Android自定義View實現拖動自動吸邊效果
本文實例為大傢分享瞭Android自定義View實現拖動自動吸邊的具體代碼，供大傢參考，具體內容如下
自定義View，一是為瞭滿足設計需求，二是開發者進階的標志之一。隨心所欲就是我等奮鬥的目標！！！
效果
實現邏輯
明確需求
1、實現控件跟隨手指拖動
2、實現控件自動貼邊
整理思路
1、既然要實現控件拖動，那麼就離不開onTouchEvent()這個方法，需要監聽裡面的按下和滑動事件。
2、 要實現自動貼邊，需要監聽onTouchEvent()中手指離開屏幕事件。對於貼邊的過程，我們用屬性動畫來解決。
3、事件的沖突問題也需要考慮，拖動、點擊關系到瞭事件的攔截。
動手實現
在需求明確、思路清晰的情況下就要開始動手實現（需要瞭解自定義View的一些基礎API），下面代碼中註釋寫的基本都差不多，很好理解。歡迎指出討論！！！
完整代碼
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 {
//判斷是否需要滑動
if (customIsDrag) {
//當前手指的坐標
val mRawX = it.rawX
val mRawY = it.rawY
when (it.action) {
MotionEvent.ACTION_DOWN -> {//手指按下
isDrug = false
//記錄按下的位置
mLastRawX = mRawX
mLastRawY = mRawY
if (parent is ViewGroup) {
val mViewGroup = parent as ViewGroup
val location = IntArray(2)
mViewGroup.getLocationInWindow(location)
//獲取父佈局的高度
mRootMeasuredHeight = mViewGroup.measuredHeight
mRootMeasuredWidth = mViewGroup.measuredWidth
//獲取父佈局頂點的坐標
mRootTopY = location[1]
}
}
MotionEvent.ACTION_MOVE -> {//手指滑動
if (mRawX >= 0 && mRawX <= mRootMeasuredWidth && mRawY >= mRootTopY && mRawY <= (mRootMeasuredHeight + mRootTopY)) {
//手指X軸滑動距離
val differenceValueX: Float = mRawX - mLastRawX
//手指Y軸滑動距離
val differenceValueY: Float = mRawY - mLastRawY
//判斷是否為拖動操作
if (!isDrug) {
isDrug =
sqrt(((differenceValueX * differenceValueX) + (differenceValueY * differenceValueY)).toDouble()) >= 2
}
//獲取手指按下的距離與控件本身X軸的距離
val ownX = x
//獲取手指按下的距離與控件本身Y軸的距離
val ownY = y
//理論中X軸拖動的距離
var endX: Float = ownX + differenceValueX
//理論中Y軸拖動的距離
var endY: Float = ownY + differenceValueY
//X軸可以拖動的最大距離
val maxX: Float = mRootMeasuredWidth - width.toFloat()
//Y軸可以拖動的最大距離
val maxY: Float = mRootMeasuredHeight - height.toFloat()
//X軸邊界限制
endX = if (endX < 0) 0F else (if (endX > maxX) maxX else endX)
//Y軸邊界限制
endY = if (endY < 0) 0F else (if (endY > maxY) maxY else endY)
//開始移動
x = endX
y = endY
//記錄位置
mLastRawX = mRawX
mLastRawY = mRawY
}
}
MotionEvent.ACTION_UP -> {//手指離開
if (customIsAttach) {
//判斷是否為點擊事件
if (isDrug) {
val center = mRootMeasuredWidth / 2
//自動貼邊
if (mLastRawX <= center) {
//向左貼邊
animate()
.setInterpolator(BounceInterpolator())
.setDuration(500)
.x(0F)
.start()
} else {
//向右貼邊
animate()
.setInterpolator(BounceInterpolator())
.setDuration(500)
.x(mRootMeasuredWidth - width.toFloat())
.start()
}
}
}
}
}
}
}
//是否攔截事件
return if (isDrug) isDrug else super.onTouchEvent(event)
}
}
Java
/**
* 自定義View實現拖動並自動吸邊效果
* <p>
* 處理滑動和貼邊 {@link #onTouchEvent(MotionEvent)}
* 處理事件分發 {@link #dispatchTouchEvent(MotionEvent)}
* </p>
*
* @attr customIsAttach //是否需要自動吸邊
* @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);
}
/**
* 初始化自定義屬性
*/
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) {
//判斷是否需要滑動
if (customIsDrag) {
//當前手指的坐標
float mRawX = ev.getRawX();
float mRawY = ev.getRawY();
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN://手指按下
isDrug = false;
//記錄按下的位置
mLastRawX = mRawX;
mLastRawY = mRawY;
ViewGroup mViewGroup = (ViewGroup) getParent();
if (mViewGroup != null) {
int[] location = new int[2];
mViewGroup.getLocationInWindow(location);
//獲取父佈局的高度
mRootMeasuredHeight = mViewGroup.getMeasuredHeight();
mRootMeasuredWidth = mViewGroup.getMeasuredWidth();
//獲取父佈局頂點的坐標
mRootTopY = location[1];
}
break;
case MotionEvent.ACTION_MOVE://手指滑動
if (mRawX >= 0 && mRawX <= mRootMeasuredWidth && mRawY >= mRootTopY && mRawY <= (mRootMeasuredHeight + mRootTopY)) {
//手指X軸滑動距離
float differenceValueX = mRawX - mLastRawX;
//手指Y軸滑動距離
float differenceValueY = mRawY - mLastRawY;
//判斷是否為拖動操作
if (!isDrug) {
if (Math.sqrt(differenceValueX * differenceValueX + differenceValueY * differenceValueY) < 2) {
isDrug = false;
} else {
isDrug = true;
}
}
//獲取手指按下的距離與控件本身X軸的距離
float ownX = getX();
//獲取手指按下的距離與控件本身Y軸的距離
float ownY = getY();
//理論中X軸拖動的距離
float endX = ownX + differenceValueX;
//理論中Y軸拖動的距離
float endY = ownY + differenceValueY;
//X軸可以拖動的最大距離
float maxX = mRootMeasuredWidth - getWidth();
//Y軸可以拖動的最大距離
float maxY = mRootMeasuredHeight - getHeight();
//X軸邊界限制
endX = endX < 0 ? 0 : endX > maxX ? maxX : endX;
//Y軸邊界限制
endY = endY < 0 ? 0 : endY > maxY ? maxY : endY;
//開始移動
setX(endX);
setY(endY);
//記錄位置
mLastRawX = mRawX;
mLastRawY = mRawY;
}
break;
case MotionEvent.ACTION_UP://手指離開
//根據自定義屬性判斷是否需要貼邊
if (customIsAttach) {
//判斷是否為點擊事件
if (isDrug) {
float center = mRootMeasuredWidth / 2;
//自動貼邊
if (mLastRawX <= center) {
//向左貼邊
AttachButton.this.animate()
.setInterpolator(new BounceInterpolator())
.setDuration(500)
.x(0)
.start();
} else {
//向右貼邊
AttachButton.this.animate()
.setInterpolator(new BounceInterpolator())
.setDuration(500)
.x(mRootMeasuredWidth - getWidth())
.start();
}
}
}
break;
}
}
//是否攔截事件
return isDrug ? isDrug : super.onTouchEvent(ev);
}
}
自定義屬性
<declare-styleable name="AttachButton"> <!--是否需要自動吸邊--> <attr name="customIsAttach" format="boolean" /> <!--是否可拖曳--> <attr name="customIsDrag" format="boolean" /> </declare-styleable>
以上就是本文的全部內容，希望對大傢的學習有所幫助，也希望大傢多多支持WalkonNet。
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