android中碰撞屏幕边界反弹问题

其实碰撞问题只是涉及到一点小算法而已，但在实际应用，尤其游戏中有可能会遇到，下面给出一个小示例，代码如下：

MainActivity：

package com.lovo;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.app.Activity;
public class MainActivity extends Activity {
private Handler handler;
public static final int MOVE_IMAGE = 1;
// 移动方向和距离
private int decX = 5;
private int decY = 5;
// 坐标
private int moveX;
private int moveY;
private boolean isMove;// 是否正在移动
private RelativeLayout relative;
private ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageView = (ImageView) findViewById(R.id.activity_main_image);
handler = new MyHandler(this);
relative = (RelativeLayout) findViewById(R.id.activity_main_relativelayout);
Button endBtn = (Button) findViewById(R.id.activity_main_btn_end);
endBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
isMove = false;
}
});
Button btn = (Button) findViewById(R.id.activity_main_btn_start);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (!isMove) {
isMove = true;
} else {
return;
}
new Thread() {
public void run() {
while (isMove) {
moveX += decX;
moveY += decY;
if ((moveX + imageView.getWidth()) >= relative
.getWidth() || moveX < 0) {
decX = -decX;
}
if ((moveY + imageView.getHeight()) >= relative
.getHeight() || moveY < 0) {
decY = -decY;
}
Message message = new Message();
message.what = MOVE_IMAGE;
Bundle bundle = new Bundle();
bundle.putInt("moveX", moveX);
bundle.putInt("moveY", moveY);
message.setData(bundle);
handler.sendMessage(message);
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
}.start();
}
});
}
}

MyHandler类：

package com.lovo;
import android.app.Activity;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class MyHandler extends Handler {
private Activity activity;
private ImageView imageView;
public MyHandler(Activity activity) {
this.activity = activity;
}
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
imageView = (ImageView) activity.findViewById(R.id.activity_main_image);
if (msg.what == MainActivity.MOVE_IMAGE) {
android.widget.RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT,
RelativeLayout.LayoutParams.WRAP_CONTENT);
// 利用Margin改变小球的位置
lp.setMargins(msg.getData().getInt("moveX"),
msg.getData().getInt("moveY"), 0, 0);
imageView.setLayoutParams(lp);
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/activity_main_relativelayout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true" >
<Button
android:id="@+id/activity_main_btn_start"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="开始" />
<Button
android:id="@+id/activity_main_btn_end"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="停止" />
</LinearLayout>
<ImageView
android:id="@+id/activity_main_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ball" />
</RelativeLayout>

附上图片效果：

巴特西

android中碰撞屏幕边界反弹问题

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