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/*
* Copyright (C) 2017 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 com.android.dialer.contactsfragment;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.TextView;
/** Widget to add fast scrolling to {@link ContactsFragment}. */
public class FastScroller extends RelativeLayout {
private final int touchTargetWidth;
private ContactsAdapter adapter;
private LinearLayoutManager layoutManager;
private TextView container;
private View scrollBar;
private boolean dragStarted;
public FastScroller(Context context, AttributeSet attrs) {
super(context, attrs);
touchTargetWidth =
context.getResources().getDimensionPixelSize(R.dimen.fast_scroller_touch_target_width);
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
container = findViewById(R.id.fast_scroller_container);
scrollBar = findViewById(R.id.fast_scroller_scroll_bar);
}
void setup(ContactsAdapter adapter, LinearLayoutManager layoutManager) {
this.adapter = adapter;
this.layoutManager = layoutManager;
setVisibility(VISIBLE);
}
@Override
public boolean onTouchEvent(@NonNull MotionEvent event) {
// Don't override if touch event isn't within desired touch target and dragging hasn't started.
if (!dragStarted && getWidth() - touchTargetWidth - event.getX() > 0) {
return super.onTouchEvent(event);
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
dragStarted = true;
container.setVisibility(VISIBLE);
scrollBar.setSelected(true);
// fall through
case MotionEvent.ACTION_MOVE:
setContainerAndScrollBarPosition(event.getY());
setRecyclerViewPosition(event.getY());
return true;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
dragStarted = false;
container.setVisibility(INVISIBLE);
scrollBar.setSelected(false);
return true;
}
return super.onTouchEvent(event);
}
private void setRecyclerViewPosition(float y) {
final int itemCount = adapter.getItemCount();
float scrolledPosition = getScrolledPercentage(y) * (float) itemCount;
int targetPos = getValueInRange(0, itemCount - 1, (int) scrolledPosition);
layoutManager.scrollToPositionWithOffset(targetPos, 0);
container.setText(adapter.getHeaderString(targetPos));
}
// Returns a float in range [0, 1] which represents the position of the scroller.
private float getScrolledPercentage(float y) {
if (scrollBar.getY() == 0) {
return 0f;
} else if (scrollBar.getY() + scrollBar.getHeight() >= getHeight()) {
return 1f;
} else {
return y / (float) getHeight();
}
}
private int getValueInRange(int min, int max, int value) {
int minimum = Math.max(min, value);
return Math.min(minimum, max);
}
void updateContainerAndScrollBarPosition(RecyclerView recyclerView) {
if (!scrollBar.isSelected()) {
int verticalScrollOffset = recyclerView.computeVerticalScrollOffset();
int verticalScrollRange = recyclerView.computeVerticalScrollRange();
float proportion = (float) verticalScrollOffset / ((float) verticalScrollRange - getHeight());
setContainerAndScrollBarPosition(getHeight() * proportion);
}
}
private void setContainerAndScrollBarPosition(float y) {
int scrollBarHeight = scrollBar.getHeight();
int containerHeight = container.getHeight();
scrollBar.setY(
getValueInRange(0, getHeight() - scrollBarHeight, (int) (y - scrollBarHeight / 2)));
container.setY(
getValueInRange(
0, getHeight() - containerHeight - scrollBarHeight / 2, (int) (y - containerHeight)));
}
}
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