The drawing cache is per view, so if you need to capture several views (sibling, and not a subtree like you are doing in your example) if would be better to allocate a single bitmap. This works of course only if all the views have the same size.
On Thu, Jun 23, 2011 at 5:06 PM, rukiman <[email protected]> wrote: > I am suspecting using the view cache system causes the view system to > allocate memory for the view. > Now lets say I can to capture 3 views, does that mean memory is > allocated for 3 views worth of caches if I don't destroy the cache? > > Also I noticed through profiling that this code runs around 100ms > view.setDrawingCacheEnabled(true); > view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH); > view.setDrawingCacheBackgroundColor(Color.BLACK); > Bitmap bitmap = view.getDrawingCache(); > Bitmap retVal = bitmap == null ? null : > bitmap.copy(bitmap.getConfig(), false); > view.destroyDrawingCache(); > view.setDrawingCacheEnabled(false); > return retVal; > > while this runs at around 60ms > mCanvas.setBitmap(mBitmapCapture); > view.draw(mCanvas); > Bitmap retVal = mBitmapCapture; > > I have to capture a few views and trying to speed them as quick as > possible and at the same time not use much memory. I guess the slight > speed difference is in enabling and destroying the view drawing cache? > What is the effect of not destroying it? Does that mean it will suffer > from my approach above that is double the workload on each frame as > well? > > Going back to my approach my code is just as I pasted it, should I be > saving the canvas and restoring it in the dispatchDraw? Any help is > appreciated. Thanks. > > > > > On Jun 24, 9:47 am, Romain Guy <[email protected]> wrote: >> It's either because you don't properly save/restore the state of your >> offline Canvas or maybe because of the bitmap config (although it >> should work just fine in 565.) >> >> What I don't understand however is why you refuse to use the drawing >> cache API that already exists for this purpose? Using this API will >> not necessarily force another redraw of the view. With the drawing >> cache, the cache is automatically redrawn whenever the view changes. >> Your approach however doubles the workload on *every* frame. >> >> >> >> >> >> >> >> >> >> On Thu, Jun 23, 2011 at 4:23 PM, rukiman <[email protected]> wrote: >> > I am trying to understand which this code which works perfectly for >> > capturing almost any view except if there is a ScrollView in the >> > framelayout, in this case there is a slight issue with the top and >> > bottom areas where scrollview fades its contents. There is some >> > corruption occurring. >> >> > public class FrameLayoutWithOfflineBitmap extends FrameLayout { >> >> > private Bitmap mOfflineBitmap; >> > private Canvas mOfflineCanvas; >> >> > public FrameLayoutWithOfflineBitmap(Context context) { >> > super(context); >> > } >> >> > @Override >> > public void onSizeChanged(int w, int h, int oldw, int oldh) { >> > // just in case we already had the bitmap allocated before >> > if(mOfflineBitmap != null) { >> > mOfflineBitmap.recycle(); >> > } >> > mOfflineBitmap = Bitmap.createBitmap(w, h, >> > Bitmap.Config.RGB_565); >> > mOfflineCanvas = new Canvas(); >> > mOfflineCanvas.setBitmap(mOfflineBitmap); >> > } >> >> > @Override >> > public void dispatchDraw(Canvas canvas) { >> > // draw to our offline bitmap >> > super.dispatchDraw(mOfflineCanvas); >> > // now draw our offline bitmap to the system canvas >> > canvas.drawBitmap(mOfflineBitmap, 0, 0, null); >> > } >> >> > public Bitmap getScreenSnapshot() { >> > return mOfflineBitmap; >> > } >> > } >> >> > I understand there are other ways to capture the view such as using >> > the View's drawing cache, but I am not interested in this method. Can >> > someone explain to me what is going on here and if there is way to >> > address this issue? Basically I am trying to get access to a snapshot >> > of a view as quick as possible. My idea is that the view is already >> > drawn onto the screen, we should be able to get access to this without >> > having to force another redundant redraw of the view. >> >> > I am also very keen to understand the flaw with the above code in >> > terms of the scrollview. Thanks. >> >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Android Developers" group. >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> >http://groups.google.com/group/android-developers?hl=en >> >> -- >> Romain Guy >> Android framework engineer >> [email protected] >> >> Note: please don't send private questions to me, as I don't have time >> to provide private support. All such questions should be posted on >> public forums, where I and others can see and answer them > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > -- Romain Guy Android framework engineer [email protected] Note: please don't send private questions to me, as I don't have time to provide private support. All such questions should be posted on public forums, where I and others can see and answer them -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
