Java RecyclerView.Recycler方法代碼示例

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
private int fixLayoutEndGap(int endOffset, RecyclerView.Recycler recycler,
                            RecyclerView.State state, boolean canOffsetChildren) {
    int gap = mOrientationHelper.getEndAfterPadding() - endOffset;
    int fixOffset = 0;
    if (gap > 0) {
        fixOffset = -scrollByInner(-gap, recycler, state);
    } else {
        return 0; // nothing to fix
    }
    // move offset according to scroll amount
    endOffset += fixOffset;
    if (canOffsetChildren) {
        // re-calculate gap, see if we could fix it
        gap = mOrientationHelper.getEndAfterPadding() - endOffset;
        if (gap > 0) {
            mOrientationHelper.offsetChildren(gap);
            return gap + fixOffset;
        }
    }
    return fixOffset;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
/**
 * @return The final offset amount for children
 */
private int fixLayoutStartGapExpose(int startOffset, RecyclerView.Recycler recycler,
                                    RecyclerView.State state, boolean canOffsetChildren) {
    int gap = startOffset - mOrientationHelper.getStartAfterPadding();
    int fixOffset = 0;
    if (gap > 0) {
        // check if we should fix this gap.
        fixOffset = -scrollInternalBy(gap, recycler, state);
    } else {
        return 0; // nothing to fix
    }
    startOffset += fixOffset;
    if (canOffsetChildren) {
        // re-calculate gap, see if we could fix it
        gap = startOffset - mOrientationHelper.getStartAfterPadding();
        if (gap > 0) {
            mOrientationHelper.offsetChildren(-gap);
            return fixOffset - gap;
        }
    }
    return fixOffset;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
/** @return views which moved from screen, but not deleted*/
@Override
public DisappearingViewsContainer getDisappearingViews(RecyclerView.Recycler recycler) {
    final List<RecyclerView.ViewHolder> scrapList = recycler.getScrapList();
    DisappearingViewsContainer container = new DisappearingViewsContainer();

    for (RecyclerView.ViewHolder holder : scrapList) {
        final View child = holder.itemView;
        final RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams) child.getLayoutParams();
        if (!lp.isItemRemoved()) {
            if (lp.getViewAdapterPosition() < canvas.getMinPositionOnScreen()) {
                container.backwardViews.put(lp.getViewAdapterPosition(), child);
            } else if (lp.getViewAdapterPosition() > canvas.getMaxPositionOnScreen()) {
                container.forwardViews.put(lp.getViewAdapterPosition(), child);
            }
        }
    }

    return container;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
protected void layoutChunkAddView(View view, RecyclerView.Recycler recycler, RecyclerView.LayoutParams params, LayoutState layoutState) {
    if (layoutState.mScrapList == null) {
        if (mShouldReverseLayout == (layoutState.mLayoutDirection
                == LayoutState.LAYOUT_START)) {
            /**熟悉的{@link RecyclerView#addView(View)}*/
            addView(view);//this
        } else {
            addView(view, 0);
        }
    } else {
        if (mShouldReverseLayout == (layoutState.mLayoutDirection
                == LayoutState.LAYOUT_START)) {
            addDisappearingView(view);
        } else {
            addDisappearingView(view, 0);
        }
    }
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
/**
 * Remove and recycle all items in this 'row'. If the row includes a row-spanning cell then all
 * cells in the spanned rows will be removed.
 */
private void recycleRow(
        int rowIndex, RecyclerView.Recycler recycler, RecyclerView.State state) {
    int firstPositionInRow = getFirstPositionInSpannedRow(rowIndex);
    int lastPositionInRow = getLastPositionInSpannedRow(rowIndex, state);
    int toRemove = lastPositionInRow;
    while (toRemove >= firstPositionInRow) {
        int index = toRemove - firstVisiblePosition;
        removeAndRecycleViewAt(index, recycler);
        toRemove--;
    }
    if (rowIndex == firstVisibleRow) {
        firstVisiblePosition = lastPositionInRow + 1;
        firstVisibleRow = getRowIndex(firstVisiblePosition);
    }
    if (rowIndex == lastVisibleRow) {
        lastVisiblePosition = firstPositionInRow - 1;
        lastVisibleRow = getRowIndex(lastVisiblePosition);
    }
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
private void runPostLayout(RecyclerView.Recycler recycler, RecyclerView.State state, int scrolled) {
    mNested--;
    if (mNested <= 0) {
        mNested = 0;
        final int startPosition = findFirstVisibleItemPosition();
        final int endPosition = findLastVisibleItemPosition();
        for (LayoutHelper layoutHelper : mHelperFinder) {
            try {
                layoutHelper.afterLayout(recycler, state, startPosition, endPosition, scrolled, this);
            } catch (Exception e) {
                if (VirtualLayoutManager.sDebuggable) {
                    throw e;
                }
            }
        }
    }
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
@Override
protected RecyclerView.LayoutManager getLayoutManager() {
    LinearLayoutManager manager = new LinearLayoutManager(this.getContext()) {
        @Override
        public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
            try {
                super.onLayoutChildren(recycler, state);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    };
    return manager;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
@Override
public void afterLayout(RecyclerView.Recycler recycler, RecyclerView.State state, int startPosition, int endPosition, int scrolled, LayoutManagerHelper helper) {
    super.afterLayout(recycler, state, startPosition, endPosition, scrolled, helper);
    mLayoutWithAnchor = false;
    if (startPosition > getRange().getUpper() || endPosition < getRange().getLower()) {
        //do not in visible screen, skip
        return;
    }
    if (!state.isPreLayout() && helper.getChildCount() > 0) {
        // call after doing layout, to check whether there is a gap between staggered layout and other layouts
        ViewCompat.postOnAnimation(helper.getChildAt(0), checkForGapsRunnable);
    }
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
@Override
public void beforeLayout(RecyclerView.Recycler recycler, RecyclerView.State state, LayoutManagerHelper helper) {
    super.beforeLayout(recycler, state, helper);


    if (mFixView != null && helper.isViewHolderUpdated(mFixView)) {
        // recycle view for later usage
        helper.removeChildView(mFixView);
        recycler.recycleView(mFixView);
        mFixView = null;
    }

    mDoNormalHandle = false;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
/**
 * @param recycler the object
 * @param state    the state
 */
@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
    try {
        super.onLayoutChildren(recycler, state);
    } catch (Exception e) {

    }
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
void onAnchorReady(RecyclerView.Recycler recycler, RecyclerView.State state,
                   AnchorInfo anchorInfo, int firstLayoutItemDirection) {
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
@Override
public void afterLayout(RecyclerView.Recycler recycler, RecyclerView.State state,
                        int startPosition, int endPosition, int scrolled,
                        LayoutManagerHelper helper) {
    if (DEBUG) {
        Log.d(TAG, "call afterLayout() on " + this.getClass().getSimpleName());
    }


    if (requireLayoutView()) {
        if (isValidScrolled(scrolled) && mLayoutView != null) {
            // initial layout do reset
            mLayoutRegion.union(mLayoutView.getLeft(), mLayoutView.getTop(), mLayoutView.getRight(), mLayoutView.getBottom());
        }


        if (!mLayoutRegion.isEmpty()) {
            if (isValidScrolled(scrolled)) {
                if (helper.getOrientation() == VirtualLayoutManager.VERTICAL) {
                    mLayoutRegion.offset(0, -scrolled);
                } else {
                    mLayoutRegion.offset(-scrolled, 0);
                }
            }
            int contentWidth = helper.getContentWidth();
            int contentHeight = helper.getContentHeight();
            if (helper.getOrientation() == VirtualLayoutManager.VERTICAL ?
                    mLayoutRegion.intersects(0, -contentHeight / 4, contentWidth, contentHeight + contentHeight / 4) :
                    mLayoutRegion.intersects(-contentWidth / 4, 0, contentWidth + contentWidth / 4, contentHeight)) {

                if (mLayoutView == null) {
                    mLayoutView = helper.generateLayoutView();
                    helper.addOffFlowView(mLayoutView, true);
                }
                //finally fix layoutRegion's height and with here to avoid visual blank
                if (helper.getOrientation() == VirtualLayoutManager.VERTICAL) {
                    mLayoutRegion.left = helper.getPaddingLeft() + mMarginLeft;
                    mLayoutRegion.right = helper.getContentWidth() - helper.getPaddingRight() - mMarginRight;
                } else {
                    mLayoutRegion.top = helper.getPaddingTop() + mMarginTop;
                    mLayoutRegion.bottom = helper.getContentWidth() - helper.getPaddingBottom() - mMarginBottom;
                }

                bindLayoutView(mLayoutView);
                return;
            } else {
                mLayoutRegion.set(0, 0, 0, 0);
                if (mLayoutView != null) {
                    mLayoutView.layout(0, 0, 0, 0);
                }
            }
        }
    }

    if (mLayoutView != null) {
        if (mLayoutViewUnBindListener != null) {
            mLayoutViewUnBindListener.onUnbind(mLayoutView, this);
        }
        helper.removeChildView(mLayoutView);
        mLayoutView = null;
    }

}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
@Override
public int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state) {
	if (getChildCount() == 0) {
		return 0;
	}
	
	//Take leftmost measurements from the top-left child
	final View topView = getChildAt(0);
	//Take rightmost measurements from the top-right child
	final View bottomView = getChildAt(mVisibleColumnCount-1);
	
	//Optimize the case where the entire data set is too small to scroll
	int viewSpan = getDecoratedRight(bottomView) - getDecoratedLeft(topView);
	if (viewSpan < getHorizontalSpace()) {
		//We cannot scroll in either direction
		return 0;
	}
	
	int delta;
	boolean leftBoundReached = getFirstVisibleColumn() == 0;
	boolean rightBoundReached = getLastVisibleColumn() >= getTotalColumnCount();
	if (dx > 0) { // Contents are scrolling left
		//Check right bound
		if (rightBoundReached) {
			//If we've reached the last column, enforce limits
			int rightOffset = getHorizontalSpace() - getDecoratedRight(bottomView) + getPaddingRight();
			delta = Math.max(-dx, rightOffset);
		} else {
			//No limits while the last column isn't visible
			delta = -dx;
		}
	} else { // Contents are scrolling right
		//Check left bound
		if (leftBoundReached) {
			int leftOffset = -getDecoratedLeft(topView) + getPaddingLeft();
			delta = Math.min(-dx, leftOffset);
		} else {
			delta = -dx;
		}
	}
	
	offsetChildrenHorizontal(delta);
	
	if (dx > 0) {
		if (getDecoratedRight(topView) < 0 && !rightBoundReached) {
			fillGrid(DIRECTION_END, recycler, state);
		} else if (!rightBoundReached) {
			fillGrid(DIRECTION_NONE, recycler, state);
		}
	} else {
		if (getDecoratedLeft(topView) > 0 && !leftBoundReached) {
			fillGrid(DIRECTION_START, recycler, state);
		} else if (!leftBoundReached) {
			fillGrid(DIRECTION_NONE, recycler, state);
		}
	}

       /*
        * Return value determines if a boundary has been reached
        * (for edge effects and flings). If returned value does not
        * match original delta (passed in), RecyclerView will draw
        * an edge effect.
        */
	return -delta;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
/**
 * Lay out a given 'row'. We might actually add more that one row if the requested row contains
 * a row-spanning cell. Returns the pixel height of the rows laid out.
 * <p>
 * To simplify logic & book-keeping, views are attached in adapterData order, that is child 0 will
 * always be the earliest position displayed etc.
 */
private int layoutRow(
        int rowIndex, int startTop, RecyclerView.Recycler recycler, RecyclerView.State state) {
    int firstPositionInRow = getFirstPositionInSpannedRow(rowIndex);
    int lastPositionInRow = getLastPositionInSpannedRow(rowIndex, state);
    boolean containsRemovedItems = false;

    int insertPosition = (rowIndex < firstVisibleRow) ? 0 : getChildCount();
    for (int position = firstPositionInRow;
         position <= lastPositionInRow;
         position++, insertPosition++) {

        View view = recycler.getViewForPosition(position);
        LayoutParams lp = (LayoutParams) view.getLayoutParams();
        containsRemovedItems |= lp.isItemRemoved();
        GridCell cell = cells.get(position);
        addView(view, insertPosition);

        // TODO use orientation helper
        int wSpec = getChildMeasureSpec(
                cellBorders[cell.column + cell.columnSpan] - cellBorders[cell.column],
                View.MeasureSpec.EXACTLY, 0, lp.width, false);
        int hSpec = getChildMeasureSpec(cell.rowSpan * cellHeight,
                View.MeasureSpec.EXACTLY, 0, lp.height, true);
        measureChildWithDecorationsAndMargin(view, wSpec, hSpec);

        int left = cellBorders[cell.column] + lp.leftMargin;
        int top = startTop + (cell.row * cellHeight) + lp.topMargin;
        int right = left + getDecoratedMeasuredWidth(view);
        int bottom = top + getDecoratedMeasuredHeight(view);
        layoutDecorated(view, left, top, right, bottom);
        lp.columnSpan = cell.columnSpan;
        lp.rowSpan = cell.rowSpan;
    }

    if (firstPositionInRow < firstVisiblePosition) {
        firstVisiblePosition = firstPositionInRow;
        firstVisibleRow = getRowIndex(firstVisiblePosition);
    }
    if (lastPositionInRow > lastVisiblePosition) {
        lastVisiblePosition = lastPositionInRow;
        lastVisibleRow = getRowIndex(lastVisiblePosition);
    }
    if (containsRemovedItems) return 0; // don't consume space for rows with disappearing items

    GridCell first = cells.get(firstPositionInRow);
    GridCell last = cells.get(lastPositionInRow);
    return (last.row + last.rowSpan - first.row) * cellHeight;
}
 

import android.support.v7.widget.RecyclerView; //導入方法依賴的package包/類
@Override
public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state) {
	if (getChildCount() == 0) {
		return 0;
	}
	
	//Take top measurements from the top-left child
	final View topView = getChildAt(0);
	//Take bottom measurements from the bottom-right child.
	final View bottomView = getChildAt(getChildCount()-1);
	
	//Optimize the case where the entire data set is too small to scroll
	int viewSpan = getDecoratedBottom(bottomView) - getDecoratedTop(topView);
	if (viewSpan < getVerticalSpace()) {
		//We cannot scroll in either direction
		return 0;
	}
	
	int delta;
	int maxRowCount = getTotalRowCount();
	boolean topBoundReached = getFirstVisibleRow() == 0;
	boolean bottomBoundReached = getLastVisibleRow() >= maxRowCount;
	if (dy > 0) { // Contents are scrolling up
		//Check against bottom bound
		if (bottomBoundReached) {
			//If we've reached the last row, enforce limits
			int bottomOffset;
			if (rowOfIndex(getChildCount() - 1) >= (maxRowCount - 1)) {
				//We are truly at the bottom, determine how far
				bottomOffset = getVerticalSpace() - getDecoratedBottom(bottomView)
						+ getPaddingBottom();
			} else {
                   /*
                    * Extra space added to account for allowing bottom space in the grid.
                    * This occurs when the overlap in the last row is not large enough to
                    * ensure that at least one element in that row isn't fully recycled.
                    */
				bottomOffset = getVerticalSpace() - (getDecoratedBottom(bottomView)
						+ mDecoratedChildHeight) + getPaddingBottom();
			}
			
			delta = Math.max(-dy, bottomOffset);
		} else {
			//No limits while the last row isn't visible
			delta = -dy;
		}
	} else { // Contents are scrolling down
		//Check against top bound
		if (topBoundReached) {
			int topOffset = -getDecoratedTop(topView) + getPaddingTop();
			
			delta = Math.min(-dy, topOffset);
		} else {
			delta = -dy;
		}
	}
	
	offsetChildrenVertical(delta);
	
	if (dy > 0) {
		if (getDecoratedBottom(topView) < 0 && !bottomBoundReached) {
			fillGrid(DIRECTION_DOWN, recycler, state);
		} else if (!bottomBoundReached) {
			fillGrid(DIRECTION_NONE, recycler, state);
		}
	} else {
		if (getDecoratedTop(topView) > 0 && !topBoundReached) {
			fillGrid(DIRECTION_UP, recycler, state);
		} else if (!topBoundReached) {
			fillGrid(DIRECTION_NONE, recycler, state);
		}
	}

       /*
        * Return value determines if a boundary has been reached
        * (for edge effects and flings). If returned value does not
        * match original delta (passed in), RecyclerView will draw
        * an edge effect.
        */
	return -delta;
}