cabana: fix drawing sparkline at half width on hi-dpi screen (#27746)

tools/cabana/signalview.cc

@@ -400,7 +400,7 @@ void SignalItemDelegate::drawSparkline(QPainter *painter, const QStyleOptionView
 
     int h_margin = option.widget->style()->pixelMetric(QStyle::PM_FocusFrameHMargin);
     int v_margin = std::max(option.widget->style()->pixelMetric(QStyle::PM_FocusFrameVMargin) + 2, 4);
-    const double xscale = (option.rect.width() - 175.0 * option.widget->devicePixelRatioF() - h_margin * 2) / settings.sparkline_range;
+    const double xscale = (option.rect.width() - 175.0 - h_margin * 2) / settings.sparkline_range;
     const double yscale = (option.rect.height() - v_margin * 2) / (max - min);
     const int left = option.rect.left();
     const int top = option.rect.top() + v_margin;