feat(android): add HippyRecyclerView extends from androidx recyclerview

android/sdk/build.gradle

@@ -137,7 +137,8 @@ android {
 
 dependencies {
   api fileTree(dir: 'libs', include: ['*.jar'])
-  implementation 'com.android.support:support-annotations:28.0.0'
+  implementation 'androidx.annotation:annotation:1.0.0'
+  implementation 'androidx.recyclerview:recyclerview:1.1.0'
   if (!INCLUDE_SUPPORT_UI.toBoolean()) {
     compileOnly('com.tencent.mtt:support-ui:99.2.3')
   }

android/sdk/proguard-rules.pro

@@ -186,3 +186,19 @@ public <fields>;
 protected <fields>;
 }
 
+-keepclasseswithmembers class androidx.recyclerview.widget.** {
+public <methods>;
+}
+
+-keepclasseswithmembers class androidx.recyclerview.widget.** {
+protected <methods>;
+}
+
+-keepclasseswithmembers class androidx.recyclerview.widget.** {
+public <fields>;
+}
+
+-keepclasseswithmembers class androidx.recyclerview.widget.** {
+protected <fields>;
+}
+

android/sdk/src/main/java/androidx/recyclerview/widget/EasyLinearLayoutManager.java

@@ -0,0 +1,159 @@
+/* Tencent is pleased to support the open source community by making easy-recyclerview-helper available.
+ * Copyright (C) 2020 THL A29 Limited, a Tencent company. All rights reserved.
+ *
+ * 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 androidx.recyclerview.widget;
+
+import android.content.Context;
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView.Adapter;
+import androidx.recyclerview.widget.RecyclerView.LayoutParams;
+import androidx.recyclerview.widget.RecyclerView.State;
+import android.util.AttributeSet;
+import android.view.View;
+import java.util.HashMap;
+
+public class EasyLinearLayoutManager extends LinearLayoutManager {
+
+    /**
+     * 无效的高度
+     */
+    public static final int INVALID_HEIGHT = -1;
+    private static final LayoutParams ITEM_LAYOUT_PARAMS = new LayoutParams(0, 0);
+    /**
+     * 由于排版后才知道对应item的高度，topMargin和bottomMargin，所以这里缓存一下这些值
+     */
+    protected HashMap<Integer, Integer> itemHeightMaps = new HashMap<>();
+    protected HashMap<Integer, Integer> itemTopMarginMaps = new HashMap<>();
+    protected HashMap<Integer, Integer> itemBottomMarginMaps = new HashMap<>();
+
+    public EasyLinearLayoutManager(Context context) {
+        super(context);
+    }
+
+    public EasyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
+        super(context, orientation, reverseLayout);
+    }
+
+    public EasyLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+
+    /**
+     * 排版完成后，缓存view的排版信息
+     */
+    @Override
+    public void layoutDecoratedWithMargins(@NonNull View child, int left, int top, int right, int bottom) {
+        super.layoutDecoratedWithMargins(child, left, top, right, bottom);
+        cacheItemLayoutParams(bottom - top, (LayoutParams) child.getLayoutParams(), getPosition(child));
+    }
+
+    /**
+     * 缓存Item排版信息，缓存信息有两种来源
+     * 一种是排版过程中的得到实际上屏的排版信息 {@link #layoutDecoratedWithMargins(View, int, int, int, int)}
+     * 一种是从adapter获取的item的预排版信息 {@link #getItemHeightFromAdapter(int)}
+     *
+     * @param height item的高度
+     * @param layoutParams 排版参数
+     * @param position 位置
+     */
+    private void cacheItemLayoutParams(int height, LayoutParams layoutParams, int position) {
+        itemBottomMarginMaps.put(position, layoutParams.bottomMargin);
+        itemTopMarginMaps.put(position, layoutParams.topMargin);
+        itemHeightMaps.put(position, height);
+    }
+
+    /**
+     * 从adapter 获取position对应的排版信息，这里不需要排版，是item预先指定的高度
+     */
+    int getItemHeightFromAdapter(int position) {
+        Adapter adapter = mRecyclerView.getAdapter();
+        if (adapter instanceof IItemLayoutParams) {
+            IItemLayoutParams layoutInfo = (IItemLayoutParams) adapter;
+            resetLayoutParams();
+            layoutInfo.getItemLayoutParams(position, ITEM_LAYOUT_PARAMS);
+            if (ITEM_LAYOUT_PARAMS.height >= 0) {
+                cacheItemLayoutParams(ITEM_LAYOUT_PARAMS.height, ITEM_LAYOUT_PARAMS, position);
+                return ITEM_LAYOUT_PARAMS.height + ITEM_LAYOUT_PARAMS.bottomMargin + ITEM_LAYOUT_PARAMS.topMargin;
+            }
+        }
+        return INVALID_HEIGHT;
+    }
+
+    /**
+     * 清除之前的缓存数据,ITEM_LAYOUT_PARAMS 不是最终用来排版的，只是一个参数的载体
+     */
+    private static void resetLayoutParams() {
+        ITEM_LAYOUT_PARAMS.height = 0;
+        ITEM_LAYOUT_PARAMS.topMargin = 0;
+        ITEM_LAYOUT_PARAMS.rightMargin = 0;
+        ITEM_LAYOUT_PARAMS.leftMargin = 0;
+        ITEM_LAYOUT_PARAMS.bottomMargin = 0;
+    }
+
+    /**
+     * 计算position以前（包含position）的高度，如果发现其中有一个没有缓存，那么得出来的值是无效的
+     */
+    int getHeightUntilPosition(int position) {
+        int totalHeight = 0;
+        for (int i = 0; i <= position; i++) {
+            Integer height = itemHeightMaps.get(i);
+            if (height == null) {
+                height = getItemHeightFromAdapter(i);
+            }
+            if (height != null && height != INVALID_HEIGHT) {
+                totalHeight += height;
+            } else {
+                return INVALID_HEIGHT;
+            }
+        }
+        return totalHeight;
+    }
+
+    /**
+     * 由于父类的computeVerticalScrollOffset是基于平均值计算高度。对于Item类型和高度不一样的情况，计算是有误差的。
+     * 用第一个可见view的前面总的内容高度减去第一个可见view的底部位置
+     *
+     * @return 当前的内容偏移，也就是被推出顶部以外的内容高度。
+     */
+    @Override
+    public int computeVerticalScrollOffset(State state) {
+        if (getChildCount() <= 0 || getItemCount() <= 0) {
+            return 0;
+        }
+        int firstVisiblePosition = findFirstVisibleItemPosition();
+        View firstVisibleView = findViewByPosition(firstVisiblePosition);
+        int heightUntilPosition = getHeightUntilPosition(firstVisiblePosition);
+        if (firstVisibleView != null && heightUntilPosition != INVALID_HEIGHT) {
+            return heightUntilPosition - mOrientationHelper.getDecoratedEnd(firstVisibleView);
+        }
+        return super.computeVerticalScrollOffset(state);
+    }
+
+
+    /**
+     * 由于父类的computeVerticalScrollRange是基于平均值计算高度。对于Item类型和高度不一样的情况，计算是有误差的。
+     *
+     * @return 内容的总高度
+     **/
+    @Override
+    public int computeVerticalScrollRange(State state) {
+        int heightUntilPosition = getHeightUntilPosition(getItemCount() - 1);
+        if (heightUntilPosition != INVALID_HEIGHT) {
+            return heightUntilPosition;
+        }
+        return super.computeVerticalScrollRange(state);
+    }
+}