/// <summary>
/// Sets opacity and/or transparent color.
/// </summary>
/// <param name="allowTransparency">Set or remove WS_EX_LAYERED style that is required for transparency. If false, other parameters are not used.</param>
/// <param name="opacity">Opacity from 0 (completely transparent) to 255 (opaque). Does not change if null. If less than 0 or greater than 255, makes 0 or 255.</param>
/// <param name="colorKey">Make pixels of this color completely transparent. Does not change if null. The alpha byte is not used.</param>
/// <exception cref="AuWndException"/>
/// <remarks>
/// Uses API <msdn>SetLayeredWindowAttributes</msdn>.
/// On Windows 7 works only with top-level windows, on newer OS also with controls.
/// </remarks>
public void SetTransparency(bool allowTransparency, int?opacity = null, ColorInt?colorKey = null)
{
var est = ExStyle;
bool layered = (est & WS2.LAYERED) != 0;
if (allowTransparency)
{
uint col = 0, f = 0; byte op = 0;
if (colorKey != null)
{
f |= 1; col = (uint)colorKey.GetValueOrDefault().ToBGR();
}
if (opacity != null)
{
f |= 2; op = (byte)AMath.MinMax(opacity.GetValueOrDefault(), 0, 255);
}
if (!layered)
{
SetExStyle(est | WS2.LAYERED);
}
if (!Api.SetLayeredWindowAttributes(this, col, op, f))
{
ThrowUseNative();
}
}
else if (layered)
{
SetExStyle(est & ~WS2.LAYERED); //tested: resets attributes, ie after adding WS2.LAYERED the window will be normal
}
}
public void SetLevel(int level)
{
this.level = (ushort)AMath.MinMax(level, 0, 0xffff);
}