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Commit 93c567cd authored by Romain Guy's avatar Romain Guy
Browse files

Skip unnecessary measurements when possible 

This change introduces a new measure cache to View, to remember
the measured dimensions for previous pairs of measure specs. The
measure cache is cleared whenever a View requests layout.

Unfortunately some Views rely on measure being always called when
layout is invoked. To work around this problem, we need to remember
when we hit the measure cache to force a call to measure just prior
to calling onLayout(). This does not completely removes all measure
calls but enough to optimize a number of layouts.

Change-Id: Ie085fbcf186e9d7505e1127e0786a12968ebc344
parent d91f8af4

core/java/android/view/View.java

+40 −2
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ import android.text.TextUtils; 
import android.util.AttributeSet;

import android.util.FloatProperty;

import android.util.Log;

import android.util.LongSparseLongArray;

import android.util.Pools.SynchronizedPool;

import android.util.Property;

import android.util.SparseArray;
@@ -2199,6 +2200,12 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 
     */

    static final int PFLAG3_HAS_LAYOUT = 0x4;













    /**













     * Flag indicating that a call to measure() was skipped and should be done













     * instead when layout() is invoked.













     */













    static final int PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT = 0x8;









































    /* End of masks for mPrivateFlags3 */
























@@ -2979,6 +2986,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













     */















    int mOldHeightMeasureSpec = Integer.MIN_VALUE;



























    private LongSparseLongArray mMeasureCache;



























    @ViewDebug.ExportedProperty(deepExport = true, prefix = "bg_")















    private Drawable mBackground;
























@@ -14401,12 +14410,19 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













     */















    @SuppressWarnings({"unchecked"})















    public void layout(int l, int t, int r, int b) {













        if ((mPrivateFlags3 & PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT) != 0) {













            onMeasure(mOldWidthMeasureSpec, mOldHeightMeasureSpec);













            mPrivateFlags3 &= ~PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT;













        }



























        int oldL = mLeft;















        int oldT = mTop;















        int oldB = mBottom;















        int oldR = mRight;



























        boolean changed = isLayoutModeOptical(mParent) ?















                setOpticalFrame(l, t, r, b) : setFrame(l, t, r, b);



























        if (changed || (mPrivateFlags & PFLAG_LAYOUT_REQUIRED) == PFLAG_LAYOUT_REQUIRED) {















            onLayout(changed, l, t, r, b);















            mPrivateFlags &= ~PFLAG_LAYOUT_REQUIRED;









@@ -14421,6 +14437,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













                }















            }















        }



























        mPrivateFlags &= ~PFLAG_FORCE_LAYOUT;















        mPrivateFlags3 |= PFLAG3_HAS_LAYOUT;















    }










@@ -15898,6 +15915,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













     * handle possible request-during-layout errors correctly.</p>















     */















    public void requestLayout() {













        if (mMeasureCache != null) mMeasureCache.clear();



























        if (mAttachInfo != null && mAttachInfo.mViewRequestingLayout == null) {















            // Only trigger request-during-layout logic if this is the view requesting it,















            // not the views in its parent hierarchy










@@ -15927,6 +15946,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













     * on the parent.















     */















    public void forceLayout() {













        if (mMeasureCache != null) mMeasureCache.clear();



























        mPrivateFlags |= PFLAG_FORCE_LAYOUT;















        mPrivateFlags |= PFLAG_INVALIDATED;















    }










@@ -15960,6 +15981,11 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













            widthMeasureSpec  = MeasureSpec.adjust(widthMeasureSpec,  optical ? -oWidth  : oWidth);















            heightMeasureSpec = MeasureSpec.adjust(heightMeasureSpec, optical ? -oHeight : oHeight);















        }

























        // Suppress sign extension for the low bytes













        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) {









@@ -15969,8 +15995,17 @@ public class View implements Drawable.Callback, KeyEvent.Callback,



























            resolveRtlPropertiesIfNeeded();



























            int cacheIndex = mMeasureCache.indexOfKey(key);













            if (cacheIndex < 0) {















                // measure ourselves, this should set the measured dimension flag back















                onMeasure(widthMeasureSpec, heightMeasureSpec);













                mPrivateFlags3 &= ~PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT;













            } else {













                long value = mMeasureCache.valueAt(cacheIndex);













                // Casting a long to int drops the high 32 bits, no mask needed













                setMeasuredDimension((int) (value >> 32), (int) value);













                mPrivateFlags3 |= PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT;













            }





























            // flag not set, setMeasuredDimension() was not invoked, we raise















            // an exception to warn the developer









@@ -15985,6 +16020,9 @@ public class View implements Drawable.Callback, KeyEvent.Callback,



























        mOldWidthMeasureSpec = widthMeasureSpec;















        mOldHeightMeasureSpec = heightMeasureSpec;

























        mMeasureCache.put(key, ((long) mMeasuredWidth) << 32 |













                (long) mMeasuredHeight & 0xffffffffL); // suppress sign extension















    }





























    /**