Develop Reference

Incorrect GLSurfaceView positioning

I have a GLSurfaceView with a renderer assigned to it. On this view, I draw images which seem to be offset to the left compared to where I have requested that they be drawn on it. This problem has only arisen since I switched from Canvas-based rendering, which rendered the images in their correct positions, to OpenGL 1.0 rendering, which doesn't.
I have read through my code and have found absolutely nothing that could be causing this. What frustrates me is that I know there is nothing wrong with the positions I set using my code, but the problem still persists.
Now, here's the best part of it all. When I pause the application by pressing the home button, and then restart the application through the task manager, the positions are fixed and are exactly how they should be, which leads me to believe that the problem isn't with the positions I set using my code, but how I've set up my surface view. I've checked the dimensions in the onSurfaceChanged() parameters only to find that they are always as they should be, which leaves me even more confused.
Does anyone have any idea what could be causing this problem?

After much digging through my project, I discovered I was setting positions based on the dimensions of the GLSurfaceView before onSurfaceChanged had been called in the onSurfaceCreated method, therefore the width/height of the view at this point was 0 which affected the positions of my objects on the screen.
I feel really stupid now.

Draw View before displaying during animation

I have two views in a ViewFlipper and have a fast/complex animation between them. The second view contains a list, so at the moment that view become visibile half way through the animation, getView() is called a bunch of times and causes a very noticeable stutter (usually stalling for the entire second half of the animation)
Ideally I would like to pre-render (measure, layout, draw) the second view before starting the animation, but I have not found a simple way to do this.
I have also explored using the drawing cache, off-screen canvases, etc - but I cannot find a simple way to achieve this either. Seems to be a problem anyone animating between two views would have. Any help?

You can do that by specifying a layer type and calling buildLayer() before you start your animation, which forces rendering the view.
newView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
newView.buildLayer();
You could also use LAYER_TYPE_SOFTWARE. The default value is LAYER_TYPE_NONE, which prevents buildLayer() to do anything.

android: Smoothest and most efficient way to animate drawn circles on a canvas

What is the best way to draw circles on a canvas that should have an alpha layer and change sizes? Should I use a View or a Surfaceview? The circles should also be clickable. And it should be smooth transitions when changing color size and position?
Should I put this in a runnable or use invlaidate in onDraw?
I would prefer that something like this also worked smoothly in low-end devices.
Any suggestions? I'm new to this kind of animations in Android.

If you are constantly drawing and taking user input at the same time, I would use a SurfaceView. However, if the only draw changes you plan on making to the circles happen when you touch them, then a simple View onDraw() override would probably do the trick. In the end it will just depend on what all is going on.
The point of the SurfaceView is to have that separate thread for drawing. If what you're doing could be in any way considered "game-like," then go for a SurfaceView; otherwise, stick with a View.
I say this because I'm currently working on a project with constant drawing using a View. The shapes that I'm drawing respond to touch and you can scroll through the View while it is still invalidating over and over. All this with a View and it still runs just fine on lower-end devices (I've only gone back to GingerBread, though).
Good luck!
I should also mention that in the project drawing in a View, almost everything has various alpha values and what not and runs fine.

Rotated (not animated) views in XML pre-honeycomb?

Is it possible to rotate views in XML with APIs previous to Honeycomb - maybe with the support package? Or is the only way to create a custom class, like described here Vertical (rotated) label in Android
Edit: What I need is a statically rotated view (specifically a TextView, but I guess it's enough to know how to do it with a View). Starting with honeycomb there's a rotation attribute which can be used in XML. I need something like that.
The only thing I have found until now is use an animation with duration 0 but this still moves a bit at start and I don't want that. I tried setting the views invisible and attaching a listener to the animation which makes them visible on animation finished callback, but that made strange results... that changed the position of the views, for some reason.

The best way is with the custom subclass implementation that you linked to, where you can rotate the canvas and resize the view appropriately. This ensures that the view bounds are also set to match the text that is drawn.
The only method of transforming views externally prior to HC is the animation framework, and applying an Animation to the view with a duration of 0 and fillAfter set to true will work, but you may notice flickering on some devices as often the view will render normally on its first frame and then animated to its final position from that point onward. You can work around this by hiding the view and displaying it a bit late...but you can see how hacks are starting to stack up.
In addition, doing an Animation prior to HC will not transform the view bounds themselves, so you won't be able to neatly pack other views around this one because its position from a layout perspective will still be the rectangle calculated for the horizontal (non-rotated) text.
The simple subclass is definitely the preferred method.
HTH

Is it possible to rotate views in XML with APIs previous to Honeycomb
There is RotateAnimation. However, depending on what you are trying to accomplish, that may not meet your needs.

Android custom zoom animation poor performance

I have a bit specific problem, but hopefully someone will chime in and help.
I've written a custom zoom animation (posting runnables that change the target view to a handler between certain amount of time) but when i change the view's width and height it is as if I've performed a zoom around (0,0) of the view whereas I want to zoom around its center so I move the view by changing its margins accordingly. The thing is though that when the zoom iteration step is too small (i.e 0.01f and less) I have to change the margins of the view by something like 1px sometimes only in one of the directions which makes it look as if the animation is glitchy. I'm not sure of the exact reason but I've tried the following things:
1) I tried changing the margins by overriding onLayout() of my parent view which will be caled when setting the layoutParams upon zooming( I did this in order to avoid a second call to setLayoutParams() upon moving which actually now doesn't seem quite reasonable since setLayoutParams() just sets some flag which will be used later on).
2) I'm checking the new margins to set so that they are set only when there's a difference between the new and the old margins in both X and Y directions.
3)I tried using view.offsetLeftAndRight() view.offsetTopAndBottom() instead of changing the layout params in order to move the view, but it was again to no avail.
Any suggestions what will do the trick?

If I undestand you correctly you need to get Bitmap cache from view and draw it manually. In this case bitmap will be drawn without glitches (if Bitmap filtering is on).
You can do it in following steps:
get view cache - through View.getDrawingCache or by calling View.draw function
hide view
get current system time - SystemClock.elapsedRealtime (thanks to this you can calculate animation progress)
start posting runnables to invalidate your screen and check whether animation is ended
show view
Possibly it can be done via Android Animation class but I do not use it as it quite limited.