Question

我有一个不透明度设置为0的表单。我怎样才能在该表单中绘制一个填充的矩形，即50％透明？

//brush1 transparency is set at 128 (50%)
SolidBrush brush1 = new SolidBrush(Color.FromArgb(128, 100, 100, 100));

private void Form1_Paint(object sender, PaintEventArgs e)
{
    e.Grapics.FillRectangle(brush1, rectangle1);
}

如果我使用e.Graphics进行绘画，则屏幕上不会绘制任何内容，因为表单的不透明度为0.

我尝试使用Graphics g = Graphics.FromHwnd(IntPtr.Zero);进行绘制，但速度很慢（只有透明度较慢的刷子），这绝对是无效的。

编辑：我这样做是为了绘制到屏幕上。表单正在使用透明画布以实现这一目标。我尝试使用BackColor = Color.LightGreen; TransparencyKey = Color.LightGreen;，但只绘制了矩形LightGreen。

这就是我想要实现的目标：

Answer 1

您可以使用两种形式来实现此目的。一个在背景上具有部分不透明度，另一个在前景上具有透明度键。

enter image description here

透明窗口位于名为Foreground_Form的表单上的Label中。背景是一个名为Form_TransparentBack

的表单

<强> Form_TransparentBack

public partial class Form_TransparentBack : Form
{
    public Form_TransparentBack(Form _foregroundForm)
    {
        InitializeComponent();
        StartPosition = _foregroundForm.StartPosition;
        Location = _foregroundForm.Location;
        Size = _foregroundForm.Size;
        _foregroundForm.Resize += _foregroundForm_Resize;
        FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
        _foregroundForm.LocationChanged += _foregroundForm_LocationChanged;
        ShowInTaskbar = false;
        BackColor = Color.WhiteSmoke;
        Opacity = 0.5;
        Timer timer = new Timer() { Interval = 10};
        timer.Tick += delegate(object sn, EventArgs ea)
        {
            (sn as Timer).Stop();
            _foregroundForm.ShowDialog();
        };
        timer.Start();
        Show();
    }

    void _foregroundForm_LocationChanged(object sender, EventArgs e)
    {
        Location = (sender as Form).Location;
    }

    void _foregroundForm_Resize(object sender, EventArgs e)
    {
        WindowState = (sender as Form).WindowState;
        Size = (sender as Form).Size;
    }
}

<强> Foreground_Form

public partial class Foreground_Form : Form
{
    public Foreground_Form()
    {
        InitializeComponent();
        FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;  // required
        TransparencyKey = this.BackColor;  // required
        StartPosition = FormStartPosition.CenterScreen;
        this.Paint += Foreground_Form_Paint;
    }

    void Foreground_Form_Paint(object sender, PaintEventArgs e)
    {
        //this is for the Stroke
        e.Graphics.DrawRectangle(Pens.White, new Rectangle(0, 0, Width - 1, Height - 1));
    }
}

现在您可以使用透明背景调用任何表单。对于透明度，您应将TransparencyKey设置为要显示的表单。

private void button1_Click(object sender, EventArgs e)
{
    new Form_TransparentBack(new Foreground_Form());
}

在透明表格上绘制填充矩形

1 个答案: