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Строка 1: |
| - | In this part of the Java Swing tutorial, we will create a resizable component.
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| | | | |
| - | == Resizable component ==
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| - |
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| - | Resizable components are most often used when creating charts, diagrams and similar. The most common resizable component is a chart in a spreadsheet application. For example, when we create a chart in a OpenOffice application. The chart can be moved over the grid widget of the application and resized.
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| - |
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| - | In order to create a component that can be freely dragged over a panel, we need a panel with absolute positioning enabled.
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| - | We must not use a layout manager.
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| - | In our example, we will create a component (a JPanel) that we can freely move over a parent window and resize.
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| - |
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| - | In order to distinguish which component has a focus, we draw 8 small rectangles on the border of our resizable component.
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| - | This way we know, that the component has focus. The rectangles serve as a dragging points, where we can draw the component and start resizing. I have learnt to use resizable components from <a href="http://www.jroller.com/santhosh/category/Swing">this</a> blog.
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| - |
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| - | <source lang="java">
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| - | package resizablecomponent;
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| - |
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| - | import java.awt.Color;
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| - | import java.awt.Dimension;
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| - | import java.awt.event.MouseAdapter;
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| - | import java.awt.event.MouseEvent;
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| - |
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| - | import javax.swing.JFrame;
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| - | import javax.swing.JPanel;
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| - |
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| - |
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| - | /* ResizableComponent.java */
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| - |
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| - | public class ResizableComponent extends JFrame {
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| - |
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| - | private JPanel panel = new JPanel(null);
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| - | private Resizable resizer;
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| - | public ResizableComponent() {
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| - |
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| - | add(panel);
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| - |
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| - | JPanel area = new JPanel();
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| - | area.setBackground(Color.white);
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| - | resizer = new Resizable(area);
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| - | resizer.setBounds(50, 50, 200, 150);
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| - | panel.add(resizer);
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| - |
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| - |
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| - | setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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| - | setSize(new Dimension(350, 300));
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| - | setTitle("Resizable Component");
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| - | setLocationRelativeTo(null);
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| - |
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| - | addMouseListener(new MouseAdapter() {
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| - | public void mousePressed(MouseEvent me) {
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| - |
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| - | requestFocus();
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| - | resizer.repaint();
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| - | }
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| - | });
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| - | }
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| - |
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| - | public static void main(String[] args) {
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| - | ResizableComponent rc = new ResizableComponent();
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| - | rc.setVisible(true);
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| - | }
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| - | }
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| - | </source>
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| - |
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| - | The <b>ResizableComponent</b> sets up the panel and the component.
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| - |
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| - | <source lang="java">
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| - | private JPanel panel = new JPanel(null);
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| - | </source>
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| - |
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| - | We have already mentioned, that we cannot use any layout manager. We must use absolute positioning for resizable component.
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| - | By providing null to the constructor, we create a panel with absolute positioning.
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| - |
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| - | <source lang="java">
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| - | addMouseListener(new MouseAdapter() {
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| - | public void mousePressed(MouseEvent me) {
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| - |
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| - | requestFocus();
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| - | resizer.repaint();
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| - | }
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| - | });
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| - | </source>
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| - |
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| - | If we press on the parent panel, e.g outside the resizable component, we grab focus and repaint the component. The rectangles over the border will disappear.
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| - |
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| - | <source lang="java">
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| - | package resizablecomponent;
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| - |
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| - | import java.awt.Color;
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| - | import java.awt.Component;
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| - | import java.awt.Cursor;
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| - | import java.awt.Graphics;
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| - | import java.awt.Insets;
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| - | import java.awt.Rectangle;
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| - | import java.awt.event.MouseEvent;
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| - |
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| - | import javax.swing.SwingConstants;
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| - | import javax.swing.border.Border;
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| - |
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| - | // ResizableBorder.java
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| - |
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| - | public class ResizableBorder implements Border {
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| - | private int dist = 8;
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| - |
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| - | int locations[] =
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| - | {
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| - | SwingConstants.NORTH, SwingConstants.SOUTH, SwingConstants.WEST,
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| - | SwingConstants.EAST, SwingConstants.NORTH_WEST,
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| - | SwingConstants.NORTH_EAST, SwingConstants.SOUTH_WEST,
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| - | SwingConstants.SOUTH_EAST
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| - | };
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| - |
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| - | int cursors[] =
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| - | {
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| - | Cursor.N_RESIZE_CURSOR, Cursor.S_RESIZE_CURSOR, Cursor.W_RESIZE_CURSOR,
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| - | Cursor.E_RESIZE_CURSOR, Cursor.NW_RESIZE_CURSOR, Cursor.NE_RESIZE_CURSOR,
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| - | Cursor.SW_RESIZE_CURSOR, Cursor.SE_RESIZE_CURSOR
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| - | };
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| - |
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| - | public ResizableBorder(int dist) {
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| - | this.dist = dist;
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| - | }
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| - |
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| - | public Insets getBorderInsets(Component component) {
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| - | return new Insets(dist, dist, dist, dist);
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| - | }
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| - |
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| - | public boolean isBorderOpaque() {
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| - | return false;
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| - | }
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| - |
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| - | public void paintBorder(Component component, Graphics g, int x, int y,
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| - | int w, int h) {
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| - | g.setColor(Color.black);
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| - | g.drawRect(x + dist / 2, y + dist / 2, w - dist, h - dist);
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| - |
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| - | if (component.hasFocus()) {
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| - |
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| - | for (int i = 0; i < locations.length; i++) {
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| - | Rectangle rect = getRectangle(x, y, w, h, locations[i]);
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| - | g.setColor(Color.WHITE);
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| - | g.fillRect(rect.x, rect.y, rect.width - 1, rect.height - 1);
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| - | g.setColor(Color.BLACK);
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| - | g.drawRect(rect.x, rect.y, rect.width - 1, rect.height - 1);
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| - | }
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| - | }
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| - | }
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| - |
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| - | private Rectangle getRectangle(int x, int y, int w, int h, int location) {
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| - | switch (location) {
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| - | case SwingConstants.NORTH:
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| - | return new Rectangle(x + w / 2 - dist / 2, y, dist, dist);
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| - | case SwingConstants.SOUTH:
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| - | return new Rectangle(x + w / 2 - dist / 2, y + h - dist, dist,
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| - | dist);
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| - | case SwingConstants.WEST:
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| - | return new Rectangle(x, y + h / 2 - dist / 2, dist, dist);
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| - | case SwingConstants.EAST:
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| - | return new Rectangle(x + w - dist, y + h / 2 - dist / 2, dist,
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| - | dist);
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| - | case SwingConstants.NORTH_WEST:
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| - | return new Rectangle(x, y, dist, dist);
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| - | case SwingConstants.NORTH_EAST:
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| - | return new Rectangle(x + w - dist, y, dist, dist);
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| - | case SwingConstants.SOUTH_WEST:
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| - | return new Rectangle(x, y + h - dist, dist, dist);
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| - | case SwingConstants.SOUTH_EAST:
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| - | return new Rectangle(x + w - dist, y + h - dist, dist, dist);
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| - | }
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| - | return null;
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| - | }
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| - | public int getCursor(MouseEvent me) {
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| - | Component c = me.getComponent();
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| - | int w = c.getWidth();
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| - | int h = c.getHeight();
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| - |
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| - | for (int i = 0; i < locations.length; i++) {
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| - | Rectangle rect = getRectangle(0, 0, w, h, locations[i]);
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| - | if (rect.contains(me.getPoint()))
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| - | return cursors[i];
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| - | }
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| - |
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| - | return Cursor.MOVE_CURSOR;
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| - | }
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| - | }
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| - |
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| - | </source>
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| - |
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| - | The <b>ResizableBorder</b> is responsible for drawing the border of the component and determining the type of the cursor to use.
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| - |
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| - | <source lang="java">
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| - | int locations[] =
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| - | {
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| - | SwingConstants.NORTH, SwingConstants.SOUTH, SwingConstants.WEST,
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| - | SwingConstants.EAST, SwingConstants.NORTH_WEST,
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| - | SwingConstants.NORTH_EAST, SwingConstants.SOUTH_WEST,
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| - | SwingConstants.SOUTH_EAST
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| - | };
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| - | </source>
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| - |
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| - | These are locations, where we will draw rectangles. These locations are grabbing points, where we can grab the
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| - | component and resize it.
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| - |
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| - | <source lang="java">
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| - | g.setColor(Color.black);
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| - | g.drawRect(x + dist / 2, y + dist / 2, w - dist, h - dist);
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| - | </source>
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| - |
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| - | In the <b>paintBorder()</b> method, we draw the border of the resizable component.
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| - | The upper code draws the outer border of the component.
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| - |
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| - | <source lang="java">
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| - | if (component.hasFocus()) {
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| - |
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| - | for (int i = 0; i < locations.length; i++) {
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| - | Rectangle rect = getRectangle(x, y, w, h, locations[i]);
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| - | g.setColor(Color.WHITE);
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| - | g.fillRect(rect.x, rect.y, rect.width - 1, rect.height - 1);
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| - | g.setColor(Color.BLACK);
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| - | g.drawRect(rect.x, rect.y, rect.width - 1, rect.height - 1);
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| - | }
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| - | }
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| - |
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| - | </source>
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| - |
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| - | The eight rectangles are drawn only in case that the resizable component has currently focus.
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| - |
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| - | Finally, the <b>getCursor()</b> methods gets the cursor type for the grab point in question.
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| - |
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| - | <source lang="java">
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| - | package resizablecomponent;
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| - |
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| - | import java.awt.BorderLayout;
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| - | import java.awt.Component;
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| - | import java.awt.Cursor;
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| - | import java.awt.Point;
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| - | import java.awt.Rectangle;
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| - | import java.awt.event.MouseEvent;
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| - |
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| - | import javax.swing.JComponent;
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| - | import javax.swing.event.MouseInputAdapter;
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| - | import javax.swing.event.MouseInputListener;
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| - |
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| - | // Resizable.java
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| - |
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| - | public class Resizable extends JComponent {
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| - |
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| - | public Resizable(Component comp) {
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| - | this(comp, new ResizableBorder(8));
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| - | }
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| - |
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| - | public Resizable(Component comp, ResizableBorder border) {
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| - | setLayout(new BorderLayout());
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| - | add(comp);
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| - | addMouseListener(resizeListener);
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| - | addMouseMotionListener(resizeListener);
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| - | setBorder(border);
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| - | }
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| - |
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| - | private void resize() {
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| - | if (getParent() != null) {
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| - | ((JComponent)getParent()).revalidate();
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| - | }
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| - | }
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| - |
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| - | MouseInputListener resizeListener = new MouseInputAdapter() {
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| - | public void mouseMoved(MouseEvent me) {
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| - | if (hasFocus()) {
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| - | ResizableBorder border = (ResizableBorder)getBorder();
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| - | setCursor(Cursor.getPredefinedCursor(border.getCursor(me)));
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| - | }
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| - | }
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| - |
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| - | public void mouseExited(MouseEvent mouseEvent) {
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| - | setCursor(Cursor.getDefaultCursor());
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| - | }
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| - |
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| - | private int cursor;
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| - | private Point startPos = null;
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| - | public void mousePressed(MouseEvent me) {
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| - | ResizableBorder border = (ResizableBorder)getBorder();
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| - | cursor = border.getCursor(me);
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| - | startPos = me.getPoint();
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| - | requestFocus();
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| - | repaint();
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| - | }
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| - |
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| - | public void mouseDragged(MouseEvent me) {
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| - |
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| - | if (startPos != null) {
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| - |
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| - | int x = getX();
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| - | int y = getY();
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| - | int w = getWidth();
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| - | int h = getHeight();
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| - | int dx = me.getX() - startPos.x;
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| - | int dy = me.getY() - startPos.y;
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| - |
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| - | switch (cursor) {
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| - | case Cursor.N_RESIZE_CURSOR:
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| - | if (!(h - dy < 50)) {
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| - | setBounds(x, y + dy, w, h - dy);
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.S_RESIZE_CURSOR:
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| - | if (!(h + dy < 50)) {
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| - | setBounds(x, y, w, h + dy);
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| - | startPos = me.getPoint();
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.W_RESIZE_CURSOR:
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| - | if (!(w - dx < 50)) {
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| - | setBounds(x + dx, y, w - dx, h);
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.E_RESIZE_CURSOR:
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| - | if (!(w + dx < 50)) {
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| - | setBounds(x, y, w + dx, h);
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| - | startPos = me.getPoint();
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.NW_RESIZE_CURSOR:
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| - | if (!(w - dx < 50) && !(h - dy < 50)) {
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| - | setBounds(x + dx, y + dy, w - dx, h - dy);
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.NE_RESIZE_CURSOR:
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| - | if (!(w + dx < 50) && !(h - dy < 50)) {
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| - | setBounds(x, y + dy, w + dx, h - dy);
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| - | startPos = new Point(me.getX(), startPos.y);
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.SW_RESIZE_CURSOR:
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| - | if (!(w - dx < 50) && !(h + dy < 50)) {
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| - | setBounds(x + dx, y, w - dx, h + dy);
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| - | startPos = new Point(startPos.x, me.getY());
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.SE_RESIZE_CURSOR:
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| - | if (!(w + dx < 50) && !(h + dy < 50)) {
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| - | setBounds(x, y, w + dx, h + dy);
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| - | startPos = me.getPoint();
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | case Cursor.MOVE_CURSOR:
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| - | Rectangle bounds = getBounds();
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| - | bounds.translate(dx, dy);
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| - | setBounds(bounds);
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| - | resize();
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| - | }
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| - |
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| - |
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| - | setCursor(Cursor.getPredefinedCursor(cursor));
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| - | }
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| - | }
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| - |
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| - | public void mouseReleased(MouseEvent mouseEvent) {
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| - | startPos = null;
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| - | }
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| - | };
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| - | }
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| - |
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| - | </source>
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| - |
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| - | The <b>Resizable</b> class represents the component, that is being resized and moved on the window.
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| - |
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| - | <source lang="java">
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| - | private void resize() {
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| - | if (getParent() != null) {
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| - | ((JComponent)getParent()).revalidate();
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| - | }
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| - | }
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| - | </source>
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| - |
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| - | The <b>revalidate()</b> method
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| - | will cause the component to be redrawn.
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| - |
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| - |
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| - | <source lang="java">
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| - | MouseInputListener resizeListener = new MouseInputAdapter() {
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| - | public void mouseMoved(MouseEvent me) {
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| - | if (hasFocus()) {
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| - | ResizableBorder border = (ResizableBorder)getBorder();
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| - | setCursor(Cursor.getPredefinedCursor(border.getCursor(me)));
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| - | }
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| - | }
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| - | </source>
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| - |
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| - | We change the cursor type, when we hover the cursor over the grip points. The cursor type changes only if the component has focus.
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| - |
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| - | <source lang="java">
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| - | public void mousePressed(MouseEvent me) {
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| - | ResizableBorder border = (ResizableBorder)getBorder();
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| - | cursor = border.getCursor(me);
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| - | startPos = me.getPoint();
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| - | requestFocus();
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| - | repaint();
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| - | }
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| - | </source>
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| - |
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| - | If we click on the resizable component, we change the cursor, get the starting point of dragging, give focus to the component and redraw it.
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| - |
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| - | <source lang="java">
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| - | int x = getX();
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| - | int y = getY();
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| - | int w = getWidth();
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| - | int h = getHeight();
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| - |
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| - | int dx = me.getX() - startPos.x;
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| - | int dy = me.getY() - startPos.y;
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| - | </source>
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| - |
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| - | In the <b>mouseDragged()</b> method, we determine the x, y coordinates of the cursor, width and height of the
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| - | component. We calculate the distances, that we make during the mouse drag event.
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| - |
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| - | <source lang="java">
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| - | case Cursor.N_RESIZE_CURSOR:
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| - | if (!(h - dy < 50)) {
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| - | setBounds(x, y + dy, w, h - dy);
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| - | resize();
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| - | }
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| - | break;
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| - |
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| - | </source>
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| - |
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| - | For all resizing we ensure, that the component is not smaller than 50 px. Otherwise, we could make it so small, that we would eventually hide the component. The <b>setBounds()</b> method relocates and resizes the component.
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| - | [[image: java_swing_resizablecomponent.png | center]]
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| - | [[Категория:Java]]
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