Java tutorial
/* * Copyright (C) 2015 The Android Open Source Project * * 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 android.support.v7.widget; import android.content.Context; import android.support.v4.view.NestedScrollingParent; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.util.Log; import android.view.View; import android.view.ViewGroup; import android.widget.FrameLayout; public class TestedFrameLayout extends FrameLayout implements NestedScrollingParent { static final int TEST_NESTED_SCROLL_MODE_IGNORE = 0; static final int TEST_NESTED_SCROLL_MODE_CONSUME = 1; private int mNestedScrollMode; private int mNestedFlingMode; private boolean mNestedStopNestedScrollCalled; public TestedFrameLayout(Context context) { super(context); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { RecyclerView recyclerView = getRvChild(); if (recyclerView == null) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); return; } FullControlLayoutParams lp = (FullControlLayoutParams) recyclerView.getLayoutParams(); if (lp.wSpec == null && lp.hSpec == null) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); return; } final int childWidthMeasureSpec; if (lp.wSpec != null) { childWidthMeasureSpec = lp.wSpec; } else if (lp.width == LayoutParams.MATCH_PARENT) { final int width = Math.max(0, getMeasuredWidth() - lp.leftMargin - lp.rightMargin); childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); } else { childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, lp.leftMargin + lp.rightMargin, lp.width); } final int childHeightMeasureSpec; if (lp.hSpec != null) { childHeightMeasureSpec = lp.hSpec; } else if (lp.height == LayoutParams.MATCH_PARENT) { final int height = Math.max(0, getMeasuredHeight() - lp.topMargin - lp.bottomMargin); childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); } else { childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, lp.topMargin + lp.bottomMargin, lp.height); } recyclerView.measure(childWidthMeasureSpec, childHeightMeasureSpec); if (MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY && MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.EXACTLY) { setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(heightMeasureSpec)); } else { setMeasuredDimension( chooseSize(widthMeasureSpec, recyclerView.getWidth() + getPaddingLeft() + getPaddingRight(), getMinimumWidth()), chooseSize(heightMeasureSpec, recyclerView.getHeight() + getPaddingTop() + getPaddingBottom(), getMinimumHeight())); } } public static int chooseSize(int spec, int desired, int min) { final int mode = View.MeasureSpec.getMode(spec); final int size = View.MeasureSpec.getSize(spec); switch (mode) { case View.MeasureSpec.EXACTLY: return size; case View.MeasureSpec.AT_MOST: return Math.min(size, desired); case View.MeasureSpec.UNSPECIFIED: default: return Math.max(desired, min); } } private RecyclerView getRvChild() { for (int i = 0; i < getChildCount(); i++) { if (getChildAt(i) instanceof RecyclerView) { return (RecyclerView) getChildAt(i); } } return null; } @Override protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { return p instanceof FullControlLayoutParams; } @Override protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { return new FullControlLayoutParams(p); } @Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new FullControlLayoutParams(getContext(), attrs); } @Override protected LayoutParams generateDefaultLayoutParams() { return new FullControlLayoutParams(getWidth(), getHeight()); } @Override public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { // Always start nested scroll return mNestedFlingMode == TEST_NESTED_SCROLL_MODE_CONSUME || mNestedScrollMode == TEST_NESTED_SCROLL_MODE_CONSUME; } @Override public boolean onNestedPreFling(View target, float velocityX, float velocityY) { Log.d("TestedFrameLayout", "onNestedPreFling: " + mNestedFlingMode); return mNestedFlingMode == TEST_NESTED_SCROLL_MODE_CONSUME; } @Override public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { if (mNestedScrollMode == TEST_NESTED_SCROLL_MODE_CONSUME) { // We consume all scroll deltas consumed[0] = dx; consumed[1] = dy; } } @Override public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { // ignore } @Override public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { // ignore return false; } @Override public void onNestedScrollAccepted(View child, View target, int axes) { // ignore } @Override public int getNestedScrollAxes() { // We can scroll in both direction return ViewCompat.SCROLL_AXIS_HORIZONTAL | ViewCompat.SCROLL_AXIS_VERTICAL; } @Override public void onStopNestedScroll(View target) { mNestedStopNestedScrollCalled = true; } public boolean stopNestedScrollCalled() { return mNestedStopNestedScrollCalled; } public void setNestedScrollMode(int mode) { mNestedScrollMode = mode; } public void setNestedFlingMode(int mode) { mNestedFlingMode = mode; } public static class FullControlLayoutParams extends FrameLayout.LayoutParams { Integer wSpec; Integer hSpec; public FullControlLayoutParams(Context c, AttributeSet attrs) { super(c, attrs); } public FullControlLayoutParams(int width, int height) { super(width, height); } public FullControlLayoutParams(ViewGroup.LayoutParams source) { super(source); } public FullControlLayoutParams(FrameLayout.LayoutParams source) { super(source); } public FullControlLayoutParams(MarginLayoutParams source) { super(source); } } }