A search interface in a 320×240 touchscreen

Last evenings I spent some time on my raspberry pi + hifiberry amp + piTFT + squeezebox project. Previously I created the interface to load a predefined playlist, and to control basics like volume and time. I also finished the integration of the display in the top of the Mission 731i speaker and placed the pi and amp inside the box (will post some pictures soon).

This time I wanted to extend the user interface with a feature to search and browse in the mp3 collection. But that immediately raised the question: what kind of interface works best for a small screen size (320×240) and touch input (no keyboard, no mouse)? A possibility was a virtual keyboard with a entry or a combo, but my first mockup in glade resulted in 300×140 pixels just for the keyboard – leaving very little space for the search results. So I tried a treeview so the user can quickly scroll through the results. To reduce the number of results I added a combo with a prefix (a-z0-9) to the top.

The results work reasonably well, but there are some issues to resolve.

First of all the scrolling in the GtkTreeView is not using “kinetic scrolling” (you can’t scroll like you normally do on a touchscreen) although I enabled kinetic scrolling for the GtkScrolledWindow parent in glade. Scrolling using the scrollbar on the side works, but kinetic scrolling would work better.

Second, most touchscreen users kind of expect the context menu when you hold your finger for a while. I hoped this was automatically translated to a right-click, but that doesn’t work. So I have to find a way now to catch these events for the context menu’s (anybody a hint how to do this?).

The last issue I have is not related to the touchscreen. I have some scaling layout issues, sometimes a multiline label with a long text forces some buttons off the screen.

So I also have to find out how ellipsize works with multiline labels.