所以我有一个动画 gif，我像这样加载到 ImageIcon 中：
Image image = new ImageIcon("image.gif").getImage();
我可以用这个来画它：
g.drawImage(image, x, y, null);
我知道我可以使用 AffineTransform 即时镜像它，但我需要能够在加载后水平镜像它，这样我就可以在需要时绘制镜像的镜像，而无需每次转换它的开销重绘。有没有办法使用 swing/awt 来做到这一点？
可以做到这一点的图书馆也将是一个巨大的帮助。
【问题讨论】：
标签： java swing animation awt imageicon
正如您所指出的，问题在于 gif 是动画的。
除非您非常想接手必须自己渲染每一帧的工作，否则您唯一的选择就是在paint方法中使用AffineTransform。
一般来说，您不应该看到显着差异（在渲染方面）。
如果你真的很绝望，你可以简单地在外部预渲染 gif 并提供一个镜像版本
更新了“某种”工作示例
这是this 和this 答案的组合，使用this GIF 作家。
这个例子的主要作用是读取原始 gif 图像，逐帧镜像，然后写回镜像文件。
然后它会将原始文件和镜像文件加载回ImageIcons，主要是因为我真的不打算重新发明轮子来显示动画 gif。是的，你可以做到，你需要的一切都在里面提供..
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.imageio.IIOException;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.stream.FileImageOutputStream;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class MirrorImage {
public static void main(String[] args) {
new MirrorImage();
}
public MirrorImage() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private ImageIcon orig;
private ImageIcon mirror;
public TestPane() {
mirror(new File("java_animated.gif"), new File("Mirror.gif"));
orig = new ImageIcon("java_animated.gif");
mirror = new ImageIcon("Mirror.gif");
}
@Override
public Dimension getPreferredSize() {
return mirror == null ? new Dimension(200, 200) : new Dimension(orig.getIconWidth(), orig.getIconHeight() * 2);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (orig != null) {
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - orig.getIconWidth()) / 2;
int y = (getHeight() - (orig.getIconHeight() * 2)) / 2;
g2d.drawImage(orig.getImage(), x, y, this);
// AffineTransform at = new AffineTransform();
// at.setToScale(1, -1);
// at.translate(0, -mirror.getIconHeight());
// g2d.setTransform(at);
g2d.drawImage(mirror.getImage(), x, y + mirror.getIconHeight(), this);
g2d.dispose();
}
}
}
public static void mirror(File source, File dest) {
List<BufferedImage> images = new ArrayList<>(25);
List<Integer> delays = new ArrayList<>(25);
int delay = 0;
ImageOutputStream output = null;
GifSequenceWriter writer = null;
try {
String[] imageatt = new String[]{
"imageLeftPosition",
"imageTopPosition",
"imageWidth",
"imageHeight"
};
ImageReader reader = (ImageReader) ImageIO.getImageReadersByFormatName("gif").next();
ImageInputStream ciis = ImageIO.createImageInputStream(source);
reader.setInput(ciis, false);
int noi = reader.getNumImages(true);
BufferedImage master = null;
for (int i = 0; i < noi; i++) {
BufferedImage image = reader.read(i);
IIOMetadata metadata = reader.getImageMetadata(i);
Node tree = metadata.getAsTree("javax_imageio_gif_image_1.0");
NodeList children = tree.getChildNodes();
for (int j = 0; j < children.getLength(); j++) {
Node nodeItem = children.item(j);
System.out.println(nodeItem.getNodeName());
if (nodeItem.getNodeName().equals("ImageDescriptor")) {
Map<String, Integer> imageAttr = new HashMap<String, Integer>();
NamedNodeMap attr = nodeItem.getAttributes();
// for (int index = 0; index < attr.getLength(); index++) {
// Node node = attr.item(index);
// System.out.println("----> " + node.getNodeName() + "=" + node.getNodeValue());
// }
for (int k = 0; k < imageatt.length; k++) {
Node attnode = attr.getNamedItem(imageatt[k]);
imageAttr.put(imageatt[k], Integer.valueOf(attnode.getNodeValue()));
}
if (master == null) {
master = new BufferedImage(imageAttr.get("imageWidth"), imageAttr.get("imageHeight"), BufferedImage.TYPE_INT_ARGB);
}
Graphics2D g2d = master.createGraphics();
g2d.drawImage(image, imageAttr.get("imageLeftPosition"), imageAttr.get("imageTopPosition"), null);
g2d.dispose();
BufferedImage frame = mirror(copyImage(master));
ImageIO.write(frame, "png", new File("img" + i + ".png"));
images.add(frame);
} else if (nodeItem.getNodeName().equals("GraphicControlExtension")) {
NamedNodeMap attr = nodeItem.getAttributes();
Node delayNode = attr.getNamedItem("delayTime");
if (delayNode != null) {
delay = Math.max(delay, Integer.valueOf(delayNode.getNodeValue()));
delays.add(delay);
}
}
}
}
output = new FileImageOutputStream(dest);
writer = new GifSequenceWriter(output, images.get(0).getType(), delay * 10, true);
for (int i = 0; i < images.size(); i++) {
BufferedImage nextImage = images.get(i);
writer.writeToSequence(nextImage);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
writer.close();
} catch (Exception e) {
}
try {
output.close();
} catch (Exception e) {
}
}
}
public static BufferedImage mirror(BufferedImage img) {
BufferedImage mirror = createCompatibleImage(img);
Graphics2D g2d = mirror.createGraphics();
AffineTransform at = new AffineTransform();
at.setToScale(1, -1);
at.translate(0, -img.getHeight());
g2d.setTransform(at);
g2d.drawImage(img, 0, 0, null);
g2d.dispose();
return mirror;
}
public static BufferedImage copyImage(BufferedImage img) {
int width = img.getWidth();
int height = img.getHeight();
BufferedImage newImage = createCompatibleImage(img);
Graphics graphics = newImage.createGraphics();
int x = (width - img.getWidth()) / 2;
int y = (height - img.getHeight()) / 2;
graphics.drawImage(img, x, y, img.getWidth(), img.getHeight(), null);
graphics.dispose();
return newImage;
}
public static BufferedImage createCompatibleImage(BufferedImage image) {
return getGraphicsConfiguration().createCompatibleImage(image.getWidth(), image.getHeight(), image.getTransparency());
}
public static GraphicsConfiguration getGraphicsConfiguration() {
return GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
}
public static class GifSequenceWriter {
protected ImageWriter gifWriter;
protected ImageWriteParam imageWriteParam;
protected IIOMetadata imageMetaData;
/**
* Creates a new GifSequenceWriter
*
* @param outputStream the ImageOutputStream to be written to
* @param imageType one of the imageTypes specified in BufferedImage
* @param timeBetweenFramesMS the time between frames in miliseconds
* @param loopContinuously wether the gif should loop repeatedly
* @throws IIOException if no gif ImageWriters are found
*
* @author Elliot Kroo (elliot[at]kroo[dot]net)
*/
public GifSequenceWriter(
ImageOutputStream outputStream,
int imageType,
int timeBetweenFramesMS,
boolean loopContinuously) throws IIOException, IOException {
// my method to create a writer
gifWriter = getWriter();
imageWriteParam = gifWriter.getDefaultWriteParam();
ImageTypeSpecifier imageTypeSpecifier
= ImageTypeSpecifier.createFromBufferedImageType(imageType);
imageMetaData
= gifWriter.getDefaultImageMetadata(imageTypeSpecifier,
imageWriteParam);
String metaFormatName = imageMetaData.getNativeMetadataFormatName();
IIOMetadataNode root = (IIOMetadataNode) imageMetaData.getAsTree(metaFormatName);
IIOMetadataNode graphicsControlExtensionNode = getNode(
root,
"GraphicControlExtension");
graphicsControlExtensionNode.setAttribute("disposalMethod", "none");
graphicsControlExtensionNode.setAttribute("userInputFlag", "FALSE");
graphicsControlExtensionNode.setAttribute(
"transparentColorFlag",
"FALSE");
graphicsControlExtensionNode.setAttribute(
"delayTime",
Integer.toString(timeBetweenFramesMS / 10));
graphicsControlExtensionNode.setAttribute(
"transparentColorIndex",
"0");
IIOMetadataNode commentsNode = getNode(root, "CommentExtensions");
commentsNode.setAttribute("CommentExtension", "Created by MAH");
IIOMetadataNode appEntensionsNode = getNode(
root,
"ApplicationExtensions");
IIOMetadataNode child = new IIOMetadataNode("ApplicationExtension");
child.setAttribute("applicationID", "NETSCAPE");
child.setAttribute("authenticationCode", "2.0");
int loop = loopContinuously ? 0 : 1;
child.setUserObject(new byte[]{0x1, (byte) (loop & 0xFF), (byte) ((loop >> 8) & 0xFF)});
appEntensionsNode.appendChild(child);
imageMetaData.setFromTree(metaFormatName, root);
gifWriter.setOutput(outputStream);
gifWriter.prepareWriteSequence(null);
}
public void writeToSequence(RenderedImage img) throws IOException {
gifWriter.writeToSequence(
new IIOImage(
img,
null,
imageMetaData),
imageWriteParam);
}
/**
* Close this GifSequenceWriter object. This does not close the underlying
* stream, just finishes off the GIF.
*/
public void close() throws IOException {
gifWriter.endWriteSequence();
}
/**
* Returns the first available GIF ImageWriter using
* ImageIO.getImageWritersBySuffix("gif").
*
* @return a GIF ImageWriter object
* @throws IIOException if no GIF image writers are returned
*/
private static ImageWriter getWriter() throws IIOException {
Iterator<ImageWriter> iter = ImageIO.getImageWritersBySuffix("gif");
if (!iter.hasNext()) {
throw new IIOException("No GIF Image Writers Exist");
} else {
return iter.next();
}
}
/**
* Returns an existing child node, or creates and returns a new child node
* (if the requested node does not exist).
*
* @param rootNode the <tt>IIOMetadataNode</tt> to search for the child
* node.
* @param nodeName the name of the child node.
*
* @return the child node, if found or a new node created with the given
* name.
*/
private static IIOMetadataNode getNode(
IIOMetadataNode rootNode,
String nodeName) {
int nNodes = rootNode.getLength();
for (int i = 0; i < nNodes; i++) {
if (rootNode.item(i).getNodeName().compareToIgnoreCase(nodeName)
== 0) {
return ((IIOMetadataNode) rootNode.item(i));
}
}
IIOMetadataNode node = new IIOMetadataNode(nodeName);
rootNode.appendChild(node);
return (node);
}
}
}
注意事项
Gif 编写器目前仅适用于固定速率的 gif。应该可以改一下，但是我没时间。
基本上，据我了解，您需要将“帧”延迟传递给 writeToSquence 方法。在此方法中，您需要构造一个适当的IIOMetadata，其中包含所有必需的属性以及帧延迟...
播放原始 gif 后更新
我正在玩的 GIF 进行了优化。也就是说，每一帧都“添加”到动画中，而不是一个全新的帧。你的情况正好相反。每一帧都是一个完整的图像。
现在，您可能有很多方法可以检查这个，但现在，我无暇顾及......
相反...在mirror(File, File) 方法中，我对其进行了更改，以便不再使用单个“主”图像，而是每帧创建一个新的BufferedImage
BufferedImage frame = new BufferedImage(imageAttr.get("imageWidth"), imageAttr.get("imageHeight"), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = frame.createGraphics();
g2d.drawImage(image, imageAttr.get("imageLeftPosition"), imageAttr.get("imageTopPosition"), null);
g2d.dispose();
frame = mirror(frame);
ImageIO.write(frame, "png", new File("img" + i + ".png"));
images.add(frame);
我还更新了GifSequenceWriter 以将元数据设置为更接近原始数据...
graphicsControlExtensionNode.setAttribute("disposalMethod", "restoreToBackgroundColor");
graphicsControlExtensionNode.setAttribute("userInputFlag", "FALSE");
graphicsControlExtensionNode.setAttribute(
"transparentColorFlag",
"TRUE");
【讨论】：
..每次转换的开销..
该开销大约为 0。但如果您不想使用 AffineTransform，只需在循环中更改 x,y。
有关更多提示，另请参阅Show an animated BG in Swing。
这个：
g.drawImage(image, x, y, null);
应该是：
g.drawImage(image, x, y, this); // containers are typically an ImageObserver!
【讨论】：
对于非动画图像，您可以创建镜像。
// Width and height
int w = image.getWidth(null);
int h = image.getHeight(null);
// Create a new BufferedImage
BufferedImage mirror = new BufferedImage(w, h);
// Draw the image flipping it horizontally
Graphics2D g = mirror.createGraphics();
g.drawImage(image, 0, 0, w, h, w, 0, 0, h, null);
// Dispose the graphics.
g.dispose();
然后您可以使用已经水平镜像的mirror。
【讨论】：