C＃Windows窗体透明背景图像

当我尝试透明背景时，它并不完全透明。 我为这个问题尝试了两个代码块。 首先，我尝试这样的代码：

public Form1() { InitializeComponent(); SetStyle(ControlStyles.SupportsTransparentBackColor, true); this.BackColor = Color.Transparent; this.FormBorderStyle = FormBorderStyle.None; //this.WindowState = System.Windows.Forms.FormWindowState.Maximized; } 

它看起来像这张照片;

然后我发现了一些不同的代码并尝试了这个;

  public Form1() { InitializeComponent(); this.TransparencyKey = Color.White; this.BackColor = Color.White; this.FormBorderStyle = FormBorderStyle.None; this.WindowState = System.Windows.Forms.FormWindowState.Maximized; } 

这看起来像这张照片;

您可以看到带有白色边框的徽标。 我想只显示.png徽标完全透明。 我该怎么办？ 怎么办呢？

这是我的Logo图像.png;

Answer 1

您可以使用分层Windows

使用分层窗口可以显着提高具有复杂形状，动画形状或希望使用Alpha混合效果的窗口的性能和视觉效果。 系统自动组合并重新绘制分层窗口和底层应用程序的窗口。 结果，分层窗口平滑地呈现，而没有复杂窗口区域的典型闪烁。 此外，分层窗口可以是部分半透明的，即α混合。

在Windows窗体中创建分层窗口

以下是msdn代码库中的一些代码，演示了如何在Windows窗体中创建分层Windows。 它允许您创建一个形状的闪屏，让您通过鼠标移动它。

将PerPixelAlphaForm添加到项目中，然后它就足以inheritance此表单并调用其SelectBitmap并将png传递给方法以创建分层窗口。

PerPixelAlphaForm.cs

 #region Using directives using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Drawing.Imaging; using System.Runtime.InteropServices; #endregion namespace CSWinFormLayeredWindow { public partial class PerPixelAlphaForm : Form { public PerPixelAlphaForm() { this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None; this.ShowInTaskbar = false; this.StartPosition = FormStartPosition.CenterScreen; this.Load += PerPixelAlphaForm_Load; } void PerPixelAlphaForm_Load(object sender, EventArgs e) { this.TopMost = true; } protected override CreateParams CreateParams { get { // Add the layered extended style (WS_EX_LAYERED) to this window. CreateParams createParams = base.CreateParams; if(!DesignMode) createParams.ExStyle |= WS_EX_LAYERED; return createParams; } } /// 
 /// Let Windows drag this window for us (thinks its hitting the title /// bar of the window) /// 
 ///  protected override void WndProc(ref Message message) { if (message.Msg == WM_NCHITTEST) { // Tell Windows that the user is on the title bar (caption) message.Result = (IntPtr)HTCAPTION; } else { base.WndProc(ref message); } } /// 
 /// /// 
 ///  public void SelectBitmap(Bitmap bitmap) { SelectBitmap(bitmap, 255); } /// 
 /// /// 
 ///  /// ///  ///  /// Specifies an alpha transparency value to be used on the entire source /// bitmap. The SourceConstantAlpha value is combined with any per-pixel /// alpha values in the source bitmap. The value ranges from 0 to 255. If /// you set SourceConstantAlpha to 0, it is assumed that your image is /// transparent. When you only want to use per-pixel alpha values, set /// the SourceConstantAlpha value to 255 (opaque). ///  public void SelectBitmap(Bitmap bitmap, int opacity) { // Does this bitmap contain an alpha channel? if (bitmap.PixelFormat != PixelFormat.Format32bppArgb) { throw new ApplicationException("The bitmap must be 32bpp with alpha-channel."); } // Get device contexts IntPtr screenDc = GetDC(IntPtr.Zero); IntPtr memDc = CreateCompatibleDC(screenDc); IntPtr hBitmap = IntPtr.Zero; IntPtr hOldBitmap = IntPtr.Zero; try { // Get handle to the new bitmap and select it into the current // device context. hBitmap = bitmap.GetHbitmap(Color.FromArgb(0)); hOldBitmap = SelectObject(memDc, hBitmap); // Set parameters for layered window update. Size newSize = new Size(bitmap.Width, bitmap.Height); Point sourceLocation = new Point(0, 0); Point newLocation = new Point(this.Left, this.Top); BLENDFUNCTION blend = new BLENDFUNCTION(); blend.BlendOp = AC_SRC_OVER; blend.BlendFlags = 0; blend.SourceConstantAlpha = (byte)opacity; blend.AlphaFormat = AC_SRC_ALPHA; // Update the window. UpdateLayeredWindow( this.Handle, // Handle to the layered window screenDc, // Handle to the screen DC ref newLocation, // New screen position of the layered window ref newSize, // New size of the layered window memDc, // Handle to the layered window surface DC ref sourceLocation, // Location of the layer in the DC 0, // Color key of the layered window ref blend, // Transparency of the layered window ULW_ALPHA // Use blend as the blend function ); } finally { // Release device context. ReleaseDC(IntPtr.Zero, screenDc); if (hBitmap != IntPtr.Zero) { SelectObject(memDc, hOldBitmap); DeleteObject(hBitmap); } DeleteDC(memDc); } } #region Native Methods and Structures const Int32 WS_EX_LAYERED = 0x80000; const Int32 HTCAPTION = 0x02; const Int32 WM_NCHITTEST = 0x84; const Int32 ULW_ALPHA = 0x02; const byte AC_SRC_OVER = 0x00; const byte AC_SRC_ALPHA = 0x01; [StructLayout(LayoutKind.Sequential)] struct Point { public Int32 x; public Int32 y; public Point(Int32 x, Int32 y) { this.x = x; this.y = y; } } [StructLayout(LayoutKind.Sequential)] struct Size { public Int32 cx; public Int32 cy; public Size(Int32 cx, Int32 cy) { this.cx = cx; this.cy = cy; } } [StructLayout(LayoutKind.Sequential, Pack = 1)] struct ARGB { public byte Blue; public byte Green; public byte Red; public byte Alpha; } [StructLayout(LayoutKind.Sequential, Pack = 1)] struct BLENDFUNCTION { public byte BlendOp; public byte BlendFlags; public byte SourceConstantAlpha; public byte AlphaFormat; } [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)] static extern bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst, ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, Int32 crKey, ref BLENDFUNCTION pblend, Int32 dwFlags); [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)] static extern IntPtr CreateCompatibleDC(IntPtr hDC); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] static extern IntPtr GetDC(IntPtr hWnd); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC); [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)] static extern bool DeleteDC(IntPtr hdc); [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)] static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject); [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)] static extern bool DeleteObject(IntPtr hObject); #endregion } } 

SplashScreen.cs

 public partial class Form4 : CSWinFormLayeredWindow.PerPixelAlphaForm { public Form4() { InitializeComponent(); this.SelectBitmap(Properties.Resources.splash); } } 

注意

最初的答案是基于关闭双缓冲区并覆盖OnPaintBackground并绘制图像而不调用基本方法。 答案有一个已知的问题; 虽然表单是不动的，但它运行良好但是如果表单正在移动或者窗体后面的窗口被更改，则窗口不会更新。 您可以在修订版中看到以前的代码。 完全基于MSDN代码的当前编辑没有任何已知问题。

Answer 2

您可以通过更改0到255之间的alpha系数来选择图像的透明度。图像也可以是背景图像，没有问题

 private static Image ToGrayscale(Image s,int alpha) { Bitmap tImage = new Bitmap(s); for (int x = 0; x < tImage.Width; x++) { for (int y = 0; y < tImage.Height; y++) { Color tCol = tImage.GetPixel(x, y); Color newColor = Color.FromArgb(alpha, tCol.R, tCol.G, tCol.B); tImage.SetPixel(x, y, newColor); } } return tImage; }