齐白石画的虾馆多少钱:A lovely goldfish desktop pet (using alpha-PNG and GDI+)

• Download demo - 449 KB
• Download source code - 412 KB

Introduction

This article demonstrates a very lovely goldfish desktop pet, using alpha-PNG and GD+. This cute goldfish can swim from one side to another of your desktop, and tries to escape when you try to catch it using your mouse.

Background

After I posted these articles: A Cool Vista Sidebar Gadget Style CPUInfo Animate Control! (Fixed)A cool Vista-Sidebar-style clock control (4 style)(fixed)! many people asked me how to make a real alpha-transparent form using these controls. Now, this has become a reality! This is a real alpha-transparent form with animation, even in some none-Vista OSs such as XP!

Have fun! And, do not forget to vote! :)

Using the code

To make a form transparent, use this code to set an alpha-transparent PNG picture as its background:

public void SetBits(Bitmap bitmap){    if (!haveHandle) return;    if (!Bitmap.IsCanonicalPixelFormat(bitmap.PixelFormat) ||         !Bitmap.IsAlphaPixelFormat(bitmap.PixelFormat))        throw new ApplicationException("The picture must be " +                   "32bit picture with alpha channel");    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(bitmap.Width, bitmap.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 = 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);    }}

OK, so simple! Now, you can use a timer control to implement the animation function.

Sorry for my poor English! Please see the source code for more details.

Points of Interest

• Developing with GDI+ and C# is a very interesting thing!
• PNG format is very good for drawing alpha pics!
• For more code samples, please visit my personal web site.

History

• 2008/9/8: First posted on cnpopsoft.com.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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