Lightpen on

.gitignore

@@ -1,4 +1,7 @@
 j3270.log.*
+*.txt
+*.py
+*.pcap
 build/*
 *.log
 .DS_Store

j3270/src/main/java/org/pubvm/j3270/J3270App.java

@@ -131,6 +131,10 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
             terminalPanel.repaint();
         }));
         actionsMenu.addSeparator();
+        actionsMenu.add(createMenuItem("Toggle Light Pen (Alt+L)", KeyEvent.VK_L, () -> {
+            terminalPanel.toggleLightPen();
+        }, true));
+        actionsMenu.addSeparator();
         actionsMenu.add(createMenuItem("File Transfer...", KeyEvent.VK_T, this::showFileTransferDialog));
         menuBar.add(actionsMenu);
 
@@ -149,18 +153,22 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
         return menu;
     }
 
-    private JMenuItem createMenuItem(String text, int acceleratorKey, Runnable action) {
+    private JMenuItem createMenuItem(String name, int mnemonic, Runnable action, boolean useAlt) {
-        JMenuItem item = new JMenuItem(text);
+        JMenuItem item = new JMenuItem(name);
         item.setBackground(new Color(40, 40, 40));
         item.setForeground(new Color(200, 200, 200));
-        if (acceleratorKey > 0) {
+        if (mnemonic > 0) {
-            item.setAccelerator(KeyStroke.getKeyStroke(acceleratorKey,
+            int modifier = useAlt ? KeyEvent.ALT_DOWN_MASK : Toolkit.getDefaultToolkit().getMenuShortcutKeyMaskEx();
-                    Toolkit.getDefaultToolkit().getMenuShortcutKeyMaskEx()));
+            item.setAccelerator(KeyStroke.getKeyStroke(mnemonic, modifier));
         }
         item.addActionListener(e -> action.run());
         return item;
     }
 
+    private JMenuItem createMenuItem(String name, int mnemonic, Runnable action) {
+        return createMenuItem(name, mnemonic, action, false);
+    }
+
     private void showFileTransferDialog() {
         if (client == null) {
             JOptionPane.showMessageDialog(this, "Connect to a host before using File Transfer.",
@@ -278,7 +286,7 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
         client.addScreenUpdateListener(this);
 
         terminalPanel.setClient(client);
-        statusBar.setClient(client);
+        statusBar.setClient(client, terminalPanel);
 
         String tlsIndicator = config.isUseTls() ? (config.isTlsVerifyCert() ? " [TLS]" : " [TLS/Unverified]") : "";
         setTitle("j3270 — " + config.getHost() + ":" + config.getPort() + tlsIndicator);
@@ -312,7 +320,7 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
             client.disconnect();
             client = null;
             terminalPanel.setClient(null);
-            statusBar.setClient(null);
+            statusBar.setClient(null, terminalPanel);
             terminalPanel.repaint();
             setTitle("j3270 — Java TN3270 Terminal Emulator");
         }

j3270/src/main/java/org/pubvm/j3270/ui/StatusBar.java

@@ -22,6 +22,7 @@ public class StatusBar extends JPanel {
     private final JLabel modelInfo;
 
     private Telnet3270Client client;
+    private TerminalPanel terminalPanel;
 
     // OIA colors
     private static final Color OIA_BG = new Color(20, 20, 20);
@@ -44,6 +45,19 @@ public class StatusBar extends JPanel {
         modelInfo = createLabel("", oiaFont, OIA_DIM);
         cursorPosition = createLabel("001/001", oiaFont, OIA_FG);
 
+        JButton lpButton = new JButton("LightPen: OFF");
+        lpButton.setFont(oiaFont);
+        lpButton.setForeground(OIA_FG);
+        lpButton.setBackground(OIA_BG);
+        lpButton.setBorder(BorderFactory.createEmptyBorder(0, 5, 0, 5));
+        lpButton.setFocusable(false);
+        lpButton.addActionListener(e -> {
+            if (terminalPanel != null) {
+                terminalPanel.toggleLightPen();
+                lpButton.setText("LightPen: " + (terminalPanel.isLightPenMode() ? "ON" : "OFF"));
+            }
+        });
+
         add(Box.createHorizontalStrut(6));
         add(connectionStatus);
         add(Box.createHorizontalStrut(10));
@@ -52,6 +66,8 @@ public class StatusBar extends JPanel {
         add(luName);
         add(Box.createHorizontalStrut(12));
         add(lockStatus);
+        add(Box.createHorizontalStrut(12));
+        add(lpButton);
         add(Box.createHorizontalGlue());
         add(modelInfo);
         add(Box.createHorizontalStrut(12));
@@ -66,8 +82,9 @@ public class StatusBar extends JPanel {
         return label;
     }
 
-    public void setClient(Telnet3270Client client) {
+    public void setClient(Telnet3270Client client, TerminalPanel terminalPanel) {
         this.client = client;
+        this.terminalPanel = terminalPanel;
     }
 
     public void updateStatus() {

j3270/src/main/java/org/pubvm/j3270/ui/TerminalPanel.java

@@ -62,6 +62,9 @@ public class TerminalPanel extends JPanel {
     private static final Color SELECTION_COLOR = new Color(75, 110, 175, 100);
 
     // ========== Resize guard ==========
+    private boolean lightPenMode = false;
+    private long lastGraphicsUpdateCount = -1;
+    private java.awt.image.BufferedImage cachedGraphicsImage = null;
     private boolean resizeGuard = false;
 
     /**
@@ -207,6 +210,12 @@ public class TerminalPanel extends JPanel {
                             int newAddr = selectionStartRow * sb.getCols() + selectionStartCol;
                             sb.setCursorAddress(newAddr);
                             clearSelection();
+                            if (lightPenMode) {
+                                if (client.getInputProcessor().lightPenSelect(newAddr)) {
+                                    refreshScreen();
+                                    return;
+                                }
+                            }
                             
                             if (client.getGocaDecoder() != null && client.getGraphicsPlane() != null) {
                                 int ox = getRenderOffsetX();
@@ -558,6 +567,7 @@ public class TerminalPanel extends JPanel {
         int shortcutMask = Toolkit.getDefaultToolkit().getMenuShortcutKeyMaskEx();
         im.put(KeyStroke.getKeyStroke(KeyEvent.VK_C, shortcutMask), "j3270-COPY");
         im.put(KeyStroke.getKeyStroke(KeyEvent.VK_V, shortcutMask), "j3270-PASTE");
+        im.put(KeyStroke.getKeyStroke(KeyEvent.VK_L, java.awt.event.InputEvent.ALT_DOWN_MASK), "j3270-LIGHTPEN");
 
         // Create actions for all bound keys
         am.put("j3270-ENTER", createAction(this::handleEnter));
@@ -586,6 +596,7 @@ public class TerminalPanel extends JPanel {
         // Copy/Paste actions
         am.put("j3270-COPY", createAction(this::copySelection));
         am.put("j3270-PASTE", createAction(this::pasteClipboard));
+        am.put("j3270-LIGHTPEN", createAction(this::toggleLightPen));
 
         for (int i = 1; i <= 24; i++) {
             final int pf = i;
@@ -900,9 +911,13 @@ public class TerminalPanel extends JPanel {
             int gHeight = client.getGraphicsPlane().getCanvasHeight();
             int[] rgb = client.getGraphicsPlane().getRgbBuffer();
             if (rgb != null && gWidth > 0 && gHeight > 0) {
-                java.awt.image.BufferedImage img = new java.awt.image.BufferedImage(gWidth, gHeight, java.awt.image.BufferedImage.TYPE_INT_ARGB);
+                long currentUpdateCount = client.getGraphicsPlane().getUpdateCount();
-                img.setRGB(0, 0, gWidth, gHeight, rgb, 0, gWidth);
+                if (cachedGraphicsImage == null || currentUpdateCount != lastGraphicsUpdateCount || cachedGraphicsImage.getWidth() != gWidth || cachedGraphicsImage.getHeight() != gHeight) {
-                g2.drawImage(img, ox, oy, gridW, gridH, null);
+                    cachedGraphicsImage = new java.awt.image.BufferedImage(gWidth, gHeight, java.awt.image.BufferedImage.TYPE_INT_ARGB);
+                    cachedGraphicsImage.setRGB(0, 0, gWidth, gHeight, rgb, 0, gWidth);
+                    lastGraphicsUpdateCount = currentUpdateCount;
+                }
+                g2.drawImage(cachedGraphicsImage, ox, oy, gridW, gridH, null);
             }
         }
 
@@ -1039,8 +1054,14 @@ public class TerminalPanel extends JPanel {
         if (client.getGocaDecoder() != null && client.getGocaDecoder().isGraphicsCursorActive() && client.getGraphicsPlane() != null) {
             int gocaX = client.getGocaDecoder().getGraphicCursorX();
             int gocaY = client.getGocaDecoder().getGraphicCursorY();
-            int px = ox + client.getGraphicsPlane().mapX(gocaX);
+            int canvasPx = client.getGraphicsPlane().mapX(gocaX);
-            int py = oy + client.getGraphicsPlane().mapY(gocaY);
+            int canvasPy = client.getGraphicsPlane().mapY(gocaY);
+            int gridW = cols * cellWidth;
+            int gridH = rows * cellHeight;
+            int gWidth = client.getGraphicsPlane().getCanvasWidth();
+            int gHeight = client.getGraphicsPlane().getCanvasHeight();
+            int px = ox + (gWidth > 0 ? (int)Math.round((double)canvasPx * gridW / gWidth) : canvasPx);
+            int py = oy + (gHeight > 0 ? (int)Math.round((double)canvasPy * gridH / gHeight) : canvasPy);
 
             g2.setColor(Color.WHITE);
             g2.setXORMode(Color.BLACK);
@@ -1103,4 +1124,15 @@ public class TerminalPanel extends JPanel {
         if (blinkTimer != null)
             blinkTimer.stop();
     }
+    public void toggleLightPen() {
+        this.lightPenMode = !this.lightPenMode;
+        if (client != null && client.getGocaDecoder() != null) {
+            client.getGocaDecoder().setGraphicsCursorActive(this.lightPenMode);
+            repaint();
+        }
+    }
+    
+    public boolean isLightPenMode() {
+        return this.lightPenMode;
+    }
 }

lib3270j/src/main/java/org/lib3270j/graphics/GocaDecoder.java

@@ -829,39 +829,51 @@ public class GocaDecoder {
 
     private void processArc(byte[] data, int off, int len, boolean fromCurPos, boolean isFull) {
         int pos = off;
-        int startX = curX;
+        int centerX = curX;
-        int startY = curY;
+        int centerY = curY;
 
         if (!fromCurPos && pos + 4 <= off + len) {
-            startX = readCoord(data, pos);
+            centerX = readCoord(data, pos);
-            startY = readCoord(data, pos + 2);
+            centerY = readCoord(data, pos + 2);
             pos += 4;
         }
 
-        double multiplier = 1.0;
+        double sweepFraction = 1.0;
-        if (pos + 2 <= off + len) {
+        if (!isFull && pos + 2 <= off + len) {
-            multiplier = (data[pos] & 0xFF) + ((data[pos + 1] & 0xFF) / 255.0);
+            byte intPart = data[pos];
-            if (multiplier == 0.0) multiplier = 1.0;
+            double fracPart = (data[pos + 1] & 0xFF) / 256.0;
+            sweepFraction = intPart + (intPart >= 0 ? fracPart : -fracPart);
         }
 
-        int dxP = Math.abs(arcParamP - arcParamR);
+        int pxCenter = plane.mapX(centerX);
-        int dyQ = Math.abs(arcParamQ - arcParamS);
+        int pyCenter = plane.mapY(centerY);
-        if (dxP == 0) dxP = 10;
+        int pxCur = plane.mapX(curX);
-        if (dyQ == 0) dyQ = 10;
+        int pyCur = plane.mapY(curY);
 
-        int rxVirtual = (int) (dxP * multiplier);
+        double radius = Math.sqrt(Math.pow(pxCur - pxCenter, 2) + Math.pow(pyCur - pyCenter, 2));
-        int ryVirtual = (int) (dyQ * multiplier);
+        int rx = (int) Math.round(radius);
+        int ry = rx;
+        if (rx <= 0) {
+            rx = 10;
+            ry = 10;
+        }
 
-        int rx = Math.abs(plane.mapX(rxVirtual) - plane.mapX(0));
+        double startAngleRad = Math.atan2(pyCenter - pyCur, pxCur - pxCenter);
-        int ry = Math.abs(plane.mapY(ryVirtual) - plane.mapY(0));
+        double startAngleDeg = Math.toDegrees(startAngleRad);
-        if (rx <= 0) rx = 10;
+        if (startAngleDeg < 0) startAngleDeg += 360.0;
-        if (ry <= 0) ry = 10;
         
-        plane.drawArc(plane.mapX(startX), plane.mapY(startY), rx, ry, 0.0, 360.0,
+        double sweepAngleDeg = isFull ? 360.0 : (sweepFraction * 360.0);
+
+        plane.drawArc(pxCenter, pyCenter, rx, ry, startAngleDeg, sweepAngleDeg,
                       curColor, lineType, lineWidth, isFull);
 
-        curX = startX;
+        // Arc ends at the end of the sweep
-        curY = startY;
+        double endAngleRad = Math.toRadians(startAngleDeg + sweepAngleDeg);
+        int pxEnd = (int) Math.round(pxCenter + rx * Math.cos(endAngleRad));
+        int pyEnd = (int) Math.round(pyCenter - ry * Math.sin(endAngleRad));
+        
+        curX = plane.unmapX(pxEnd);
+        curY = plane.unmapY(pyEnd);
     }
 
     private void processFillet(byte[] data, int off, int len, boolean fromCurPos) {
@@ -932,8 +944,9 @@ public class GocaDecoder {
         int textLen = end - pos;
         if (textLen <= 0) return;
 
-        int cw = charWidth > 0 ? (int) Math.round((double) charWidth * plane.getCanvasWidth() / (plane.getScreenCols() * 9.0)) : 12;
+        // IBM 3279 vector graphics base cell is 9x12
-        int ch = charHeight > 0 ? (int) Math.round((double) charHeight * plane.getCanvasHeight() / (plane.getScreenRows() * 16.0)) : 20;
+        int cw = charWidth > 0 ? (int) Math.round((double) charWidth * plane.getCanvasWidth() / (plane.getScreenCols() * 9.0)) : 10;
+        int ch = charHeight > 0 ? (int) Math.round((double) charHeight * plane.getCanvasHeight() / (plane.getScreenRows() * 12.0)) : 14;
 
         if (charSet != 0 && programSymbolManager != null) {
             for (int i = 0; i < textLen; i++) {

lib3270j/src/main/java/org/lib3270j/graphics/GraphicsPlane.java

@@ -40,6 +40,7 @@ public class GraphicsPlane {
     private int canvasHeight = 600;
     private int[] rgbBuffer;
     private boolean hasContent = false;
+    private long updateCount = 0;
 
     private int screenCols = 80;
     private int screenRows = 24;
@@ -79,6 +80,11 @@ public class GraphicsPlane {
             Arrays.fill(rgbBuffer, 0);
         }
         hasContent = false;
+        updateCount++;
+    }
+
+    public synchronized long getUpdateCount() {
+        return updateCount;
     }
 
     public synchronized boolean hasContent() {
@@ -162,6 +168,7 @@ public class GraphicsPlane {
         if (x >= 0 && x < canvasWidth && y >= 0 && y < canvasHeight) {
             rgbBuffer[y * canvasWidth + x] = colorArgb;
             hasContent = true;
+        updateCount++;
         }
     }
 
@@ -203,6 +210,7 @@ public class GraphicsPlane {
             }
         }
         hasContent = true;
+        updateCount++;
     }
 
     private boolean shouldPlotLinePixel(int step, int lineType) {
@@ -266,6 +274,7 @@ public class GraphicsPlane {
             prevY = nextY;
         }
         hasContent = true;
+        updateCount++;
     }
 
     /**
@@ -304,6 +313,7 @@ public class GraphicsPlane {
             }
         }
         hasContent = true;
+        updateCount++;
     }
 
     /**
@@ -380,6 +390,7 @@ public class GraphicsPlane {
             }
         }
         hasContent = true;
+        updateCount++;
     }
 
     /**
@@ -445,6 +456,7 @@ public class GraphicsPlane {
                 break;
         }
         hasContent = true;
+        updateCount++;
     }
 
     private static final int[] VSS_OFFSETS = new int[256];
@@ -493,6 +505,7 @@ public class GraphicsPlane {
             }
         }
         hasContent = true;
+        updateCount++;
     }
 
     private void drawVssChar(int x, int y, char c, int color, int cw, int ch) {
@@ -558,5 +571,6 @@ public class GraphicsPlane {
             }
         }
         hasContent = true;
+        updateCount++;
     }
 }

lib3270j/src/main/java/org/lib3270j/input/InputProcessor.java

@@ -352,6 +352,59 @@ public class InputProcessor {
 
     // ========== Cursor movement ==========
 
+    /**
+     * Simulate a Text Light Pen selection.
+     */
+    public boolean lightPenSelect(int address) {
+        if (screen == null || !screen.isFormatted()) {
+            return false;
+        }
+        int size = screen.getRows() * screen.getCols();
+        int faPos = screen.findFieldAttribute(address);
+        if (faPos < 0) {
+            return false;
+        }
+
+        ExtendedAttribute faCell = screen.getCell(faPos);
+        int fa = faCell.fa & 0xFF;
+        if (!org.lib3270j.protocol.DS3270Constants.faIsSelectable(fa)) {
+            return false;
+        }
+
+        int designatorPos = (faPos + 1) % size;
+        ExtendedAttribute desCell = screen.getCell(designatorPos);
+        int ebcdic = desCell.ec & 0xFF;
+        char ascii = (char) desCell.ucs4;
+
+        screen.setCursorAddress(designatorPos);
+
+        if (ebcdic == 0x00 || ebcdic == 0x40 || ascii == ' ' || ascii == 0 || (ebcdic != 0x50 && ascii != '&' && ebcdic != 0x6F && ascii != '?' && ebcdic != 0x6E && ascii != '>')) {
+            faCell.fa |= org.lib3270j.protocol.DS3270Constants.FA_MODIFY;
+            sendAid(org.lib3270j.protocol.DS3270Constants.AID_SELECT);
+            return true;
+        } else if (ebcdic == 0x50 || ascii == '&') {
+            faCell.fa |= org.lib3270j.protocol.DS3270Constants.FA_MODIFY;
+            sendAid(org.lib3270j.protocol.DS3270Constants.AID_ENTER);
+            return true;
+        } else if (ebcdic == 0x6F || ascii == '?') {
+            desCell.ec = (byte) 0x6E;
+            desCell.ucs4 = '>';
+            faCell.fa |= org.lib3270j.protocol.DS3270Constants.FA_MODIFY;
+            screen.updateDisplaySnapshot();
+            return true;
+        } else if (ebcdic == 0x6E || ascii == '>') {
+            desCell.ec = (byte) 0x6F;
+            desCell.ucs4 = '?';
+            faCell.fa &= ~org.lib3270j.protocol.DS3270Constants.FA_MODIFY;
+            screen.updateDisplaySnapshot();
+            return true;
+        } else {
+            faCell.fa |= org.lib3270j.protocol.DS3270Constants.FA_MODIFY;
+            sendAid(org.lib3270j.protocol.DS3270Constants.AID_SELECT);
+            return true;
+        }
+    }
+
     public void cursorUp() {
         int addr = screen.getCursorAddress();
         addr -= screen.getCols();