wip: different heights for jump arrows

Note that this is very incomplete, for two different reasons:
- it's O(n^2) or potentially worse
- it makes the GC work hard (it invokes `new` in
  `LCanvas.DragLayout.layout()`)

For the second reason this does not clearly fit the criteria of
CONTRIBUTING.md, but I have yet to figure out ways to work around this
(or make the algorithm more efficient).

core/src/mindustry/logic/LCanvas.java

@@ -21,8 +21,10 @@ import mindustry.ui.*;
 
 public class LCanvas extends Table{
     public static final int maxJumpsDrawn = 100;
+    private static final int invalidJump = Integer.MAX_VALUE; // terrible hack
     //ew static variables
     static LCanvas canvas;
+    private static boolean dynamicJumpHeights = false;
 
     public DragLayout statements;
     public ScrollPane pane;
@@ -108,6 +110,8 @@ public class LCanvas extends Table{
         statements = new DragLayout();
         jumps = statements.jumps;
 
+        dynamicJumpHeights = Core.settings.getBool("dynamicjumpheights", false);
+
         pane = pane(t -> {
             t.center();
             t.add(statements).pad(2f).center().width(targetWidth);
@@ -196,6 +200,7 @@ public class LCanvas extends Table{
         int insertPosition = 0;
         boolean invalidated;
         public Group jumps = new WidgetGroup();
+        private Seq<JumpCurve> processedJumps = new Seq<JumpCurve>();
 
         {
             setTransform(true);
@@ -251,13 +256,73 @@ public class LCanvas extends Table{
                 }
             }
 
-            if(parent != null) parent.invalidateHierarchy();
+            if(dynamicJumpHeights) setJumpHeights();
+
+            if(parent != null) parent.invalidateHierarchy();//don't invalid self
 
             if(parent != null && parent instanceof Table){
                 setCullingArea(parent.getCullingArea());
             }
         }
 
+        private void setJumpHeights(){
+            SnapshotSeq<Element> jumpsChildren = jumps.getChildren();
+            processedJumps.clear();
+            jumpsChildren.each(e -> {
+                if(e instanceof JumpCurve e2){
+                    e2.prepareHeight();
+                    if(e2.jumpUIBegin != invalidJump){
+                        processedJumps.add(e2);
+                    }
+                }
+            });
+            processedJumps.sort((a,b) -> a.jumpUIBegin - b.jumpUIBegin);
+
+            Seq<JumpCurve> occupiers = new Seq<JumpCurve>();
+            Bits occupied = new Bits();
+            for(int i = 0; i < processedJumps.size; i++){
+                JumpCurve cur = processedJumps.get(i);
+                occupiers.retainAll(e -> {
+                    if(e.jumpUIEnd > cur.jumpUIBegin) return true;
+                    occupied.clear(e.predHeight);
+                    return false;
+                });
+                int h = getJumpHeight(i, occupiers, occupied);
+                occupiers.add(cur);
+                occupied.set(h);
+            }
+        }
+
+        private int getJumpHeight(int index, Seq<JumpCurve> occupiers, Bits occupied){
+            JumpCurve jmp = processedJumps.get(index);
+            if(jmp.markedDone) return jmp.predHeight;
+
+            // TODO: optimize for LESS cloning
+            Seq<JumpCurve> tmpOccupiers = new Seq<JumpCurve>(occupiers);
+            Bits tmpOccupied = new Bits();
+            tmpOccupied.set(occupied);
+
+            int max = -1;
+            for(int i = index + 1; i < processedJumps.size; i++){
+                JumpCurve cur = processedJumps.get(i);
+                if(cur.jumpUIEnd > jmp.jumpUIEnd) continue;
+                tmpOccupiers.retainAll(e -> {
+                    if(e.jumpUIEnd > cur.jumpUIBegin) return true;
+                    tmpOccupied.clear(e.predHeight);
+                    return false;
+                });
+                int h = getJumpHeight(i, tmpOccupiers, tmpOccupied);
+                tmpOccupiers.add(cur);
+                tmpOccupied.set(h);
+                max = Math.max(max, h);
+            }
+
+            jmp.predHeight = occupied.nextClearBit(max + 1);
+            jmp.markedDone = true;
+
+            return jmp.predHeight;
+        }
+
         @Override
         public float getPrefWidth(){
             return prefWidth;
@@ -452,12 +517,14 @@ public class LCanvas extends Table{
         ClickListener listener;
 
         public JumpCurve curve;
+        public StatementElem elem;
 
-        public JumpButton(Prov<StatementElem> getter, Cons<StatementElem> setter){
+        public JumpButton(Prov<StatementElem> getter, Cons<StatementElem> setter, StatementElem elem){
             super(Tex.logicNode, new ImageButtonStyle(){{
                 imageUpColor = Color.white;
             }});
 
+            this.elem = elem;
             to = getter;
             addListener(listener = new ClickListener());
 
@@ -518,6 +585,11 @@ public class LCanvas extends Table{
     public static class JumpCurve extends Element{
         public JumpButton button;
 
+        // for jump prediction; see DragLayout
+        public int predHeight = 0;
+        public boolean markedDone = false;
+        public int jumpUIBegin = 0, jumpUIEnd = 0;
+
         public JumpCurve(JumpButton button){
             this.button = button;
         }
@@ -575,7 +647,7 @@ public class LCanvas extends Table{
             Lines.stroke(4f, button.color);
             Draw.alpha(parentAlpha);
 
-            float dist = 100f;
+            float dist = 100f + 100f * (float) predHeight;
 
             //square jumps
             if(false){
@@ -599,5 +671,20 @@ public class LCanvas extends Table{
             x2, y2,
             Math.max(18, (int)(Mathf.dst(x, y, x2, y2) / 6)));
         }
+
+        public void prepareHeight(){
+            if(this.button.to.get() == null){
+                this.markedDone = true;
+                this.predHeight = 0;
+                this.jumpUIBegin = this.jumpUIEnd = invalidJump;
+            } else {
+                this.markedDone = false;
+                int i = this.button.elem.index;
+                int j = this.button.to.get().index;
+                this.jumpUIBegin = Math.min(i,j);
+                this.jumpUIEnd = Math.max(i,j);
+                // height will be recalculated later
+            }
+        }
     }
 }

core/src/mindustry/logic/LStatements.java

@@ -870,7 +870,7 @@ public class LStatements{
             table.table(this::rebuild);
 
             table.add().growX();
-            table.add(new JumpButton(() -> dest, s -> dest = s)).size(30).right().padLeft(-8);
+            table.add(new JumpButton(() -> dest, s -> dest = s, this.elem)).size(30).right().padLeft(-8);
 
             String name = name();
 

core/src/mindustry/ui/dialogs/SettingsMenuDialog.java

@@ -502,6 +502,8 @@ public class SettingsMenuDialog extends BaseDialog{
         if(!mobile){
             Core.settings.put("swapdiagonal", false);
         }
+
+        graphics.checkPref("dynamicjumpheights", true);
     }
 
     public void exportData(Fi file) throws IOException{