Java LayoutManager.canScrollHorizontally方法代码示例

import android.support.v7.widget.RecyclerView.LayoutManager; //导入方法依赖的package包/类
public void onMoved(RecyclerView recyclerView, ViewHolder viewHolder, int fromPos, ViewHolder target, int toPos, int x, int y) {
    LayoutManager layoutManager = recyclerView.getLayoutManager();
    if (layoutManager instanceof ViewDropHandler) {
        ((ViewDropHandler) layoutManager).prepareForDrop(viewHolder.itemView, target.itemView, x, y);
        return;
    }
    if (layoutManager.canScrollHorizontally()) {
        if (layoutManager.getDecoratedLeft(target.itemView) <= recyclerView.getPaddingLeft()) {
            recyclerView.scrollToPosition(toPos);
        }
        if (layoutManager.getDecoratedRight(target.itemView) >= recyclerView.getWidth() - recyclerView.getPaddingRight()) {
            recyclerView.scrollToPosition(toPos);
        }
    }
    if (layoutManager.canScrollVertically()) {
        if (layoutManager.getDecoratedTop(target.itemView) <= recyclerView.getPaddingTop()) {
            recyclerView.scrollToPosition(toPos);
        }
        if (layoutManager.getDecoratedBottom(target.itemView) >= recyclerView.getHeight() - recyclerView.getPaddingBottom()) {
            recyclerView.scrollToPosition(toPos);
        }
    }
}
 

import android.support.v7.widget.RecyclerView.LayoutManager; //导入方法依赖的package包/类
private ViewHolder findSwipedView(MotionEvent motionEvent) {
    LayoutManager lm = this.mRecyclerView.getLayoutManager();
    if (this.mActivePointerId == -1) {
        return null;
    }
    int pointerIndex = MotionEventCompat.findPointerIndex(motionEvent, this.mActivePointerId);
    float dy = MotionEventCompat.getY(motionEvent, pointerIndex) - this.mInitialTouchY;
    float absDx = Math.abs(MotionEventCompat.getX(motionEvent, pointerIndex) - this.mInitialTouchX);
    float absDy = Math.abs(dy);
    if (absDx < ((float) this.mSlop) && absDy < ((float) this.mSlop)) {
        return null;
    }
    if (absDx > absDy && lm.canScrollHorizontally()) {
        return null;
    }
    if (absDy > absDx && lm.canScrollVertically()) {
        return null;
    }
    View child = findChildView(motionEvent);
    if (child != null) {
        return this.mRecyclerView.getChildViewHolder(child);
    }
    return null;
}
 

import android.support.v7.widget.RecyclerView.LayoutManager; //导入方法依赖的package包/类
public int calculateDxToMakeVisible(View view, int snapPreference) {
    LayoutManager layoutManager = getLayoutManager();
    if (layoutManager == null || !layoutManager.canScrollHorizontally()) {
        return 0;
    }
    LayoutParams params = (LayoutParams) view.getLayoutParams();
    return calculateDtToFit(layoutManager.getDecoratedLeft(view) - params.leftMargin, layoutManager.getDecoratedRight(view) + params.rightMargin, layoutManager.getPaddingLeft(), layoutManager.getWidth() - layoutManager.getPaddingRight(), snapPreference);
}
 

import android.support.v7.widget.RecyclerView.LayoutManager; //导入方法依赖的package包/类
private boolean scrollIfNecessary() {
    if (this.mSelected == null) {
        this.mDragScrollStartTimeInMs = Long.MIN_VALUE;
        return false;
    }
    long scrollDuration;
    long now = System.currentTimeMillis();
    if (this.mDragScrollStartTimeInMs == Long.MIN_VALUE) {
        scrollDuration = 0;
    } else {
        scrollDuration = now - this.mDragScrollStartTimeInMs;
    }
    LayoutManager lm = this.mRecyclerView.getLayoutManager();
    if (this.mTmpRect == null) {
        this.mTmpRect = new Rect();
    }
    int scrollX = 0;
    int scrollY = 0;
    lm.calculateItemDecorationsForChild(this.mSelected.itemView, this.mTmpRect);
    if (lm.canScrollHorizontally()) {
        int curX = (int) (this.mSelectedStartX + this.mDx);
        int leftDiff = (curX - this.mTmpRect.left) - this.mRecyclerView.getPaddingLeft();
        if (this.mDx < 0.0f && leftDiff < 0) {
            scrollX = leftDiff;
        } else if (this.mDx > 0.0f) {
            int rightDiff = ((this.mSelected.itemView.getWidth() + curX) + this.mTmpRect.right) - (this.mRecyclerView.getWidth() - this.mRecyclerView.getPaddingRight());
            if (rightDiff > 0) {
                scrollX = rightDiff;
            }
        }
    }
    if (lm.canScrollVertically()) {
        int curY = (int) (this.mSelectedStartY + this.mDy);
        int topDiff = (curY - this.mTmpRect.top) - this.mRecyclerView.getPaddingTop();
        if (this.mDy < 0.0f && topDiff < 0) {
            scrollY = topDiff;
        } else if (this.mDy > 0.0f) {
            int bottomDiff = ((this.mSelected.itemView.getHeight() + curY) + this.mTmpRect.bottom) - (this.mRecyclerView.getHeight() - this.mRecyclerView.getPaddingBottom());
            if (bottomDiff > 0) {
                scrollY = bottomDiff;
            }
        }
    }
    if (scrollX != 0) {
        scrollX = this.mCallback.interpolateOutOfBoundsScroll(this.mRecyclerView, this.mSelected.itemView.getWidth(), scrollX, this.mRecyclerView.getWidth(), scrollDuration);
    }
    if (scrollY != 0) {
        scrollY = this.mCallback.interpolateOutOfBoundsScroll(this.mRecyclerView, this.mSelected.itemView.getHeight(), scrollY, this.mRecyclerView.getHeight(), scrollDuration);
    }
    if (scrollX == 0 && scrollY == 0) {
        this.mDragScrollStartTimeInMs = Long.MIN_VALUE;
        return false;
    }
    if (this.mDragScrollStartTimeInMs == Long.MIN_VALUE) {
        this.mDragScrollStartTimeInMs = now;
    }
    this.mRecyclerView.scrollBy(scrollX, scrollY);
    return true;
}
 

import android.support.v7.widget.RecyclerView.LayoutManager; //导入方法依赖的package包/类
/***
 * Well composition does not work so we copy this method from {@link LinearSnapHelper}.
 * That sucks!
 *
 * @param layoutManager
 * @param velocityX
 * @param velocityY
 * @return
 */
@Override
public int findTargetSnapPosition(final LayoutManager layoutManager, final int velocityX, final int velocityY) {
    if (!(layoutManager instanceof RecyclerView.SmoothScroller.ScrollVectorProvider)) {
        return RecyclerView.NO_POSITION;
    }

    final int itemCount = layoutManager.getItemCount();
    if (itemCount == 0) {
        return RecyclerView.NO_POSITION;
    }

    final View currentView = findSnapView(layoutManager);
    if (currentView == null) {
        return RecyclerView.NO_POSITION;
    }

    final int currentPosition = layoutManager.getPosition(currentView);
    if (currentPosition == RecyclerView.NO_POSITION) {
        return RecyclerView.NO_POSITION;
    }

    RecyclerView.SmoothScroller.ScrollVectorProvider vectorProvider =
            (RecyclerView.SmoothScroller.ScrollVectorProvider) layoutManager;
    // deltaJumps sign comes from the velocity which may not match the order of children in
    // the LayoutManager. To overcome this, we ask for a vector from the LayoutManager to
    // get the direction.
    PointF vectorForEnd = vectorProvider.computeScrollVectorForPosition(itemCount - 1);
    if (vectorForEnd == null) {
        // cannot get a vector for the given position.
        return RecyclerView.NO_POSITION;
    }

    int vDeltaJump, hDeltaJump;
    if (layoutManager.canScrollHorizontally()) {
        hDeltaJump = estimateNextPositionDiffForFling(layoutManager,
                getHorizontalHelper(layoutManager), velocityX, 0);
        if (vectorForEnd.x < 0) {
            hDeltaJump = -hDeltaJump;
        }
    } else {
        hDeltaJump = 0;
    }
    if (layoutManager.canScrollVertically()) {
        vDeltaJump = estimateNextPositionDiffForFling(layoutManager,
                getVerticalHelper(layoutManager), 0, velocityY);
        if (vectorForEnd.y < 0) {
            vDeltaJump = -vDeltaJump;
        }
    } else {
        vDeltaJump = 0;
    }

    int deltaJump = layoutManager.canScrollVertically() ? vDeltaJump : hDeltaJump;
    if (deltaJump == 0) {
        return RecyclerView.NO_POSITION;
    }

    int targetPos = currentPosition + deltaJump;
    if (targetPos < 0) {
        targetPos = 0;
    }
    if (targetPos >= itemCount) {
        targetPos = itemCount - 1;
    }
    return targetPos;
}
 

import android.support.v7.widget.RecyclerView.LayoutManager; //导入方法依赖的package包/类
/**
 * Override this method to snap to a particular point within the target view or the container
 * view on any axis.
 * <p>
 * This method is called when the {@link SnapHelper} has intercepted a fling and it needs
 * to know the exact distance required to scroll by in order to snap to the target view.
 *
 * @param layoutManager the {@link RecyclerView.LayoutManager} associated with the attached
 *                      {@link RecyclerView}
 * @param targetView the target view that is chosen as the view to snap
 *
 * @return the output coordinates the put the result into. out[0] is the distance
 * on horizontal axis and out[1] is the distance on vertical axis.
 */
@Nullable
@Override
public int[] calculateDistanceToFinalSnap(@NonNull final LayoutManager layoutManager, @NonNull final View targetView) {
    int[] out = new int[2];
    out[0] = layoutManager.canScrollHorizontally() ? getXCoordinateToSnapPos(layoutManager, targetView) : 0;
    out[1] = layoutManager.canScrollVertically() ? getYCoordinateToSnapPos(layoutManager, targetView) : 0;
    return out;
}