fix(rendering): compute beaming bounds for beats without notes

packages/alphatab/src/rendering/LineBarRenderer.ts

@@ -1008,27 +1008,29 @@ export abstract class LineBarRenderer extends BarRendererBase {
                 if (h.hasTuplet && tupletDirection === direction) {
                     topY -= this.tupletSize + this.tupletOffset;
                 }
-                const lowestBeat = isRest ? h.beats[0] : h.beatOfLowestNote;
+                const lowestNote = h.lowestNoteInHelper;
+                const lowestBeat = lowestNote ? lowestNote.beat : h.beats[0];
                 if (h.hasTuplet && tupletDirection !== direction) {
                     // Use flag position (matches paintTuplets); getLowestNoteY skips content below the notehead.
                     bottomY = this.getFlagBottomY(lowestBeat, tupletDirection) + this.tupletSize + this.tupletOffset;
                 } else if (isRest) {
                     bottomY = this.getRestY(lowestBeat, NoteYPosition.Bottom);
-                } else {
+                } else if (lowestNote) {
                     bottomY = this.voiceContainer.getLowestNoteY(lowestBeat, NoteYPosition.Bottom);
                 }
             } else {
                 bottomY = Math.max(drawingInfo.startY, drawingInfo.endY);
                 if (h.hasTuplet && tupletDirection === direction) {
                     bottomY += this.tupletSize + this.tupletOffset;
                 }
-                const highestBeat = isRest ? h.beats[0] : h.beatOfHighestNote;
+                const highestNote = h.highestNoteInHelper;
+                const highestBeat = highestNote ? highestNote.beat : h.beats[0];
                 if (h.hasTuplet && tupletDirection !== direction) {
                     // Use flag position (matches paintTuplets); getHighestNoteY skips octave dots.
                     topY = this.getFlagTopY(highestBeat, tupletDirection) - this.tupletSize - this.tupletOffset;
                 } else if (isRest) {
                     topY = this.getRestY(highestBeat, NoteYPosition.Top);
-                } else {
+                } else if (highestNote) {
                     topY = this.voiceContainer.getHighestNoteY(highestBeat, NoteYPosition.Top);
                 }
             }
@@ -1287,18 +1289,24 @@ export abstract class LineBarRenderer extends BarRendererBase {
         // 4. let middle elements shift up/down
         if (h.beats.length > 1) {
             // check if highest note shifts bar up or down
+            const highestNote = h.highestNoteInHelper;
+            const lowestNote = h.lowestNoteInHelper;
             if (direction === BeamDirection.Up) {
-                const yNeededForHighestNote = barDrawingShift + this.getFlagTopY(h.beatOfHighestNote, direction);
-                const yGivenByCurrentValues = drawingInfo.calcY(this.getBeatX(h.beatOfHighestNote, BeatXPosition.Stem));
+                if (highestNote) {
+                    const highestBeat = highestNote.beat;
+                    const yNeededForHighestNote = barDrawingShift + this.getFlagTopY(highestBeat, direction);
+                    const yGivenByCurrentValues = drawingInfo.calcY(this.getBeatX(highestBeat, BeatXPosition.Stem));
 
-                const diff = yGivenByCurrentValues - yNeededForHighestNote;
-                if (diff > 0) {
-                    drawingInfo.startY -= diff;
-                    drawingInfo.endY -= diff;
+                    const diff = yGivenByCurrentValues - yNeededForHighestNote;
+                    if (diff > 0) {
+                        drawingInfo.startY -= diff;
+                        drawingInfo.endY -= diff;
+                    }
                 }
-            } else {
-                const yNeededForLowestNote = barDrawingShift + this.getFlagBottomY(h.beatOfLowestNote, direction);
-                const yGivenByCurrentValues = drawingInfo.calcY(this.getBeatX(h.beatOfLowestNote, BeatXPosition.Stem));
+            } else if (lowestNote) {
+                const lowestBeat = lowestNote.beat;
+                const yNeededForLowestNote = barDrawingShift + this.getFlagBottomY(lowestBeat, direction);
+                const yGivenByCurrentValues = drawingInfo.calcY(this.getBeatX(lowestBeat, BeatXPosition.Stem));
 
                 const diff = yNeededForLowestNote - yGivenByCurrentValues;
                 if (diff > 0) {

packages/alphatab/src/rendering/utils/BeamingHelper.ts

@@ -307,14 +307,6 @@ export class BeamingHelper {
         return ModelUtils.getIndex(a.duration) - 2 - barIndex > 0 && ModelUtils.getIndex(b.duration) - 2 - barIndex > 0;
     }
 
-    public get beatOfLowestNote(): Beat {
-        return this.lowestNoteInHelper!.beat;
-    }
-
-    public get beatOfHighestNote(): Beat {
-        return this.highestNoteInHelper!.beat;
-    }
-
     /**
      * Per-direction beam drawing info cache. BeamDirection is a 2-value enum
      * (Up=0, Down=1) so we use two pre-allocated `BeamingHelperDrawInfo`

packages/alphatab/test/visualTests/issues/BrokenRenders.test.ts

@@ -160,6 +160,21 @@ describe('BrokenRendersTests', () => {
         }
     });
 
+    it('dead-slapped-beats', () => {
+        for (const tex of [
+            '\\staff {score tabs slash numbered} r.1 {ds}',
+            '\\staff {numbered} \\ts 8 4 :-2 r {ds}',
+            '\\staff {score tabs slash numbered} \\ts 3 2 :1 C4 {tu 3} C4 {tu 3} r {tu 3 ds}',
+            '\\staff {score tabs slash numbered} :8 r {ds beam merge} r {ds} r r r r r r'
+        ]) {
+            const results = renderSvg(ScoreLoader.loadAlphaTex(tex), 1300);
+            expect(results.length, tex).toBeGreaterThan(0);
+            for (const r of results) {
+                expect(r.includes('NaN'), `NaN in SVG for ${tex}`).toBe(false);
+            }
+        }
+    });
+
     it('squeezed-bar-warning', () => {
         const settings = new Settings();
         settings.core.engine = 'svg';