Official layout widgets like ListView/GridView should have a selection mode when an item is long-pressed.
Once in selection mode, ListTile/GridTile becomes toggleable, and the AppBar allows the appropriate options to 'Select all, Cancel, or perform actions on items (share, etc)'.
From material design spec: https://material.io/guidelines/patterns/selection.html#selection-usage
Official layout widgets like ListView/GridView should have a selection mode when an item is long-pressed.
Once in selection mode, ListTile/GridTile becomes toggleable, and the AppBar allows the appropriate options to 'Select all, Cancel, or perform actions on items (share, etc)'.
From material design spec: https://material.io/guidelines/patterns/selection.html#selection-usage