Smoothly Fading Controls

问题

I am trying to fade a label but it doesn't seem to have the opacity property like the form itself.

Is there another way to fade controls?

回答1:

You can use my Transparent control that accept transparent color and have opacity property(0 - 100):

   public class TranspCtrl : Control
    {
        public bool drag = false;
        public bool enab = false;
        private int m_opacity = 100;

        private int alpha;
        public TranspCtrl()
        {
            SetStyle(ControlStyles.SupportsTransparentBackColor, true);
            SetStyle(ControlStyles.Opaque, true);
            this.BackColor = Color.Transparent;
        }

        public int Opacity
        {
            get
            {
                if (m_opacity > 100)
                {
                    m_opacity = 100;
                }
                else if (m_opacity < 1)
                {
                    m_opacity = 1;
                }
                return this.m_opacity;
            }
            set
            {
                this.m_opacity = value;
                if (this.Parent != null)
                {
                    Parent.Invalidate(this.Bounds, true);
                }
            }
        }

        protected override CreateParams CreateParams
        {
            get
            {
                CreateParams cp = base.CreateParams;
                cp.ExStyle = cp.ExStyle | 0x20;
                return cp;
            }
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            if (!DesignMode)
            {
                Graphics g = e.Graphics;
                Rectangle bounds = new Rectangle(0, 0, this.Width - 1, this.Height - 1);

                Color frmColor = this.Parent.BackColor;
                Brush bckColor = default(Brush);

                alpha = (m_opacity * 255) / 100;

                if (drag)
                {
                    Color dragBckColor = default(Color);

                    if (BackColor != Color.Transparent)
                    {
                        int Rb = BackColor.R * alpha / 255 + frmColor.R * (255 - alpha) / 255;
                        int Gb = BackColor.G * alpha / 255 + frmColor.G * (255 - alpha) / 255;
                        int Bb = BackColor.B * alpha / 255 + frmColor.B * (255 - alpha) / 255;
                        dragBckColor = Color.FromArgb(Rb, Gb, Bb);
                    }
                    else
                    {
                        dragBckColor = frmColor;
                    }

                    alpha = 255;
                    bckColor = new SolidBrush(Color.FromArgb(alpha, dragBckColor));
                }
                else
                {
                    bckColor = new SolidBrush(Color.FromArgb(alpha, this.BackColor));
                }

                if (this.BackColor != Color.Transparent | drag)
                {
                    g.FillRectangle(bckColor, bounds);
                }

                bckColor.Dispose();
                g.Dispose();
            }
            base.OnPaint(e);
        }

        protected override void OnBackColorChanged(EventArgs e)
        {
            if (this.Parent != null)
            {
                Parent.Invalidate(this.Bounds, true);
            }
            base.OnBackColorChanged(e);
        }

        protected override void OnParentBackColorChanged(EventArgs e)
        {
            this.Invalidate();
            base.OnParentBackColorChanged(e);
        }
    }

It's not a label but you can change onpaint code to draw a text.

来源：https://stackoverflow.com/questions/9551464/smoothly-fading-controls