Lightpen on

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

@@ -35,9 +35,9 @@ public class GocaDecoder {
     private int charHeight = 16;
     private int charSet = 0;
     private int arcParamP = 1;
-    private int arcParamQ = 1;
+    private int arcParamQ = 0;
     private int arcParamR = 0;
-    private int arcParamS = 0;
+    private int arcParamS = 1;
 
     private ProgramSymbolManager programSymbolManager;
 
@@ -832,48 +832,70 @@ public class GocaDecoder {
         int centerX = curX;
         int centerY = curY;
 
+        // For absolute variants, read the center point from data
         if (!fromCurPos && pos + 4 <= off + len) {
             centerX = readCoord(data, pos);
             centerY = readCoord(data, pos + 2);
             pos += 4;
         }
 
-        double sweepFraction = 1.0;
-        if (!isFull && pos + 2 <= off + len) {
-            byte intPart = data[pos];
-            double fracPart = (data[pos + 1] & 0xFF) / 256.0;
-            sweepFraction = intPart + (intPart >= 0 ? fracPart : -fracPart);
+        // Read the multiplier (integer.fraction format)
+        double multiplier = 1.0;
+        if (pos + 2 <= off + len) {
+            int intPart = data[pos]; // signed byte
+            int fracPart = data[pos + 1] & 0xFF;
+            multiplier = intPart + fracPart / 256.0;
+            if (multiplier == 0.0) multiplier = 1.0;
+            pos += 2;
         }
 
-        int pxCenter = plane.mapX(centerX);
-        int pyCenter = plane.mapY(centerY);
-        int pxCur = plane.mapX(curX);
-        int pyCur = plane.mapY(curY);
+        // Compute semi-axes from arc parameters scaled by multiplier
+        // P,Q and R,S are conjugate semi-diameter vectors
+        double pScaled = arcParamP * multiplier;
+        double qScaled = arcParamQ * multiplier;
+        double rScaled = arcParamR * multiplier;
+        double sScaled = arcParamS * multiplier;
 
-        double radius = Math.sqrt(Math.pow(pxCur - pxCenter, 2) + Math.pow(pyCur - pyCenter, 2));
-        int rx = (int) Math.round(radius);
-        int ry = rx;
-        if (rx <= 0) {
-            rx = 10;
-            ry = 10;
+        // Semi-axis lengths in GOCA coordinate space
+        double semiAxis1 = Math.sqrt(pScaled * pScaled + qScaled * qScaled);
+        double semiAxis2 = Math.sqrt(rScaled * rScaled + sScaled * sScaled);
+        if (semiAxis1 < 1.0) semiAxis1 = 1.0;
+        if (semiAxis2 < 1.0) semiAxis2 = 1.0;
+
+        // Map to pixel space
+        int rx = Math.abs(plane.mapX((int) Math.round(semiAxis1)) - plane.mapX(0));
+        int ry = Math.abs(plane.mapY(0) - plane.mapY((int) Math.round(semiAxis2)));
+        if (rx <= 0) rx = 1;
+        if (ry <= 0) ry = 1;
+
+        // For partial arcs, read sweep start and sweep angle
+        double startAngleDeg = 0.0;
+        double sweepAngleDeg = 360.0;
+        if (!isFull && pos + 4 <= off + len) {
+            // Sweep start: integer.fraction of full revolution
+            int startInt = data[pos];
+            int startFrac = data[pos + 1] & 0xFF;
+            startAngleDeg = (startInt + startFrac / 256.0) * 360.0;
+            pos += 2;
+            // Sweep angle: integer.fraction of full revolution
+            int sweepInt = data[pos];
+            int sweepFrac = data[pos + 1] & 0xFF;
+            sweepAngleDeg = (sweepInt + sweepFrac / 256.0) * 360.0;
+        } else if (!isFull) {
+            // No sweep data — default to full circle
+            sweepAngleDeg = 360.0;
         }
 
-        double startAngleRad = Math.atan2(pyCenter - pyCur, pxCur - pxCenter);
-        double startAngleDeg = Math.toDegrees(startAngleRad);
-        if (startAngleDeg < 0) startAngleDeg += 360.0;
-        
-        double sweepAngleDeg = isFull ? 360.0 : (sweepFraction * 360.0);
+        System.out.println("processArc: center=(" + centerX + "," + centerY + ") mult=" + multiplier 
+            + " P=" + arcParamP + " Q=" + arcParamQ + " R=" + arcParamR + " S=" + arcParamS 
+            + " rx=" + rx + " ry=" + ry + " start=" + startAngleDeg + " sweep=" + sweepAngleDeg 
+            + " isFull=" + isFull);
 
-        plane.drawArc(pxCenter, pyCenter, rx, ry, startAngleDeg, sweepAngleDeg,
+        plane.drawArc(plane.mapX(centerX), plane.mapY(centerY), rx, ry, startAngleDeg, sweepAngleDeg,
                       curColor, lineType, lineWidth, isFull);
 
-        // Arc ends at the end of the sweep
-        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);
+        curX = centerX;
+        curY = centerY;
     }
 
     private void processFillet(byte[] data, int off, int len, boolean fromCurPos) {

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

@@ -357,16 +357,20 @@ public class InputProcessor {
      */
     public boolean lightPenSelect(int address) {
         if (screen == null || !screen.isFormatted()) {
+            System.out.println("LP: screen null or unformatted");
             return false;
         }
         int size = screen.getRows() * screen.getCols();
         int faPos = screen.findFieldAttribute(address);
         if (faPos < 0) {
+            System.out.println("LP: no FA found for addr=" + address);
             return false;
         }
 
         ExtendedAttribute faCell = screen.getCell(faPos);
         int fa = faCell.fa & 0xFF;
+        System.out.println("LP: addr=" + address + " faPos=" + faPos + " fa=0x" + String.format("%02X", fa) 
+            + " selectable=" + org.lib3270j.protocol.DS3270Constants.faIsSelectable(fa));
         if (!org.lib3270j.protocol.DS3270Constants.faIsSelectable(fa)) {
             return false;
         }