Winform控件优化之背景透明那些事2：窗体背景透明、镂空穿透、SetStyle、GDI透明效果等 {callout color="#f0ad4e"}简介： 两行代码就能实现Form窗体的(背景)透明效果，它不是Opacity属性的整个窗体透明，TransparencyKey实现窗体的透明、窗体中间部分镂空效果...{/callout}Winform窗体的透明{callout color="#f0ad4e"}此方法也需要.Net Framework 4.0及以上的版本才可以。关键在于TransparencyKey指定和BackColor一样的颜色。窗体默认不支持背景透明设置，指定Color.Transparent无效。TransparencyKey不能取值Color.Black（黑色）。{/callout}两行代码就能实现Form窗体的(背景)透明效果，它不是Opacity属性的整个窗体的透明，而只是背景透明，加上去除边框和标题栏，就能实现很好的背景透明效果。{callout color="#f0ad4e"}// 透明窗体内的透明控件的背景图边缘 会有 BackColor 颜色的白边this.BackColor = Color.LimeGreen;this.TransparencyKey = Color.LimeGreen;{/callout}它会将Form窗体控件设置为透明背景的效果，非常棒。但是会有个小问题，就是透明Form上的透明控件上的图片或背景图片会有一个相应颜色的白边，这算是一个小瑕疵【可以设置窗体的BackColor/TransparencyKey颜色与原本控件上背景图片的颜色尽量一致，尽量避免多出的白边问题】，如下：【这个白边即使指定Color.Empty也无法解除】目前测试，设置背景颜色和TransparencyKey不能取值Color.Black（黑色），它会导致窗体原本的拖动、标题栏中最大最小关闭按钮失效【如果是无边框，则此问题应当不算问题】。BackColor = Color.Lime; // Color.Red\Color.Blue等 TransparencyKey = BackColor;加上无边框窗体的效果：FormBorderStyle = FormBorderStyle.None;理论上设置SupportsTransparentBackColor支持背景透明就可以，但实际无效（猜测，应该是因为主窗体没有父控件的原因，需要有父控件才能生效。不知添加CreateParams的透明设置是否有效）//// 无效 SetStyle(ControlStyles.UserPaint, true); SetStyle(ControlStyles.OptimizedDoubleBuffer, true); SetStyle(ControlStyles.SupportsTransparentBackColor, true); this.BackColor = Color.Transparent; this.TransparencyKey = BackColor;永远显示在窗口最前方，可鼠标穿透的窗体镂空效果通过设置TransparencyKey实现窗体的透明、窗体中间部分镂空，鼠标等可以透过并从透过的部分操作。在一些录屏软件中会需要这种效果，整个窗体镂空部分框选的是录屏的区域，调整区域大小进行适当录屏范围，比如GifCam录屏软件。TopLevel设置Form为顶层窗体，TopMost设置Form始终在最前面。TopLevel=true; TopMost=true; BackColor = Color.Empty; TransparencyKey = BackColor;演示效果如下：TextBox控件的透明TextBox和Form一样，默认不支持设置透明背景色：textBox1.BackColor = Color.Transparent; 会发生异常，控件不支持透明的背景色。通过SetStyle设置支持背景透明。不过TextBox透明也没啥意义，因为透明后看不见文字编辑区域了。 public class TransparentTextBox : TextBox { public TransparentTextBox() { SetStyle(ControlStyles.SupportsTransparentBackColor | ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.ResizeRedraw | ControlStyles.UserPaint, true); BackColor = Color.Transparent; } }背景的不完全透明BackColor = Transparent等实现的都是完全透明，要实现不完全透明，在“完全透明”的基础上，设置BackgroundImage为一张带有百分比透明度的图片。通过图片的透明度，来间接设置控件的透明度CreateParams实现控件透明的设置在继承控件时，通过重写CreateParams，指定透明样式，也可以实现透明。{callout color="#f0ad4e"}该效果只是实现了透明，控件本身、所占位置均存在，且鼠标不能透过操作底层显示出的控件。{/callout}/// <summary> /// A transparent control. /// </summary> public class TransparentPanel : Panel { protected override CreateParams CreateParams { get { CreateParams createParams = base.CreateParams; createParams.ExStyle |= 0x00000020; // WS_EX_TRANSPARENT return createParams; } } }GDI+直接绘制图片或文字实现透明效果（可以针对多图片）此部分参考自 How to Use Transparent Images and Labels in Windows Forms定义通用类绘制图片和文字的通用类，直接继承自Panel，包含抽象方法OnDraw和用于绘制的Graphics对象using System; using System.Drawing; using System.Windows.Forms; using System.Drawing.Drawing2D; /// <span class="code-SummaryComment"><summary></span> /// Use this for drawing custom graphics and text with transparency. /// Inherit from DrawingArea and override the OnDraw method. /// <span class="code-SummaryComment"></summary></span> abstract public class DrawingArea : Panel { /// <span class="code-SummaryComment"><summary></span> /// Drawing surface where graphics should be drawn. /// Use this member in the OnDraw method. /// <span class="code-SummaryComment"></summary></span> protected Graphics graphics; /// <span class="code-SummaryComment"><summary></span> /// Override this method in subclasses for drawing purposes. /// <span class="code-SummaryComment"></summary></span> abstract protected void OnDraw(); }重写CreateParams属性，确保控件实例化时有正确的样式protected override CreateParams CreateParams { get { CreateParams cp = base.CreateParams; cp.ExStyle |= 0x00000020; //WS_EX_TRANSPARENT return cp; } }确保背景不会绘制，需要重写OnPaintBackground方法，并且不进行任何操作；重写OnPaint方法，用于空间绘制自己时调用此处理protected override void OnPaintBackground(PaintEventArgs pevent) { // Don't paint background } protected override void OnPaint(PaintEventArgs e) { // Update the private member so we can use it in the OnDraw method this.graphics = e.Graphics; // Set the best settings possible (quality-wise) this.graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; this.graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear; this.graphics.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality; this.graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; // Calls the OnDraw subclass method OnDraw(); }同时定义一个DrawText方法，用于很方便的绘制文本 #region DrawText helper functions protected void DrawText(string text, Point position) { DrawingArea.DrawText(this.graphics, text, "Microsoft Sans Serif", 8.25f , FontStyle.Regular, Brushes.Black, position); } protected void DrawText(string text, Brush color, Point position) { DrawingArea.DrawText(this.graphics, text, "Microsoft Sans Serif", 8.25f , FontStyle.Regular, color, position); } protected void DrawText(string text, FontStyle style, Point position) { DrawingArea.DrawText(this.graphics, text, "Microsoft Sans Serif", 8.25f , style, Brushes.Black, position); } protected void DrawText(string text, FontStyle style, Brush color, Point position) { DrawingArea.DrawText(this.graphics, text, "Microsoft Sans Serif", 8.25f , style, color, position); } protected void DrawText(string text, float fontSize, FontStyle style, Brush color , Point position) { DrawingArea.DrawText(this.graphics, text, "Microsoft Sans Serif", fontSize , style, color, position); } protected void DrawText(string text, string fontFamily, float fontSize , FontStyle style, Brush color, Point position) { DrawingArea.DrawText(this.graphics, text, fontFamily, fontSize, style, color, position); } static public void DrawText(Graphics graphics, string text, string fontFamily , float fontSize, FontStyle style, Brush color, Point position) { Font font = new Font(fontFamily, fontSize, style); SizeF textSizeF = graphics.MeasureString(text, font); int width = (int)Math.Ceiling(textSizeF.Width); int height = (int)Math.Ceiling(textSizeF.Height); Size textSize = new Size(width, height); Rectangle rectangle = new Rectangle(position, textSize); graphics.DrawString(text, font, color, rectangle); } #endregion使用控件绘制带透明的图片和文本添加一个新类并继承自DrawingArea，在重写的OnDraw方法中实现对图片和文本的绘制class BroculosDrawing : DrawingArea { protected override void OnDraw() { // Gets the image from the global resources Image broculoImage = global::WindowsApplication1.Properties.Resources.broculo; // Sets the images' sizes and positions int width = broculoImage.Size.Width; int height = broculoImage.Size.Height; Rectangle big = new Rectangle(0, 0, width, height); Rectangle small = new Rectangle(50, 50, (int)(0.75 * width), (int)(0.75 * height)); // Draws the two images this.graphics.DrawImage(broculoImage, big); this.graphics.DrawImage(broculoImage, small); // Sets the text's font and style and draws it float fontSize = 8.25f; Point textPosition = new Point(50, 100); DrawText("http://www.broculos.net", "Microsoft Sans Serif", fontSize , FontStyle.Underline, Brushes.Blue, textPosition); } }参考How to: Give Your Control a Transparent Background C# Windows Form Application Transparent button Transparent background on winforms?