Android手掌抑制功能的實現
近期需要實現一個功能，在Activity中有一個手寫區域，爲了更好的用戶體驗，需要知足即便整個手掌放在屏幕上時（android平板，屏幕比較大）也僅僅響應手寫區域內的操做，即在支持多點觸控的狀況下，僅僅響應指定的區域，我將這個功能稱做「手掌抑制」，即在手寫時。手掌放在屏幕上面不作不論什麼響應。html
初看這個功能很是easy，依照以前處理listview、gridview裏面的子view不能響應的方式，僅僅要在activity層不攔截向手寫view傳遞的消息就能夠實現想要的效果，但通過實際測試和對android消息機制的具體研究發現。要實現這個功能會有點小複雜。java
1、android的消息傳遞機制：android
一、基礎知識：編程
(1) 所有Touch事件都被封裝成了MotionEvent對象。包含Touch的位置、時間、歷史記錄以及第幾個手指(多指觸摸)等。canvas
(2) 事件類型分爲ACTION_DOWN, ACTION_UP, ACTION_MOVE, ACTION_POINTER_DOWN, ACTION_POINTER_UP, ACTION_CANCEL，每個事件都是以ACTION_DOWN開始ACTION_UP結束。ide
(3) 對事件的處理包含三類：函數
傳遞——dispatchTouchEvent()spa
攔截——onInterceptTouchEvent().net
消費——onTouchEvent()和OnTouchListenercode
二、傳遞流程
(1) 事件從Activity.dispatchTouchEvent()開始傳遞，僅僅要沒有被中止或攔截，從最上層的View(ViewGroup)開始一直往下(子View)傳遞。子View可以經過onTouchEvent()對事件進行處理。
(2) 事件由父View(ViewGroup)傳遞給子View，ViewGroup可以經過onInterceptTouchEvent()對事件作攔截，中止其往下傳遞。
(3) 假設事件從上往下傳遞過程當中一直沒有被中止，且最底層子View沒有消費事件。事件會反向往上傳遞，這時父View(ViewGroup)可以進行消費，假設仍是沒有被消費的話，最後會到Activity的onTouchEvent()函數。
(4) 假設View沒有對ACTION_DOWN進行消費，以後的其它事件不會傳遞過來。
(5) OnTouchListener優先於onTouchEvent()對事件進行消費。
上面的消費即表示對應函數返回值爲true。
三、實際狀況：
能夠響應事件處理方法的控件包含：ViewGroup、View、Activity，各種控件對三個事件響應處理方法的支持狀況例如如下：
這三個控件。Activity是處於最外層的，消息的傳遞首先是系統回調消息給Activity。Activity將消息傳遞給每一個ViewGroup，而後ViewGroup會將消息傳遞給對應地子View。
本文所描寫敘述的手寫控件是一個view，在有系統消息回調時僅僅有上層控件將消息分發下來，它才能夠消費和處理這些消息。
2、問題現象：
接着咱們進入正題，依照我在開篇介紹的那種處理方式，寫一個手寫view，在Activity和ViewGroup（本身定義一個Layout就能夠）層將消息分發給該view，眼下的代碼看上去是這樣子的：
public class DrawView extends View {
public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPaintView( );
}
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
initPaintView( );
}
public DrawView(Context context) {
super(context);
initPaintView( );
}
public void clear() {
if (null != mPath) {
mPath.reset();
invalidate();
}
}
private void initPaintView() {
mPaint.setAntiAlias(true);
mPaint.setColor(Color.WHITE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(5f);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mViewWidth = MeasureSpec.getSize(widthMeasureSpec); //獲取ViewGroup寬度
mViewHeight = MeasureSpec.getSize(heightMeasureSpec); //獲取ViewGroup高度
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawPath(mPath, mPaint);
}
public boolean inArea( float x, float y ){
return ( x >= 0 && x <= mViewWidth && y >= 0 && y <= mViewHeight)?true:false;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX( );
float eventY = event.getY( );
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
mPath.moveTo(eventX, eventY);
mLastTouchX = eventX;
mLastTouchY = eventY;
invalidate( );
}
return true;
case MotionEvent.ACTION_MOVE:{
drawView( event, eventX, eventY );
}
break;
case MotionEvent.ACTION_UP:{
drawView( event, eventX, eventY );
}
break;
default:
return false;
}
return true;
}
private void drawView( MotionEvent event, float eventX, float eventY ){
resetDirtyRect(eventX, eventY);
int historySize = event.getHistorySize();
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
getDirtyRect(historicalX, historicalY);
mPath.lineTo(historicalX, historicalY);
}
mPath.lineTo(eventX, eventY);
invalidate((int) (mDirtyRect.left - HALF_STROKE_WIDTH),
(int) (mDirtyRect.top - HALF_STROKE_WIDTH),
(int) (mDirtyRect.right + HALF_STROKE_WIDTH),
(int) (mDirtyRect.bottom + HALF_STROKE_WIDTH));
mLastTouchX = eventX;
mLastTouchY = eventY;
}
private void getDirtyRect(float historicalX, float historicalY) {
if (historicalX < mDirtyRect.left) {
mDirtyRect.left = historicalX;
} else if (historicalX > mDirtyRect.right) {
mDirtyRect.right = historicalX;
}
if (historicalY < mDirtyRect.top) {
mDirtyRect.top = historicalY;
} else if (historicalY > mDirtyRect.bottom) {
mDirtyRect.bottom = historicalY;
}
}
private void resetDirtyRect(float eventX, float eventY) {
mDirtyRect.left = Math.min(mLastTouchX, eventX);
mDirtyRect.right = Math.max(mLastTouchX, eventX);
mDirtyRect.top = Math.min(mLastTouchY, eventY);
mDirtyRect.bottom = Math.max(mLastTouchY, eventY);
}
private static final float STROKE_WIDTH = 5f;
private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
private float mLastTouchX = 0;
private float mLastTouchY = 0;
private int mViewWidth = 0;
private int mViewHeight = 0;
private final RectF mDirtyRect = new RectF();
private Paint mPaint = new Paint();
private Path mPath = new Path();
}
你會發現，當你將activity的dispatchTouchEvent和viewgroup的dispatchTouchEvent、onInterceptTouchEvent方法的返回值都設置爲false時，整個屏幕都不會響應不論什麼消息了，當咱們去掉activity和viewgroup的dispatchTouchEvent方法，僅僅有viewgroup的onInterceptTouchEvent返回值被置爲false時，手寫區域能夠響應。但當手掌靠在手寫區域外，在手寫區域內手寫就失效了，事實上和去掉viewgroupd的onInterceptTouchEvent方法效果是同樣的，也就是說明這樣的處理方式是不可行的。
3、解決方式：
加了贊成分發消息的方法。不攔截向下分發消息反而還不行，這個問題詳細緣由我沒有找到。我的以爲是系統針對activity的消息事件處理作了特殊處理，它的優先級是最高的，儘管可以複寫它的消息分發dispatchTouchEvent方法，但是不管是返回true仍是false結果都是屏幕不能響應不論什麼操做。這一點有知道的大拿歡迎指點指點。
要實現本文想要的功能顯然不能使用開篇講到的方法，在研究這個問題的過程當中，發現儘管activity的dispatchTouchEvent沒法控制，但其onTouchEvent方法是有效的，僅僅要在屏幕的不論什麼一個地方操做，onTouchEvent裏面都會有打印消息，細緻回想上面提到的android消息分發機制會發現，僅僅要咱們在屏幕上操做時，模擬系統在activity的onTouchEvent方法裏面向手寫view派發消息就能夠實現想要的功能。詳細方法例如如下：
一、向下派發消息的實現以及view和activity之間的座標轉換：
如上面所講，當在屏幕上操做時監聽activity的onTouchEvent方法，將在手寫控件內的操做派發給手寫view就能夠實現想要的功能。
（1）座標轉換：
本文的手寫view基於activity居中的，它的座標原點和activity的座標原點不一樣樣，爲了推斷在acitivity上操做的地方是否在手寫view內。需要經過座標轉換以後才幹推斷：
如上圖所看到的，在activity中推斷一個點(x,y)是否在手寫view裏面時，轉換成的座標應該是(x-view.getLeft(),y-view.getTop())。
（2）眼下的view和activity看起來是這樣子的：
DrawView：
public class DrawView extends View {
public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPaintView( );
}
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
initPaintView( );
}
public DrawView(Context context) {
super(context);
initPaintView( );
}
public void clear() {
if (null != mPath) {
mPath.reset();
invalidate();
}
}
private void initPaintView() {
mPaint.setAntiAlias(true);
mPaint.setColor(Color.WHITE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(5f);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mViewWidth = MeasureSpec.getSize(widthMeasureSpec); //獲取ViewGroup寬度
mViewHeight = MeasureSpec.getSize(heightMeasureSpec); //獲取ViewGroup高度
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawPath(mPath, mPaint);
}
public boolean inArea( float x, float y ){
return ( x >= 0 && x <= mViewWidth && y >= 0 && y <= mViewHeight)?true:false;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = -1;
float eventY = -1;
int pointId = 0;
int pointCnt = event.getPointerCount( );
for( int index = 0; index < pointCnt; index++ ){
if( inArea( event.getX( index ) - getLeft( ), event.getY( index ) - getTop( ) ) ){
pointId = index;
eventX = event.getX( index ) - getLeft( );
eventY = event.getY( index ) - getTop( );
break;
}
}
if( ( eventX == -1 || eventY == -1 ) || ( eventX == 0 || eventY == 0 ) ){
return false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
mPath.moveTo(eventX, eventY);
mLastTouchX = eventX;
mLastTouchY = eventY;
invalidate( );
}
return true;
case MotionEvent.ACTION_MOVE:{
drawView( event, eventX, eventY, pointId );
}
break;
case MotionEvent.ACTION_UP:{
drawView( event, eventX, eventY, pointId );
}
break;
default:
return false;
}
return true;
}
private void drawView( MotionEvent event, float eventX, float eventY, int pointId ){
resetDirtyRect(eventX, eventY);
int historySize = event.getHistorySize();
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(pointId,i) - getLeft( );
float historicalY = event.getHistoricalY(pointId,i) - getTop( );
getDirtyRect(historicalX, historicalY);
mPath.lineTo(historicalX, historicalY);
}
mPath.lineTo(eventX, eventY);
invalidate((int) (mDirtyRect.left - HALF_STROKE_WIDTH),
(int) (mDirtyRect.top - HALF_STROKE_WIDTH),
(int) (mDirtyRect.right + HALF_STROKE_WIDTH),
(int) (mDirtyRect.bottom + HALF_STROKE_WIDTH));
mLastTouchX = eventX;
mLastTouchY = eventY;
}
private void getDirtyRect(float historicalX, float historicalY) {
if (historicalX < mDirtyRect.left) {
mDirtyRect.left = historicalX;
} else if (historicalX > mDirtyRect.right) {
mDirtyRect.right = historicalX;
}
if (historicalY < mDirtyRect.top) {
mDirtyRect.top = historicalY;
} else if (historicalY > mDirtyRect.bottom) {
mDirtyRect.bottom = historicalY;
}
}
private void resetDirtyRect(float eventX, float eventY) {
mDirtyRect.left = Math.min(mLastTouchX, eventX);
mDirtyRect.right = Math.max(mLastTouchX, eventX);
mDirtyRect.top = Math.min(mLastTouchY, eventY);
mDirtyRect.bottom = Math.max(mLastTouchY, eventY);
}
private static final float STROKE_WIDTH = 5f;
private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
private float mLastTouchX = 0;
private float mLastTouchY = 0;
private int mViewWidth = 0;
private int mViewHeight = 0;
private final RectF mDirtyRect = new RectF();
private Paint mPaint = new Paint();
private Path mPath = new Path();
}
Activity：
@Override
public boolean onTouchEvent(MotionEvent event) {
int pointCnt = event.getPointerCount( );
for( int index = 0; index < pointCnt; index++ ){
if( mDrawView.inArea( event.getX( index ) - mDrawView.getLeft( ), event.getY( index ) - mDrawView.getTop( ) ) ){
mDrawView.onTouchEvent( event );
System.out.println( "action === pointIndex " + index );
return false;
}
}
//mDrawView.setInView( false );
return super.onTouchEvent(event);
}
DrawView的inArea方法爲核心方法。通過上面的處理後，能夠實現當手掌放在手寫區域外時在手寫區域手寫的功能。效果例如如下圖所看到的。但你會發現當在手寫區域手寫的手指擡起再放下繼續手寫時，會直接畫一條直線。經過接下來對android事件機制中ACTION_DOWN和ACTION_UP消息的分析，該問題將會獲得解決。
二、android消息事件中ACTION_DOWN和ACTION_UP的觸發時機即改善方案：
經過實際測試發現，android消息事件中ACTION_DOWN和ACTION_UP的觸發時機分別爲：
ACTION_DOWN：僅僅要有手指接觸屏幕即會觸發；
ACTION_UP：當屏幕上沒有不論什麼觸控操做時觸發；
對於多點觸控。當某個手指擡起或者鬆開時會分別觸發：ACTION_POINTER_DOWN和ACTION_POINTER_UP，因此對於上面遇到的問題，是由於在多點觸控的狀況下，僅僅點下或者鬆開某一根手指時，這兩個消息不會觸發致使，將ACTION_POINTER_DOWN和ACTION_POINTER_UP這兩類消息在DrawView的onTouchEvent方法中一併處理就能夠解決，改善後的view代碼是這樣子的：
public class DrawView extends View {
public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPaintView( );
}
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
initPaintView( );
}
public DrawView(Context context) {
super(context);
initPaintView( );
}
public void clear() {
if (null != mPath) {
mPath.reset();
invalidate();
}
}
private void initPaintView() {
mPaint.setAntiAlias(true);
mPaint.setColor(Color.WHITE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(5f);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mViewWidth = MeasureSpec.getSize(widthMeasureSpec); //獲取ViewGroup寬度
mViewHeight = MeasureSpec.getSize(heightMeasureSpec); //獲取ViewGroup高度
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawPath(mPath, mPaint);
}
public boolean inArea( float x, float y ){
return ( x >= 0 && x <= mViewWidth && y >= 0 && y <= mViewHeight)?true:false;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = -1;
float eventY = -1;
int pointId = 0;
int pointCnt = event.getPointerCount( );
for( int index = 0; index < pointCnt; index++ ){
if( inArea( event.getX( index ) - getLeft( ), event.getY( index ) - getTop( ) ) ){
pointId = index;
eventX = event.getX( index ) - getLeft( );
eventY = event.getY( index ) - getTop( );
break;
}
}
if( ( eventX == -1 || eventY == -1 ) || ( eventX == 0 || eventY == 0 ) ){
return false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_POINTER_1_DOWN:
case MotionEvent.ACTION_POINTER_2_DOWN:
case MotionEvent.ACTION_POINTER_3_DOWN:
case MotionEvent.ACTION_DOWN: {
mPath.moveTo(eventX, eventY);
mLastTouchX = eventX;
mLastTouchY = eventY;
invalidate( );
}
return true;
case MotionEvent.ACTION_MOVE:{
drawView( event, eventX, eventY, pointId );
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_1_UP:
case MotionEvent.ACTION_POINTER_2_UP:
case MotionEvent.ACTION_POINTER_3_UP:{
drawView( event, eventX, eventY, pointId );
}
break;
default:
return false;
}
return true;
}
private void drawView( MotionEvent event, float eventX, float eventY, int pointId ){
resetDirtyRect(eventX, eventY);
int historySize = event.getHistorySize();
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(pointId,i) - getLeft( );
float historicalY = event.getHistoricalY(pointId,i) - getTop( );
getDirtyRect(historicalX, historicalY);
mPath.lineTo(historicalX, historicalY);
}
mPath.lineTo(eventX, eventY);
invalidate((int) (mDirtyRect.left - HALF_STROKE_WIDTH),
(int) (mDirtyRect.top - HALF_STROKE_WIDTH),
(int) (mDirtyRect.right + HALF_STROKE_WIDTH),
(int) (mDirtyRect.bottom + HALF_STROKE_WIDTH));
mLastTouchX = eventX;
mLastTouchY = eventY;
}
private void getDirtyRect(float historicalX, float historicalY) {
if (historicalX < mDirtyRect.left) {
mDirtyRect.left = historicalX;
} else if (historicalX > mDirtyRect.right) {
mDirtyRect.right = historicalX;
}
if (historicalY < mDirtyRect.top) {
mDirtyRect.top = historicalY;
} else if (historicalY > mDirtyRect.bottom) {
mDirtyRect.bottom = historicalY;
}
}
private void resetDirtyRect(float eventX, float eventY) {
mDirtyRect.left = Math.min(mLastTouchX, eventX);
mDirtyRect.right = Math.max(mLastTouchX, eventX);
mDirtyRect.top = Math.min(mLastTouchY, eventY);
mDirtyRect.bottom = Math.max(mLastTouchY, eventY);
}
private static final float STROKE_WIDTH = 5f;
private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
private float mLastTouchX = 0;
private float mLastTouchY = 0;
private int mViewWidth = 0;
private int mViewHeight = 0;
private final RectF mDirtyRect = new RectF();
private Paint mPaint = new Paint();
private Path mPath = new Path();
}
效果也算比較理想了：
三、邊界問題處理：
通過上面兩步操做，基本上能夠實現手掌抑制功能了，但通過細緻測試會發現，當多點觸控屏幕時。某根手指從手寫控件外移動到手寫控件內時，會在手寫區域邊界直接繪製成直線的現象，例如如下圖：
這是因爲在android中一個完整的消息流程離不開ACTION_DOWN和ACTION_UP，當手指從手寫區域外移動到手寫區域內時，手寫區域根本沒有接收到ACTION_DOWN消息，針對這樣的狀況，咱們需要在activity中對view作特殊處理。即當檢測到有手指在手寫區域但沒有觸發ACTION_DOWN消息時，在ACTION_MOVE消息中處理ACTION_DOWN消息應該處理的事情。
改善後的代碼是這個樣子的：
DrawView：
public class DrawView extends View {
public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPaintView( );
}
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
initPaintView( );
}
public DrawView(Context context) {
super(context);
initPaintView( );
}
public void clear() {
if (null != mPath) {
mPath.reset();
invalidate();
}
}
private void initPaintView() {
mPaint.setAntiAlias(true);
mPaint.setColor(Color.WHITE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(5f);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mViewWidth = MeasureSpec.getSize(widthMeasureSpec); //獲取ViewGroup寬度
mViewHeight = MeasureSpec.getSize(heightMeasureSpec); //獲取ViewGroup高度
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawPath(mPath, mPaint);
}
public boolean inArea( float x, float y ){
return ( x >= 0 && x <= mViewWidth && y >= 0 && y <= mViewHeight)?true:false;
}
@SuppressWarnings("deprecation")
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = -1;
float eventY = -1;
int pointId = 0;
int pointCnt = event.getPointerCount( );
for( int index = 0; index < pointCnt; index++ ){
if( inArea( event.getX( index ) - getLeft( ), event.getY( index ) - getTop( ) ) ){
pointId = index;
eventX = event.getX( index ) - getLeft( );
eventY = event.getY( index ) - getTop( );
break;
}
}
if( ( eventX == -1 || eventY == -1 ) || ( eventX == 0 || eventY == 0 ) ){
return false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_POINTER_1_DOWN:
case MotionEvent.ACTION_POINTER_2_DOWN:
case MotionEvent.ACTION_POINTER_3_DOWN:
case MotionEvent.ACTION_DOWN: {
mPath.moveTo(eventX, eventY);
mLastTouchX = eventX;
mLastTouchY = eventY;
mInView = true;
invalidate( );
}
return true;
case MotionEvent.ACTION_MOVE:{
if( !mInView ){
mInView = true;
mLastTouchX = eventX;
mLastTouchY = eventY;
mPath.moveTo(eventX, eventY);
}
drawView( event, eventX, eventY, pointId );
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_1_UP:
case MotionEvent.ACTION_POINTER_2_UP:
case MotionEvent.ACTION_POINTER_3_UP:{
drawView( event, eventX, eventY, pointId );
}
break;
default:
return false;
}
return true;
}
public void setInView( boolean inView ){
mInView = inView;
}
private void drawView( MotionEvent event, float eventX, float eventY, int pointId ){
resetDirtyRect(eventX, eventY);
int historySize = event.getHistorySize();
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(pointId,i) - getLeft( );
float historicalY = event.getHistoricalY(pointId,i) - getTop( );
getDirtyRect(historicalX, historicalY);
mPath.lineTo(historicalX, historicalY);
}
mPath.lineTo(eventX, eventY);
invalidate((int) (mDirtyRect.left - HALF_STROKE_WIDTH),
(int) (mDirtyRect.top - HALF_STROKE_WIDTH),
(int) (mDirtyRect.right + HALF_STROKE_WIDTH),
(int) (mDirtyRect.bottom + HALF_STROKE_WIDTH));
mLastTouchX = eventX;
mLastTouchY = eventY;
}
private void getDirtyRect(float historicalX, float historicalY) {
if (historicalX < mDirtyRect.left) {
mDirtyRect.left = historicalX;
} else if (historicalX > mDirtyRect.right) {
mDirtyRect.right = historicalX;
}
if (historicalY < mDirtyRect.top) {
mDirtyRect.top = historicalY;
} else if (historicalY > mDirtyRect.bottom) {
mDirtyRect.bottom = historicalY;
}
}
private void resetDirtyRect(float eventX, float eventY) {
mDirtyRect.left = Math.min(mLastTouchX, eventX);
mDirtyRect.right = Math.max(mLastTouchX, eventX);
mDirtyRect.top = Math.min(mLastTouchY, eventY);
mDirtyRect.bottom = Math.max(mLastTouchY, eventY);
}
private static final float STROKE_WIDTH = 5f;
private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
private float mLastTouchX = 0;
private float mLastTouchY = 0;
private boolean mInView = false;
private int mViewWidth = 0;
private int mViewHeight = 0;
private final RectF mDirtyRect = new RectF();
private Paint mPaint = new Paint();
private Path mPath = new Path();
}
activity也需要添加一句話：
@Override
public boolean onTouchEvent(MotionEvent event) {
int pointCnt = event.getPointerCount( );
for( int index = 0; index < pointCnt; index++ ){
if( mDrawView.inArea( event.getX( index ) - mDrawView.getLeft( ), event.getY( index ) - mDrawView.getTop( ) ) ){
mDrawView.onTouchEvent( event );
System.out.println( "action === pointIndex " + index );
return false;
}
}
mDrawView.setInView( false );
return super.onTouchEvent(event);
}
最後最終實現了咱們想要的效果：
4、參考文檔：
5、代碼：
最後附上本文的代碼：Android手掌抑制demo
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