如何使用java制作图像的渐变边框？ [英] How to make gradient border of an image using java?

问题描述

我如何将图像边框制作为渐变。我搜索了很多，但没有找到正确的建议。任何人都可以帮助我......

任何建议请... ...

解决方案

这是一个很有意思的问题。我首先想到应该有一个简单的解决方案，使用一些 Graphics＃drawRoundRect 调用相应的 Paint ，但它是不太简单。

然而，在下面的例子中实现了一个解决方案：

图像被涂成原样成一个新的形象。然后绘制边缘和角落。这些由矩形组成。一个边的每个矩形都填充有完全透明和完全不透明之间的 GradientPaint 。类似地，角落的矩形在相同颜色之间插入 RadialGradientPaint 。这些都是用 AlphaComposite.DstOut 构图规则绘制的，以便图像的实际像素缓慢地向外拼接到边框。

< （棋盘图案仅在组件的背景中绘制，以强调它在边界处对透明像素）

  import java.awt.AlphaComposite; 
 import java.awt.Color; 
 import java.awt.Dimension; 
 import java.awt.GradientPaint; 
 import java.awt.Graphics; 
 import java.awt.Graphics2D; 
 import java.awt.GridLayout; 
 import java.awt.MultipleGradientPaint.CycleMethod; 
 import java.awt.RadialGradientPaint; 
 import java.awt.geom.Point2D; 
 import java.awt.geom.Rectangle2D; 
 import java.awt.image.BufferedImage; 
 import java.io.File; 
 import java.io.IOException; 
 
 import javax.imageio.ImageIO; 
 import javax.swing.JFrame; 
 import javax.swing.JPanel; 
导入javax.swing.SwingUtilities; 
 
 
 public class BorderBlurTest 
 {
 public static void main（String [] args）
 {
 SwingUtilities.invokeLater（new Runnable（ ）
 {
 @Override 
 public void run（）
 {
 createAndShowGUI（）; 
} 
}）; 
 
 
 private static void createAndShowGUI（）
 {
 JFrame f = new JFrame（）; 
 f.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 
 BufferedImage input = null; 
尝试
 {
 input = ImageIO.read（new File（KCR0B.jpg））; 
} 
 catch（IOException e）
 {
 e.printStackTrace（）; 
} 
 
 BufferedImage输出= blurBorder（input，20）; 
 f.getContentPane（）。setLayout（new GridLayout（））; 
 f.getContentPane（）。add（new ImagePanel（input））; 
 f.getContentPane（）。add（new ImagePanel（output））; 
 f.pack（）; 
 f.setLocationRelativeTo（null）; 
 f.setVisible（true）; 
} 
 
 private static BufferedImage blurBorder（BufferedImage input，double border）
 {
 int w = input.getWidth（）; 
 int h = input.getHeight（）; 
 BufferedImage output = new BufferedImage（
 w，h，BufferedImage.TYPE_INT_ARGB）; 
 
 Graphics2D g = output.createGraphics（）; 
 g.drawImage（input，0，0，null）; 
 
 g.setComposite（AlphaComposite.DstOut）; 
颜色c0 =新颜色（0,0,0,255）; 
颜色c1 =新颜色（0,0,0,0）; 
 
 double cy = border; 
 double cx = border; 
 
 // Left 
 g.setPaint（new GradientPaint（
 new Point2D.Double（0，cy），c0，
 new Point2D.Double（cx，cy ），c1））; 
 g.fill（new Rectangle2D.Double（
 0，cy，cx，h-cy-cy））; 
 
 // Right 
 g.setPaint（new GradientPaint（
 new Point2D.Double（w-cx，cy），c1，
 new Point2D.Double（w ，cy），c0））; 
 g.fill（new Rectangle2D.Double（
 w-cx，cy，cx，h-cy-cy））; 
 
 $ Top 
 g.setPaint（new GradientPaint（
 new Point2D.Double（cx，0），c0，
 new Point2D.Double（cx，cy ），c1））; 
 g.fill（new Rectangle2D.Double（
 cx，0，w-cx-cx，cy））; 
 
 //底部
 g.setPaint（new GradientPaint（
 new Point2D.Double（cx，h-cy），c1，
 new Point2D.Double（cx ，h），c0））; 
 g.fill（new Rectangle2D.Double（
 cx，h-cy，w-cx-cx，cy））; 
 
 
 //左上角
 g.setPaint（new RadialGradientPaint（
 new Rectangle2D.Double（0，0，cx + cx，cy + cy），
 new float [] {0,1}，new Color [] {c1，c0}，CycleMethod.NO_CYCLE））; 
 g.fill（new Rectangle2D.Double（0，0，cx，cy））; 
 
 //右上角
 g.setPaint（new RadialGradientPaint（
 new Rectangle2D.Double（w-cx-cx，0，cx + cx，cy + cy），
 new float [] {0,1}，new Color [] {c1，c0}，CycleMethod.NO_CYCLE））; 
 g.fill（new Rectangle2D.Double（w-cx，0，cx，cy））; 
 
 //左下角
 g.setPaint（new RadialGradientPaint（
 new Rectangle2D.Double（0，h-cy-cy，cx + cx，cy + cy），
 new float [] {0,1}，new Color [] {c1，c0}，CycleMethod.NO_CYCLE））; 
 g.fill（new Rectangle2D.Double（0，h-cy，cx，cy））; 
 
 //右下角
 g.setPaint（new RadialGradientPaint（
 new Rectangle2D.Double（w-cx-cx，h-cy-cy，cx + cx，cy + cy），
 new float [] {0,1}，new Color [] {c1，c0}，CycleMethod.NO_CYCLE））; 
 g.fill（new Rectangle2D.Double（w-cx，h-cy，cx，cy））; 
 
 g.dispose（）; 
 
返回输出; 
 
 
 
 static class ImagePanel extends JPanel 
 {
 private final BufferedImage image; 
 
 ImagePanel（BufferedImage图像）
 {
 this.image = image; 
 
 $ b @Override 
 public Dimension getPreferredSize（）
 {
 if（super.isPreferredSizeSet（））
 {
返回super.getPreferredSize（）; 
} 
返回新的Dimension（image.getWidth（），image.getHeight（））; 
} 
 
 @Override 
 protected void paintComponent（Graphics g）
 {
 super.paintComponent（g）; 
 int s = 8; 
 int w = getWidth（）; 
 int h = getHeight（）; 
 for（int x = 0; x  {
 for（int y = 0; y  {
 if（ （（x + y）& 1）== 0）
 {
 g.setColor（Color.WHITE）; 
} 
 else 
 {
 g.setColor（Color.LIGHT_GRAY）; 
} 
 g.fillRect（x * s，y * s，s，s）; 
} 
} 
 g.drawImage（image，0，0，null）; 
} 
} 
 
} 
  

How can I make an image border as gradient. I googled a lot, but didn't find correct suggestion. Any one can help me...

Any suggestion please...

解决方案

This is an interesting one. I first thought that there should be a simple solution, using some Graphics#drawRoundRect call with the appropriate Paint, but it's not sooo simple.

However, one solution is implemented in the following example:

The image is painted as-it-is into a new image. Then the edges and corners are painted. These consist of rectangles. Each rectangle for one edge is filled with a GradientPaint that interpolates between "completely transparent" and "completely opaque". Similarily, the rectangles for the corners are filled with a RadialGradientPaint interpolating between the same colors. These are painted with the AlphaComposite.DstOut composition rule, so that the actual pixels of the image are slowly "blending out" towards the border.

(The checkerboard pattern is only painted in the background of the component, to emphasize that it iterpolates towards transparent pixels at the border)

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.MultipleGradientPaint.CycleMethod;
import java.awt.RadialGradientPaint;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;


public class BorderBlurTest
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {
                createAndShowGUI();
            }
        });
    }

    private static void createAndShowGUI()
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        BufferedImage input = null;
        try
        {
            input = ImageIO.read(new File("KCR0B.jpg"));
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        BufferedImage output = blurBorder(input, 20);
        f.getContentPane().setLayout(new GridLayout());
        f.getContentPane().add(new ImagePanel(input));
        f.getContentPane().add(new ImagePanel(output));
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static BufferedImage blurBorder(BufferedImage input, double border)
    {
        int w = input.getWidth();
        int h = input.getHeight();
        BufferedImage output = new BufferedImage(
            w, h, BufferedImage.TYPE_INT_ARGB);

        Graphics2D g = output.createGraphics();
        g.drawImage(input, 0, 0, null);

        g.setComposite(AlphaComposite.DstOut);
        Color c0 = new Color(0,0,0,255);
        Color c1 = new Color(0,0,0,0);

        double cy = border;
        double cx = border;

        // Left
        g.setPaint(new GradientPaint(
            new Point2D.Double(0, cy), c0,
            new Point2D.Double(cx,cy), c1));
        g.fill(new Rectangle2D.Double(
            0, cy, cx, h-cy-cy));

        // Right
        g.setPaint(new GradientPaint(
            new Point2D.Double(w-cx, cy), c1,
            new Point2D.Double(w,cy), c0));
        g.fill(new Rectangle2D.Double(
            w-cx, cy, cx, h-cy-cy));

        // Top
        g.setPaint(new GradientPaint(
            new Point2D.Double(cx, 0), c0,
            new Point2D.Double(cx, cy), c1));
        g.fill(new Rectangle2D.Double(
            cx, 0, w-cx-cx, cy));

        // Bottom
        g.setPaint(new GradientPaint(
            new Point2D.Double(cx, h-cy), c1,
            new Point2D.Double(cx, h), c0));
        g.fill(new Rectangle2D.Double(
            cx, h-cy, w-cx-cx, cy));


        // Top Left
        g.setPaint(new RadialGradientPaint(
            new Rectangle2D.Double(0, 0, cx+cx, cy+cy),
            new float[]{0,1}, new Color[]{c1, c0}, CycleMethod.NO_CYCLE));
        g.fill(new Rectangle2D.Double(0, 0, cx, cy));

        // Top Right
        g.setPaint(new RadialGradientPaint(
            new Rectangle2D.Double(w-cx-cx, 0, cx+cx, cy+cy),
            new float[]{0,1}, new Color[]{c1, c0}, CycleMethod.NO_CYCLE));
        g.fill(new Rectangle2D.Double(w-cx, 0, cx, cy));

        // Bottom Left
        g.setPaint(new RadialGradientPaint(
            new Rectangle2D.Double(0, h-cy-cy, cx+cx, cy+cy),
            new float[]{0,1}, new Color[]{c1, c0}, CycleMethod.NO_CYCLE));
        g.fill(new Rectangle2D.Double(0, h-cy, cx, cy));

        // Bottom Right
        g.setPaint(new RadialGradientPaint(
            new Rectangle2D.Double(w-cx-cx, h-cy-cy, cx+cx, cy+cy),
            new float[]{0,1}, new Color[]{c1, c0}, CycleMethod.NO_CYCLE));
        g.fill(new Rectangle2D.Double(w-cx, h-cy, cx, cy));

        g.dispose();

        return output;
    }


    static class ImagePanel extends JPanel
    {
        private final BufferedImage image;

        ImagePanel(BufferedImage image)
        {
            this.image = image;
        }

        @Override
        public Dimension getPreferredSize()
        {
            if (super.isPreferredSizeSet())
            {
                return super.getPreferredSize();
            }
            return new Dimension(image.getWidth(), image.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g)
        {
            super.paintComponent(g);
            int s = 8;
            int w = getWidth();
            int h = getHeight();
            for (int x=0; x<w; x++)
            {
                for (int y=0; y<h; y++)
                {
                    if (((x+y) & 1) == 0)
                    {
                        g.setColor(Color.WHITE);
                    }
                    else
                    {
                        g.setColor(Color.LIGHT_GRAY);
                    }
                    g.fillRect(x*s,y*s,s,s);
                }
            }
            g.drawImage(image, 0, 0, null);
        }
    }

}

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