool IsRegionInfinite = g.Clip.IsInfinite(g);
IntPtr hdc = g.GetHdc();
NativeWindowCommon.SetBkMode(hdc, NativeWindowCommon.TRANSPARENT);
NativeWindowCommon.SetTextColor(hdc, ColorTranslator.ToWin32(color));
// Text rectangle as clip Region
IntPtr clipRegion = NativeWindowCommon.CreateRectRgn(rect.Left, rect.Top, rect.Right, rect.Bottom);
// If Text starts above control, it needs to clip
if (topOffset < 0)
{
// if current graphics is already clipped, then we need to merge with current text rectangle clip
if (!IsRegionInfinite)
{
NativeWindowCommon.CombineRgn(currentclippedRegion, currentclippedRegion, clipRegion, NativeWindowCommon.RGN_AND);
}
}
if (IsRegionInfinite)
{
// If there is no clip region on graphics, set text rectangle as clip region
region = clipRegion;
}
else if (currentclippedRegion != IntPtr.Zero)
{
// use intersected region as clip region
region = currentclippedRegion;
}
// Select resultant clipped region on DC
if (region != IntPtr.Zero)
{
NativeWindowCommon.SelectClipRgn(hdc, region);
}
if (clipRegion != IntPtr.Zero)
{
NativeWindowCommon.DeleteObject(clipRegion);
}
// Draw text
DrawText(hdc, color, rect, topOffset, orientation, fontDescription, text, contentAlignment, flags, rightToLeft);
// release objects
g.ReleaseHdc(hdc);
if (currentclippedRegion != IntPtr.Zero)
{
g.Clip.ReleaseHrgn(currentclippedRegion);
}
}
/// <summary>
/// Paint the border
/// </summary>
/// <param name="m"></param>
private void WMNCPaint(ref Message m)
{
IntPtr hDC = NativeWindowCommon.GetWindowDC(m.HWnd);
if (hDC != IntPtr.Zero)
{
IntPtr hrgnWindow = IntPtr.Zero;
IntPtr hrgnClient = IntPtr.Zero;
try
{
Rectangle rect = new Rectangle(1, 1, Width - 2, Height - 2);
hrgnWindow = NativeWindowCommon.CreateRectRgn(0, 0, Width, Height);
hrgnClient = NativeWindowCommon.CreateRectRgn(rect.Left, rect.Top, rect.Right, rect.Bottom);
//Creates the union of two combined regions except for any overlapping areas.
NativeWindowCommon.CombineRgn(hrgnWindow, hrgnWindow, hrgnClient, NativeWindowCommon.RGN_XOR);
NativeWindowCommon.SelectClipRgn(hDC, hrgnWindow);
using (Graphics g = Graphics.FromHdc(hDC))
{
g.Clear(VisualStyleInformation.TextControlBorder);
}
m.Result = IntPtr.Zero;
}
finally
{
NativeWindowCommon.ReleaseDC(m.HWnd, hDC);
if (hrgnWindow != IntPtr.Zero)
{
NativeWindowCommon.DeleteObject(hrgnWindow);
}
if (hrgnClient != IntPtr.Zero)
{
NativeWindowCommon.DeleteObject(hrgnClient);
}
}
}
}
