我有一个创建多个PNG文件的java程序（截图）。我现在需要找到一种从这些文件创建动画GIF的方法，并且不知道从哪里开始。
如何将多个PNG文件转换为动画GIF？
答案 0 :(得分：1)
改编自旧thread on Sun forums。不包括电池，所有保修均为零和空隙。
import java.awt.image.BufferedImage;
import java.io.File;
import org.w3c.dom.Node;
import javax.imageio.*;
import javax.imageio.metadata.*;
import javax.imageio.stream.ImageOutputStream;
/**
* Creates an animated GIF from GIF frames. A thin wrapper to code written by
* other people, as documented on the thread on the Sun forums 'Create animated
* GIF using imageio' http://forums.sun.com/thread.jspa?threadID=5395006 See the
* printUsage() method for details on paramaters required.
*
* @author Andrew Thompson
*/
class WriteAnimatedGif {
/**
* See http://forums.sun.com/thread.jspa?messageID=10755673#10755673
*
* @author Maxideon
* @param delayTime String Frame delay for this frame.
*/
public static void configure(IIOMetadata meta,
String delayTime,
int imageIndex) {
String metaFormat = meta.getNativeMetadataFormatName();
if (!"javax_imageio_gif_image_1.0".equals(metaFormat)) {
throw new IllegalArgumentException(
"Unfamiliar gif metadata format: " + metaFormat);
}
Node root = meta.getAsTree(metaFormat);
//find the GraphicControlExtension node
Node child = root.getFirstChild();
while (child != null) {
if ("GraphicControlExtension".equals(child.getNodeName())) {
break;
}
child = child.getNextSibling();
}
IIOMetadataNode gce = (IIOMetadataNode) child;
gce.setAttribute("userDelay", "FALSE");
gce.setAttribute("delayTime", delayTime);
//only the first node needs the ApplicationExtensions node
if (imageIndex == 0) {
IIOMetadataNode aes
= new IIOMetadataNode("ApplicationExtensions");
IIOMetadataNode ae
= new IIOMetadataNode("ApplicationExtension");
ae.setAttribute("applicationID", "NETSCAPE");
ae.setAttribute("authenticationCode", "2.0");
byte[] uo = new byte[]{
//last two bytes is an unsigned short (little endian) that
//indicates the the number of times to loop.
//0 means loop forever.
0x1, 0x0, 0x0
};
ae.setUserObject(uo);
aes.appendChild(ae);
root.appendChild(aes);
}
try {
meta.setFromTree(metaFormat, root);
} catch (IIOInvalidTreeException e) {
//shouldn't happen
throw new Error(e);
}
}
/**
* See http://forums.sun.com/thread.jspa?messageID=9988198
*
* @author GeoffTitmus
* @param file File A File in which to store the animation.
* @param frames BufferedImage[] Array of BufferedImages, the frames of the
* animation.
* @param delayTimes String[] Array of Strings, representing the frame delay
* times.
*/
public static void saveAnimate(
File file,
BufferedImage[] frames,
String[] delayTimes) throws Exception {
ImageWriter iw = ImageIO.getImageWritersByFormatName("gif").next();
ImageOutputStream ios = ImageIO.createImageOutputStream(file);
iw.setOutput(ios);
iw.prepareWriteSequence(null);
for (int i = 0; i < frames.length; i++) {
BufferedImage src = frames[i];
ImageWriteParam iwp = iw.getDefaultWriteParam();
IIOMetadata metadata = iw.getDefaultImageMetadata(
new ImageTypeSpecifier(src), iwp);
configure(metadata, delayTimes[i], i);
IIOImage ii = new IIOImage(src, null, metadata);
iw.writeToSequence(ii, null);
}
iw.endWriteSequence();
ios.close();
}
/**
* Dump the usage to the System.err stream.
*/
public static void printUsage() {
StringBuffer sb = new StringBuffer();
String eol = System.getProperty("line.separator");
sb.append("Usage: 2 forms each using 3 arguments");
sb.append(eol);
sb.append("1) output (animated GIF) file name");
sb.append(eol);
sb.append("2) input files (animation frames), separated by ','");
sb.append(eol);
sb.append("3) single frame rate, or comma separared list of frame rates");
sb.append(eol);
sb.append("java WriteAnimatedGif animate.gif frm1.gif,frm2.gif,..,frmN.gif 100");
sb.append(eol);
sb.append("java WriteAnimatedGif animate.gif frm1.gif,frm2.gif,..,frmN.gif 100,40,..,N");
sb.append(eol);
sb.append("The 2nd form must have exactly as many integers as there are frames.");
sb.append(eol);
sb.append("Frame rates are specified in increments of 1/100th second, NOT milliseconds.");
sb.append(eol);
System.err.print(sb);
}
/**
* Checks that a String intended as a delayTime is an integer>0. If not,
* dumps a warning message and the usage, then exits. If successful, returns
* the String unaltered.
*/
public static String checkDelay(String delay) {
try {
int val = Integer.parseInt(delay);
if (val < 1) {
System.err.println(
"Animation frame delay '"
+ val
+ "' is < 1!");
printUsage();
System.exit(1);
}
} catch (NumberFormatException nfe) {
System.err.println(
"Could not parse '"
+ delay
+ "' as an integer.");
printUsage();
System.exit(1);
}
return delay;
}
/**
* Parse the arguments and if successful, attempt to write the animated GIF.
*/
public static void main(String[] args) throws Exception {
if (args.length != 3) {
printUsage();
System.exit(1);
}
// deal with the output file name
File f = new File(args[0]);
// deal with the input file names
String[] names = args[1].split(",");
if (names.length < 2) {
System.err.println("An animation requires 2 or more frames!");
printUsage();
System.exit(1);
}
BufferedImage[] frames = new BufferedImage[names.length];
for (int ii = 0; ii < names.length; ii++) {
frames[ii] = ImageIO.read(new File(names[ii]));
}
// deal with the frame rates
String[] delays = args[2].split(",");
// note: length of names, not delays
String[] delayTimes = new String[names.length];
if (delays.length != names.length) {
System.err.println(delays.length
+ " delays specified for "
+ names.length
+ " frames!");
printUsage();
System.exit(1);
} else if (delays.length == 1) {
for (int ii = 0; ii < delayTimes.length; ii++) {
// fill all values with the single delayTime
delayTimes[ii] = checkDelay(delays[0]);
}
} else {
for (int ii = 0; ii < delayTimes.length; ii++) {
delayTimes[ii] = checkDelay(delays[ii]);
}
}
// save an animated GIF
saveAnimate(f, frames, delayTimes);
}
}