Android/frameworks_base
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

View measurement optimization

Browse Source 
If a view hasn't explicitly requested layout and it's asked to measure
with MeasureSpec.EXACTLY in both dimensions and sizes that match its
current measured size, the measure operation is a no-op.

This helps out a number of ViewGroups that perform initial speculative
measurements with AT_MOST or UNSPECIFIED followed by looping over
child views and measuring EXACTLY to lock in the final measurement
with perhaps some extra leftover space distributed. In practice this
happens a fair bit, especially for views high up in the view
hierarchy. This optimization allows ViewGroup measurement code to be a
little cleaner in not having to keep track of this on its own.

Change-Id: I88ff46a7d37aeda7a4cd16204b68cab0d051b341
This commit is contained in:
Adam Powell
2014-10-14 19:15:18 -07:00
parent 074c5b5b65
commit 9cefbda11e
1 changed files with 10 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
core/java/android/view/View.java
View File

@@ -17418,17 +17418,22 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
long key = (long) widthMeasureSpec << 32 | (long) heightMeasureSpec & 0xffffffffL;
if (mMeasureCache == null) mMeasureCache = new LongSparseLongArray(2);
if ((mPrivateFlags & PFLAG_FORCE_LAYOUT) == PFLAG_FORCE_LAYOUT ||
widthMeasureSpec != mOldWidthMeasureSpec ||
heightMeasureSpec != mOldHeightMeasureSpec) {
final boolean forceLayout = (mPrivateFlags & PFLAG_FORCE_LAYOUT) == PFLAG_FORCE_LAYOUT;
final boolean isExactly = MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY &&
MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.EXACTLY;
final boolean matchingSize = isExactly &&
getMeasuredWidth() == MeasureSpec.getSize(widthMeasureSpec) &&
getMeasuredHeight() == MeasureSpec.getSize(heightMeasureSpec);
if (forceLayout || !matchingSize &&
(widthMeasureSpec != mOldWidthMeasureSpec ||
heightMeasureSpec != mOldHeightMeasureSpec)) {
// first clears the measured dimension flag
mPrivateFlags &= ~PFLAG_MEASURED_DIMENSION_SET;
resolveRtlPropertiesIfNeeded();
int cacheIndex = (mPrivateFlags & PFLAG_FORCE_LAYOUT) == PFLAG_FORCE_LAYOUT ? -1 :
mMeasureCache.indexOfKey(key);
int cacheIndex = forceLayout ? -1 : mMeasureCache.indexOfKey(key);
if (cacheIndex < 0 || sIgnoreMeasureCache) {
// measure ourselves, this should set the measured dimension flag back
onMeasure(widthMeasureSpec, heightMeasureSpec);