自定义listview快速滚动条

1.滚动条

package com.example.myviews.views;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.Point;

import android.graphics.RectF;

import android.util.AttributeSet;

import android.util.Log;

import android.view.MotionEvent;

import android.view.View;

import android.widget.AbsListView;

import android.widget.AbsListView.OnScrollListener;

import android.widget.ListAdapter;

import android.widget.ListView;

import com.example.myviews.R;

import com.example.myviews.utils.DensityUtil;

/**

* create by sclgxt at 2017.4.11

*

* */

public class ScrollView extends View {

private float scrollbarWidth;

private float scrollbarHeight;

private float scrollbarRId;

private float scrollbarY;

private Paint scrollbarPaint;

private RectF rectFScrollbar;

private float topY;

private float hScrollview;

private float wScrollview;

private Point pDown;

private Point pMove;

private Bitmap scrollbarBitmap;

public static final String TAG = "ScrollView";

private ListView listView;

private float hListViewItemSum;

protected int mCurrentfirstVisibleItem;

private boolean onTouch;

private float percentY;

// the height of your listview's item

int dp40 = DensityUtil.dip2px(getContext(), 40);

public ScrollView(Context context, AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

// TODO Auto-generated constructor stub

init();

}

public ScrollView(Context context, AttributeSet attrs) {

super(context, attrs);

// TODO Auto-generated constructor stub

init();

}

public ScrollView(Context context) {

super(context);

// TODO Auto-generated constructor stub

init();

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

// TODO Auto-generated method stub

Log.i(TAG, "-->onMeasure");

scrollbarWidth = DensityUtil.dip2px(getContext(), 5);

// scrollbarHeight = 40;

hScrollview = getMeasuredHeight();

wScrollview = getMeasuredWidth();

topY = getMeasuredHeight();

// To be exactaly,the scrollbarHeight is the result of the height of

// listview divided by the sum of all listview's child

// mulitiplied by the height of scrollview!

// I think the height of listview is as high as scrollview

// you can change this !

if (hListViewItemSum != 0) {

scrollbarHeight = (float) getMeasuredHeight() / hListViewItemSum

* getMeasuredHeight();

} else {

scrollbarHeight = getMeasuredHeight();

}

scrollbarY = scrollbarHeight / 2;

Log.i(TAG, "-->getMeasuredHeight(): " + getMeasuredHeight()

+ ", hListViewItemSum: " + hListViewItemSum

+ ", scrollbarHeight: " + scrollbarHeight);

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

}

@Override

protected void onDraw(Canvas canvas) {

// TODO Auto-generated method stub

super.onDraw(canvas);

hScrollview = getHeight();

wScrollview = getWidth();

topY = getHeight();

if (hListViewItemSum != 0) {

scrollbarHeight = (float) getHeight() / hListViewItemSum

* getHeight();

} else {

scrollbarHeight = getHeight();

}

if (percentY != -1) {

scrollbarY = percentY * hScrollview;

percentY = -1;

}

Log.i(TAG, "-->getHeight " + getHeight());

rectFScrollbar = new RectF(wScrollview / 2 - scrollbarWidth / 2,

scrollbarY, wScrollview / 2 + scrollbarWidth / 2, scrollbarY

+ scrollbarHeight);

canvas.drawBitmap(scrollbarBitmap, null, rectFScrollbar, scrollbarPaint);

}

@Override

public boolean onTouchEvent(MotionEvent event) {

// TODO Auto-generated method stub

Log.i(TAG, "--> event.getY(): " + event.getY());

int action = event.getAction();

switch (action) {

case MotionEvent.ACTION_DOWN:

onTouch = true;

pDown = new Point((int) event.getX(), (int) event.getY());

if (pDown.y + scrollbarHeight / 2 >= topY) {

scrollbarY = topY - scrollbarHeight;

} else if (pDown.y < scrollbarHeight / 2) {

scrollbarY = 0;

} else {

scrollbarY = pDown.y - scrollbarHeight / 2;

}

break;

case MotionEvent.ACTION_MOVE:

onTouch = true;

pMove = new Point((int) event.getX(), (int) event.getY());

if (pMove.y + scrollbarHeight / 2 >= topY) {

scrollbarY = topY - scrollbarHeight;

} else if (pMove.y < scrollbarHeight / 2) {

scrollbarY = 0;

} else {

scrollbarY = pMove.y - scrollbarHeight / 2;

}

Log.i(TAG, "--> event.ACTION_MOVE()");

break;

case MotionEvent.ACTION_UP:

onTouch = false;

break;

default:

break;

}

Log.i(TAG, "-->scrollbarY: " + scrollbarY);

if (listView != null) {

int sumoffset = (int) ((event.getY() - scrollbarHeight / 2)

/ hScrollview * hListViewItemSum);

int position = sumoffset / dp40;

int offset = sumoffset % dp40;

Log.i(TAG, "-->sumoffset: " + sumoffset);

Log.i(TAG, "-->position: " + position + " offset: " + offset);

listView.setSelectionFromTop(position, -offset);

}

invalidate();

return super.onTouchEvent(event);

}

private void init() {

scrollbarPaint = new Paint();

scrollbarBitmap = BitmapFactory.decodeResource(getResources(),

R.drawable.main_dial_pointe2r);

}

private void caculateListViewOffset() {

listView.setOnScrollListener(new OnScrollListener() {

@Override

public void onScrollStateChanged(AbsListView view, int scrollState) {

// TODO Auto-generated method stub

}

@Override

public void onScroll(AbsListView view, int firstVisibleItem,

int visibleItemCount, int totalItemCount) {

mCurrentfirstVisibleItem = firstVisibleItem;

View firstView = view.getChildAt(0);

if (null != firstView) {

int height = 0;

for (int i = 0; i < mCurrentfirstVisibleItem; i++) {

height += dp40;

}

// In my project,the height of listview's item is fixed!

int h = height - firstView.getTop();// 滚动距离

if (!onTouch)

scrollTo(h);

}

}

});

}

public void setListView(ListView listView) {

this.listView = listView;

ListAdapter listAdapter = listView.getAdapter();

hListViewItemSum = listAdapter.getCount() * dp40;

caculateListViewOffset();

}

/** The method was used in which the size of data had changed */

public void notifySizeChanged() {

hListViewItemSum = listView.getAdapter().getCount() * dp40;

if (hListViewItemSum != 0) {

scrollbarHeight = (float) getMeasuredHeight() / hListViewItemSum

* getMeasuredHeight();

} else {

scrollbarHeight = getMeasuredHeight();

}

scrollbarY = scrollbarHeight / 2;

Log.i(TAG, "-->listView.getMeasuredHeight(): " + getMeasuredHeight()

+ ", hListViewItemSum: " + hListViewItemSum

+ ", scrollbarHeight: " + scrollbarHeight);

invalidate();

}

public void scrollTo(int y) {

// TODO Auto-generated method stub

// I found that while the phone close then opened the life of scrollview

// will rerun,onMeasuered->onDraw,and the height was changed!then I sava

// the percentY.

hScrollview = getHeight();

percentY = y / hListViewItemSum;

invalidate();

Log.i(TAG, "-->list view onScroll: ");

}

}

2.使用

2.1布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="horizontal"

tools:context=".MainActivity" >

<ListView

android:id="@+id/lv_main"

android:layout_width="0dp"

android:layout_height="match_parent"

android:layout_weight="1" />

<com.example.myviews.views.ScrollView

android:id="@+id/sv_main"

android:layout_width="40dp"

android:layout_height="match_parent"

android:background="#88ededed"

android:clickable="true" />

</LinearLayout>

2.2 代码

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

List<String> list = new ArrayList<String>();

for (int i = 0; i < 120; i++) {

list.add(i + "");

}

ArrayAdapter<String> adapter = new ArrayAdapter<String>(

getApplicationContext(), R.layout.item_lv_main,

R.id.tv_item_lv, list);

ListView listView = (ListView) findViewById(R.id.lv_main);

listView.setAdapter(adapter);

ScrollView scrollView = (ScrollView) findViewById(R.id.sv_main);

scrollView.setListView(listView);

scrollView.notifySizeChanged();

}

3.效果