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POPrevent characters from KeyListener being added to a string
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2013-06-08T01:45:11.137
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How to prevent characters from <code>KeyListener</code> being added to a string that won't render properly with <code>Graphics.drawString()</code>? What I am trying to prevent is characters from java.atw.event.KeyListener form being added to a string that won't render properly with java.atw.Graphics.drawString(). For instance, if I press shift my program will detect it to be an invalid character and not add it to a string that will later be rendered java.atw.Graphics.drawString(). Sure I can do a check for it but is there some easy way of doing it? Not in a way that involves 1000 character checks. My program is a small remake of javax.swing.JTextField. I have tried looking at the src code for that, but I couldn't find anything. Here is is (this can be added to a Frame as any swing component): <pre><code>// Lots of imports public class TextField extends JComponent implements KeyListener, Runnable, MouseInputListener, ClipboardOwner, FocusListener{ private static final long serialVersionUID = 1; private String text; private int head = 0; private int draggedFrom = 0; private boolean renderHead = false; private boolean insert = false; private boolean dragging = false; private int renderOffset; private int time = 0; private int doubleClickTimer = -1; private boolean editable = true; private int historyIndex = 0; private ArrayList<String> history = new ArrayList<String>(); private boolean focus = this.hasFocus(); public TextField() { this(null); } public TextField(String text){ this.text = text == null ? "" : text; this.addMouseListener(this); this.addMouseMotionListener(this); this.addKeyListener(this); this.addFocusListener(this); this.setFocusable(true); new Thread(this).start(); this.setFont(new Font(null, 0, 40)); this.setDoubleBuffered(false); this.setVisible(true); } @Override public void run() { try{ while (focus){ Thread.sleep(1); if (doubleClickTimer != -1){ doubleClickTimer++; } if (doubleClickTimer >= 250){ doubleClickTimer = -1; } time++; if (time == 500){ time = 0; renderHead = !renderHead; repaint(10 - renderOffset + (head == 0 ? 0 : this.getFontMetrics(this.getFont()).stringWidth(text.substring(0, head))), this.getHeight() / 2 - this.getFontMetrics(this.getFont()).getHeight() / 2, insert ? 5 : 2, this.getFontMetrics(this.getFont()).getHeight()); } } }catch (InterruptedException e){ e.printStackTrace(); } } @Override public void paint(Graphics gr) { Graphics2D g = (Graphics2D) gr; g.clearRect(0, 0, this.getWidth(), this.getHeight()); if (!editable){ g.setColor(Color.GRAY); g.fillRect(0, 0, this.getWidth(), this.getHeight()); } if (text != null){ g.setFont(this.getFont()); int height = this.getHeight() / 2 - g.getFontMetrics().getHeight() / 2; int width = (head == 0 ? 0 : g.getFontMetrics().stringWidth(text.substring(0, head))); if (width - renderOffset > this.getWidth() - 20){ renderOffset = width - this.getWidth() + 20; }else if (renderOffset > width){ renderOffset = width; }else if (renderOffset > 0 && g.getFontMetrics().stringWidth(text) - renderOffset < this.getWidth() - 20){ renderOffset = g.getFontMetrics().stringWidth(text) - this.getWidth() + 20; if (renderOffset < 0){ renderOffset = 0; } } if (draggedFrom != head && focus){ g.setColor(new Color (150, 150, 255)); if (head < draggedFrom){ g.fillRect(10 - renderOffset + width, height, g.getFontMetrics().stringWidth(text.substring(head, draggedFrom)) + (insert ? 5 : 2), g.getFontMetrics().getHeight()); }else{ g.fillRect(10 - renderOffset + g.getFontMetrics().stringWidth(text.substring(0, draggedFrom)), height, g.getFontMetrics().stringWidth(text.substring(draggedFrom, head)) + (insert ? 5 : 2), g.getFontMetrics().getHeight()); } } if (((editable && renderHead) || dragging) && focus){ g.setColor(Color.BLACK); g.fillRect(10 - renderOffset + width, height, insert ? 5 : 2, g.getFontMetrics().getHeight()); } g.setColor(Color.BLACK); g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g.drawString(text, 10 - renderOffset, height + g.getFontMetrics().getAscent()); } g.setColor(Color.BLACK); g.drawRect(0, 0, this.getWidth() - 1, this.getHeight() - 1); g.dispose(); } @Override public void keyPressed(KeyEvent e) { if (editable){ time = -1; renderHead = true; if (e.isControlDown() && (e.getKeyCode() == KeyEvent.VK_Z || e.getKeyCode() == KeyEvent.VK_Y)){ if (e.getKeyCode() == KeyEvent.VK_Z ? historyIndex > 0 : history.size() > historyIndex + 1){ if (e.getKeyCode() == KeyEvent.VK_Z){ historyIndex--; }else{ historyIndex++; } String s = history.get(historyIndex); head = s.length(); draggedFrom = 0; if (text.length() > 0 && s.length() > 0 && s.length() > text.length()){ while (draggedFrom < Math.min(text.length(), s.length()) && text.charAt(draggedFrom) == s.charAt(draggedFrom)){ draggedFrom++; } int textIndex = text.length() - 1; int sIndex = s.length() - 1; while (Math.min(textIndex, sIndex) >= 0 && text.charAt(textIndex) == s.charAt(sIndex)){ head--; textIndex--; sIndex--; } }else{ draggedFrom = head; } text = s; repaint(); } return; }else if (e.getKeyCode() == KeyEvent.VK_RIGHT){ if (head < text.length()){ head++; } this.draggedFrom = head; repaint(); return; }else if (e.getKeyCode() == KeyEvent.VK_LEFT){ if (head > 0){ head--; } this.draggedFrom = head; repaint(); return; }else if (e.getKeyCode() == KeyEvent.VK_INSERT){ insert = !insert; repaint(); return; }else if (e.isControlDown() && e.getKeyCode() == KeyEvent.VK_A){ if (text.length() > 0){ this.head = text.length(); this.draggedFrom = 0; repaint(); } return; } if (e.getKeyCode() != KeyEvent.VK_SHIFT && e.getKeyCode() != KeyEvent.VK_CONTROL && e.getKeyCode() != KeyEvent.VK_ALT && e.getKeyCode() != 12 && e.getKeyCode() != KeyEvent.VK_ESCAPE && !e.isActionKey()){ for (int i = history.size() - 1; i >= historyIndex; i--){ history.remove(i); } if (history.size() > 200){ history.remove(0); historyIndex--; } history.add(text); historyIndex++; if (history.size() > 1 && history.get(history.size() - 2).equals(history.get(history.size() - 1))){ history.remove(history.size() - 1); historyIndex--; } } if (e.getKeyCode() == KeyEvent.VK_ENTER){ for (ActionListener a : listenerList.getListeners(ActionListener.class)){ a.actionPerformed(new ActionEvent(this, 0, text)); } }else if (e.isControlDown() && e.getKeyCode() == KeyEvent.VK_C){ if (draggedFrom != head){ Clipboard board = Toolkit.getDefaultToolkit().getSystemClipboard(); board.setContents(new StringSelection(draggedFrom < head ? text.substring(draggedFrom, head) : text.substring(head, draggedFrom)), this); } }else if (e.isControlDown() && e.getKeyCode() == KeyEvent.VK_V){ Clipboard board = Toolkit.getDefaultToolkit().getSystemClipboard(); if (board.isDataFlavorAvailable(DataFlavor.stringFlavor)){ try{ String clipboard = (String) board.getData(DataFlavor.stringFlavor); if (draggedFrom != head){ if (head <= draggedFrom){ text = text.substring(0, head) + clipboard + text.substring(draggedFrom); draggedFrom = head; head += clipboard.length(); }else{ text = text.substring(0, draggedFrom) + clipboard + text.substring(head); head = draggedFrom + clipboard.length(); } }else{ if (head == text.length()){ text += clipboard; }else if (head == 0){ text = clipboard + text; }else{ text = text.substring(0, head) + clipboard + text.substring(insert ? head + 1 : head, text.length()); } draggedFrom = head; head += clipboard.length(); } }catch (Exception exc){ } } }else if (e.isControlDown() && e.getKeyCode() == KeyEvent.VK_X){ if (draggedFrom != head){ Clipboard board = Toolkit.getDefaultToolkit().getSystemClipboard(); board.setContents(new StringSelection(draggedFrom < head ? text.substring(draggedFrom, head) : text.substring(head, draggedFrom)), this); if (head <= draggedFrom){ text = text.substring(0, head) + text.substring(draggedFrom); }else{ text = text.substring(0, draggedFrom) + text.substring(head); head = draggedFrom; } draggedFrom = head; } }else if (e.getKeyCode() == KeyEvent.VK_DELETE){ if (text.length() > 0){ if (draggedFrom != head){ if (head <= draggedFrom){ text = text.substring(0, head) + text.substring(draggedFrom); }else{ text = text.substring(0, draggedFrom) + text.substring(head); head = draggedFrom; } }else if (head == 0){ text = text.substring(1); }else if (head != text.length()){ text = text.substring(0, head) + text.substring(head + 1); } this.draggedFrom = head; } }else if (e.getKeyCode() == KeyEvent.VK_BACK_SPACE){ if (draggedFrom != head){ if (head <= draggedFrom){ text = text.substring(0, head) + text.substring(draggedFrom); }else{ text = text.substring(0, draggedFrom) + text.substring(head); head = draggedFrom; } }else if (head > 0){ head--; if (head == text.length()){ text = text.substring(0, head); }else{ text = text.substring(0, head) + text.substring(head + 1, text.length()); } } this.draggedFrom = head; }else if (e.getKeyCode() != KeyEvent.VK_SHIFT && e.getKeyCode() != KeyEvent.VK_CONTROL && e.getKeyCode() != KeyEvent.VK_ALT && e.getKeyCode() != 12 && e.getKeyCode() != KeyEvent.VK_ESCAPE && !e.isActionKey()){ if (draggedFrom != head){ if (head <= draggedFrom){ text = text.substring(0, head) + e.getKeyChar() + text.substring(draggedFrom); head++; }else{ text = text.substring(0, draggedFrom) + e.getKeyChar() + text.substring(head); head = draggedFrom + 1; } }else{ if (head == text.length()){ text += e.getKeyChar(); }else if (head == 0){ text = e.getKeyChar() + (insert ? text.substring(1) : text); }else{ text = text.substring(0, head) + e.getKeyChar() + text.substring(insert ? head + 1 : head, text.length()); } head++; } this.draggedFrom = head; } this.repaint(); } } public void setEditable(boolean editable) { if (this.editable != editable){ this.editable = editable; this.repaint(); } } public String getText() { return text; } public void setText(String text) { if (!this.text.equals(text == null ? "" : text)){ this.text = text == null ? "" : text; this.draggedFrom = this.head = this.text.length(); history.clear(); historyIndex = 0; this.repaint(); } } @Override public void mouseMoved(MouseEvent e) { if (this.getCursor() != Cursor.getPredefinedCursor(Cursor.TEXT_CURSOR)){ this.setCursor(Cursor.getPredefinedCursor(Cursor.TEXT_CURSOR)); } } @Override public void mousePressed(MouseEvent e) { time = -1; renderHead = true; draggedFrom = head = this.getHead(e.getX()); if (doubleClickTimer != -1){ doubleClickTimer = -1; if (head == text.length()){ draggedFrom = 0; }else if (head > 0 && this.isSplitCharacter(text.charAt(head - 1))){ draggedFrom--; }else if (head == 0){ while (draggedFrom < text.length() && !this.isSplitCharacter(text.charAt(draggedFrom))){ draggedFrom++; } }else{ while (head < text.length() && !this.isSplitCharacter(text.charAt(head))){ head++; } while (draggedFrom > 0 && !this.isSplitCharacter(text.charAt(draggedFrom - 1))){ draggedFrom--; } } }else{ doubleClickTimer = 0; } this.repaint(); this.requestFocusInWindow(); } private boolean isSplitCharacter (char c){ final String splitCharacters = "!@#$%^&*()\\/?<>:;\"\'}{[]`~,.-=+| "; for (char a : splitCharacters.toCharArray()){ if (a == c) return true; } return false; } @Override public void mouseReleased(MouseEvent e) { dragging = false; } @Override public void setFont(Font font) { super.setFont(font); this.repaint(); } @Override public void mouseDragged(MouseEvent e) { doubleClickTimer = -1; dragging = true; int newPlace = this.getHead(e.getX()); if (head != newPlace){ head = newPlace; this.repaint(); } } private int getHead(int x){ x += renderOffset - 7; if (text.length() != 0){ for (int i = 1; i <= text.length(); i++){ if (x <= this.getFontMetrics(this.getFont()).stringWidth(text.substring(0, i)) - this.getFontMetrics(this.getFont()).stringWidth(text.substring(i - 1, i)) / 2){ return i - 1; } } } return text.length(); } public void addActionListener(ActionListener e) { this.listenerList.add(ActionListener.class, e); } public void removeActionListener(ActionListener e){ this.listenerList.remove(ActionListener.class, e); } public void keyTyped(KeyEvent e) {} public void keyReleased(KeyEvent e) {} public void mouseClicked(MouseEvent e) {} public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} public void lostOwnership(Clipboard clipboard, Transferable contents) {} @Override public void focusGained(FocusEvent e) { this.renderHead = true; this.time = 0; focus = true; new Thread(this).start(); repaint(); } @Override public void focusLost(FocusEvent e) { this.renderHead = false; this.time = 0; focus = false; repaint(); } } </code></pre>
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<java><swing><keylistener><jcomponent>
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Prevent characters from KeyListener being added to a string
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1. COUh, a GUI object implementing `Runnable`?
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 POPrevent characters from KeyListener being added to a string
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2. COIt's for any sort of timer related things. I could use java.util.Timer but that just ends up using a Runnable anyway.
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 POPrevent characters from KeyListener being added to a string
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