Hello everyone! I have recently been working with the Gallery (SDK1.0_r2) and have found the following 3 issues, the first 2 of which have caused me a fair amount of pain:
1. not having a callback on the 'last item selected' in the gallery during a fling and/or scroll, 2. Gallery layout change when setSelected(position) is called results in layout changes for other views of the activity displayed, 3. a 'nothing-selected-state' after a fling with no item selected (in the middle). Issue #1 is a feature request. Let me elaborate; possibly I am missing something and someone more knowledgeable may shed some light for me on these things. I would be very thankful for that. My main layout consists of a simple Gallery 'bar' on top (with a few TextViews in its adapter), and a SurfaceView below the Gallery, filling the rest of the screen. (1.) In my application, when an item is selected in the Gallery, the Surface below it must be updated. This update does not take too long to complete, but it takes long enough to make the 'fling' of the Gallery not perfectly smooth. I am already setting setCallbackDuringFling(false), but this only hides selection events of items in between the second and last items selected. I figure this is because at the beginning of a fling android does not yet know if it is going to be a fling or just a simple scroll to the side. However, i really hated those small hickups in the otherwise nice&smooth fling animation, so I have implemented a crazy scheme, tracking scrollstates and touch events with delayed message-sending/handling to achieve what I needed: a single event being fired when the final selection on the Gallery is made during either scroll or fling motion. I'd like to suggest adding API support necessary to handle this kind of event, as I believe others might use it too. (NOTE: try switching the background on your phone: the wallpaper gallery suffers from the same kind of hickup I am describing - doesn't it annoy anyone but me?! ;) (2.) In another scenario my application needs to select an item of the gallery, while doing some CPU intensive tasks updating the Surface below it. On the Surface I am making use of SurfaceHolder.lockCanvas (DirtyRect) @ 30FPS and again, everything is fine and smooth, until the selection in the gallery messes up my Surface buffer. It appears that the Gallery.setSelection(pos) call fires off a requestLayout() event (inherited from AbsSpinner). For reasons unknown to me, this later results in some kind of layout invalidation of my SurfaceView as well. The surfaceChanged() callback of the SurfaceHolder is called and I seem to loose valid pixel regions of one of the two buffers of the Surface as a result. The next frame thus displays with some black pixels, where the previously locked dirtyRect region is replaced with a full surface lock(); my SurfaceView area blinks. Just a single fr...@30fps, but still: ugly. After a considerable amount of time I realized that a Gallery.setSelection(pos, false) call does NOT result in this layout madness. I dont care for animation, so this workaround is acceptable for now. I just dont understand, why a regular setSelection on a Gallery should invalidate the layout of other views. I think it should not. (3.) At least two times during testing I have managed to stop the gallery fling in a state where NO item was selected. In this state there was also no item centered, meaning two of my items in the gallery where equally close to the 'center' of the gallery bar. Anyone else experiencing these issues? Are there any known/better solutions to them? Any comment will be greatly appreciated. -Szabolcs --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
