我正在用Java开发一个简单的形状编辑器,我正在BufferedImage上绘制所有内容,因为我想保存绘制的图像。用户可以通过从菜单中选择形状来绘制形状,然后单击图像。我开始实现拖动形状。当我拖动一个形状时,正在创建该形状的路径...我认为是因为我在BufferedImage上绘制,所以就像“临时”一样。还是我错了?我当时想重新编写所有内容,这次不是在BufferedImage上绘图,而只是创建Graphics2D,但是我在实现侦听器时遇到了问题,因为我需要将我的Graphics2D转移到那里以在其中添加形状,而且我也不知道如何调用重绘在例如。我的MouseListener类。当用户想要保存图像时,我打算创建BufferedImage,我可以在存储所有形状的矢量的帮助下创建它(还是更好的方法?)。这是我的小组课程:
public class Panel {
public static Graphics2D img2;
public static Graphics2D getIm() {
return this.img2;
}
public Panel(JFrame frame) {
JPanel panel = new JPanel(true) {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
img2 = (Graphics2D)g.create();
img2.dispose();
};
};
RenderingHints.VALUE_ANTIALIAS_ON); // setting rendering to achieve better looking shapes
panel.setBackground(Color.WHITE);
MouseListenerShapes mouseListenerShapes = new MouseListenerShapes();
panel.addMouseListener(mouseListenerShapes);
//MouseMoveAdapter mouseMouseMoveAdapter = new MouseMoveAdapter();
//panel.addMouseMotionListener(mouseMouseMoveAdapter);
//panel.addMouseListener(mouseMouseMoveAdapter);
frame.add(panel);
};
}
我做了很多阅读,但仍然无法正确完成,我需要调整形状,移动形状等,但是同时我想随后保存图像,
我要提出的解决方案还远远不能完成,但是我希望它能说明一些可以帮助您获得成功的概念。我将用两个可移动的图像构建一个面板,但是将使用使该代码更易于维护的模式来进行此操作。
我强烈建议您将渲染层(JComponents
)和模型层(形状及其位置)分成不同的对象。这称为关注点分离,从长远来看,它将使您的生活更加轻松。
[首先,请定义您出现在屏幕中的一个形状。我将保持非常简单,并使用位置,大小和BufferedImage
创建一个:
class DrawNode
{
private Rectangle bounds;
private BufferedImage image;
public DrawNode()
{
}
public Rectangle getBounds()
{
return bounds;
}
public void setBounds( Rectangle bounds )
{
this.bounds = bounds;
}
public BufferedImage getImage()
{
return image;
}
public void setImage( BufferedImage image )
{
this.image = image;
}
}
接下来,我们创建一个模型来保存您的形状集合。我们可以用模型做的一件整洁的事情是让它接受一个侦听器,该侦听器将在我们的2D空间的某些部分变为“无效”时被调用。如果节点先前在给定区域中并已移至新区域,则部分空间可能变得无效,并且需要重新粉刷。我们还将包括一些用于确定给定空间占据哪种形状的辅助方法,等等。可以在效率方面极大地优化这些辅助方法,但是我的简单版本将使用蛮力迭代:
class DrawPanelModel
{
private final List<DrawNode> nodes;
private final Consumer<Rectangle> invalidAreaListener;
public DrawPanelModel( Consumer<Rectangle> invalidAreaListener )
{
this.invalidAreaListener = invalidAreaListener;
nodes = new ArrayList<>();
}
public void addNode( DrawNode node )
{
nodes.add( node );
}
public Optional<DrawNode> getNodeForPoint( Point p )
{
return nodes.stream()
.filter( node -> node.getBounds().contains( p ))
.findFirst();
}
public Stream<DrawNode> getNodesInRectangle( Rectangle r )
{
return nodes.stream()
.filter( node -> node.getBounds().intersects( r ));
}
public void setNodeLocation( DrawNode node, Point p )
{
Rectangle bounds = (Rectangle)node.getBounds().clone();
bounds.setLocation( p );
setNodeBounds( node, bounds );
}
public void setNodeBounds( DrawNode node, Rectangle bounds )
{
Rectangle old = node.getBounds();
node.setBounds( Objects.requireNonNull( bounds ));
if ( old == null || !old.equals( bounds ))
{
invalidAreaListener.accept( bounds );
if ( old != null ) {
invalidAreaListener.accept( old );
}
}
}
}
接下来,我们需要一种将形状/节点渲染到屏幕上的方法。每次调用paint(...)
时,我们都可以绘制每个节点,但这并不是很有效,因为我们只需要重新绘制无效区域即可。通过确保JComponent
使用双缓冲,我们可以不理会其余区域:https://docs.oracle.com/javase/7/docs/api/javax/swing/JComponent.html#setDoubleBuffered(boolean)
在Swing中用于完成此操作的一种常用技术是将CellRendererPane
与用作渲染器的JLabel
结合使用。每当我们需要在特定位置绘制节点时,我们都可以将所需的图像和大小分配给JLabel
,并在绘制过程中(可能不止一次)在不同位置使CellRendererPane
渲染该JLabel
。
让我们创建这样的JLabel
子类,并给它一个帮助器方法以初始化其从给定节点的状态:
class ShapeRenderer extends JLabel
{
private static final long serialVersionUID = 1L;
public ShapeRenderer() {
}
public void initFrom( DrawNode node )
{
setIcon( new ImageIcon( node.getImage() ));
setSize( node.getBounds().getSize() );
}
// Methods below are overridden as a performance optimization:
@Override
public void invalidate() {
}
@Override
public void validate() {
}
@Override
public void revalidate() {
}
@Override
public void repaint( long tm, int x, int y, int width, int height ) {
}
@Override
public void repaint( Rectangle r ) {
}
@Override
public void repaint() {
}
@Override
protected void firePropertyChange( String propertyName, Object oldValue, Object newValue ) {
}
@Override
public void firePropertyChange( String propertyName, boolean oldValue, boolean newValue ) {
}
}
至此,我们剩下JComponent
,让我们创建一个自定义的。我们给它一个DrawPanelModel
,CellRendererPane
和我们的ShapeRenderer
。它将作为侦听器订阅模型,并在节点移动时响应区域中的模型无效而调用repaint(Rectangle)
。请记住,repaint(...)
立即进行绘制,而不是安排在将来的某个时间发生绘制事件。这意味着我们实际上可以移动多个节点,并且Swing框架将为我们提供一个绘画事件,该事件将所有无效矩形的并集指定为Graphic's
剪辑区域。但是,我们的代码并不真正在乎是否合并无效区域。如果框架决定为我们使无效的每个区域提供绘画事件,我们也可以处理:class DrawPanel extends JComponent
{
private static final long serialVersionUID = 1L;
private final CellRendererPane renderPane;
private final ShapeRenderer renderer;
private final DrawPanelModel model;
public DrawPanel()
{
renderPane = new CellRendererPane();
add( renderPane );
setDoubleBuffered( true );
renderer = new ShapeRenderer();
model = new DrawPanelModel( this::repaint );
DrawMouseListener listener = new DrawMouseListener();
addMouseListener( listener );
addMouseMotionListener( listener );
}
public void addNode( BufferedImage image, Point loc )
{
DrawNode node = new DrawNode();
node.setImage( image );
model.addNode( node );
model.setNodeBounds( node, new Rectangle( loc, new Dimension( image.getWidth(), image.getHeight() )));
}
@Override
public void doLayout()
{
renderPane.setSize( getSize() );
}
private void paintBackground( Graphics2D g )
{
g.setColor( Color.WHITE );
g.fill( g.getClip() );
}
private void paintNodes( Graphics2D g )
{
model.getNodesInRectangle( g.getClipBounds() )
.forEach( node -> paintNode( node, g ));
}
private void paintNode( DrawNode node, Graphics2D g )
{
Rectangle r = node.getBounds();
renderer.initFrom( node );
renderPane.paintComponent( g, renderer, this, r );
}
@Override
public void paintComponent( Graphics aG )
{
Graphics2D g = (Graphics2D)aG.create();
paintBackground( g );
paintNodes( g );
}
class DrawMouseListener extends MouseAdapter
{
private Optional<DrawNode> movingNode;
public DrawMouseListener()
{
movingNode = Optional.empty();
}
@Override
public void mousePressed( MouseEvent e )
{
movingNode = model.getNodeForPoint( e.getPoint() );
}
@Override
public void mouseReleased( MouseEvent e )
{
movingNode = Optional.empty();
}
@Override
public void mouseDragged( MouseEvent e )
{
movingNode.ifPresent( node -> {
model.setNodeLocation( node, e.getPoint() );
} );
}
}
}
最后是手动测试:
@Test
public void testPanel() throws InvocationTargetException, InterruptedException
{
SwingUtilities.invokeLater( () -> {
// Create frame:
JFrame frame = new JFrame();
frame.setLayout( new GridLayout( 1, 1 ));
// Create draw panel:
DrawPanel drawPanel = new DrawPanel();
frame.add( drawPanel );
// Show frame:
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setSize( new Dimension( 1000, 600 ));
frame.setVisible( true );
// Create first image:
BufferedImage image1 = new BufferedImage( 50, 50, BufferedImage.TYPE_INT_ARGB );
Graphics2D g = image1.createGraphics();
g.setColor( Color.BLUE );
g.fillOval( 0, 0, 50, 50 );
// Add first image to draw panel:
drawPanel.addNode( image1, new Point( 100, 100 ));
// Create second image:
BufferedImage image2 = new BufferedImage( 50, 50, BufferedImage.TYPE_INT_ARGB );
Graphics2D g2 = image2.createGraphics();
g2.setColor( Color.RED );
g2.fillOval( 0, 0, 50, 50 );
// Add second image to draw panel:
drawPanel.addNode( image2, new Point( 200, 100 ));
} );
Thread.sleep( Long.MAX_VALUE );
}
结果: