timeline plugin: fix negative offset rendering (#2470)

* timeline plugin: negative offset rendering issue * add entry to changelog
katspaugh · Mar 4, 2022 · 5af6502 · 5af6502
1 parent 8d33268
commit 5af6502
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,6 +1,11 @@
 wavesurfer.js changelog
 =======================
 
+6.0.4 (unreleased)
+------------------
+- Timeline plugin:
+  - Fix rendering issue for negative `offset` values (#2463)
+
 6.0.3 (01.03.2022)
 ------------------
 - Cursor plugin:

diff --git a/src/plugin/timeline/index.js b/src/plugin/timeline/index.js
@@ -371,7 +371,13 @@ export default class TimelinePlugin {
         // build an array of position data with index, second and pixel data,
         // this is then used multiple times below
         const positioning = [];
-        for (i = 0; i < totalSeconds / timeInterval; i++) {
+
+        // render until end in case we have a negative offset
+        const renderSeconds = (this.params.offset < 0)
+            ? totalSeconds - this.params.offset
+            : totalSeconds;
+
+        for (i = 0; i < renderSeconds / timeInterval; i++) {
             positioning.push([i, curSeconds, curPixel]);
             curSeconds += timeInterval;
             curPixel += pixelsPerSecond * timeInterval;