Question

我有一个使用drawLine（）绘制网格的applet，然后允许用户通过单击网格来放置和删除.png图像。现在我想在绘图空间的右侧添加一些界面按钮，我该怎么做？目前一个按钮拒绝移动到我想要的坐标，当然有正确的方法可以做到吗？

package test2;

import java.applet.Applet;
import java.awt.Button;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.net.URL;

public class MainClass extends Applet implements MouseListener{

    final int columnNumber = 10; //Number of columns
    final int rowNumber = 8; //Number of rows

    final int gridSize = 51;

    private URL base;

    //element images
    private Image whiteSquare, resistanceHor, resistanceVer;

    //creating a GridElement array
    GridElement[][] gridElement = new GridElement[columnNumber][rowNumber];

    public void init()  {

        setSize(columnNumber*gridSize + 100, rowNumber*gridSize);
        //Here I try to add a button
        Button resistanceButton = new Button("Button1");
        resistanceButton.setLocation(columnNumber*gridSize, 20);
        this.add(resistanceButton);

        try {
            base = getDocumentBase();
        } catch (Exception e) {
            // TODO: handle exception
        }

        resistanceHor = getImage(base, "data/resistance_hor.png");
        resistanceVer = getImage(base, "data/resistance_ver.png");
        whiteSquare = getImage(base, "data/white_square.png");

        // Add the MouseListener to applet
        addMouseListener(this);

        for(int xcount=0; xcount<columnNumber;xcount++){

            for(int ycount=0; ycount<rowNumber;ycount++){
                //set top left corner  coordinates for all grid elements and declare them empty and non-vertical
                gridElement[xcount][ycount] = new GridElement(gridSize*xcount, gridSize*ycount,true,false);

            }
        }
    }

    public void update(Graphics g) {
        paint(g);
    }

    public void paint(Graphics g){

        //set grid color
        Color gridGrey = new Color(208,195,195);        
        g.setColor(gridGrey); 

        //draw grid
        for(int xcount=0; xcount<columnNumber;xcount++){

            g.drawLine(xcount*gridSize, 0, xcount*gridSize, rowNumber*gridSize);
        }

        for(int ycount=0; ycount<rowNumber;ycount++){

            g.drawLine(0, ycount*gridSize, columnNumber*gridSize, ycount*gridSize);
        }

        //draw png images in non-empty squares
        for(int xcount=0; xcount<columnNumber;xcount++){

            for(int ycount=0; ycount<rowNumber;ycount++){

                if(gridElement[xcount][ycount].isEmpty() == false){
                    g.drawImage(resistanceHor, gridElement[xcount][ycount].getxTopLeftCorner(), gridElement[xcount][ycount].getyTopLeftCorner(), this);
                }
                else{
                    g.setColor( getBackground() );
                    g.fillRect(gridElement[xcount][ycount].getxTopLeftCorner()+1, gridElement[xcount][ycount].getyTopLeftCorner()+1, gridSize-1, gridSize-1);
                }
            }
        }
    }

    public void mouseClicked (MouseEvent me) {

        int col = me.getX() / gridSize;   // Column where user clicked.
        int row = me.getY() / gridSize;   // Row where user clicked.

        //if a square is empty, make it not empty, if it is not empty, make it empty
        if(gridElement[col][row].isEmpty() == true){
            gridElement[col][row].setEmpty(false);
        }
        else{
            gridElement[col][row].setEmpty(true);
        }

        repaint();
    }   
    public void mousePressed (MouseEvent me) {}
    public void mouseReleased (MouseEvent me) {} 
    public void mouseEntered (MouseEvent me) {}
    public void mouseExited (MouseEvent me) {} 
}

package test2;

public class GridElement {

private int xTopLeftCorner;
private int yTopLeftCorner;

private boolean vertical;
private boolean empty;

private boolean isResistor;

GridElement(int xTopLeftCorner, int yTopLeftCorner,  boolean empty, boolean vertical){
    this.xTopLeftCorner = xTopLeftCorner;
    this.yTopLeftCorner = yTopLeftCorner;
    this.empty = empty;
    this.vertical = vertical;

}

public boolean isResistor() {
    return isResistor;
}

public void setResistor(boolean isResistor) {
    this.isResistor = isResistor;
}

public boolean isVertical() {
    return vertical;
}
public boolean isEmpty() {
    return empty;
}
public void setVertical(boolean vertical) {
    this.vertical = vertical;
}
public void setEmpty(boolean empty) {
    this.empty = empty;
}

public int getxTopLeftCorner() {
    return xTopLeftCorner;
}

public int getyTopLeftCorner() {
    return yTopLeftCorner;
}

public void setxTopLeftCorner(int xTopLeftCorner) {
    this.xTopLeftCorner = xTopLeftCorner;
}

public void setyTopLeftCorner(int yTopLeftCorner) {
    this.yTopLeftCorner = yTopLeftCorner;
}

}

Answer 1

You need to learn about layout managers.

基本上是顶级容器，如Applet，JApplet，Frame，JFrame，Dialog，JDialog等。拥有BorderLayout的默认布局管理器。当您add(component)到具有BorderLayout的容器时，该组件会被添加到BorderLayout.CENTER位置。不仅如此，BorderLayout还不尊重组件的首选大小，这意味着组件将伸展以适应容器。在您的情况下，它将占用整个框架。

解。

不要在applet组件上绘制。换句话说是Panel。将面板添加到applet容器中。（中心还可以）
创建另一个Panel并将按钮添加到那个面板，然后将面板添加到BorderLayout.LINE_END，例如add(buttonPanel, BorderLayout.LINE_END);
< / LI>

其他重要说明：

除非这是一个课堂作业，教授明确表示要使用AWT组件。不要。请改用Swing组件。 Swing组件与AWT组件非常相似。它们通常在AWT组件前加J作为前缀，例如JPanel。请参阅more about Swing
请勿像paint()方法那样明确调用update()。而是致电repaint()
如果您不打算自己绘制背景，则应在super.paint(g)方法中调用paint。如果你不这样做，你会看到剩余的油漆文物。

在Java applet中使用带图形的按钮

1 个答案: