近用到Java动态生成背景透明的图片功能,从gif和png中选择了png格式,个中缘由就不说了,于是动手到网上搜索有用的代码。现把搜索结果总结如下:
1. 生成png图片
int width = 400;
int height = 300;
// 创建BufferedImage对象
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取Graphics2D
Graphics2D g2d = image.createGraphics();
// 画图
g2d.setColor(new Color(255,0,0));
g2d.setStroke(new BasicStroke(1));
g2d.draw
//释放对象
g2d.dispose();
// 保存文件
ImageIO.write(image, "png", new File("c:/test.png"));
int width = 400;
int height = 300;
// 创建BufferedImage对象
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取Graphics2D
Graphics2D g2d = image.createGraphics();
// 画图
g2d.setColor(new Color(255,0,0));
g2d.setStroke(new BasicStroke(1));
g2d.draw
//释放对象
g2d.dispose();
// 保存文件
ImageIO.write(image, "png", new File("c:/test.png"));
这只是绘制图形的代码,其背景是黑色的,如何才能背景透明呢?继续搜索,没有得到结果,不过搜出以下代码,它只是把自己绘制的图形设置为透明或半透明,背景并不透明,如下:
2. 绘制半透明图形
int width = 400;
int height = 300;
// 创建BufferedImage对象
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取Graphics2D
Graphics2D g2d = image.createGraphics();
// 设置透明度
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, 1.0f)); // 1.0f为透明度 ,值从0-1.0,依次变得不透明
// 画图
g2d.setColor(new Color(255,0,0));
g2d.setStroke(new BasicStroke(1));
g2d.draw
//释放对象
//透明度设置 结束
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
g2d.dispose();
// 保存文件
ImageIO.write(image, "png", new File("c:/test.png"));
这样绘制的图形应该说是前景透明的,背景依然是黑色,:(
网上没有看到有益的代码,在csdn上一位说自己实现了,但却没有说怎么实现的,没办法只能自己摸索了,耗了半个多小时,几乎查看了BufferedImage 和Graphics2D 所有方法和属性,终于找到了解决方案,只不过是增加两行代码而已,如下:
int width = 400;
int height = 300;
// 创建BufferedImage对象
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取Graphics2D
Graphics2D g2d = image.createGraphics();
// ---------- 增加下面的代码使得背景透明 -----------------
image = g2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
g2d.dispose();
g2d = image.createGraphics();
// ---------- 背景透明代码结束 -----------------
// 画图
g2d.setColor(new Color(255,0,0));
g2d.setStroke(new BasicStroke(1));
g2d.draw
//释放对象
g2d.dispose();
// 保存文件
ImageIO.write(image, "png", new File("c:/test.png"));
================================================
白背景变透明
package com.goldgrid.socket.client;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import org.apache.log4j.Logger;
public class Alpha {
protected static Logger logger = Logger.getLogger(ClientSocket.class);
public byte[] transferAlpha(Image image) {
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
try {
ImageIcon imageIcon = new ImageIcon(image);
BufferedImage bufferedImage = new BufferedImage(imageIcon
.getIconWidth(), imageIcon.getIconHeight(),
BufferedImage.TYPE_4BYTE_ABGR);
Graphics2D g2D = (Graphics2D) bufferedImage.getGraphics();
g2D.drawImage(imageIcon.getImage(), 0, 0, imageIcon
.getImageObserver());
int alpha = 0;
for (int j1 = bufferedImage.getMinY(); j1
.getHeight(); j1++) {
for (int j2 = bufferedImage.getMinX(); j2
.getWidth(); j2++) {
int rgb = bufferedImage.getRGB(j2, j1);
int R =(rgb & 0xff0000 ) >> 16 ;
int G= (rgb & 0xff00 ) >> 8 ;
int B= (rgb & 0xff );
if(((255-R)<30) && ((255-G)<30) && ((255-B)<30)){
rgb = ((alpha + 1) <
}
bufferedImage.setRGB(j2, j1, rgb);
}
}
g2D.drawImage(bufferedImage, 0, 0, imageIcon.getImageObserver());
//ImageIO.write(bufferedImage, "png", new File("d:/test.png.png"));
ImageIO.write(bufferedImage, "png", byteArrayOutputStream);
} catch (Exception e) {
logger.error(e.toString());
}finally{
}
return byteArrayOutputStream.toByteArray();
}
}
提供个比较傻的思路1.取得控件背景色2.指定需要透明的颜色3.逐点扫描image,把需要透明的颜色setRGB成控件背景色预想:效率很低我记得我以前用过很简单的方法,设置透明色的,不过忘了怎么用的了,呵呵
BufferedImage temp = ImageIO.read(
new File("chess.bmp"));//取得图片
int imgHeight = temp.getHeight();//取得图片的长和宽
int imgWidth = temp.getWidth();
int c = temp.getRGB(3,3);
BufferedImage bi =new BufferedImage(imgWidth, imgHeight,
BufferedImage.TYPE_4BYTE_ABGR);//新建一个类型支持透明的BufferedImage
for(int i =0; i
{
for(int j =0; j
{
if(temp.getRGB(i, j) == c)
bi.setRGB(i, j, c &0x00ffffff);//这里把背景设为透明
else
bi.setRGB(i, j, temp.getRGB(i, j));
}
}