[英]Easier way to make a paint application in java?
所以基本上我有一些我几天前正在处理的代码,有点像 Paint,它允许你基本上使用鼠标在屏幕上绘制。 我有点偶然地发现了这个属性,我意识到它确实效率低下,我想知道是否有更实用的方法来做到这一点。 没有任何理由提供我所有的代码,但这里是重要的部分
private static void createAndShowGui() {
SimpleDraw mainPanel = new SimpleDraw();
MenuBar.createMenuBar();
JLabel label = new JLabel();
label.setText("Drawing prototype 0.0.1");
// label.setHorizontalTextPosition(JLabel.NORTH);
label.setFont(new Font("Serif", Font.BOLD, 20));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.getContentPane().setLayout(new BoxLayout(frame.getContentPane(),BoxLayout.PAGE_AXIS));
frame.setVisible(true);
frame.setJMenuBar(MenuBar.getMenuBar());
frame.setBackground(Color.WHITE);
frame.add(label);
上面的代码块设置了 jframe(窗口)
@Override
public void mouseDragged(MouseEvent e)
{
// These console outputs are just so that I know what is happening
System.out.println("Event: MOUSE_DRAG");
System.out.println(e.getX());
System.out.println(e.getY());
System.out.println(e.getComponent());
System.out.println(e.getWhen());
System.out.println(e.getButton());
MOUSE_X = e.getX() - 5; //-5 so that the cursor represents the center of the square, not the top left corner.
MOUSE_Y = e.getY() - 5; //^
rect = new Rectangle(MOUSE_X, MOUSE_Y, 10, 10 ); //This doesn't ever come into action.
repaint();
}
上面的代码几乎只是设置了 MOUSE_X 和 MOUSE_Y 变量以及 repaint(); 方法
@Override
protected void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
if (rect != null) {
if (!colorChoice.equals("Default"))
{
g2.setColor(Color.BLACK);
}
switch(colorChoice) {
case "GRAY":
g2.setColor(Color.GRAY);
break;
case "CYAN":
g2.setColor(Color.CYAN);
break;
case "BLUE":
g2.setColor(Color.BLUE);
break;
case "RED":
g2.setColor(Color.RED);
break;
case "PINK":
g2.setColor(Color.PINK);
break;
case "YELLOW":
g2.setColor(Color.YELLOW);
break;
case "GREEN":
g2.setColor(Color.GREEN);
break;
case "PURPLE":
g2.setColor(Color.MAGENTA);
break;
case "RESET":
g2.setColor(Color.WHITE);
case "WHITE":
g2.setColor(Color.WHITE);
}
g2.fillRect(MOUSE_X, MOUSE_Y, 15, 15);
if (colorChoice.equals("RESET"))
resetColorOnCursor();
}
}
public static void clearBoard()
{
tempColor = colorChoice;
setColorChoice("RESET");
frame.repaint();
}
public static void resetColorOnCursor()
{
setColorChoice(tempColor);
}
这是我偶然遇到的事情。 当我发现这一点时,我试图做的基本上是在您移动鼠标时使一个正方形跟随您的光标。 但是我忘记输入代码部分paintComponent(g);
,这将这个程序变成了我最初想要的东西。 这的底部部分基本上是我将如何清除板。 我 100% 确定这不是清除/重置这样的框架的正确方法,但我找不到其他方法。 如果有人有任何提示或更好的方法来正确执行此操作,我将不胜感激。 谢谢! :D
您当前的方法基本上是通过不调用super.paintComponent
打破绘制链的要求。 paintComponent
方法执行一组操作,您不会接管这些操作,这可能会导致一些非常奇怪的绘制工件,这些工件难以一致地复制。
Graphics
是共享资源,因此用于绘制其他控件的Graphics
上下文将与用于绘制组件的相同,除非您事先“清理”上下文,否则先前绘制到上下文的内容将保留(这就是为什么您当前的代码“似乎”有效)。
相反,您应该使用MouseListener
来定义一个锚点,它表示鼠标被按下的点,然后使用MouseMotionListener
来定义选择区域的范围,例如...
import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class SelectExample {
public static void main(String[] args) {
new SelectExample();
}
public SelectExample() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Rectangle selection;
public TestPane() {
MouseAdapter ma = new MouseAdapter() {
private Point clickPoint;
@Override
public void mousePressed(MouseEvent e) {
clickPoint = e.getPoint();
selection = null;
}
@Override
public void mouseDragged(MouseEvent e) {
Point dragPoint = e.getPoint();
int x = Math.min(clickPoint.x, dragPoint.x);
int y = Math.min(clickPoint.y, dragPoint.y);
int width = Math.max(clickPoint.x, dragPoint.x) - x;
int height = Math.max(clickPoint.y, dragPoint.y) - y;
if (selection == null) {
selection = new Rectangle(x, y, width, height);
} else {
selection.setBounds(x, y, width, height);
}
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
selection = null;
repaint();
}
};
addMouseListener(ma);
addMouseMotionListener(ma);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (selection != null) {
g.setColor(UIManager.getColor("List.selectionBackground"));
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
g2d.fill(selection);
g2d.dispose();
g2d = (Graphics2D) g.create();
g2d.draw(selection);
g2d.dispose();
}
}
}
}
只是为了强调如果您继续违反paintComponent
方法的要求将面临的问题,这就是当我不调用super.paintComponent
时会发生的情况
我只是在JFrame
添加了两个JButton
(所以甚至没有直接添加到面板中)。 paintComponent
做了一系列重要的工作,你忽略了这些工作,这会导致更多的问题和问题。
自由形式的线实际上是一种错觉,它是在一系列点之间绘制的一系列(小)线,这是因为MouseListener
不会报告它移动的每个鼠标位置,这取决于鼠标的速度搬家,你可能会收到很多或几个回电。
因此,我们不只是绘制点,而是将点存储在List
并在它们之间画线,例如......
import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class FreeFormLines {
public static void main(String[] args) {
new FreeFormLines();
}
public FreeFormLines() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private List<List<Point>> points;
public TestPane() {
points = new ArrayList<>(25);
MouseAdapter ma = new MouseAdapter() {
private List<Point> currentPath;
@Override
public void mousePressed(MouseEvent e) {
currentPath = new ArrayList<>(25);
currentPath.add(e.getPoint());
points.add(currentPath);
}
@Override
public void mouseDragged(MouseEvent e) {
Point dragPoint = e.getPoint();
currentPath.add(dragPoint);
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
currentPath = null;
}
};
addMouseListener(ma);
addMouseMotionListener(ma);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
for (List<Point> path : points) {
Point from = null;
for (Point p : path) {
if (from != null) {
g2d.drawLine(from.x, from.y, p.x, p.y);
}
from = p;
}
}
g2d.dispose();
}
}
}
这是实际绘画应用程序的一个简单示例,您可以在其中控制和更改绘图的大小和颜色。
public class Main extends Application{
@Override
public void start(Stage stage){
try{
g = can.getGraphicsContext2D();
g.setStroke(Color.BLACK);
g.setLineWidth(1);
c.setValue(Color.BLACK);
c.setOnAction(e->{
g.setStroke(c.getValue());
});
sli.setMin(1);
sli.setMax(100);
sli.setShowTickLabels(true);
sli.setShowTickMarks(true);
sli.valueProperty().addListener(e->{
double val = sli.getValue();
String str = String.format("%.1f", val);
lab.setText(str);
g.setLineWidth(val);
});
gri.addRow(0, c, sli, lab);
gri.setHgap(20);
gri.setAlignement(Pos.TOP_CENTER);
gri.setPadding( new Insets( 20, 0, 0, 0));
scene.setOnMousePressed(e->{.
g.beginPath();
g.lineTo(e.getSceneX(), e.getSceneY());
g.stroke();
});
scene.setOnMoudrDragged(e->{.
g.lineTo(e.getSceneX(), e.getSceneY());
g.stroke();
});
pan.getChildren().addAll(can, gri);
stage.setScene(scene);
stage.show();
}catch(Exception e){
e.printStrackTrace();
}
Canvas can = new Canvas(760, 490);
GraphicsContext g ;
ColorPicker c = new ColorPicker();
Slider sli = new Slider();
Label lab = new Label("1.0");
GridPane gri = new GridPane();
StackPane pan = new StackPane();
Scene scene = new Scene(pan, 760, 490);
public static void main (String [] args){
launch(args);
}
}
或者我们可以尝试只绘制 java 代码,我认为它是如此简单和强大。
package drawingbymouse;
import java.awt.*;
import java.awt.event.*;
public class DrawingByMouse extends Frame
implements MouseMotionListener{
DrawingByMouse(){
addMouseMotionListener(this);
setSize(400, 400);
setLayout(null);
setVisible(true);
}
@Override
public void mouseDragged(MouseEvent e){
Graphics g = getGraphics();
g.setColor(Color.BLACK);
g.fillOval(e.getX(), e.getY(), 10, 10);
}
public void mouseMoved(MouseEvent e){
}
public static void main (String[]args){
new DrawingByMouse();
}
}
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