JAVA + 屏幕小圆球 + 俩手指 + 变大变小

最新推荐文章于 2021-06-09 18:28:13 发布

翻译最新推荐文章于 2021-06-09 18:28:13 发布 · 319 阅读

本文介绍了一个基于Android的应用程序实例，通过重写触摸事件实现视图的拖动和缩放功能。利用多指触控特性，可以轻松地调整屏幕中元素的位置和大小。

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布局：
 <View
    android:id="@+id/view"
    android:layout_width="10dp"
    android:layout_height="10dp"
    android:background="@drawable/oval" />
 
背景：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"  android:shape="oval">
    <solid android:color="@android:color/black"/>
</shape>

代码：

package com.example.com.lianxi_02;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.widget.FrameLayout;

public class MainActivity extends AppCompatActivity {


        View view;
        public static final int DRAG = 1;
        public static final int SCALE = 2;
        int mode = 1;

        int height = 10, width = 10;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            getWindow().requestFeature(Window.FEATURE_NO_TITLE);
            setContentView(R.layout.activity_main);


            view = findViewById(R.id.view);
        }

        float length = 1;

        // 重写

        public boolean onTouchEvent(MotionEvent event) {
            int x = (int) event.getX();
            int y = (int) event.getY();
            // 多指触控
            switch (event.getAction() & event.getActionMasked()) {
                case MotionEvent.ACTION_DOWN:
                    mode = DRAG;
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    Log.e("TAG", "多指移动");
                    mode = SCALE;
                    // 两个手指开始的长度是多少呢？
                    length = calc(event);
                    break;
                case MotionEvent.ACTION_UP:
                    length = 1;
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        // 1. 单个手指
                        FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(
                                width, height);
                        params.setMargins(x, y, 0, 0);
                        view.setLayoutParams(params);
                    } else {
                        // 2. 两个手指
                        float beilv = calc(event) / length;
                        width = (int) (view.getWidth() * beilv);
                        height = (int) (view.getHeight() * beilv);
                        Log.e("TAG", beilv + "  " + width + "  " + height);

                        FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) view
                                .getLayoutParams();
                        params.width = width;
                        params.height = height;
                        view.setLayoutParams(params);
                    }
                    break;
            }
            return true;
        }

        // 类 Ponint
        public float calc(MotionEvent event) {
            float x1 = event.getX();
            float y1 = event.getY();
            float x2 = event.getX(1);
            float y2 = event.getY(1);
            return (float) Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
        }
    }