本文实例为大家分享了Android自定义View实现拖动自动吸边的具体代码，供大家参考，具体内容如下
自定义View，一是为了满足设计需求，二是开发者进阶的标志之一。随心所欲就是我等奋斗的目标！！！
效果
实现逻辑
明确需求
1、实现控件跟随手指拖动
2、实现控件自动贴边
整理思路
1、既然要实现控件拖动，那么就离不开onTouchEvent()这个方法，需要监听里面的按下和滑动事件。
2、 要实现自动贴边，需要监听onTouchEvent()中手指离开屏幕事件。对于贴边的过程，我们用属性动画来解决。
3、事件的冲突问题也需要考虑，拖动、点击关系到了事件的拦截。
动手实现
在需求明确、思路清晰的情况下就要开始动手实现（需要了解自定义View的一些基础API），下面代码中注释写的基本都差不多，很好理解。欢迎指出讨论！！！
完整代码
Kotlin
class AttachButton: View {
private var mLastRawX: Float = 0F
private var mLastRawY: Float = 0F
private var isDrug = false
private var mRootMeasuredWidth = 0
private var mRootMeasuredHeight = 0
private var mRootTopY = 0
private var customIsAttach = false
private var customIsDrag = false
constructor(context: Context) : this(context, null)
constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)
constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(
context,
attrs,
defStyleAttr
) {
isClickable = true
initAttrs(context, attrs)
}
private fun initAttrs(context: Context, attrs: AttributeSet?) {
attrs?.let {
val mTypedAttay = context.obtainStyledAttributes(it, R.styleable.AttachButton)
customIsAttach =
mTypedAttay.getBoolean(R.styleable.AttachButton_customIsAttach, true)
customIsDrag =
mTypedAttay.getBoolean(R.styleable.AttachButton_customIsDrag, true)
mTypedAttay.recycle()
}
}
override fun dispatchTouchEvent(event: MotionEvent?): Boolean {
super.dispatchTouchEvent(event)
return true
}
override fun onTouchEvent(event: MotionEvent?): Boolean {
event?.let {
//判断是否需要滑动
if (customIsDrag) {
//当前手指的坐标
val mRawX = it.rawX
val mRawY = it.rawY
when (it.action) {
MotionEvent.ACTION_DOWN -> {//手指按下
isDrug = false
//记录按下的位置
mLastRawX = mRawX
mLastRawY = mRawY
if (parent is ViewGroup) {
val mViewGroup = parent as ViewGroup
val location = IntArray(2)
mViewGroup.getLocationInWindow(location)
//获取父布局的高度
mRootMeasuredHeight = mViewGroup.measuredHeight
mRootMeasuredWidth = mViewGroup.measuredWidth
//获取父布局顶点的坐标
mRootTopY = location[1]
}
}
MotionEvent.ACTION_MOVE -> {//手指滑动
if (mRawX >= 0 && mRawX <= mRootMeasuredWidth && mRawY >= mRootTopY && mRawY <= (mRootMeasuredHeight + mRootTopY)) {
//手指X轴滑动距离
val differenceValueX: Float = mRawX - mLastRawX
//手指Y轴滑动距离
val differenceValueY: Float = mRawY - mLastRawY
//判断是否为拖动操作
if (!isDrug) {
isDrug =
sqrt(((differenceValueX * differenceValueX) + (differenceValueY * differenceValueY)).toDouble()) >= 2
}
//获取手指按下的距离与控件本身X轴的距离
val ownX = x
//获取手指按下的距离与控件本身Y轴的距离
val ownY = y
//理论中X轴拖动的距离
var endX: Float = ownX + differenceValueX
//理论中Y轴拖动的距离
var endY: Float = ownY + differenceValueY
//X轴可以拖动的最大距离
val maxX: Float = mRootMeasuredWidth - width.toFloat()
//Y轴可以拖动的最大距离
val maxY: Float = mRootMeasuredHeight - height.toFloat()
//X轴边界限制
endX = if (endX < 0) 0F else (if (endX > maxX) maxX else endX)
//Y轴边界限制
endY = if (endY < 0) 0F else (if (endY > maxY) maxY else endY)
//开始移动
x = endX
y = endY
//记录位置
mLastRawX = mRawX
mLastRawY = mRawY
}
}
MotionEvent.ACTION_UP -> {//手指离开
if (customIsAttach) {
//判断是否为点击事件
if (isDrug) {
val center = mRootMeasuredWidth / 2
//自动贴边
if (mLastRawX <= center) {
//向左贴边
animate()
.setInterpolator(BounceInterpolator())
.setDuration(500)
.x(0F)
.start()
} else {
//向右贴边
animate()
.setInterpolator(BounceInterpolator())
.setDuration(500)
.x(mRootMeasuredWidth - width.toFloat())
.start()
}
}
}
}
}
}
}
//是否拦截事件
return if (isDrug) isDrug else super.onTouchEvent(event)
}
}
Java
/** * 自定义View实现拖动并自动吸边效果 ** 处理滑动和贴边 {@link #onTouchEvent(MotionEvent)} * 处理事件分发 {@link #dispatchTouchEvent(MotionEvent)} *
* * @attr customIsAttach //是否需要自动吸边 * @attr customIsDrag //是否可拖曳 */ public class AttachButton extends View { private float mLastRawX; private float mLastRawY; private final String TAG = "AttachButton"; private boolean isDrug = false; private int mRootMeasuredWidth = 0; private int mRootMeasuredHeight = 0; private int mRootTopY = 0; private boolean customIsAttach; private boolean customIsDrag; public AttachButton(Context context) { this(context, null); } public AttachButton(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public AttachButton(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); setClickable(true); initAttrs(context, attrs); } /** * 初始化自定义属性 */ private void initAttrs(Context context, AttributeSet attrs) { TypedArray mTypedAttay = context.obtainStyledAttributes(attrs, R.styleable.AttachButton); customIsAttach = mTypedAttay.getBoolean(R.styleable.AttachButton_customIsAttach, true); customIsDrag = mTypedAttay.getBoolean(R.styleable.AttachButton_customIsDrag, true); mTypedAttay.recycle(); } @Override public boolean dispatchTouchEvent(MotionEvent event) { super.dispatchTouchEvent(event); return true; } @Override public boolean onTouchEvent(MotionEvent ev) { //判断是否需要滑动 if (customIsDrag) { //当前手指的坐标 float mRawX = ev.getRawX(); float mRawY = ev.getRawY(); switch (ev.getAction()) { case MotionEvent.ACTION_DOWN://手指按下 isDrug = false; //记录按下的位置 mLastRawX = mRawX; mLastRawY = mRawY; ViewGroup mViewGroup = (ViewGroup) getParent(); if (mViewGroup != null) { int[] location = new int[2]; mViewGroup.getLocationInWindow(location); //获取父布局的高度 mRootMeasuredHeight = mViewGroup.getMeasuredHeight(); mRootMeasuredWidth = mViewGroup.getMeasuredWidth(); //获取父布局顶点的坐标 mRootTopY = location[1]; } break; case MotionEvent.ACTION_MOVE://手指滑动 if (mRawX >= 0 && mRawX <= mRootMeasuredWidth && mRawY >= mRootTopY && mRawY <= (mRootMeasuredHeight + mRootTopY)) { //手指X轴滑动距离 float differenceValueX = mRawX - mLastRawX; //手指Y轴滑动距离 float differenceValueY = mRawY - mLastRawY; //判断是否为拖动操作 if (!isDrug) { if (Math.sqrt(differenceValueX * differenceValueX + differenceValueY * differenceValueY) < 2) { isDrug = false; } else { isDrug = true; } } //获取手指按下的距离与控件本身X轴的距离 float ownX = getX(); //获取手指按下的距离与控件本身Y轴的距离 float ownY = getY(); //理论中X轴拖动的距离 float endX = ownX + differenceValueX; //理论中Y轴拖动的距离 float endY = ownY + differenceValueY; //X轴可以拖动的最大距离 float maxX = mRootMeasuredWidth - getWidth(); //Y轴可以拖动的最大距离 float maxY = mRootMeasuredHeight - getHeight(); //X轴边界限制 endX = endX < 0 ? 0 : endX > maxX ? maxX : endX; //Y轴边界限制 endY = endY < 0 ? 0 : endY > maxY ? maxY : endY; //开始移动 setX(endX); setY(endY); //记录位置 mLastRawX = mRawX; mLastRawY = mRawY; } break; case MotionEvent.ACTION_UP://手指离开 //根据自定义属性判断是否需要贴边 if (customIsAttach) { //判断是否为点击事件 if (isDrug) { float center = mRootMeasuredWidth / 2; //自动贴边 if (mLastRawX <= center) { //向左贴边 AttachButton.this.animate() .setInterpolator(new BounceInterpolator()) .setDuration(500) .x(0) .start(); } else { //向右贴边 AttachButton.this.animate() .setInterpolator(new BounceInterpolator()) .setDuration(500) .x(mRootMeasuredWidth - getWidth()) .start(); } } } break; } } //是否拦截事件 return isDrug ? isDrug : super.onTouchEvent(ev); } }
自定义属性
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。