getSubimage(...)如何工作? [英] How does getSubimage(...) work?
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问题描述
我正在尝试从BufferedImage中提取图像的一部分.我该怎么做呢?这不是让我输入大于零的y值.
I'm trying to extract a part of an image from a BufferedImage. How do I do this? It's not letting me put a value for y that is greater than zero.
例如:
getSubimage(0,0,theImage.getWidth(),theImage.getHeight()); //OK
getSubimage(0,(int)theImage.getHeight()/2,theImage.getWidth(), theImage.getHeight()); //ERROR!
这是错误消息:
Exception in thread "main" java.awt.image.RasterFormatException: (y + height) is outside of Raster
at sun.awt.image.ByteInterleavedRaster.createWritableChild(Unknown Source)
at java.awt.image.BufferedImage.getSubimage(Unknown Source)
at Loop.renderImages(Loop.java:147)
at Loop.run(Loop.java:122)
at Driver.main(Driver.java:9)
这是完整的代码.我知道这很杂乱...仍然是编码的新手.
Here's the whole code. I know it's messy... still new to coding.
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.swing.*;
import javax.imageio.ImageIO;
public class Loop implements Runnable{
//458 = max right boundary
private static long now, lastSecond, lastFrame, deltaSecond, deltaFrame;
private boolean on = true;
private static final long second = 1000000000;
private static final int FPS = 60;
private static final long frame = second/FPS;
private static int currentFPS, framesCurrentSecond, totalFrames, seconds;
private static boolean running = true;
private static int SCPosX, SCPosY;
private static int SCXOffset, SCYOffset, bottomOffset = 120;
private static int gameWidth = FrameBuilder.WIDTH;
private static int gameHeight = FrameBuilder.HEIGHT;
private int score;
private static BufferedImage spaceCraft, spaceCraft2;
private static ImageBufferer IB;
private static FrameBuilder fb;
private Thread spaceShipThread = new Thread();
private static int boundaryLeft, boundaryRight, boundaryUp, boundaryDown;
private static boolean moveUp = false, moveDown = false, moveRight = false, moveLeft = false;
private static boolean fireMainCannon = false;
private static long cannonTick = second/3;
private static long deltaCannonTick = 0;
private static final int healthMax = 458;
private Timer animationTimer;
private static BufferedImage starOne, starOneSub;
private static int starOneY = 0, starOneStart, starOneEnd;
public Loop()
{
File S1 = new File("C:\\Users\\Andrew\\Documents\\star1.png");
try {
starOne = ImageIO.read(S1);
} catch (IOException e) {
e.printStackTrace();
}
starOneStart = (int)starOne.getHeight() - starOne.getHeight();
starOneEnd = starOne.getHeight();
animationTimer = new Timer(80, new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
on = !on;
}
});
Timer starOneTimer = new Timer(100, new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(starOneStart > 0 && starOneEnd > 0)
{
starOneStart--;
starOneEnd--;
}
else
{
starOneStart = starOne.getHeight()-((int)starOne.getHeight()/4);
starOneEnd = starOne.getHeight();
}
}
});
starOneTimer.start();
animationTimer.start();
SCXOffset = 0;
SCYOffset = 0;
spawnSpaceShip();
IB = new ImageBufferer();
fb = new FrameBuilder();
fb.c.addKeyListener(new Controls());
fb.setDefaultComponents();
score = 0;
boundaryLeft = 24;
boundaryRight = gameWidth-spaceCraft.getWidth()-64;
boundaryDown = gameHeight-bottomOffset;
SCPosX = (gameWidth/2)-(spaceCraft.getWidth()+16);
SCPosY = boundaryDown - spaceCraft.getHeight()/2;
boundaryUp = -5;
now = System.nanoTime();
lastSecond = now;
lastFrame = now;
seconds = 0;
framesCurrentSecond = 0;
totalFrames = 0;
}
public void run() {
while(running)
{
now = System.nanoTime();
deltaSecond = now - lastSecond;
deltaFrame = now - lastFrame;
if(deltaFrame >= frame)
{
handleSpaceCraft(SCXOffset, SCYOffset);
renderImages(IB.getImages(), IB.getXCoords(), IB.getYCoords());
IB.clearLists();
lastFrame = now;
framesCurrentSecond++;
}
if(deltaSecond >= second)
{
lastSecond = now;
seconds++;
totalFrames += framesCurrentSecond;
System.out.println("FPS: " + framesCurrentSecond + " TOTAL: " + totalFrames);
framesCurrentSecond = 0;
}
}
}
public void renderImages(ArrayList<BufferedImage> images, ArrayList<Integer> x, ArrayList<Integer> y)
{
BufferStrategy bs = FrameBuilder.getCanvas().getBufferStrategy();
if(bs==null)
{
FrameBuilder.getCanvas().createBufferStrategy(3);
return;
}
Graphics g = bs.getDrawGraphics();
starOneSub = starOne.getSubimage(0, (int)starOne.getHeight()/2, starOne.getWidth(), starOneEnd);
for(int i = 0; i < images.size(); i++)
{
g.drawImage(starOneSub, 0, 0, starOneSub.getWidth()+500, starOneSub.getHeight()+600,null);
g.setColor(Color.RED);
g.fillRect(24, gameHeight-72, SpaceCraft.maxHealth*4, 20);
g.setColor(Color.GREEN);
g.fillRect(24, gameHeight-72, SpaceCraft.health*(4) , 20);
g.drawImage(images.get(i), x.get(i), y.get(i) , images.get(i).getWidth()+32, images.get(i).getHeight()+32, null);
g.dispose();
}
bs.show();
}
public void handleSpaceCraft(int x, int y)
{
if(moveUp)
{
SCYOffset-=10;
if(SCPosY+SCYOffset <= boundaryUp)
SCYOffset+=10;
}
if(moveDown)
{
SCYOffset+=10;
if(SCPosY+SCYOffset >= boundaryDown)
SCYOffset-=10;
}
if(moveRight)
{
SCXOffset+=7;
if(SCPosX+SCXOffset >= boundaryRight)
SCXOffset-=7;
}
if(moveLeft)
{
SCXOffset-=7;
if(SCPosX+SCXOffset <= boundaryLeft)
SCXOffset+=7;
}
if(on)
IB.addImage(spaceCraft, SCPosX+SCXOffset, SCPosY+SCYOffset);
else
IB.addImage(spaceCraft2, SCPosX+SCXOffset, SCPosY+SCYOffset);
}
public class Controls implements KeyListener
{
@Override
public void keyTyped(KeyEvent e)
{
}
@Override
public void keyPressed(KeyEvent e)
{
int key = e.getKeyCode();
if(key == KeyEvent.VK_W)
moveUp = true;
if(key == KeyEvent.VK_A)
moveLeft = true;
if(key == KeyEvent.VK_D)
moveRight = true;
if(key == KeyEvent.VK_S)
moveDown = true;
if(key == KeyEvent.VK_SPACE)
fireMainCannon = true;
}
@Override
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_S)
moveDown = false;
if(key == KeyEvent.VK_D)
moveRight = false;
if(key == KeyEvent.VK_W)
moveUp = false;
if(key == KeyEvent.VK_A)
moveLeft = false;
if(key == KeyEvent.VK_SPACE)
{
fireMainCannon = false;
}
}
}
public void spawnSpaceShip()
{
File SC1 = new File("C:\\Users\\Andrew\\Documents\\spaceCraftGray1.png");
File SC2 = new File("C:\\Users\\Andrew\\Documents\\spaceCraftGray2.png");
try {
spaceCraft = ImageIO.read(SC1);
spaceCraft2 = ImageIO.read(SC2);
} catch (IOException e) {
e.printStackTrace();
}
}
}
推荐答案
基于调用该函数的方式，您似乎假设您先传递了左上角，然后传递了右下角.
Based on the way you called the function, it looks like you were assuming that you pass in the top left corner followed by the bottom right corner.
If you look at the Javadoc for that method, you will observe that the parameters are x,y,w,h.
也就是说，您首先使用x,y提供左上角，然后提供宽度和高度.因此，如果您尝试获取图像的下半部分，则正确的选择是将提供的高度减半.
That is, you first provide the top left corner using x,y and then provide the width and height. Consequently, if you are trying to get the bottom half of the image, the correct call is to halve the provided height.
getSubimage(0,(int)theImage.getHeight()/2,theImage.getWidth(), theImage.getHeight() / 2);
这篇关于getSubimage(...)如何工作?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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