How to avoid problems with Web Runtime Widget icons

From Symbian Developer Community

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Symbian ecosystem is large and rich, but for developers this variety can be daunting. With a variety of screens sizes and menu display modes, application icons are one of those variables that have potential to cause problems. This has been solved nicely for native applications installed via SIS files - native Symbian applications can provide scalable icons to the system - e.g. in SVG format. However, this is not the case with WRT widgets which are only allowed one raster (typically PNG) graphic that should satisfy all modes.

In fact, widget's icon is scaled on the device to fit the needs of current presentation mode (e.g. grid or list). Further, this actually translates to different sizes on different devices. Providing an icon that exactly matches expected size on one device will mean it will be scaled on the other. This has caused some concern among developers.

The problem occurs because the small original icon is very difficult to scale without loss of quality. Even using the best available scaling algorithms on a desktop computer, the results are not great.

Widget icon is 46x46 pixels

Scaled to 48x48 pixels, losses become apparent

Scaled to 32x32 pixels it is usable but not great...

The solution is very simple - the icon should be sufficiently large so that the scaling algorithm has enough information to create an accurate scaled down version. For example, given a 200x200 pixel icon, the scaling algorithm performs much better: