如何使用java製作圖像的漸變邊框？

Question

如何將圖像邊框製作爲漸變。我搜索了很多，但沒有找到正確的建議。任何一個可以幫我...

任何建議，請...

Answer 1

這是一個有趣的。我首先想到應該有一個簡單的解決方案，使用一些Graphics#drawRoundRect調用與適當的Paint，但它並不那麼簡單。

然而，一個解決方案是在以下示例實施：

的圖像被描繪成-IT-是到一個新的圖像。然後繪製邊緣和角落。這些由矩形組成。一個邊的每個矩形填充了一個在「完全透明」和「完全不透明」之間插入的GradientPaint。類似地，用於插入相同顏色之間的角的矩形填充有RadialGradientPaint。這些都使用AlphaComposite.DstOut構圖規則進行了繪製，以便圖像的實際像素可以緩慢「混合」到邊框。

（棋盤圖案是隻塗在組件的背景，以強調它向透明像素iterpolates在邊境）

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); 
     } 
    } 

} 

Answer 2

創建一個同樣大小的透明圖像，繪製白色邊框，並對其進行模糊處理。請將其複製到想要使用漸變邊框的圖像頂部。

參考：http://www.jhlabs.com/ip/blurring.html

希望幫助！