css怎么设置透明色

background:rgba(200, 54, 54, 0.5);

.footer {
  background: linear-gradient(to top, rgba(255, 255, 255, 0.8), rgba(255, 255, 255, 0));
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 50px;
}

1. filter:Alpha(enabled=bEnabled,style=iStyle,  
2. opacity=iOpacity,finishOpacity=iFinishOpacity,  
3. startX=iPercent,startY=iPercent,  
4. finishX=iPercent,finishY=iPercent);  
5.

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class TransparentColorExample extends JPanel {

    private static final Color RED = new Color(255, 0, 0);
    private static final Color GREEN = new Color(0, 255, 0);
    private static final Color BLUE = new Color(0, 0, 255);

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;

        // 扇区1
        g2d.setColor(RED);
        g2d.fillArc(50, 50, 200, 200, 0, 72);

        // 扇区2
        g2d.setColor(GREEN.withAlpha(0));
        g2d.fillArc(50, 50, 200, 200, 72, 108);

        // 扇区3
        g2d.setColor(BLUE);
        g2d.fillArc(50, 50, 200, 200, 180, 180);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Pie Chart");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);
        frame.setResizable(false);
        frame.add(new TransparentColorExample());
        frame.setVisible(true);
    }
}

import matplotlib.pyplot as plt

# 创建一个色条
colors = ['red', 'green', 'blue']
plt.bar(range(len(colors)), [1, 2, 3], color=colors, alpha=0.5)

# 显示图表
plt.show()

import javax.swing.*;
import java.awt.*;

public class TransparentTableExample extends JFrame {
    public TransparentTableExample() {
        // 设置窗口标题
        setTitle("透明表格示例");
        
        // 设置窗口大小
        setSize(400, 300);
        
        // 设置窗口关闭时的操作
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public static void main(String[] args) {
        TransparentTableExample example = new TransparentTableExample();
        
        // 显示窗口
        example.setVisible(true);
    }
}

setWindowFlags(Qt::FramelessWindowHint);

import myframe.*;

1 import java.awt.Color;
 2 import java.awt.Container;
 3 import javax.swing.JComponent;
 4 import javax.swing.JFrame;
 5 import javax.swing.JLabel;
 6 import javax.swing.JPanel;
 7 import javax.swing.JRootPane;
 8 
 9 public class BackGround {
10             //设置窗口
11             JFrame f = new JFrame("panel test");                        
12             //设置按钮
13             JLabel label=new JLabel("ABC");                                  
14     public BackGround(){
15         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
16         f.setSize(300, 200);
17         label.setBounds(80, 50, 100, 80);               
18         //第四层
19         Container root = (JRootPane) f.getRootPane();    
20         root.setBackground(Color.green);        
21         //第三层
22         Container layer=f.getLayeredPane();
23         layer.setBackground(Color.yellow);        
24         //第二层
25         Container content = (JPanel) f.getContentPane();   
26         content.setBackground(Color.orange);        
27         //第一层
28         JComponent glass=(JComponent) f.getGlassPane();
29         glass.setBackground(Color.red);                     
30         //添加组件
31         content.setLayout(null);
32         content.add(label);
33         f.setVisible(true);
34     }
35     public static void main(String[] args) {
36         new BackGround();
37     }
38 }

import tkinter as tk

1 

import numpy as np
import cv2
from PIL import Image


img = cv2.cvtColor(cv2.imread("animal-horse.jpg"), cv2.COLOR_BGR2RGB)
print(img.shape, img.dtype)  # (1200, 1600, 3) uint8
# 找白色背景部分
mask = (255 == img[:, :, 0]) & (255 == img[:, :, 1]) & (255 == img[:, :, 2])
# 计算 alpha 通道：反选前景并设为 255 不透明
# 转成 uint8，与原 RGB 的类型一致
alpha = (1 - mask.astype(np.uint8)) * 255
# 升维、拼接：RGB -> RGBA
img_rgba = np.concatenate((img, alpha[:, :, np.newaxis]), 2)
# 转成 PIL.Image
img_rgba = Image.fromarray(img_rgba)
# 保存
img_rgba.save("animal-horse.png")

import matplotlib.pyplot as plt

# 创建示例数据
x = [1, 2, 3, 4, 5]
y = [2, 4, 6, 8, 10]

# 绘制折线图
plt.plot(x, y)
plt.show()

Color transparentColor = new Color(255, 0, 0, 128);

rgba（R,G,B,A）;

width:300px;
height:200px;
margin:0 auto;
border:1px solid #ccc;
background:red;
opacity:0.2;
}

background: rgba(0, 0, 0, 0.2);

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#80000000"
    ...>
    ...
</LinearLayout>

// 创建一个完全透明的颜色
Color transparentColor = new Color(0, 0, 0, 0);

// 创建一个半透明的红色
Color translucentRed = new Color(255, 0, 0, 128);

// 创建一个半透明的蓝色
int blue = 0x0000FF;
Color translucentBlue = new Color(blue | 0x80000000, true);