How to enlarge a specific area of ​​an image on a canvas in Swing

Question

I want to enlarge a specific area of ​​the image. which is selected by the user. display image on canvas using Swing. I have already done full-scale scaling of the image on the canvas, but I can not implement the specific scale of the area. please, help

Answer 1

Canvas awt not swing . Try JPanel instead. Example .

But if you have already done the full scale image, try to do the same on the sub-image .

 BufferedImage.getSubimage(x, y, w, h); 

EDIT

 import java.awt.*; import java.awt.event.*; import java.awt.image.BufferedImage; import javax.swing.*; public class Example { private Point startPoint = new Point(0, 0); private Point rectLocale = new Point(); private Dimension rectSize = new Dimension(); private int zoom = 80; private BufferedImage capture = null; private BufferedImage raw; public Example() throws Exception { raw = new Robot().createScreenCapture(new Rectangle( Toolkit.getDefaultToolkit().getScreenSize())); MouseBehavior behavior = new MouseBehavior(); JPanel b = new JPanel() { private static final long serialVersionUID = 1L; @Override public Dimension getMinimumSize() { return new Dimension(500, 500); } @Override public Dimension getPreferredSize() { return new Dimension(500, 500); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = ((Graphics2D) g); g2d.drawImage(raw, 0, 0, null); if (capture != null) { int width2 = (int) (rectSize.width + rectSize.width * (zoom / 500d)); int height2 = (int) (rectSize.height + rectSize.height * (zoom / 500d)); int x2 = rectLocale.x - ((width2 - rectSize.width) / 2); int y2 = rectLocale.y - ((height2 - rectSize.height) / 2); Image scaledInstance = capture.getScaledInstance( width2, height2, Image.SCALE_AREA_AVERAGING); g2d.drawImage(scaledInstance, x2, y2, null); g2d.drawRect(x2, y2, width2, height2); } else { g2d.draw(new Rectangle(rectLocale, rectSize)); } } }; b.addMouseMotionListener(behavior); b.addMouseListener(behavior); b.addMouseWheelListener(behavior); JFrame f = new JFrame(); f.setLocation(10, 10); f.setDefaultCloseOperation(3); f.add(b); f.pack(); f.setVisible(true); } private class MouseBehavior extends MouseAdapter { @Override public void mousePressed(MouseEvent e) { startPoint = e.getPoint(); rectLocale = new Point(); rectSize = new Dimension(); capture = null; if (e.getSource() instanceof JComponent) { ((JComponent) e.getSource()).repaint(); } } @Override public void mouseDragged(MouseEvent e) { Point currentPoint = e.getPoint(); rectSize.width = Math.abs(currentPoint.x - startPoint.x); rectSize.height = Math.abs(currentPoint.y - startPoint.y); if (e.isShiftDown()) { rectSize.width = rectSize.height = Math.min( rectSize.width, rectSize.height); int dx = startPoint.x - rectSize.width; int dy = startPoint.y - rectSize.height; rectLocale.x = startPoint.x < currentPoint.x ? startPoint.x : Math.max(dx, dy); rectLocale.y = startPoint.y < currentPoint.y ? startPoint.y : Math.min(dx, dy); } else { rectLocale.x = Math.min(currentPoint.x, startPoint.x); rectLocale.y = Math.min(currentPoint.y, startPoint.y); } if (e.getSource() instanceof JComponent) { ((JComponent) e.getSource()).repaint(); } } @Override public void mouseReleased(MouseEvent e) { if (rectSize.width <= 0 || rectSize.height <= 0) { capture = null; } else { capture = raw.getSubimage(Math.max(0, rectLocale.x), Math.max(0, rectLocale.y), rectSize.width, rectSize.height); } if (e.getSource() instanceof JComponent) { ((JComponent) e.getSource()).repaint(); } } @Override public void mouseWheelMoved(MouseWheelEvent e) { zoom = Math.min(2000, Math.max(0, zoom + e.getUnitsToScroll() * 10)); if (e.getSource() instanceof JComponent) { ((JComponent) e.getSource()).repaint(); } } } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { Example example = new Example(); } catch (Exception e) { e.printStackTrace(); } } }); } }