Working with Scrolling Content

Pixel based scrolling tables and scrolling layers provide the ability to scroll content in a smooth and uniform fashion. Configuring table's for scrolling is covered in the chapter Creating Lists and Tables. Scrolling layers are based entirely on the bounds of their child group and control content and require a simple property enablement Enable layer scrolling behaviour within the Properties View.

When scrolling is enabled the object that is being scrolled, be it a layer or a table, is being moved as if it were positioned virtually and the object bounds provide the viewport into that virtual position. To track and measure this virtual positioning there are two internal Storyboard variables grd_xoffset and grd_yoffset that can be used to determine the virtual object position relative to the it's actual position. Considering the y offset value, when it is at 0 the content is aligned with the top of the control. When the y offset value is negative the content appears to be moving down.

When scrolling is enabled in the properties for an object the Storyboard Engine will start automatically tracking any press, release and motion events targeted at the object. While a press is active, the object will track exactly to the user motion. Once the press turns to a release, then the object will scroll automatically based on the scrolling properties configured.