Android移动开发-手势事件处理MotionEvent的实现

手势事件处理MotionEvent是智能手机的一大特性，即可用于信息输出（显示界面）又可用于输入（检测用户的触摸行为）。为了方便开发者使用，Android已经自动识别特定的几种触摸手势，包括按钮的点击事件OnClickListener、长按事件OnLongClickListener、滚动视图ScrollView的上下滚动事件、翻页视图ViewPager的左右翻页事件等。
其中dispatchTouchEvent、onInterceptTouchEvent和onTouchEvent的输入参数都是手势事件MotionEvent，其中包含触摸动作的所有信息，各种手势操作都得到MotionEvent中获取信息并进行判断处理。

以下是演示单点触摸的代码实现：

• layout/activity_touch_single.xml界面布局代码如下：

package com.fukaimei.touchevent;import java.util.Date;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.MotionEvent;import android.widget.TextView;public class TouchSingleActivity extends AppCompatActivity {    private TextView tv_touch;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_touch_single);        tv_touch = (TextView) findViewById(R.id.tv_touch);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        // 从开机到现在的毫秒数        int seconds = (int) (event.getEventTime() / 1000);        int hour = seconds / 3600;        int minute = seconds % 3600 / 60;        int second = seconds % 60;        Date date = new Date(event.getEventTime());        String desc = String.format("动作发生时间：开机距离现在%02d:%02d:%02d",                hour, minute, second);        desc = String.format("%s\n动作名称是：", desc);        int action = event.getAction();        if (action == event.ACTION_DOWN) {            desc = String.format("%s按下", desc);        } else if (action == event.ACTION_MOVE) {            desc = String.format("%s移动", desc);        } else if (action == event.ACTION_UP) {            desc = String.format("%s提起", desc);        } else if (action == event.ACTION_CANCEL) {            desc = String.format("%s取消", desc);        }        desc = String.format("%s\n动作发生位置是：横坐标%f，纵坐标%f",                desc, event.getX(), event.getY());        tv_touch.setText(desc);        return super.onTouchEvent(event);    }}

• TouchSingleActivity.java逻辑代码如下：

package com.fukaimei.touchevent;import java.util.Date;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.MotionEvent;import android.widget.TextView;public class TouchSingleActivity extends AppCompatActivity {    private TextView tv_touch;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_touch_single);        tv_touch = (TextView) findViewById(R.id.tv_touch);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        // 从开机到现在的毫秒数        int seconds = (int) (event.getEventTime() / 1000);        int hour = seconds / 3600;        int minute = seconds % 3600 / 60;        int second = seconds % 60;        Date date = new Date(event.getEventTime());        String desc = String.format("动作发生时间：开机距离现在%02d:%02d:%02d",                hour, minute, second);        desc = String.format("%s\n动作名称是：", desc);        int action = event.getAction();        if (action == event.ACTION_DOWN) {            desc = String.format("%s按下", desc);        } else if (action == event.ACTION_MOVE) {            desc = String.format("%s移动", desc);        } else if (action == event.ACTION_UP) {            desc = String.format("%s提起", desc);        } else if (action == event.ACTION_CANCEL) {            desc = String.format("%s取消", desc);        }        desc = String.format("%s\n动作发生位置是：横坐标%f，纵坐标%f",                desc, event.getX(), event.getY());        tv_touch.setText(desc);        return super.onTouchEvent(event);    }}

• Demo程序运行效果界面截图如下：

除了单点触摸外，智能手机还普通支持多点触控，即响应两个及以上手指同时按压屏幕。多点触控可用于操纵图像的缩放与旋转操作，以及需要多点处理的游戏界面等。

下面是演示多点触控的页面代码：

• layout/activity_touch_multiple.xml界面布局代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:padding="5dp">    <TextView        android:id="@+id/tv_touch_main"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="这里显示主要点触摸结果"        android:textColor="@color/black"        android:textSize="17sp" />    <TextView        android:id="@+id/tv_touch_secondary"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="这里显示次要点触摸结果"        android:textColor="@color/black"        android:textSize="17sp" /></LinearLayout>

• TouchMultipleActivity.java逻辑代码如下：

package com.fukaimei.touchevent;import java.util.Date;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.MotionEvent;import android.widget.TextView;public class TouchMultipleActivity extends AppCompatActivity {    private TextView tv_touch_main;    private TextView tv_touch_secondary;    private boolean bSecondaryPressed = false;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_touch_multiple);        tv_touch_main = (TextView) findViewById(R.id.tv_touch_main);        tv_touch_secondary = (TextView) findViewById(R.id.tv_touch_secondary);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int seconds = (int) (event.getEventTime() / 1000);        int hour = seconds / 3600;        int minute = seconds % 3600 / 60;        int second = seconds % 60;        Date date = new Date(event.getEventTime());        String desc_main = String.format("主要动作发生时间：开机距离现在%02d:%02d:%02d\n%s",                hour, minute, second, "主要动作名称是：");        String desc_secondary = "";        int action = event.getAction() & MotionEvent.ACTION_MASK;        if (action == event.ACTION_DOWN) {            desc_main = String.format("%s按下", desc_main);        } else if (action == event.ACTION_MOVE) {            desc_main = String.format("%s移动", desc_main);            if (bSecondaryPressed == true) {                desc_secondary = String.format("%s次要动作名称是：移动", desc_secondary);            }        } else if (action == event.ACTION_UP) {            desc_main = String.format("%s提起", desc_main);        } else if (action == event.ACTION_CANCEL) {            desc_main = String.format("%s取消", desc_main);        } else if (action == event.ACTION_POINTER_DOWN) {            bSecondaryPressed = true;            desc_secondary = String.format("%s次要动作名称是：按下", desc_secondary);        } else if (action == event.ACTION_POINTER_UP) {            bSecondaryPressed = false;            desc_secondary = String.format("%s次要动作名称是：提起", desc_secondary);        }        desc_main = String.format("%s\n主要动作发生位置是：横坐标%f，纵坐标%f",                desc_main, event.getX(), event.getY());        tv_touch_main.setText(desc_main);        if (bSecondaryPressed == true || desc_secondary.length() > 0) {            desc_secondary = String.format("%s\n次要动作发生位置是：横坐标%f，纵坐标%f",                    desc_secondary, event.getX(1), event.getY(1));            tv_touch_secondary.setText(desc_secondary);        }        return super.onTouchEvent(event);    }}

• Demo程序运行效果界面截图如下：

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