java - 如何在 Java 中平滑滚动 JFrame

Question

我的 Java 应用程序中有一个 JFrame，它包含一个 JPanel，其中我有一些在运行时创建的绘图对象。问题是在为大数字滚动 JFrame 时，滚动变慢并且滚动条移动不流畅。请注意，我正在使用 Graphics 2D 对象并在滚动操作上执行 repaint。

有什么方法可以使 JFrame 的滚动 Action 平滑吗？

部分代码

public class DiagramPanel implements MouseListener{

    int click=0;
    Point p1;
    Point p2;
    private Dimension panelDimension;
    .... // variables

    public void go() {
        p1 = new Point();
        p2 = new Point();

        JFrame f = new JFrame();
        f.setVisible(true);
        f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        f.setSize(1200,500);
        panelx = new DiaPanel();
        panelx.setOpaque(true);
        panelx.setBackground(Color.white);
        panelx.setAutoscrolls(true);
        panelx.addMouseListener(this);


        JScrollPane scrollPane = new JScrollPane();

        // scrollPane.add(panelx);

        ClassRectangle tempRect = null;
        for (ClassRectangle rect : this.classRectangles) {
            tempRect = rect;
        }


        Rectangle rect = new Rectangle();
        rect.setBounds(tempRect.getW() - 100, 0, 1000,
                tempLife.getEndpointY() * 500);

        panelDimension = new Dimension(0,0);
        for (ClassRectangle rectx : classRectangles){
            panelDimension.width=rectx.getW()+300;
        }
        for (LifeLine life : lifeLines) {
            panelDimension.height=life.getEndpointY()+300;
        }

        scrollPane.setViewportView(panelx);
        panelx.computeVisibleRect(rect);
        JScrollPane scrollPane1 = new JScrollPane(panelx);

        panelx.setPreferredSize(panelDimension);
        panelx.repaint();
        panelx.revalidate();
        p1.x=0;
        p1.y=0;
        p2.y=panelDimension.height;
        p2.x=panelDimension.width;
        f.add( scrollPane1);
        scrollPane.revalidate();
        f.setBackground(Color.white);
    }

    public DiagramPanel(ArrayList<Rectangle> classRectangles,
            ArrayList<Pair> pairs, ArrayList<Line> lines,
            ArrayList<Life> meth) {

            // constructing obj of DrawingPanel Here
    }

    public class SeqDiaPanel extends JPanel {
        /**
         * 
         */

        private static final long serialVersionUID = 1L;

        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d2 = (Graphics2D) g;
            g2d2.setColor(Color.orange);

            //grid
            for (int i = 0; i < panelDimension.height; i++) {
                g2d2.drawLine(0, 0 + i * 5, panelDimension.width+1000, 0 + i * 5);

            }

            for (int i = 0; i < panelDimension.width; i++) {
                g2d2.drawLine(0 + i * 5, 0, 0 + i *5,panelDimension.height+300);
            }

            g2d2.setColor(Color.black);

            // objects 
            .......... some objects here


            }
            }
            // draw Lines

            Stroke drawingStroke = new BasicStroke(2, BasicStroke.CAP_BUTT,
                    BasicStroke.JOIN_BEVEL, 0, new float[] { 5 }, 0);
            // Stroke drawingStroke = new BasicStroke();
            Graphics2D g2d = (Graphics2D) g;
            g2d.setStroke(drawingStroke);
            for (Line life : lines) {
                g2d.drawLine(life.getStartpointX(), life.getStartpointY(),
                        life.getEndpointX(), life.getEndpointY());
                panelDimension.height=life.getEndpointY()+300;
            }

            // draw methodLfe
            for (Object2 ml1 : Obj2) {
                g2d2.fill3DRect(ml1.StartX(), ml1.getMethodStartY(),
                        ml1.getBreadth(), ml1.getEndX(),true);
            }

        }


    }

    // tobeused

    public int calculateWidth(String name){
        Font font = new Font("Serif", Font.BOLD, 12);
         FontMetrics metrics = new FontMetrics(font){

            /**
             * 
             */
            private static final long serialVersionUID = 1L;};
        int tempInt2=SwingUtilities.computeStringWidth( metrics, name);
        tempInt2=tempInt2+10;
        return tempInt2;
    }




    /*public class MouseClick implements MouseListener{
        Point p =  new Point(0,0);
        @Override
        public void mouseClicked(MouseEvent evnt) {

            p.x=evnt.getX();
            p.y=evnt.getY();
            System.out.println("MouseClicked @"+p.x+":"+p.y);

        }

        @Override
        public void mouseEntered(MouseEvent arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void mouseExited(MouseEvent arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void mousePressed(MouseEvent arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void mouseReleased(MouseEvent arg0) {
            // TODO Auto-generated method stub

        }

    }*/

    @Override
    public void mouseClicked(MouseEvent evnt) {
        click++;
        if(click==1){
        //Point p= new Point();
        p1.x=evnt.getX();
        p1.y=evnt.getY();
    //  System.out.println("MouseClicked1 @"+p1.x+":"+p1.y);
        }

        if(click==2){
            p2.x=evnt.getX();
            p2.y=evnt.getY();
            //System.out.println("MouseClicked2 @"+p2.x+":"+p2.y);
            click=0;
            if(p1.x<p2.x&&p1.y<p2.y){
            panelx.repaint();
            }
            else{

            }

        }/*else{
            p1.x=0;
            p1.y=0;
            p2.x=panelDimension.width+500;
            p2.y=panelDimension.height+700;
        }*/
    }

    @Override
    public void mouseEntered(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseExited(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mousePressed(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseReleased(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }
}

Answer 1

这个想法也许能帮到你

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.*;

public class TilePainter extends JPanel implements Scrollable {

    private static final long serialVersionUID = 1L;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                JFrame frame = new JFrame("Tiles");
                frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                frame.getContentPane().add(new JScrollPane(new TilePainter()));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
    private final int TILE_SIZE = 50;
    private final int TILE_COUNT = 100;
    private final int visibleTiles = 10;
    private final boolean[][] loaded;
    private final boolean[][] loading;
    private final Random random;

    public TilePainter() {
        setPreferredSize(new Dimension(TILE_SIZE * TILE_COUNT, TILE_SIZE * TILE_COUNT));
        loaded = new boolean[TILE_COUNT][TILE_COUNT];
        loading = new boolean[TILE_COUNT][TILE_COUNT];
        random = new Random();
    }

    public boolean getTile(final int x, final int y) {
        boolean canPaint = loaded[x][y];
        if (!canPaint && !loading[x][y]) {
            loading[x][y] = true;
            Timer timer = new Timer(random.nextInt(500),
                    new ActionListener() {

                        @Override
                        public void actionPerformed(ActionEvent e) {
                            loaded[x][y] = true;
                            repaint(x * TILE_SIZE, y * TILE_SIZE, TILE_SIZE, TILE_SIZE);
                        }
                    });
            timer.setRepeats(false);
            timer.start();
        }
        return canPaint;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Rectangle clip = g.getClipBounds();
        int startX = clip.x - (clip.x % TILE_SIZE);
        int startY = clip.y - (clip.y % TILE_SIZE);
        for (int x = startX; x < clip.x + clip.width; x += TILE_SIZE) {
            for (int y = startY; y < clip.y + clip.height; y += TILE_SIZE) {
                if (getTile(x / TILE_SIZE, y / TILE_SIZE)) {
                    g.setColor(Color.GREEN);
                } else {
                    g.setColor(Color.RED);
                }
                g.fillRect(x, y, TILE_SIZE - 1, TILE_SIZE - 1);
            }
        }
    }

    @Override
    public Dimension getPreferredScrollableViewportSize() {
        return new Dimension(visibleTiles * TILE_SIZE, visibleTiles * TILE_SIZE);
    }

    @Override
    public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
        return TILE_SIZE * Math.max(1, visibleTiles - 1);
    }

    @Override
    public boolean getScrollableTracksViewportHeight() {
        return false;
    }

    @Override
    public boolean getScrollableTracksViewportWidth() {
        return false;
    }

    @Override
    public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
        return TILE_SIZE;
    }
}