Java淡入淡出图像 [英] Java fade in and out of images
问题描述
我正在尝试学习如何淡入淡出图像到另一个图像或另一个图像。因此，如果我有2张图像，此时显示1，我想在背景中显示另一张图像，并将第一张图像淡入第二张图像。或者，我想将焦点设置在新图像上并在第一张图像上慢慢淡入，然后停止显示第一张图像。
I am trying to learn how to fade in and out images into another image or from another image. So, if I have 2 images, and 1 is being displayed at the moment, I want to display another image in the background and fade the first image out into the 2nd image. OR, I want to set the focus on the new image and slowly fade it in over the 1st image, then stop displaying the 1st one.
我不确定如何：
-
设置焦点，如果需要的话。
to set focus, if even needed.
如果我将alpha更改为0并递增并仅绘制一个图像，我可以淡入，但是我无法通过任何变化将其淡出这段代码。 （即评论出一幅图像）。
I can fade in if I change the alpha to 0 and increment up and only draw one image, however I cannot get it to fade out either with any variation of this code. (i.e. commenting out one image to draw).
编辑：真的，我所担心的只是能够有2个图像并使当前正在显示的图像慢慢消失在第二个图像中。如何实现这一点并不需要与此相关。
Really, all I'm worried about is being able to have 2 images and make the image currently being displayed slowly disappear into the 2nd image. How that is accomplished doesn't need to be with this.
这是我正在搞乱的代码示例：
Here is a code sample I'm messing with:
import java.awt.AlphaComposite;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class FadeIn extends JPanel implements ActionListener {
private Image imagem;
private Image image2;
private Timer timer;
private float alpha = 1f;
public FadeIn() {
imagem = (new ImageIcon(getClass().getResource(
"/resources/1stImage.jpg"))).getImage();
image2 = (new ImageIcon(getClass().getResource(
"/resources/2ndImage.jpg"))).getImage();
timer = new Timer(20, this);
timer.start();
}
// here you define alpha 0f to 1f
public FadeIn(float alpha) {
imagem = (new ImageIcon(getClass().getResource(
"/resources/1stImage.jpg"))).getImage();
this.alpha = alpha;
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(imagem, 0, 0, 400, 300, null);
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
alpha));
g2d.drawImage(image2, 0, 0, 400, 300, null);
}
public static void main(String[] args) {
JFrame frame = new JFrame("Fade out");
frame.add(new FadeIn());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(420, 330);
// frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent e) {
alpha += -0.01f;
if (alpha <= 0) {
alpha = 0;
timer.stop();
}
repaint();
}
}
推荐答案
基本上，它的作用是使用相同的alpha值，从0-1逐渐消失然后使用相同的alpha，从1-0开始，允许两个图像交叉淡入淡出...
Basically, what this does is use the same alpha value, fading in from 0-1 and then using the same alpha, going from 1-0, allowing the two images to cross fade over each other...
基本上，魔法发生在 paintComponent 中，其中使用 alpha 值进入的图像和传出图像使用 1f - alpha 。
The magic basically, happens in the paintComponent, where the image coming in using the alpha value and the outgoing image uses 1f - alpha.
在两个图像之间切换实际上是一个相同的过程，期望 inImage 交换为 outImage
Switching between the two images is actually a the same process, expect the inImage is swapped for the outImage
时间差别不大。而不是使用标准delta（ 0.01 ）从 0-1 直接移动，而是使用时间基于算法。
The timing is little different. Instead of a straight move from 0-1 using a standard delta (ie 0.01 for example), this uses a time based algorithm.
也就是说，我使用一个每40毫秒左右滴答一次的计时器，然后根据计时器运行的时间进行计算。相应地计算 alpha 值...
That is, I use a timer which ticks every 40 milliseconds or so, it then does a calculation based on the amount of time the timer has being running and calculates the alpha value accordingly...
这允许您更改动画所需的时间，但也提供了一个稍好的算法，考虑到Swings渲染引擎的被动性...
This allows you to change the amount of time the animation will take, but also provides a slightly better algorithm that takes into account the passive nature of Swings rendering engine...
import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
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.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class FadeImage {
public static void main(String[] args) {
new FadeImage();
}
public FadeImage() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class TestPane extends JPanel {
public static final long RUNNING_TIME = 2000;
private BufferedImage inImage;
private BufferedImage outImage;
private float alpha = 0f;
private long startTime = -1;
public TestPane() {
try {
inImage = ImageIO.read(new File("/path/to/inImage"));
outImage = ImageIO.read(new File("/path/to/outImage"));
} catch (IOException exp) {
exp.printStackTrace();
}
final Timer timer = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (startTime < 0) {
startTime = System.currentTimeMillis();
} else {
long time = System.currentTimeMillis();
long duration = time - startTime;
if (duration >= RUNNING_TIME) {
startTime = -1;
((Timer) e.getSource()).stop();
alpha = 0f;
} else {
alpha = 1f - ((float) duration / (float) RUNNING_TIME);
}
repaint();
}
}
});
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
alpha = 0f;
BufferedImage tmp = inImage;
inImage = outImage;
outImage = tmp;
timer.start();
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(
Math.max(inImage.getWidth(), outImage.getWidth()),
Math.max(inImage.getHeight(), outImage.getHeight()));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(alpha));
int x = (getWidth() - inImage.getWidth()) / 2;
int y = (getHeight() - inImage.getHeight()) / 2;
g2d.drawImage(inImage, x, y, this);
g2d.setComposite(AlphaComposite.SrcOver.derive(1f - alpha));
x = (getWidth() - outImage.getWidth()) / 2;
y = (getHeight() - outImage.getHeight()) / 2;
g2d.drawImage(outImage, x, y, this);
g2d.dispose();
}
}
}
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