/* * Copyright 2014 Soichiro Kashima * * 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.github.ksoichiro.android.observablescrollview.samples; import android.os.Bundle; import android.support.v4.view.ViewCompat; import android.support.v7.widget.Toolbar; import android.view.View; import com.github.ksoichiro.android.observablescrollview.ObservableScrollView; import com.github.ksoichiro.android.observablescrollview.ObservableScrollViewCallbacks; import com.github.ksoichiro.android.observablescrollview.ScrollState; import com.github.ksoichiro.android.observablescrollview.ScrollUtils; import com.nineoldandroids.view.ViewHelper; import com.nineoldandroids.view.ViewPropertyAnimator; public class StickyHeaderScrollViewActivity extends BaseActivity implements ObservableScrollViewCallbacks { private View mHeaderView; private View mToolbarView; private ObservableScrollView mScrollView; private int mBaseTranslationY; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_stickyheaderscrollview); setSupportActionBar((Toolbar) findViewById(R.id.toolbar)); mHeaderView = findViewById(R.id.header); ViewCompat.setElevation(mHeaderView, getResources().getDimension(R.dimen.toolbar_elevation)); mToolbarView = findViewById(R.id.toolbar); mScrollView = (ObservableScrollView) findViewById(R.id.scroll); mScrollView.setScrollViewCallbacks(this); } @Override public void onScrollChanged(int scrollY, boolean firstScroll, boolean dragging) { if (dragging) { int toolbarHeight = mToolbarView.getHeight(); if (firstScroll) { float currentHeaderTranslationY = ViewHelper.getTranslationY(mHeaderView); if (-toolbarHeight < currentHeaderTranslationY) { mBaseTranslationY = scrollY; } } float headerTranslationY = ScrollUtils.getFloat(-(scrollY - mBaseTranslationY), -toolbarHeight, 0); ViewPropertyAnimator.animate(mHeaderView).cancel(); ViewHelper.setTranslationY(mHeaderView, headerTranslationY); } } @Override public void onDownMotionEvent() { } @Override public void onUpOrCancelMotionEvent(ScrollState scrollState) { mBaseTranslationY = 0; if (scrollState == ScrollState.DOWN) { showToolbar(); } else if (scrollState == ScrollState.UP) { int toolbarHeight = mToolbarView.getHeight(); int scrollY = mScrollView.getCurrentScrollY(); if (toolbarHeight <= scrollY) { hideToolbar(); } else { showToolbar(); } } else { // Even if onScrollChanged occurs without scrollY changing, toolbar should be adjusted if (!toolbarIsShown() && !toolbarIsHidden()) { // Toolbar is moving but doesn't know which to move: // you can change this to hideToolbar() showToolbar(); } } } private boolean toolbarIsShown() { return ViewHelper.getTranslationY(mHeaderView) == 0; } private boolean toolbarIsHidden() { return ViewHelper.getTranslationY(mHeaderView) == -mToolbarView.getHeight(); } private void showToolbar() { float headerTranslationY = ViewHelper.getTranslationY(mHeaderView); if (headerTranslationY != 0) { ViewPropertyAnimator.animate(mHeaderView).cancel(); ViewPropertyAnimator.animate(mHeaderView).translationY(0).setDuration(200).start(); } } private void hideToolbar() { float headerTranslationY = ViewHelper.getTranslationY(mHeaderView); int toolbarHeight = mToolbarView.getHeight(); if (headerTranslationY != -toolbarHeight) { ViewPropertyAnimator.animate(mHeaderView).cancel(); ViewPropertyAnimator.animate(mHeaderView).translationY(-toolbarHeight).setDuration(200).start(); } } }