Example usage for android.view Gravity CENTER

Introduction

In this page you can find the example usage for android.view Gravity CENTER_HORIZONTAL.

Prototype

int CENTER_HORIZONTAL

To view the source code for android.view Gravity CENTER_HORIZONTAL.

Click Source Link

Document

Place object in the horizontal center of its container, not changing its size.

Usage

From source file:cn.bmob.otaku.number_z.view.imagepager.PinchImageViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns.//from   ww  w  .j  a  va2 s. c o  m
 *
 * @param position Position index of the first page currently being displayed.
 *                 Page position+1 will be visible if positionOffset is nonzero.
 * @param offset Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }

    if (mPageTransformer != null) {
        final int scrollX = getScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;
}

From source file:t3.giftbook.util.FlipViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns.//from  w  ww  . j  av  a  2  s .co m
 *
 * @param position Position index of the first page currently being displayed.
 *                 Page position+1 will be visible if positionOffset is nonzero.
 * @param offset Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }

    if (mPageTransformer != null) {
        final int scrollX = getScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;

    this.mPosition = position;
    this.mOffset = offset;
    this.mOffsetPixels = offsetPixels;
}

From source file:com.viewpagerindicator.MyDirectionalViewPager.java

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    final int count = getChildCount();
    int width = r - l;
    int height = b - t;
    int paddingLeft = getPaddingLeft();
    int paddingTop = getPaddingTop();
    int paddingRight = getPaddingRight();
    int paddingBottom = getPaddingBottom();
    final int scrollX = getScrollX();
    final int scrollY = getScrollY();

    int decorCount = 0;

    // First pass - decor views. We need to do this in two passes so that
    // we have the proper offsets for non-decor views later.
    for (int i = 0; i < count; i++) {
        final View child = getChildAt(i);
        if (child.getVisibility() != GONE) {
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            int childLeft = 0;
            int childTop = 0;
            if (lp.isDecor) {
                final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
                final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK;
                switch (hgrav) {
                default:
                    childLeft = paddingLeft;
                    break;
                case Gravity.LEFT:
                    childLeft = paddingLeft;
                    paddingLeft += child.getMeasuredWidth();
                    break;
                case Gravity.CENTER_HORIZONTAL:
                    childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                    break;
                case Gravity.RIGHT:
                    childLeft = width - paddingRight - child.getMeasuredWidth();
                    paddingRight += child.getMeasuredWidth();
                    break;
                }/*from  www.ja  v a 2s .  c  o m*/
                switch (vgrav) {
                default:
                    childTop = paddingTop;
                    break;
                case Gravity.TOP:
                    childTop = paddingTop;
                    paddingTop += child.getMeasuredHeight();
                    break;
                case Gravity.CENTER_VERTICAL:
                    childTop = Math.max((height - child.getMeasuredHeight()) / 2, paddingTop);
                    break;
                case Gravity.BOTTOM:
                    childTop = height - paddingBottom - child.getMeasuredHeight();
                    paddingBottom += child.getMeasuredHeight();
                    break;
                }
                if (mOrientation == HORIZONTAL) {
                    childLeft += scrollX;
                } else {
                    childTop += scrollY;
                }
                child.layout(childLeft, childTop, childLeft + child.getMeasuredWidth(),
                        childTop + child.getMeasuredHeight());
                decorCount++;
            }
        }
    }

    final int childWidth = width - paddingLeft - paddingRight;
    final int childHeight = height - paddingTop - paddingBottom;
    // Page views. Do this once we have the right padding offsets from above.
    for (int i = 0; i < count; i++) {
        final View child = getChildAt(i);
        if (child.getVisibility() != GONE) {
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            ItemInfo ii;
            if (!lp.isDecor && (ii = infoForChild(child)) != null) {
                int loff;
                int childLeft;
                int childTop;
                if (mOrientation == HORIZONTAL) {
                    loff = (int) (childWidth * ii.offset);
                    childLeft = paddingLeft + loff;
                    childTop = paddingTop;
                    if (lp.needsMeasure) {
                        // This was added during layout and needs measurement.
                        // Do it now that we know what we're working with.
                        lp.needsMeasure = false;
                        final int widthSpec = MeasureSpec.makeMeasureSpec((int) (childWidth * lp.widthFactor),
                                MeasureSpec.EXACTLY);
                        final int heightSpec = MeasureSpec.makeMeasureSpec(
                                (int) (height - paddingTop - paddingBottom), MeasureSpec.EXACTLY);
                        child.measure(widthSpec, heightSpec);
                    }
                } else {
                    loff = (int) (childHeight * ii.offset);
                    childLeft = paddingLeft;
                    childTop = paddingTop + loff;
                    if (lp.needsMeasure) {
                        // This was added during layout and needs measurement.
                        // Do it now that we know what we're working with.
                        lp.needsMeasure = false;
                        final int widthSpec = MeasureSpec.makeMeasureSpec((int) (childWidth),
                                MeasureSpec.EXACTLY);
                        final int heightSpec = MeasureSpec.makeMeasureSpec((int) (childHeight * lp.widthFactor),
                                MeasureSpec.EXACTLY);
                        child.measure(widthSpec, heightSpec);
                    }
                }
                //                    if (DEBUG) 
                //                    Log.v(TAG, "Positioning #" + i + " " + child + " f=" + ii.object
                //                            + ":" + childLeft + "," + childTop + " " + child.getMeasuredWidth()
                //                            + "x" + child.getMeasuredHeight());
                child.layout(childLeft, childTop, childLeft + child.getMeasuredWidth(),
                        childTop + child.getMeasuredHeight());
            }
        }
    }
    mTopPageBounds = paddingTop;
    mBottomPageBounds = height - paddingBottom;
    mDecorChildCount = decorCount;

    if (mFirstLayout) {
        scrollToItem(mCurItem, false, 0, false);
    }
    mFirstLayout = false;
}

From source file:dev.dworks.libs.widget.ViewPager.java

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    final int count = getChildCount();
    int width = r - l;
    int height = b - t;
    int paddingLeft = getPaddingLeft();
    int paddingTop = getPaddingTop();
    int paddingRight = getPaddingRight();
    int paddingBottom = getPaddingBottom();
    final int scrollX = getScrollX();
    final int scrollY = getScrollY();

    int decorCount = 0;

    // First pass - decor views. We need to do this in two passes so that
    // we have the proper offsets for non-decor views later.
    for (int i = 0; i < count; i++) {
        final View child = getChildAt(i);
        if (child.getVisibility() != GONE) {
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            int childLeft = 0;
            int childTop = 0;
            if (lp.isDecor) {
                final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
                final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK;
                switch (hgrav) {
                default:
                    childLeft = paddingLeft;
                    break;
                case Gravity.LEFT:
                    childLeft = paddingLeft;
                    paddingLeft += child.getMeasuredWidth();
                    break;
                case Gravity.CENTER_HORIZONTAL:
                    childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                    break;
                case Gravity.RIGHT:
                    childLeft = width - paddingRight - child.getMeasuredWidth();
                    paddingRight += child.getMeasuredWidth();
                    break;
                }/*from   w  w  w.j  av  a  2s  .  com*/
                switch (vgrav) {
                default:
                    childTop = paddingTop;
                    break;
                case Gravity.TOP:
                    childTop = paddingTop;
                    paddingTop += child.getMeasuredHeight();
                    break;
                case Gravity.CENTER_VERTICAL:
                    childTop = Math.max((height - child.getMeasuredHeight()) / 2, paddingTop);
                    break;
                case Gravity.BOTTOM:
                    childTop = height - paddingBottom - child.getMeasuredHeight();
                    paddingBottom += child.getMeasuredHeight();
                    break;
                }
                if (mOrientation == HORIZONTAL) {
                    childLeft += scrollX;
                } else {
                    childTop += scrollY;
                }
                child.layout(childLeft, childTop, childLeft + child.getMeasuredWidth(),
                        childTop + child.getMeasuredHeight());
                decorCount++;
            }
        }
    }

    final int childWidth = width - paddingLeft - paddingRight;
    final int childHeight = height - paddingTop - paddingBottom;
    // Page views. Do this once we have the right padding offsets from above.
    for (int i = 0; i < count; i++) {
        final View child = getChildAt(i);
        if (child.getVisibility() != GONE) {
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            ItemInfo ii;
            if (!lp.isDecor && (ii = infoForChild(child)) != null) {
                int loff;
                int childLeft = paddingLeft;
                int childTop = paddingTop;
                if (mOrientation == HORIZONTAL) {
                    loff = (int) (childWidth * ii.offset);
                    childLeft += loff;
                } else {
                    loff = (int) (childHeight * ii.offset);
                    childTop += loff;
                }
                if (lp.needsMeasure) {
                    // This was added during layout and needs measurement.
                    // Do it now that we know what we're working with.
                    lp.needsMeasure = false;
                    final int widthSpec = MeasureSpec.makeMeasureSpec((int) (childWidth * lp.widthFactor),
                            MeasureSpec.EXACTLY);
                    final int heightSpec = MeasureSpec.makeMeasureSpec((int) (childHeight),
                            MeasureSpec.EXACTLY);
                    child.measure(widthSpec, heightSpec);
                }
                if (DEBUG)
                    Log.v(TAG, "Positioning #" + i + " " + child + " f=" + ii.object + ":" + childLeft + ","
                            + childTop + " " + child.getMeasuredWidth() + "x" + child.getMeasuredHeight());
                child.layout(childLeft, childTop, childLeft + child.getMeasuredWidth(),
                        childTop + child.getMeasuredHeight());
            }
        }
    }
    if (mOrientation == HORIZONTAL) {
        mTopPageBounds = paddingTop;
        mBottomPageBounds = height - paddingBottom;
    } else {
        mLeftPageBounds = paddingLeft;
        mRightPageBounds = width - paddingRight;
    }
    mDecorChildCount = decorCount;

    if (mFirstLayout) {
        scrollToItem(mCurItem, false, 0, false);
    }
    mFirstLayout = false;
}

From source file:org.hpdroid.base.view.LoopViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as
 * part of a programmatically initiated smooth scroll or a user initiated
 * touch scroll. If you override this method you must call through to the
 * superclass implementation (e.g. super.onPageScrolled(position, offset,
 * offsetPixels)) before onPageScrolled returns.
 *
 * @param position// ww  w  . ja va2 s. com
 *            Position index of the first page currently being displayed.
 *            Page position+1 will be visible if positionOffset is nonzero.
 * @param offset
 *            Value from [0, 1) indicating the offset from the page at
 *            position.
 * @param offsetPixels
 *            Value in pixels indicating the offset from position.
 */
@SuppressLint("RtlHardcoded")
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    mCalledSuper = true;
}

From source file:com.clouder.watch.call.ui.MyViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns./*w  w w. ja  v  a2  s  .c  o m*/
 *
 * @param position     Position index of the first page currently being displayed.
 *                     Page position+1 will be visible if positionOffset is nonzero.
 * @param offset       Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    dispatchOnPageScrolled(position, offset, offsetPixels);

    if (mPageTransformer != null) {
        final int scrollX = getScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;
}

From source file:com.edgar.banner.LoopViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns./*from w w w.  j  a v a2 s  .  c om*/
 *
 * @param position Position index of the first page currently being displayed.
 *                 Page position+1 will be visible if positionOffset is nonzero.
 * @param offset Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    position = getLoopPagerPosition(position);
    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }

    if (mPageTransformer != null) {
        final int scrollX = getScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;
}

From source file:cn.trinea.android.common.view.CycleViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns./*w  w  w  .  j ava2  s. co m*/
 *
 * @param position Position index of the first page currently being displayed.
 *                 Page position+1 will be visible if positionOffset is nonzero.
 * @param offset Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }

    if (mPageTransformer != null) {
        final int scrollX = getScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;
}

From source file:com.android.launcher3.ViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns.//from  w w w  . j  a  va 2 s .co  m
 *
 * @param position     Position index of the first page currently being displayed.
 *                     Page position+1 will be visible if positionOffset is nonzero.
 * @param offset       Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
@CallSuper
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    mPosition = position;
    off = offset;
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    dispatchOnPageScrolled(position, offset, offsetPixels);

    if (mPageTransformer != null) {
        final int scrollX = getScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;
}

From source file:com.minoon.stackviewpagersample.StackViewPager.java

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns./*  www. j a va  2s .c  om*/
 *
 * @param position Position index of the first page currently being displayed.
 *                 Page position+1 will be visible if positionOffset is nonzero.
 * @param offset Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        // [Changed]
        //            final int scrollX = getScrollX();
        final int scrollX = getOverlapScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor)
                continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
            default:
                childLeft = paddingLeft;
                break;
            case Gravity.LEFT:
                childLeft = paddingLeft;
                paddingLeft += child.getWidth();
                break;
            case Gravity.CENTER_HORIZONTAL:
                childLeft = Math.max((width - child.getMeasuredWidth()) / 2, paddingLeft);
                break;
            case Gravity.RIGHT:
                childLeft = width - paddingRight - child.getMeasuredWidth();
                paddingRight += child.getMeasuredWidth();
                break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }

    if (mPageTransformer != null) {
        // [Changed]
        //            final int scrollX = getScrollX();
        final int scrollX = getOverlapScrollX();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();

            if (lp.isDecor)
                continue;

            final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth();
            mPageTransformer.transformPage(child, transformPos);
        }
    }

    mCalledSuper = true;
}

Example usage for android.view Gravity CENTER_HORIZONTAL

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