Java tutorial
/* * Copyright (C) 2017. BoBoMEe(wbwjx115@gmail.com) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.bobomee.android.tab_navigator.recyclerview; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.support.annotation.ColorRes; import android.support.annotation.DimenRes; import android.support.annotation.DrawableRes; import android.support.v4.content.ContextCompat; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.View; /** * Created by yqritc on 2015/01/08. */ public abstract class FlexibleDividerDecoration extends RecyclerView.ItemDecoration { private static final int DEFAULT_SIZE = 2; private static final int[] ATTRS = new int[] { android.R.attr.listDivider }; protected enum DividerType { DRAWABLE, PAINT, COLOR } protected DividerType mDividerType = DividerType.DRAWABLE; protected VisibilityProvider mVisibilityProvider; protected PaintProvider mPaintProvider; protected ColorProvider mColorProvider; protected DrawableProvider mDrawableProvider; protected SizeProvider mSizeProvider; protected boolean mShowLastDivider; protected boolean mPositionInsideItem; private Paint mPaint; protected FlexibleDividerDecoration(Builder builder) { if (builder.mPaintProvider != null) { mDividerType = DividerType.PAINT; mPaintProvider = builder.mPaintProvider; } else if (builder.mColorProvider != null) { mDividerType = DividerType.COLOR; mColorProvider = builder.mColorProvider; mPaint = new Paint(); setSizeProvider(builder); } else { mDividerType = DividerType.DRAWABLE; if (builder.mDrawableProvider == null) { TypedArray a = builder.mContext.obtainStyledAttributes(ATTRS); final Drawable divider = a.getDrawable(0); a.recycle(); mDrawableProvider = new DrawableProvider() { @Override public Drawable drawableProvider(int position, RecyclerView parent) { return divider; } }; } else { mDrawableProvider = builder.mDrawableProvider; } mSizeProvider = builder.mSizeProvider; } mVisibilityProvider = builder.mVisibilityProvider; mShowLastDivider = builder.mShowLastDivider; mPositionInsideItem = builder.mPositionInsideItem; } private void setSizeProvider(Builder builder) { mSizeProvider = builder.mSizeProvider; if (mSizeProvider == null) { mSizeProvider = new SizeProvider() { @Override public int dividerSize(int position, RecyclerView parent) { return DEFAULT_SIZE; } }; } } @Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) { RecyclerView.Adapter adapter = parent.getAdapter(); if (adapter == null) { return; } int itemCount = adapter.getItemCount(); int lastDividerOffset = getLastDividerOffset(parent); int validChildCount = parent.getChildCount(); int lastChildPosition = -1; for (int i = 0; i < validChildCount; i++) { View child = parent.getChildAt(i); int childPosition = parent.getChildAdapterPosition(child); if (childPosition < lastChildPosition) { // Avoid remaining divider when animation starts continue; } lastChildPosition = childPosition; if (!mShowLastDivider && childPosition >= itemCount - lastDividerOffset) { // Don't draw divider for last line if mShowLastDivider = false continue; } if (wasDividerAlreadyDrawn(childPosition, parent)) { // No need to draw divider again as it was drawn already by previous column continue; } int groupIndex = getGroupIndex(childPosition, parent); if (mVisibilityProvider.shouldHideDivider(groupIndex, parent)) { continue; } Rect bounds = getDividerBound(groupIndex, parent, child); switch (mDividerType) { case DRAWABLE: Drawable drawable = mDrawableProvider.drawableProvider(groupIndex, parent); drawable.setBounds(bounds); drawable.draw(c); break; case PAINT: mPaint = mPaintProvider.dividerPaint(groupIndex, parent); c.drawLine(bounds.left, bounds.top, bounds.right, bounds.bottom, mPaint); break; case COLOR: mPaint.setColor(mColorProvider.dividerColor(groupIndex, parent)); mPaint.setStrokeWidth(mSizeProvider.dividerSize(groupIndex, parent)); c.drawLine(bounds.left, bounds.top, bounds.right, bounds.bottom, mPaint); break; } } } @Override public void getItemOffsets(Rect rect, View v, RecyclerView parent, RecyclerView.State state) { int position = parent.getChildAdapterPosition(v); int itemCount = parent.getAdapter().getItemCount(); int lastDividerOffset = getLastDividerOffset(parent); if (!mShowLastDivider && position >= itemCount - lastDividerOffset) { // Don't set item offset for last line if mShowLastDivider = false return; } int groupIndex = getGroupIndex(position, parent); if (mVisibilityProvider.shouldHideDivider(groupIndex, parent)) { return; } setItemOffsets(rect, groupIndex, parent); } /** * Check if recyclerview is reverse layout * * @param parent RecyclerView * @return true if recyclerview is reverse layout */ protected boolean isReverseLayout(RecyclerView parent) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof LinearLayoutManager) { return ((LinearLayoutManager) layoutManager).getReverseLayout(); } else { return false; } } /** * In the case mShowLastDivider = false, * Returns offset for how many views we don't have to draw a divider for, * for LinearLayoutManager it is as simple as not drawing the last child divider, * but for a GridLayoutManager it needs to take the span count for the last items into account * until we use the span count configured for the grid. * * @param parent RecyclerView * @return offset for how many views we don't have to draw a divider or 1 if its a * LinearLayoutManager */ private int getLastDividerOffset(RecyclerView parent) { if (parent.getLayoutManager() instanceof GridLayoutManager) { GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager(); GridLayoutManager.SpanSizeLookup spanSizeLookup = layoutManager.getSpanSizeLookup(); int spanCount = layoutManager.getSpanCount(); int itemCount = parent.getAdapter().getItemCount(); for (int i = itemCount - 1; i >= 0; i--) { if (spanSizeLookup.getSpanIndex(i, spanCount) == 0) { return itemCount - i; } } } return 1; } /** * Determines whether divider was already drawn for the row the item is in, * effectively only makes sense for a grid * * @param position current view position to draw divider * @param parent RecyclerView * @return true if the divider can be skipped as it is in the same row as the previous one. */ private boolean wasDividerAlreadyDrawn(int position, RecyclerView parent) { if (parent.getLayoutManager() instanceof GridLayoutManager) { GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager(); GridLayoutManager.SpanSizeLookup spanSizeLookup = layoutManager.getSpanSizeLookup(); int spanCount = layoutManager.getSpanCount(); return spanSizeLookup.getSpanIndex(position, spanCount) > 0; } return false; } /** * Returns a group index for GridLayoutManager. * for LinearLayoutManager, always returns position. * * @param position current view position to draw divider * @param parent RecyclerView * @return group index of items */ private int getGroupIndex(int position, RecyclerView parent) { if (parent.getLayoutManager() instanceof GridLayoutManager) { GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager(); GridLayoutManager.SpanSizeLookup spanSizeLookup = layoutManager.getSpanSizeLookup(); int spanCount = layoutManager.getSpanCount(); return spanSizeLookup.getSpanGroupIndex(position, spanCount); } return position; } protected abstract Rect getDividerBound(int position, RecyclerView parent, View child); protected abstract void setItemOffsets(Rect outRect, int position, RecyclerView parent); /** * Interface for controlling divider visibility */ public interface VisibilityProvider { /** * Returns true if divider should be hidden. * * @param position Divider position (or group index for GridLayoutManager) * @param parent RecyclerView * @return True if the divider at position should be hidden */ boolean shouldHideDivider(int position, RecyclerView parent); } /** * Interface for controlling paint instance for divider drawing */ public interface PaintProvider { /** * Returns {@link Paint} for divider * * @param position Divider position (or group index for GridLayoutManager) * @param parent RecyclerView * @return Paint instance */ Paint dividerPaint(int position, RecyclerView parent); } /** * Interface for controlling divider color */ public interface ColorProvider { /** * Returns {@link android.graphics.Color} value of divider * * @param position Divider position (or group index for GridLayoutManager) * @param parent RecyclerView * @return Color value */ int dividerColor(int position, RecyclerView parent); } /** * Interface for controlling drawable object for divider drawing */ public interface DrawableProvider { /** * Returns drawable instance for divider * * @param position Divider position (or group index for GridLayoutManager) * @param parent RecyclerView * @return Drawable instance */ Drawable drawableProvider(int position, RecyclerView parent); } /** * Interface for controlling divider size */ public interface SizeProvider { /** * Returns size value of divider. * Height for horizontal divider, width for vertical divider * * @param position Divider position (or group index for GridLayoutManager) * @param parent RecyclerView * @return Size of divider */ int dividerSize(int position, RecyclerView parent); } public static class Builder<T extends Builder> { private Context mContext; protected Resources mResources; private PaintProvider mPaintProvider; private ColorProvider mColorProvider; private DrawableProvider mDrawableProvider; private SizeProvider mSizeProvider; private VisibilityProvider mVisibilityProvider = new VisibilityProvider() { @Override public boolean shouldHideDivider(int position, RecyclerView parent) { return false; } }; private boolean mShowLastDivider = false; private boolean mPositionInsideItem = false; public Builder(Context context) { mContext = context; mResources = context.getResources(); } public T paint(final Paint paint) { return paintProvider(new PaintProvider() { @Override public Paint dividerPaint(int position, RecyclerView parent) { return paint; } }); } public T paintProvider(PaintProvider provider) { mPaintProvider = provider; return (T) this; } public T color(final int color) { return colorProvider(new ColorProvider() { @Override public int dividerColor(int position, RecyclerView parent) { return color; } }); } public T colorResId(@ColorRes int colorId) { return color(ContextCompat.getColor(mContext, colorId)); } public T colorProvider(ColorProvider provider) { mColorProvider = provider; return (T) this; } public T drawable(@DrawableRes int id) { return drawable(ContextCompat.getDrawable(mContext, id)); } public T drawable(final Drawable drawable) { return drawableProvider(new DrawableProvider() { @Override public Drawable drawableProvider(int position, RecyclerView parent) { return drawable; } }); } public T drawableProvider(DrawableProvider provider) { mDrawableProvider = provider; return (T) this; } public T size(final int size) { return sizeProvider(new SizeProvider() { @Override public int dividerSize(int position, RecyclerView parent) { return size; } }); } public T sizeResId(@DimenRes int sizeId) { return size(mResources.getDimensionPixelSize(sizeId)); } public T sizeProvider(SizeProvider provider) { mSizeProvider = provider; return (T) this; } public T visibilityProvider(VisibilityProvider provider) { mVisibilityProvider = provider; return (T) this; } public T showLastDivider() { mShowLastDivider = true; return (T) this; } public T positionInsideItem(boolean positionInsideItem) { mPositionInsideItem = positionInsideItem; return (T) this; } protected void checkBuilderParams() { if (mPaintProvider != null) { if (mColorProvider != null) { throw new IllegalArgumentException( "Use setColor method of Paint class to specify line color. Do not provider ColorProvider if you set PaintProvider."); } if (mSizeProvider != null) { throw new IllegalArgumentException( "Use setStrokeWidth method of Paint class to specify line size. Do not provider SizeProvider if you set PaintProvider."); } } } } }