DO NOT MERGE Set the cap at alpha to 80% of the total available.
DO NOT MERGE Set the cap at alpha to 80% of the total available.

No matter how much the user drags, the alpha like the height
should not get greater than a max and that max is 80% of what
is available in the image.

Change-Id: I57d181d6ea685461a44ed3ee29f83a675bc07fbc

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base