1.首先我们得有这样一张阴影图片。
2.然后分别有两个窗体去实现这个阴影效果。
- SkinForm - 用于实现阴影的绘制，特性：鼠标可穿透，无法点击，跟随窗体。
- SkinMain - 主窗体，也是承载控件的容器窗体， 特性：与普通窗体无一区别，移动和拉伸，阴影窗体都会跟随。
3.在SkinMain主窗体的OnVisibleChanged事件中new出阴影窗体
- //绘制层
- private SkinForm skin;
- skin = new SkinForm(this);
- skin.Show(this);
4.阴影窗体中绘制不规则透明图片的代码：
public
void
SetBits() {
//绘制绘图层背景
Bitmap bitmap =
new
Bitmap(Main.Width + 10, Main.Height + 10);
Rectangle _BacklightLTRB =
new
Rectangle(20, 20, 20, 20);
//窗体光泽重绘边界
Graphics g = Graphics.FromImage(bitmap);
g.SmoothingMode = SmoothingMode.HighQuality;
//高质量
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
//高像素偏移质量
ImageDrawRect.DrawRect(g, Properties.Resources.main_light_bkg_top123, ClientRectangle, Rectangle.FromLTRB(_BacklightLTRB.X, _BacklightLTRB.Y, _BacklightLTRB.Width, _BacklightLTRB.Height), 1, 1);
if
(!Bitmap.IsCanonicalPixelFormat(bitmap.PixelFormat) || !Bitmap.IsAlphaPixelFormat(bitmap.PixelFormat))
throw
new
ApplicationException(
"图片必须是32位带Alhpa通道的图片。"
);
IntPtr oldBits = IntPtr.Zero;
IntPtr screenDC = Win32.GetDC(IntPtr.Zero);
IntPtr hBitmap = IntPtr.Zero;
IntPtr memDc = Win32.CreateCompatibleDC(screenDC);
try
{
Win32.Point topLoc =
new
Win32.Point(Left, Top);
Win32.Size bitMapSize =
new
Win32.Size(Width, Height);
Win32.BLENDFUNCTION blendFunc =
new
Win32.BLENDFUNCTION();
Win32.Point srcLoc =
new
Win32.Point(0, 0);
hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
oldBits = Win32.SelectObject(memDc, hBitmap);
blendFunc.BlendOp = Win32.AC_SRC_OVER;
blendFunc.SourceConstantAlpha = Byte.Parse(
"255"
);
blendFunc.AlphaFormat = Win32.AC_SRC_ALPHA;
blendFunc.BlendFlags = 0;
Win32.UpdateLayeredWindow(Handle, screenDC,
ref
topLoc,
ref
bitMapSize, memDc,
ref
srcLoc, 0,
ref
blendFunc, Win32.ULW_ALPHA);
}
finally
{
if
(hBitmap != IntPtr.Zero) {
Win32.SelectObject(memDc, oldBits);
Win32.DeleteObject(hBitmap);
}
Win32.ReleaseDC(IntPtr.Zero, screenDC);
Win32.DeleteDC(memDc);
}
}