最初的方法中辉光显得更暗的主要原因很可能是您没有使用带有预乘 alpha 分量的图像。 JavaDoc 的卷积运算 http://docs.oracle.com/javase/8/docs/api/java/awt/image/ConvolveOp.html包含有关在卷积过程中如何处理 alpha 分量的一些信息。
您可以使用“几乎完全透明的白色”来解决此问题。但另一种方法是,您可以简单地使用带有预乘 alpha 的图像,即具有以下类型的图像TYPE_INT_ARGB_PRE
.
这里有一个MCVE https://stackoverflow.com/help/mcve它绘制了一个带有一些文本的面板,以及文本周围的一些脉冲发光(删除计时器并设置固定半径以删除脉冲 - 我无法抗拒在这里玩一点......)。
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class TextGlowTest
{
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);
f.getContentPane().add(new TextGlowPanel());
f.setSize(300,200);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class TextGlowPanel extends JPanel
{
private BufferedImage image;
private int radius = 1;
TextGlowPanel()
{
Timer t = new Timer(50, new ActionListener()
{
long startMillis = -1;
@Override
public void actionPerformed(ActionEvent e)
{
if (startMillis == -1)
{
startMillis = System.currentTimeMillis();
}
long d = System.currentTimeMillis() - startMillis;
double s = d / 1000.0;
radius = (int)(1 + 15 * (Math.sin(s * 3) * 0.5 + 0.5));
repaint();
}
});
t.start();
}
@Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
gr.setColor(Color.GRAY);
int w = getWidth();
int h = getHeight();
gr.fillRect(0, 0, w, h);
if (image == null || image.getWidth() != w || image.getHeight() != h)
{
// Must be prmultiplied!
image = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB_PRE);
}
Graphics2D g = image.createGraphics();
Font font = g.getFont().deriveFont(70.0f).deriveFont(Font.BOLD);
g.setFont(font);
g.setComposite(AlphaComposite.Src);
g.setColor(new Color(255,255,255,0));
g.fillRect(0,0,w,h);
g.setComposite(AlphaComposite.SrcOver);
g.setColor(new Color(255,255,255,0));
g.fillRect(0,0,w,h);
g.setColor(Color.WHITE);
g.drawString("Glow!", 50, 100);
image = getGaussianBlurFilter(radius, true).filter(image, null);
image = getGaussianBlurFilter(radius, false).filter(image, null);
g.dispose();
g = image.createGraphics();
g.setFont(font);
g.setColor(Color.BLUE);
g.drawString("Glow!", 50, 100);
g.dispose();
gr.drawImage(image, 0, 0, null);
}
// From
// http://www.java2s.com/Code/Java/Advanced-Graphics/GaussianBlurDemo.htm
public static ConvolveOp getGaussianBlurFilter(
int radius, boolean horizontal)
{
if (radius < 1)
{
throw new IllegalArgumentException("Radius must be >= 1");
}
int size = radius * 2 + 1;
float[] data = new float[size];
float sigma = radius / 3.0f;
float twoSigmaSquare = 2.0f * sigma * sigma;
float sigmaRoot = (float) Math.sqrt(twoSigmaSquare * Math.PI);
float total = 0.0f;
for (int i = -radius; i <= radius; i++)
{
float distance = i * i;
int index = i + radius;
data[index] =
(float) Math.exp(-distance / twoSigmaSquare) / sigmaRoot;
total += data[index];
}
for (int i = 0; i < data.length; i++)
{
data[i] /= total;
}
Kernel kernel = null;
if (horizontal)
{
kernel = new Kernel(size, 1, data);
}
else
{
kernel = new Kernel(1, size, data);
}
return new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
}
}