[FIX] chart: clip show value text to chart area

The text of the "Show Value" feature can go out of the chart and
overlap with the legend/title. This commit clips the text to the
chart area.

closes #7293

Task: 5125970
X-original-commit: ff8bba9
Signed-off-by: Rémi Rahir (rar) <rar@odoo.com>
Signed-off-by: Adrien Minne (adrm) <adrm@odoo.com>

Author: hokolomopo

src/components/figures/chart/chartJs/chartjs_show_values_plugin.ts

@@ -29,6 +29,10 @@ export const chartShowValuesPlugin: Plugin = {
     }
     const ctx = chart.ctx as CanvasRenderingContext2D;
     ctx.save();
+    const { left, top, height, width } = chart.chartArea;
+    ctx.beginPath();
+    ctx.rect(left, top, width, height);
+    ctx.clip();
 
     ctx.textAlign = "center";
     ctx.textBaseline = "middle";