滑鼠向左 字型縮小
滑鼠向右 字型放大
MainActivity

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

/**
 * 事件有三個方法
 * 1：事件分發  dispatchTouchEvent   2：事件攔截 onInterceptTouchEvent   3：事件響應  onTouchEvent
 * <p>
 * Activity 有兩個 1：事件分發，2：事件響應
 * View和ViewGroup 全部擁有
 * <p>
 * 從一個按鈕的點選事件進去執行流程
 * <p>
 * 1：先走Activity  2：ViewGroup 3：具體到點的那個控制元件
 */
public class MainActivity extends AppCompatActivity {
    private float x1, x2;
    private int mSize;
    private Button Click_Btn;
    private ImageView Image_View;
    private TextView tv_name;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        Click_Btn = (Button) findViewById(R.id.Click_Btn);
        Image_View = (ImageView) findViewById(R.id.Image_View);
        tv_name = (TextView) findViewById(R.id.tv_name);
        Click_Btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.e("onClick", "被點選了");
            }
        });
        Click_Btn.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                Log.e("onTouch", event.getAction() + "動作");
                return false;
            }
        });
        //直接通過方法讓按鈕直接被執行
        Click_Btn.performClick();
        Image_View.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                Log.e("Image", event.getAction() + "");
                return false;
            }
        });
    }
//事件分發 true代表這個事件被消費掉過後就不能往下執行了 false沒有被消費會一直往下邊傳遞

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        return super.dispatchTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                x1 = event.getX();
                break;
            case MotionEvent.ACTION_UP:
                x2 = event.getX();
                if (x2 - x1 > 0) {
                    mSize += 5;
                    tv_name.setTextSize(mSize);
                } else {
                    mSize -= 5;
                    tv_name.setTextSize(mSize);
                }
                break;
        }
        return super.onTouchEvent(event);
    }

}
 

佈局檔案

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
        <Button
        android:id="@+id/Click_Btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Click" />

    <ImageView
        android:id="@+id/Image_View"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/ic_launcher" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_name"
        android:layout_gravity="center"
        android:textSize="20dp"
        android:text="字型"/>
</LinearLayout>