自定义View的步骤：
1、自定义View的属性
2、在View的构造方法中获得我们自定义的属性
[ 3、重写onMesure ]
4、重写onDraw
我把3用[]标出了，所以说3不一定是必须的，当然了大部分情况下还是需要重写的。
继承View，实现自己想要的组件，那么需要使用到setMeasuredDimension这个方法，这个方法决定了当前View的大小，如果不使用setMeasuredDimension这个方法，那么View的大小将不起作用。
1
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
controlWidth = getWidth();
if (controlWidth != 0) {
setMeasuredDimension(getWidth(), itemNumber * unitHeight);
controlWidth = getWidth();
}
}
2
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
//绘制线条
3
drawLine(canvas);
//绘制数据
4
drawList(canvas);
//绘制覆盖板
5
drawMask(canvas);
}
3
/**
* 绘制线条
*
* @param canvas
*/
private void drawLine(Canvas canvas) {
if (linePaint == null) {
linePaint = new Paint();
linePaint.setColor(lineColor);
//抗锯齿
linePaint.setAntiAlias(true);
//设置空心线宽
linePaint.setStrokeWidth(1f);
}
canvas.drawLine(0, controlHeight / 2 - unitHeight / 2 + 2,
controlWidth, controlHeight / 2 - unitHeight / 2 + 2, linePaint);
canvas.drawLine(0, controlHeight / 2 + unitHeight / 2 - 2,
controlWidth, controlHeight / 2 + unitHeight / 2 - 2, linePaint);
}
4
/**
* 绘制数据
*
* @param canvas
*/
private synchronized void drawList(Canvas canvas) {
if (isClearing)
return;
try {
for (ItemObject itemObject : itemList) {
itemObject.drawSelf(canvas);
}
} catch (Exception e) {
// TODO: handle exception
}
5
/**
* 绘制遮盖板
*
* @param canvas
*/
private void drawMask(Canvas canvas) {
//线性渲染
LinearGradient lg = new LinearGradient(0, 0, 0, maskHight, 0x00f2f2f2,
0x00f2f2f2, TileMode.MIRROR);
Paint paint = new Paint();
paint.setShader(lg);
canvas.drawRect(0, 0, controlWidth, maskHight, paint);
LinearGradient lg2 = new LinearGradient(0, controlHeight - maskHight,
0, controlHeight, 0x00f2f2f2, 0x00f2f2f2, TileMode.MIRROR);
Paint paint2 = new Paint();
//设置渲染对象
paint2.setShader(lg2);
canvas.drawRect(0, controlHeight - maskHight, controlWidth,
controlHeight, paint2);
}
//LinearGradient 线性渲染
public LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1, Shader.TileMode tile)
参数x0表示渐变的起始点x坐标；参数y0表示渐变的起始点y坐标；参数x1表示渐变的终点x坐标；参数y1表示渐变的终点y坐标 ；color0表示渐变开始颜色；color1表示渐变结束颜色；参数tile表示平铺方式。Shader.TileMode有3种参数可供选择，分别为CLAMP、REPEAT和MIRROR：
CLAMP的作用是如果渲染器超出原始边界范围，则会复制边缘颜色对超出范围的区域进行着色
REPEAT的作用是在横向和纵向上以平铺的形式重复渲染位图
MIRROR的作用是在横向和纵向上以镜像的方式重复渲染位图
自定义view已经画好。现在接着进行触摸事件
6
@Override
public boolean onTouchEvent(MotionEvent event) {
// isEnable是否可用
if (!isEnable)
return true;
int y = (int) event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
/** 是否滑动中 */
isScrolling = true;
/** 按下的坐标 */
downY = (int) event.getY();
/** 按下的时间 */
downTime = System.currentTimeMillis();
break;
case MotionEvent.ACTION_MOVE:
//移动距离
7
actionMove(y - downY);
//选择监听
8
onSelectListener();
break;
case MotionEvent.ACTION_UP:
// 移动距离的绝对值
int move = (y - downY);
move = move > 0 ? move : move * (-1);
// 判断段时间移动的距离
/** 短促移动 goonTime=200*//** 短促移动距离 goonDistence=100*/
if (System.currentTimeMillis() - downTime < goonTime
&& move > goonDistence) {
10
goonMove(y - downY);
} else {
13
actionUp(y - downY);
}
17
noEmpty();
isScrolling = false;
break;
default:
break;
}
return true;
}
7
/**
* 移动的时候
*
* @param move
*/
private void actionMove(int move) {
for (ItemObject item : itemList) {
item.move(move);
}
invalidate();
}
8
/**
* 滑动监听
*/
private void onSelectListener() {
/** 选择监听 */
9
if (onSelectListener == null)
return;
for (ItemObject item : itemList) {
if (item.isSelected()) {
//监听选择
onSelectListener.selecting(item.id, item.itemText);
}
}
}
设置监听接口回调
9
/**
* 选择监听监听
*
* @author zoudong
*
*/
public interface OnSelectListener {
/**
* 结束选择
*
* @param id
* @param text
*/
public void endSelect(int id, String text);
/**
* 选中的内容
*
* @param id
* @param text
*/
public void selecting(int id, String text);
}
10
/**
* 继续移动一定距离
*/
private synchronized void goonMove(final int move) {
new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
int distence = 0;
/** 移动距离 MOVE_NUMBER=5*/
while (distence < unitHeight * MOVE_NUMBER) {
try {
Thread.sleep(5);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
11
actionThreadMove(move > 0 ? distence : distence * (-1));
distence += 10;
} 13
actionUp(move > 0 ? distence - 10 : distence * (-1) + 10);
17
noEmpty();
}
}).start();
}
/* 11
* 移动，线程中调用
*
* @param move
*/
private void actionThreadMove(int move) {
for (ItemObject item : itemList) {
item.move(move);
}
12
Message rMessage = new Message();
/** 刷新界面 REFRESH_VIEW=0x001 */
rMessage.what = REFRESH_VIEW;
handler.sendMessage(rMessage);
}
12
@SuppressLint("HandlerLeak")
Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
switch (msg.what) {
case REFRESH_VIEW:
invalidate();
break;
default:
break;
}
}
};
13
/**
* 松开的时候
*
* @param move
*/
private void actionUp(int move) {
int newMove = 0;
if (move > 0) {
for (int i = 0; i < itemList.size(); i++) {
if (itemList.get(i).isSelected()) {
14
newMove = (int) itemList.get(i).moveToSelected();
if (onSelectListener != null)
//接口回调 结束选择
onSelectListener.endSelect(itemList.get(i).id,
itemList.get(i).itemText);
break;
}
}
} else {
for (int i = itemList.size() - 1; i >= 0; i--) {
if (itemList.get(i).isSelected()) {
newMove = (int) itemList.get(i).moveToSelected();
if (onSelectListener != null)
//结束选择
onSelectListener.endSelect(itemList.get(i).id,
itemList.get(i).itemText);
break;
}
}
}
for (ItemObject item : itemList) {
15
item.newY(move + 0);
}
16
slowMove(newMove);
Message rMessage = new Message();
rMessage.what = REFRESH_VIEW;
handler.sendMessage(rMessage);
}
14
/**
* 获取移动到标准位置需要的距离
*/
public float moveToSelected() {
return (controlHeight / 2 - unitHeight / 2) - (y + move);
}
15
/**
* 设置新的坐标
*
* @param move
*/
public void newY(int _move) {
this.move = 0;
this.y = y + _move;
}
16
/**
* 缓慢移动
*
* @param move
*/
private synchronized void slowMove(final int move) {
new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
// 判断正负
int m = move > 0 ? move : move * (-1);
int i = move > 0 ? 1 : (-1);
// 移动速度
int speed = 1;
while (true) {
m = m - speed;
if (m <= 0) {
for (ItemObject item : itemList) {
item.newY(m * i);
}
Message rMessage = new Message();
rMessage.what = REFRESH_VIEW;
handler.sendMessage(rMessage);
try {
Thread.sleep(2);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
for (ItemObject item : itemList) {
item.newY(speed * i);
}
Message rMessage = new Message();
rMessage.what = REFRESH_VIEW;
handler.sendMessage(rMessage);
//释放系统资源
try {
Thread.sleep(2);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
for (ItemObject item : itemList) {
if (item.isSelected()) {
if (onSelectListener != null)
onSelectListener.endSelect(item.id, item.itemText);
break;
}
}
}
}).start();
}
17
/**
* 不能为空，必须有选项
*/
private void noEmpty() {
if (!noEmpty)
return;
for (ItemObject item : itemList) {
if (item.isSelected())
return;
}
int move = (int) itemList.get(0).moveToSelected();
if (move < 0) {
18
defaultMove(move);h
} else {
defaultMove((int) itemList.get(itemList.size() - 1)
.moveToSelected());
}
for (ItemObject item : itemList) {
if (item.isSelected()) {
if (onSelectListener != null)
onSelectListener.endSelect(item.id, item.itemText);
break;
}
}
}
18
/**
* 移动到默认位置
*
* @param move
*/
private void defaultMove(int move) {
for (ItemObject item : itemList) {
item.newY(move);
}
Message rMessage = new Message();
rMessage.what = REFRESH_VIEW;
handler.sendMessage(rMessage);
}
到了这一步 基本自定义控件搞定了 剩下就是暴漏一些自己需要的接口或者方法了~源码请查看
Android三级联动wheel代码分析（一）里面，等两天接着Android三级联动wheel代码分析（三）。
如有不对的地方请指正，因为这个代码较多 加上数字应该会看的稍微清楚点。。。
