C#雪花飘研究和学习
前几天在csnd的下载频道下载了一个C#写的雪花飘飘的程序，感觉很是惊讶，于是庖丁解牛，仔细的研究了一番。再次贴出来，以供下次学习。具体效果如下图：
其中是实现的思路是利用WinAPI，创建一个窗口句柄，然后再找个句柄窗口中去绘图和更新。
具体核心利用到的API如下
[DllImport("gdi32.dll")]
public static extern IntPtr CreateCompatibleDC(IntPtr hDC);
[DllImport("gdi32.dll")]
public static extern Bool DeleteObject(IntPtr hObject);
[DllImport("user32.dll")]
public static extern IntPtr GetDC(IntPtr handle);
[DllImport("gdi32.dll")]
public static extern IntPtr DeleteDC(IntPtr handle);
[DllImport("user32.dll", ExactSpelling = true)]
public static extern int ReleaseDC(IntPtr handle, IntPtr hObject);
[DllImport("gdi32.dll")]
public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
[DllImport("User32.dll")]
public static extern Bool UpdateLayeredWindow(IntPtr handle, IntPtr hdcDst, ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, int crKey, ref BLENDFUNCTION pblend, int dwFlags);
而实现绘制的思路如下：
private void SetBackground(Image img)
{
try
{
Bitmap bitmap = (Bitmap)img;
if (bitmap.PixelFormat != PixelFormat.Format32bppArgb)
{
throw new ApplicationException();
}
IntPtr hObject = IntPtr.Zero;
IntPtr zero = IntPtr.Zero;
IntPtr hDC = Win32.GetDC(IntPtr.Zero);
IntPtr ptr2 = Win32.CreateCompatibleDC(hDC);
try
{
hObject = bitmap.GetHbitmap(Color.FromArgb(0));
zero = Win32.SelectObject(ptr2, hObject);
Win32.Size size2 = new Win32.Size(bitmap.Width, bitmap.Height);
Win32.Size psize = size2;
Win32.Point point3 = new Win32.Point(0, 0);
Win32.Point pprSrc = point3;
point3 = new Win32.Point(base.Left, base.Top);
Win32.Point pptDst = point3;
point3 = new Win32.Point(base.Left, base.Top);
Win32.BLENDFUNCTION pblend = new Win32.BLENDFUNCTION();
pblend.BlendOp = 0;
pblend.BlendFlags = 0;
pblend.SourceConstantAlpha = 0xff;
pblend.AlphaFormat = 1;
Win32.UpdateLayeredWindow(this.Handle, hDC, ref pptDst, ref psize, ptr2, ref pprSrc, 0, ref pblend, 2);
}
catch (Exception exception1)
{
Exception exception = exception1;
throw exception;
}
finally
{
Win32.ReleaseDC(IntPtr.Zero, hDC);
if (hObject != IntPtr.Zero)
{
Win32.SelectObject(ptr2, zero);
Win32.DeleteObject(hObject);
}
Win32.DeleteDC(ptr2);
}
}
catch(Exception e)
{
MessageBox.Show(e.Message);
}
}
而根据找个实现的思路可以做出很多很炫的东西，比如透明或者半透明的软件窗体。因为主要的实现是API，所以可以使用C/C++实现超炫的界面。稍后我试试利用找个原理去做一个C#软件的登陆界面。