以下代码用于在按下按钮时插入文本：
if(actionNum == 4){
dropText = JOptionPane.showInputDialog(null, "Please enter the required text");
}
currentAction = actionNum;
然后调用下面的段将文本绘制到画布上：
if(currentAction == 4){
int w2 = getFontMetrics().stringWidth(dropText) / 2;
aShape = drawString(dropText, textPoint.x - w2, textPoint.y);
}else
两个错误不断重复：
类 Component 中的方法 getFontMetrics 不能应用于给定类型：here:: line:259
找不到符号 :here:: line:260
我试图添加到我正在使用的程序中的代码，这是一个绘画程序，可以在这里找到
程序代码如下：
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.event.*;
import java.awt.*;
import java.awt.geom.*;
import java.text.DecimalFormat;
import java.util.*;
// Allows user text to be entered, for use in text
// deployment to the canvas
import java.io.*;
import javax.swing.JOptionPane;
@SuppressWarnings("serial")
public class Splat extends JFrame
{
JButton brushBut, lineBut, clearBut, textBut, ellipseBut, rectBut, strokeBut, fillBut;
// Decleration of the string for use in text deployement on the canvas
String dropText;
private static final int W = 640;
private static final int H = 480;
private Point textPoint = new Point(W / 2, H / 2);
private Point mousePoint;
// Defines the arrays used on the DrawingBoard. These are Instantiated earlier
// so that they may be cleared in the makeMeButtons method
ArrayList<Shape> shapes = new ArrayList<Shape>();
ArrayList<Color> shapeFill = new ArrayList<Color>();
ArrayList<Color> shapeStroke = new ArrayList<Color>();
ArrayList<Float> transPercent = new ArrayList<Float>();
// Transparency slider
JSlider transSlider;
JLabel transLabel;
// Limits the transparency float to 2 decimal points
DecimalFormat dec = new DecimalFormat("#.##");
// Standard 2D drawing rules for Java
Graphics2D graphSettings;
// Used to determine the shape/button selected
int currentAction = 1;
// Transparency of the shape
float transparentVal = 1.0f;
// Default stroke and fill colors
Color strokeColor=Color.BLACK, fillColor=Color.BLACK;
public static void main(String [] args)
{
new Splat();
}
public Splat()
{
// Define the defaults for the JFrame
this.setSize(800, 600);
this.setTitle("Splat");
this.setFont(new Font("Serif", Font.ITALIC + Font.BOLD, 32));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel buttonPanel = new JPanel();
// Box that will hold the buttons
Box theBox = Box.createHorizontalBox();
// Make all the buttons by calling makeMeButtons and
// makeMeColorButton
brushBut = makeMeButtons("./src/brush.png", 1);
lineBut = makeMeButtons("./src/Line.png", 2);
clearBut = makeMeButtons("./src/Clear.png", 3);
textBut = makeMeButtons("./src/Text.png", 4);
ellipseBut = makeMeButtons("./src/Ellipse.png", 5);
rectBut = makeMeButtons("./src/Rectangle.png", 6);
// Make all the buttons in makeMeColorButton by passing the
// button icon and true for stroke color or false for fill
strokeBut = makeMeColorButton("./src/Stroke.png", 7, true);
fillBut = makeMeColorButton("./src/Fill.png", 8, false);
// Add the buttons to the box
theBox.add(brushBut);
theBox.add(lineBut);
theBox.add(clearBut);
theBox.add(textBut);
theBox.add(ellipseBut);
theBox.add(rectBut);
theBox.add(strokeBut);
theBox.add(fillBut);
// Add the transparent label and slider
transLabel = new JLabel("Transparent: 1");
// Min value, Max value and starting value for slider
transSlider = new JSlider(1, 99, 99);
// Create an instance of ListenForEvents to handle events
ListenForSlider lForSlider = new ListenForSlider();
// Tell Java that you want to be alerted when an event
// occurs on the slider
transSlider.addChangeListener(lForSlider);
theBox.add(transLabel);
theBox.add(transSlider);
// Add the box of buttons to the panel
buttonPanel.add(theBox);
// Position the buttons in the bottom of the frame
this.add(buttonPanel, BorderLayout.SOUTH);
// Make the drawing area take up the rest of the frame
this.add(new DrawingBoard(), BorderLayout.CENTER);
// Show the frame
this.setVisible(true);
}
// Spits out buttons based on the image supplied
// actionNum represents each shape to be drawn
public JButton makeMeButtons(String iconFile, final int actionNum){
JButton theBut = new JButton();
Icon butIcon = new ImageIcon(iconFile);
theBut.setIcon(butIcon);
// Make the proper actionPerformed method execute when the
// specific button is pressed
// If the action number is 3 then the DrawingBoard is blanked instantly,
// on the button press
theBut.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(actionNum == 3)
{
shapes.clear();
shapeFill.clear();
shapeStroke.clear();
transPercent.clear();
repaint();
}
else
if(actionNum == 4){
dropText = JOptionPane.showInputDialog(null, "Please enter the required text");
}
currentAction = actionNum;
}
});
return theBut;
}
// Creates the Fill Colour and Stroke Colour Buttons
public JButton makeMeColorButton(String iconFile, final int actionNum, final boolean stroke){
JButton theBut = new JButton();
Icon butIcon = new ImageIcon(iconFile);
theBut.setIcon(butIcon);
theBut.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(stroke){
// JColorChooser is a popup that lets you pick a color
strokeColor = JColorChooser.showDialog(null, "Pick a Stroke", Color.BLACK);
} else {
fillColor = JColorChooser.showDialog(null, "Pick a Fill", Color.BLACK);
}
}
});
return theBut;
}
private class DrawingBoard extends JComponent
{
Point drawStart, drawEnd;
// Monitors events on the drawing area of the frame
public DrawingBoard()
{
this.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
/*text input*/ if(currentAction == 4){
mousePoint = e.getPoint();
repaint();
}
else
if(currentAction != 1){
// When the mouse is pressed get x & y position
drawStart = new Point(e.getX(), e.getY());
drawEnd = drawStart;
repaint();
}
}
public void mouseReleased(MouseEvent e)
{
if(currentAction != 1){
// Create a shape using the starting x & y
// and finishing x & y positions
Shape aShape = null;
if (currentAction == 2){
aShape = drawLine(drawStart.x, drawStart.y,
e.getX(), e.getY());
} else
if(currentAction == 4){
int w2 = getFontMetrics().stringWidth(dropText) / 2;
aShape = drawString(dropText, textPoint.x - w2, textPoint.y);
} else
if (currentAction == 5){
aShape = drawEllipse(drawStart.x, drawStart.y,
e.getX(), e.getY());
} else
if (currentAction == 6) {
// Create a new rectangle using x & y coordinates
aShape = drawRectangle(drawStart.x, drawStart.y,
e.getX(), e.getY());
}
// Add shapes, fills and colors to there ArrayLists
shapes.add(aShape);
shapeFill.add(fillColor);
shapeStroke.add(strokeColor);
// Add transparency value to ArrayList
transPercent.add(transparentVal);
drawStart = null;
drawEnd = null;
// repaint the drawing area
repaint();
}
}
} );
this.addMouseMotionListener(new MouseMotionAdapter()
{
public void mouseDragged(MouseEvent e)
{
if(currentAction == 4){
int dx = e.getX() - mousePoint.x;
int dy = e.getY() - mousePoint.y;
textPoint.setLocation(textPoint.x + dx, textPoint.y + dy);
mousePoint = e.getPoint();
repaint();
}
else
// If this is a brush have shapes go on the screen quickly
if(currentAction == 1){
int x = e.getX();
int y = e.getY();
Shape aShape = null;
// Make stroke and fill equal to eliminate the fact that this is an ellipse
strokeColor = fillColor;
aShape = drawBrush(x,y,5,5);
shapes.add(aShape);
shapeFill.add(fillColor);
shapeStroke.add(strokeColor);
// Add the transparency value
transPercent.add(transparentVal);
}
// Get the final x & y position after the mouse is dragged
drawEnd = new Point(e.getX(), e.getY());
repaint();
}
} );
}
public void paint(Graphics g)
{
// Class used to define the shapes to be drawn
graphSettings = (Graphics2D)g;
// Antialiasing cleans up the jagged lines and defines rendering rules
graphSettings.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
// Defines the line width of the stroke
graphSettings.setStroke(new BasicStroke(4));
// Iterators created to cycle through strokes and fills
Iterator<Color> strokeCounter = shapeStroke.iterator();
Iterator<Color> fillCounter = shapeFill.iterator();
// Iterator for transparency
Iterator<Float> transCounter = transPercent.iterator();
for (Shape s : shapes)
{
// Sets the shapes transparency value
graphSettings.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, transCounter.next()));
// Grabs the next stroke from the color arraylist
graphSettings.setPaint(strokeCounter.next());
graphSettings.draw(s);
// Grabs the next fill from the color arraylist
graphSettings.setPaint(fillCounter.next());
graphSettings.fill(s);
}
// Guide shape used for drawing
if (drawStart != null && drawEnd != null)
{
// Makes the guide shape transparent
graphSettings.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, 0.40f));
// Make guide shape gray for professional look
graphSettings.setPaint(Color.LIGHT_GRAY);
Shape aShape = null;
if (currentAction == 2){
aShape = drawLine(drawStart.x, drawStart.y,
drawEnd.x, drawEnd.y);
} else
if(currentAction == 4){
int w2 = g.getFontMetrics().stringWidth(dropText) / 2;
g.drawString(dropText, textPoint.x - w2, textPoint.y);
}else
if (currentAction == 5){
aShape = drawEllipse(drawStart.x, drawStart.y,
drawEnd.x, drawEnd.y);
} else
if (currentAction == 6) {
// Create a new rectangle using x & y coordinates
aShape = drawRectangle(drawStart.x, drawStart.y,
drawEnd.x, drawEnd.y);
}
graphSettings.draw(aShape);
}
}
private Rectangle2D.Float drawRectangle(
int x1, int y1, int x2, int y2)
{
// Get the top left hand corner for the shape
// Math.min returns the points closest to 0
int x = Math.min(x1, x2);
int y = Math.min(y1, y2);
// Gets the difference between the coordinates and
int width = Math.abs(x1 - x2);
int height = Math.abs(y1 - y2);
return new Rectangle2D.Float(
x, y, width, height);
}
// The other shapes will work similarly
// More on this in the next tutorial
private Ellipse2D.Float drawEllipse(
int x1, int y1, int x2, int y2)
{
int x = Math.min(x1, x2);
int y = Math.min(y1, y2);
int width = Math.abs(x1 - x2);
int height = Math.abs(y1 - y2);
return new Ellipse2D.Float(
x, y, width, height);
}
private Line2D.Float drawLine(
int x1, int y1, int x2, int y2)
{
return new Line2D.Float(
x1, y1, x2, y2);
}
private Ellipse2D.Float drawBrush(
int x1, int y1, int brushStrokeWidth, int brushStrokeHeight)
{
return new Ellipse2D.Float(
x1, y1, brushStrokeWidth, brushStrokeHeight);
}
}
// Implements ActionListener so it can react to events on components
private class ListenForSlider implements ChangeListener{
// Called when the spinner is changed
public void stateChanged(ChangeEvent e) {
// Check if the source of the event was the button
if(e.getSource() == transSlider){
// Change the value for the label next to the spinner
// Use decimal format to make sure only 2 decimals are ever displayed
transLabel.setText("Transparent: " + dec.format(transSlider.getValue() * .01) );
// Set the value for transparency for every shape drawn after
transparentVal = (float) (transSlider.getValue() * .01);
}
}
}
}