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Signed-off-by: Tyler Ohlsen <ohltyler@amazon.com>

src/plugins/vis_type_vega/public/expressions/helpers.ts

@@ -56,6 +56,11 @@ export const cleanString = (rawString: string): string => {
   return rawString.replaceAll('"', '');
 };
 
+// When using autosize features of vega-lite, the chart is expected to reposition
+// correctly such that there is space for the chart and legend within the canvas.
+// This works for horizontal positions (left/right), but breaks for vertical positions
+// (top/bottom). To make up for this, we set the offset to 0 for these positions such that
+// the chart will not get truncated or potentially cut off within the canvas.
 export const calculateLegendOffset = (legendPosition: string): number =>
   // 18 is the default offset as of vega lite 5
   legendPosition === 'top' || legendPosition === 'bottom' ? 0 : 18;

src/plugins/vis_type_vega/public/vega_view/vega_base_view.js

@@ -271,6 +271,9 @@ export class VegaBaseView {
   // space and leave enough space to show the bottom view (the events vis).
   // Ref: https://vega.github.io/vega-lite/docs/size.html#limitations
   addPointInTimeEventPadding(view) {
+    // This value represents the pixel height of the event canvas. It is determined
+    // based on the event mark size, such that there is sufficient but minimal space
+    // needed to render the event marks.
     const eventVisHeight = 100;
     const height = Math.max(0, this._$container.height()) - eventVisHeight;
     if (view._signals.concat_0_height !== undefined) {