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Commit d6befbdd authored by Fabrice Di Meglio's avatar Fabrice Di Meglio
Browse files

Save Scroller position 

- add SaveState with scroll position and use it during the first layout

Change-Id: I0806ddb9c52d70d32055f4b474d21f6e2e5a4ea8
parent 97f41383

core/java/android/widget/ScrollView.java

+76 −0
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 


package android.widget;



import android.os.Parcel;

import android.os.Parcelable;

import com.android.internal.R;



import android.content.Context;
@@ -149,6 +151,8 @@ public class ScrollView extends FrameLayout { 
     */

    private static final int INVALID_POINTER = -1;



    private SavedState mSavedState;



    public ScrollView(Context context) {

        this(context, null);

    }
@@ -1468,6 +1472,24 @@ public class ScrollView extends FrameLayout { 
        }

        mChildToScrollTo = null;



        // There is only one child

        final View child = getChildAt(0);

        final int childHeight = child.getMeasuredHeight();

        if (!hasLayout()) {

            final int scrollRange = Math.max(0,

                    childHeight - (b - t - mPaddingBottom - mPaddingTop));

            if (mSavedState != null) {

                mScrollY = mSavedState.scrollPosition;

                mSavedState = null;

            } // mScrollY default value is "0"

            // Don't forget to clamp

            if (mScrollY > scrollRange) {

                mScrollY = scrollRange;

            } else if (mScrollY < 0) {

                mScrollY = 0;

            }

        }



        // Calling this with the present values causes it to re-claim them

        scrollTo(mScrollX, mScrollY);

    }
@@ -1637,4 +1659,58 @@ public class ScrollView extends FrameLayout { 
        }

        return n;

    }



    @Override

    protected void onRestoreInstanceState(Parcelable state) {

        SavedState ss = (SavedState) state;

        super.onRestoreInstanceState(ss.getSuperState());

        mSavedState = ss;

        requestLayout();

    }



    @Override

    protected Parcelable onSaveInstanceState() {

        Parcelable superState = super.onSaveInstanceState();

        SavedState ss = new SavedState(superState);

        ss.scrollPosition = mScrollY;

        return ss;

    }



    static class SavedState extends BaseSavedState {

        public int scrollPosition;



        SavedState(Parcelable superState) {

            super(superState);

        }



        public SavedState(Parcel source) {

            super(source);

            scrollPosition = source.readInt();

        }



        @Override

        public void writeToParcel(Parcel dest, int flags) {

            super.writeToParcel(dest, flags);

            dest.writeInt(scrollPosition);

        }



        @Override

        public String toString() {

            return "HorizontalScrollView.SavedState{"

                    + Integer.toHexString(System.identityHashCode(this))

                    + " scrollPosition=" + scrollPosition + "}";

        }



        public static final Parcelable.Creator<SavedState> CREATOR

                = new Parcelable.Creator<SavedState>() {

            public SavedState createFromParcel(Parcel in) {

                return new SavedState(in);

            }



            public SavedState[] newArray(int size) {

                return new SavedState[size];

            }

        };

    }



}