如何用c#制作两个透明层？

Question

有连续的三层，
picturebox1(.jpg) -> label1 -> picturebox2(.png transparent)我想要的是让label1和picturebox2对picturebox1透明，这样label1就可以透过picturebox2看到，但是没用..

public Form1()
{
    InitializeComponent();
    label1.Parent = pictureBox1;
    label1.BackColor = Color.Transparent;
    pictureBox2.Parent = pictureBox1;
    pictureBox2.BackColor = Color.Transparent;
    picturebox2.BringToFront(); 
}

所以请帮助我

Answer 1

如果您需要控件支持透明度，您应该覆盖控件的绘制并按以下顺序绘制控件：

在位图上绘制受您控制（基于z-index）的同一容器中的所有控件。
然后在您的控件的图形上绘制该位图。
最后画出你的控件内容。
另外你的控件BackColor应该是Color.Transparent.

这是创建 TransparentLabel 和 TransparentPictureBox 控件的结果。在下图中，依次是标签、图像、标签、图像和标签，正如您所见，图片框和标签已呈现为具有透明背景并符合 z-index：

透明标签

class TransparentLabel : Label
{
    public TransparentLabel()
    {
        this.BackColor = Color.Transparent;
    }
    protected override void OnPaint(PaintEventArgs e)
    {
        if (Parent != null && this.BackColor == Color.Transparent)
        {
            using (var bmp = new Bitmap(Parent.Width, Parent.Height))
            {
                Parent.Controls.Cast<Control>()
                      .Where(c => Parent.Controls.GetChildIndex(c) > Parent.Controls.GetChildIndex(this))
                      .Where(c => c.Bounds.IntersectsWith(this.Bounds))
                      .OrderByDescending(c => Parent.Controls.GetChildIndex(c))
                      .ToList()
                      .ForEach(c => c.DrawToBitmap(bmp, c.Bounds));

                e.Graphics.DrawImage(bmp, -Left, -Top);

            }
        }
        base.OnPaint(e);
    }
}

透明图片框

class TransparentPictureBox : PictureBox
{
    public TransparentPictureBox()
    {
        this.BackColor = Color.Transparent;
    }
    protected override void OnPaint(PaintEventArgs e)
    {
        if (Parent != null && this.BackColor==Color.Transparent)
        {
            using (var bmp = new Bitmap(Parent.Width, Parent.Height))
            {
                Parent.Controls.Cast<Control>()
                      .Where(c => Parent.Controls.GetChildIndex(c) > Parent.Controls.GetChildIndex(this))
                      .Where(c => c.Bounds.IntersectsWith(this.Bounds))
                      .OrderByDescending(c => Parent.Controls.GetChildIndex(c))
                      .ToList()
                      .ForEach(c => c.DrawToBitmap(bmp, c.Bounds));

                e.Graphics.DrawImage(bmp, -Left, -Top);

            }
        }
        base.OnPaint(e);
    }
}

如何用c#制作两个透明层？

How to make two transparent layer with c#?

.net

c#

gdi+

custom-controls

winforms