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安卓編程中如何判斷View之間的碰撞

View的移動和碰撞檢測的核心就在於如何獲取到View在屏幕中的位置,獲取的方法很多,本文中直接使用View.getX() View.getY()方法獲取到左上角的頂點位置,View之間的碰撞檢測就是在View的移動過程中不斷計算和特定View之間的距離。代碼如下:

import android.content.Context;

import android.graphics.RectF;

import android.util.AttributeSet;

import android.util.Log;

import android.view.MotionEvent;

import android.view.View;

import android.widget.RelativeLayout;

public class TouchMoveView extends RelativeLayout {

private static final String TAG="TouchMoveView";

private View mTargetView;

private View mRedView, mBlueView, mGreenView, mYellowView;

private RectF mRedRect,mBlueRect,mGreenRect,mYellowRect,mTargetRect;

private View mParentView;

public TouchMoveView(Context context) {

this(context, null);

}

public TouchMoveView(Context context, AttributeSet attrs) {

super(context, attrs);

}

@Override

protected void onFinishInflate() {

super.onFinishInflate();

mTargetView = findViewById(R.id.target_view);

mRedView = findViewById(R.id.red);

mBlueView = findViewById(R.id.blue);

mGreenView = findViewById(R.id.green);

mYellowView = findViewById(R.id.yellow);

mParentView=findViewById(R.id.parent_view);

}

private View mTouchedView;

private float mInitX;

private float mInitY;

@Override

public boolean onTouchEvent(MotionEvent event) {

initRect();

float x=event.getX();

float y=event.getY();

int action=event.getAction();

switch (action) {

case MotionEvent.ACTION_DOWN:

mTouchedView=getTouchedView((int)x, (int)y);

if(null!=mTouchedView){

mInitX=mTouchedView.getX();

mInitY=mTouchedView.getY();

}

Log.e(TAG,"mTouchedView:"+mTouchedView);

return true;

case MotionEvent.ACTION_MOVE:

if(null!=mTouchedView){

float moveX=x-mTouchedView.getWidth()/2;

float moveY=y-mTouchedView.getHeight()/2;

Log.e(TAG,"moveX:"+moveX+" moveY:"+moveY );

mTouchedView.setX(moveX);

mTouchedView.setY(moveY);

if(isTwoViewClose(mTouchedView, mTargetView)){

int colorRes=getColorRes(mTouchedView);

mTargetView.setBackgroundColor(getResources().getColor(colorRes));

}else{

mTargetView.setBackgroundColor(getResources().getColor(R.color.black));

}

}

return true;

case MotionEvent.ACTION_UP:

case MotionEvent.ACTION_CANCEL:

if(null!=mTouchedView){

mTouchedView.setX(mInitX);

mTouchedView.setY(mInitY);

}

mTargetView.setBackgroundColor(getResources().getColor(R.color.black));

return true;

default:

return false;

}

}

private int getColorRes(View view){

if(null==view){

return R.color.black;

}

int id=view.getId();

switch (id) {

case R.id.blue:

return R.color.blue;

case R.id.red:

return R.color.red;

case R.id.green:

return R.color.green;

case R.id.yellow:

return R.color.yellow;

default:

return R.color.black;

}

}

private View getTouchedView(int x,int y){

Log.e(TAG,"x:"+x+" y:"+y);

Log.e(TAG,"mRedRect"+mRedRect);

Log.e(TAG,"mBlueRect"+mBlueRect);

Log.e(TAG,"mGreenRect"+mGreenRect);

Log.e(TAG,"mYellowRect"+mYellowRect);

if(mRedRect.contains(x, y)){

return mRedView;

}

if(mBlueRect.contains(x, y)){

return mBlueView;

}

if(mGreenRect.contains(x, y)){

return mGreenView;

}

if(mYellowRect.contains(x, y)){

return mYellowView;

}

return null;

}

private void initRect(){

if(null==mRedRect){

mRedRect=getRect(mRedView);

}

if(null==mBlueRect){

mBlueRect=getRect(mBlueView);

}

if(null==mGreenRect){

mGreenRect=getRect(mGreenView);

}

if(null==mYellowRect){

mYellowRect=getRect(mYellowView);

}

if(null==mTargetRect){

mTargetRect=getNormalRect(mTargetView);

}

}

private RectF getNormalRect(View view){

return new RectF(view.getX(),view.getY(),view.getX()+view.getWidth(),view.getY()+view.getHeight());

}

private RectF getRect(View view){

RectF rectf=new RectF(view.getX(),view.getY()+mParentView.getY(),view.getX()+view.getWidth(),view.getY()+mParentView.getY()+view.getHeight());

return rectf;

}

/**判斷兩個View是否相交

* @param src

* @param target

* @return

*/

private boolean isTwoViewClose(View src,View target){

RectF rectSrc=getNormalRect(src);

RectF rectTar=getNormalRect(target);

return rectSrc.intersect(rectTar);

}

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