因为winform Form窗体的局限性，不允许设置背景色为transparent。所以不能实现透明背景。这里有一个取巧的方法，通过截取窗口后的的背景来实现背景透明效果。
先把代码贴上来：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ElectronicPlanning
{
public partial class Form1 : Form
{
private Color tr_color = Color.Transparent;
private bool b_start = false;
bool[] b_visible = null;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
SetBackgroundImageTransparent();
}
private void SetBackgroundImageTransparent()
{
Point pt = this.PointToScreen(new Point(0, 0));
Bitmap b = new Bitmap(this.Width, this.Height);
using (Graphics g = Graphics.FromImage(b))
{
g.CopyFromScreen(pt, new Point(), new Size(this.Width, this.Height));
}
this.BackgroundImage = b;
}
private void BeginSet()
{
tr_color = this.TransparencyKey;
b_start = true;
}
private void Setting()
{
if (b_start)
{
b_visible = new bool[Controls.Count];
for (int i = 0; i < Controls.Count; i++)
{
b_visible[i] = Controls[i].Visible;
Controls[i].Visible = false;
}
BackgroundImage = null;
BackColor = Color.White;
b_start = false;
this.TransparencyKey = Color.White;
}
}
private void EndSet()
{
SetBackgroundImageTransparent();
this.TransparencyKey = tr_color;
for (int i = 0; i < Controls.Count; i++)
{
Controls[i].Visible = b_visible[i];
}
b_start = false;
}
private void Form1_Resize(object sender, EventArgs e)
{
Setting();
}
private void Form1_ResizeBegin(object sender, EventArgs e)
{
BeginSet();
}
private void Form1_ResizeEnd(object sender, EventArgs e)
{
EndSet();
}
private void Form1_Move(object sender, EventArgs e)
{
Setting();
}
}
}如果想设置为半透明的效果，就添加一个panel,然后把panel的背景设置为透明，再添加一张半透明的图片即可实现半透明的遮罩图片，即可实现效果。本文来自于广州地理信息网:http://www.gzgis.com
全透明效果如下：
