[英]Java2D graphics inside JScrollPanel don't come out well
我是荷蘭計算機科學系的一名學生,我正在做一項作業,其中我必須繪制幾個形狀。 為了使這些形狀看起來更好,我設置了抗鋸齒的渲染提示。 但是現在我的問題是,當我用JScrollPanel滾動到屏幕上未顯示形狀的位置然后向后滾動時,抗鋸齒和透明效果似乎無法正常工作。
在下面鏈接的圖像中,我已滾動到形狀的一半,然后向后滾動。
我真的不知道問題出在哪里,所以我在下面的類中提供了完整的代碼。
我想先謝謝你,
米蘭訴迪克
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.*;
import javax.imageio.ImageIO;
import javax.swing.*;
@SuppressWarnings("serial")
public class AgendaPanel extends JPanel{
private final int WIDTH = 24; // width in hours
private final Color BUTTON_TOP_GRADIENT = new Color(250, 250, 250);
private final Color BUTTON_BOTTOM_GRADIENT = new Color(210, 210, 210);
private ArrayList<Line> lines = new ArrayList<Line>();
private ArrayList<Shape> shadowBoxes = new ArrayList<Shape>();
private ArrayList<Shape> itemBoxes = new ArrayList<Shape>();
private ArrayList<Image2D> images = new ArrayList<Image2D>();
private ArrayList<String2D> names = new ArrayList<String2D>();
public AgendaPanel(){
setPreferredSize(new Dimension(WIDTH*100, 300));
drawGrid();
}
public void drawGrid(){
for(int i=100; i < WIDTH*100; i+=100){
lines.add(new Line(i,0,i,300,Color.GRAY));
}
for(int i=50; i < WIDTH*100; i+=100){
lines.add(new Line(i,0,i,300, Color.LIGHT_GRAY));
}
// change to the amount of podia
for(int i=75; i < 300; i+=75){
lines.add(new Line(0, i, WIDTH*100, i, Color.black));
}
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
RenderingHints qualityHints = new RenderingHints(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON );
qualityHints.put(
RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY );
g2.setRenderingHints( qualityHints );
// Add agenda items to the draw queue
addAgendaItem("logo.png", "Minus Militia", 2, 2, 170);
//draw time grid
for(Line line : lines){
g2.setColor(line.color);
g2.drawLine(line.x1, line.y1, line.x2, line.y2);
}
//Shape roundRect = new RoundRectangle2D.Double(2, 2, 170, 71, 20, 20);
//Paint all shadow shapes as the first layer over the grid with a transparacy of 30%
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.3f));
for (Shape shadow : shadowBoxes){
paintBorderShadow(g2,4,shadow);
}
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,1f));
//Paint all boxes as second layer over the shadows
g2.setStroke(new BasicStroke());
g2.setPaint(new GradientPaint( new Point(0, 0),
BUTTON_TOP_GRADIENT,
new Point(0, 71),
BUTTON_BOTTOM_GRADIENT));
for (Shape box : itemBoxes){
g2.fill(box);
}
// Paint as third layer all the images over the boxes
for (Image2D image : images){
g2.drawImage(image.getImage() , image.getX(), image.getY(), null);
}
g2.setColor(Color.black);
//Paint all names as fourth and last layer
for (String2D name : names){
g2.drawString(name.getText(), name.getX(), name.getY());
}
}
private void addAgendaItem(String imageFile,String name, int x, int y, int length){
shadowBoxes.add(new RoundRectangle2D.Double(x+3, y+3, length-3, 68, 20, 20));
itemBoxes.add(new RoundRectangle2D.Double(x, y, length, 71, 20, 20));
BufferedImage in = null;
try {
in = ImageIO.read(new File("logo.png"));
} catch (IOException e) {
e.printStackTrace();
}
images.add(new Image2D(x+8, y+8 ,drawPicture(scaleImage(in, 55, 55,Color.black),20)));
names.add(new String2D(x+73,y+38, name));
}
private BufferedImage drawPicture(BufferedImage image, int cornerRadius){
int w = image.getWidth();
int h = image.getHeight();
BufferedImage output = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = output.createGraphics();
g2.setComposite(AlphaComposite.Src);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(Color.WHITE);
g2.fill(new RoundRectangle2D.Float(0, 0, w, h, cornerRadius, cornerRadius));
g2.setComposite(AlphaComposite.SrcAtop);
g2.drawImage(image, 0, 0, null);
g2.dispose();
return output;
}
public BufferedImage scaleImage(BufferedImage img, int width, int height, Color background) {
int imgWidth = img.getWidth();
int imgHeight = img.getHeight();
if (imgWidth*height < imgHeight*width) {
width = imgWidth*height/imgHeight;
} else {
height = imgHeight*width/imgWidth;
}
BufferedImage output = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = output.createGraphics();
try {
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
g.setBackground(background);
g.clearRect(0, 0, width, height);
g.drawImage(img, 0, 0, width, height, null);
} finally {
g.dispose();
}
return output;
}
private void paintBorderShadow(Graphics2D g2, int shadowWidth, Shape shape) {
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
int sw = shadowWidth*2;
for (int i=sw; i >= 2; i-=2) {
float pct = (float)(sw - i) / (sw - 1);
g2.setColor(getMixedColor(Color.DARK_GRAY, pct,
Color.DARK_GRAY, 1.0f-pct));
g2.setStroke(new BasicStroke(i));
g2.draw(shape);
}
}
private static Color getMixedColor(Color c1, float pct1, Color c2, float pct2) {
float[] clr1 = c1.getComponents(null);
float[] clr2 = c2.getComponents(null);
for (int i = 0; i < clr1.length; i++) {
clr1[i] = (clr1[i] * pct1) + (clr2[i] * pct2);
}
return new Color(clr1[0], clr1[1], clr1[2], clr1[3]);
}
}
Image2D,String2D和Line類:
public class String2D {
private int x = 0;
private int y = 0;
private String text = "";
public String2D(int x, int y, String text){
this.x = x;
this.y = y;
this.text = text;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
}
import java.awt.image.BufferedImage;
public class Image2D {
private int x = 0;
private int y = 0;
private BufferedImage image = null;
public Image2D(int x, int y, BufferedImage image){
this.x = x;
this.y = y;
this.image = image;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public BufferedImage getImage() {
return image;
}
public void setImage(BufferedImage image) {
this.image = image;
}
}
import java.awt.*;
public class Line{
public int x1;
public int x2;
public int y1;
public int y2;
public Color color;
public Line(int x1, int y1, int x2, int y2, Color color){
this.x1 = x1;
this.x2 = x2;
this.y1 = y1;
this.y2 = y2;
this.color = color;
}
}
經過個人的尤里卡片刻之后,我發現了我的問題所在。 我正在調整大小,並在每次重畫時給圓角圖像,這使g2對象以某種方式禁用了我的渲染提示。 我已將此代碼放入構造函數中,現在一切都運行順利。
下面的代碼就是問題所在:
private BufferedImage drawPicture(BufferedImage image, int cornerRadius){
int w = image.getWidth();
int h = image.getHeight();
BufferedImage output = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = output.createGraphics();
g2.setComposite(AlphaComposite.Src);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(Color.WHITE);
g2.fill(new RoundRectangle2D.Float(0, 0, w, h, cornerRadius, cornerRadius));
g2.setComposite(AlphaComposite.SrcAtop);
g2.drawImage(image, 0, 0, null);
g2.dispose();
return output;
}
public BufferedImage scaleImage(BufferedImage img, int width, int height, Color background) {
int imgWidth = img.getWidth();
int imgHeight = img.getHeight();
if (imgWidth*height < imgHeight*width) {
width = imgWidth*height/imgHeight;
} else {
height = imgHeight*width/imgWidth;
}
BufferedImage output = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = output.createGraphics();
try {
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
g.setBackground(background);
g.clearRect(0, 0, width, height);
g.drawImage(img, 0, 0, width, height, null);
} finally {
g.dispose();
}
return output;
}
我在paintcomponent例程中調用了此方法:
addAgendaItem("logo.png", "Minus Militia", 2, 2, 170);
這是哪種方法:
private void addAgendaItem(String imageFile,String name, int x, int y, int length){
shadowBoxes.add(new RoundRectangle2D.Double(x+3, y+3, length-3, 68, 20, 20));
itemBoxes.add(new RoundRectangle2D.Double(x, y, length, 71, 20, 20));
BufferedImage in = null;
try {
in = ImageIO.read(new File("logo.png"));
} catch (IOException e) {
e.printStackTrace();
}
images.add(new Image2D(x+8, y+8 ,drawPicture(scaleImage(in, 55, 55,Color.black),20)));
names.add(new String2D(x+73,y+38, name));
}
這就調用了上述兩種方法(每次重繪),這導致了我的性能和繪圖問題。
這是一種方法,有時可能會提高CPU效率(以及消耗更多的內存),但是,這可以解決此問題。
存在此問題的原因是,您正在更改作為“ paintComponent”方法的參數提供的Graphics對象的狀態。 這是一個常見錯誤,會導致各種奇怪的圖形錯誤。
您不應該更改對象狀態的原因是,因為該對象是由其父組件傳遞到您的組件的,而父組件是從其父組件獲取的,依此類推。 鏈中的每個組件(一直到擁有的窗口)都使用相同的Graphics對象來繪制自身。 相同的Graphics對象也將自動傳遞給組件的任何子代。 這是Swing工作原理的基礎(關於將Swing與AWT甚至SWT進行比較的討論是完全不同的主題)。
相反,您應該做的就是保留狀態。 這可以通過以下兩種方式之一來完成:
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