137 lines
4.5 KiB
Java
137 lines
4.5 KiB
Java
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.dialer.contactsfragment;
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import android.content.Context;
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import android.support.annotation.NonNull;
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import android.support.v7.widget.LinearLayoutManager;
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import android.support.v7.widget.RecyclerView;
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import android.util.AttributeSet;
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import android.view.MotionEvent;
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import android.view.View;
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import android.widget.RelativeLayout;
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import android.widget.TextView;
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/** Widget to add fast scrolling to {@link ContactsFragment}. */
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public class FastScroller extends RelativeLayout {
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private final int touchTargetWidth;
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private ContactsAdapter adapter;
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private LinearLayoutManager layoutManager;
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private TextView container;
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private View scrollBar;
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private boolean dragStarted;
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public FastScroller(Context context, AttributeSet attrs) {
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super(context, attrs);
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touchTargetWidth =
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context.getResources().getDimensionPixelSize(R.dimen.fast_scroller_touch_target_width);
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}
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@Override
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protected void onFinishInflate() {
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super.onFinishInflate();
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container = findViewById(R.id.fast_scroller_container);
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scrollBar = findViewById(R.id.fast_scroller_scroll_bar);
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}
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void setup(ContactsAdapter adapter, LinearLayoutManager layoutManager) {
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this.adapter = adapter;
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this.layoutManager = layoutManager;
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setVisibility(VISIBLE);
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}
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@Override
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public boolean onTouchEvent(@NonNull MotionEvent event) {
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// Don't override if touch event isn't within desired touch target and dragging hasn't started.
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if (!dragStarted && getWidth() - touchTargetWidth - event.getX() > 0) {
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return super.onTouchEvent(event);
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}
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switch (event.getAction()) {
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case MotionEvent.ACTION_DOWN:
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dragStarted = true;
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container.setVisibility(VISIBLE);
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scrollBar.setSelected(true);
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// fall through
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case MotionEvent.ACTION_MOVE:
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setContainerAndScrollBarPosition(event.getY());
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setRecyclerViewPosition(event.getY());
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return true;
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case MotionEvent.ACTION_UP:
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case MotionEvent.ACTION_CANCEL:
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dragStarted = false;
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container.setVisibility(INVISIBLE);
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scrollBar.setSelected(false);
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return true;
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default:
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return super.onTouchEvent(event);
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}
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}
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public boolean isDragStarted() {
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return dragStarted;
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}
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private void setRecyclerViewPosition(float y) {
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final int itemCount = adapter.getItemCount();
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float scrolledPosition = getScrolledPercentage(y) * (float) itemCount;
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int targetPos = getValueInRange(0, itemCount - 1, (int) scrolledPosition);
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layoutManager.scrollToPositionWithOffset(targetPos, 0);
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container.setText(adapter.getHeaderString(targetPos));
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adapter.refreshHeaders();
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}
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// Returns a float in range [0, 1] which represents the position of the scroller.
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private float getScrolledPercentage(float y) {
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if (scrollBar.getY() == 0) {
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return 0f;
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} else if (scrollBar.getY() + scrollBar.getHeight() >= getHeight()) {
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return 1f;
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} else {
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return y / (float) getHeight();
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}
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}
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private int getValueInRange(int min, int max, int value) {
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int minimum = Math.max(min, value);
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return Math.min(minimum, max);
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}
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void updateContainerAndScrollBarPosition(RecyclerView recyclerView) {
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if (!scrollBar.isSelected()) {
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int verticalScrollOffset = recyclerView.computeVerticalScrollOffset();
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int verticalScrollRange = recyclerView.computeVerticalScrollRange();
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float proportion = (float) verticalScrollOffset / ((float) verticalScrollRange - getHeight());
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setContainerAndScrollBarPosition(getHeight() * proportion);
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}
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}
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private void setContainerAndScrollBarPosition(float y) {
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int scrollBarHeight = scrollBar.getHeight();
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int containerHeight = container.getHeight();
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scrollBar.setY(
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getValueInRange(0, getHeight() - scrollBarHeight, (int) (y - scrollBarHeight / 2)));
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container.setY(
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getValueInRange(
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0, getHeight() - containerHeight - scrollBarHeight / 2, (int) (y - containerHeight)));
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}
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}
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