Android使用滑动条SeekBar

Posted 2022-12-12 油醋三椒

layout布局文件（clear_activity.xml）：

SeekBar的属性值介绍：

android:max=“255” （最大的滑动值，从0开始）

android:progress=“255”（初始时滑动条的位置）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#e0e0e0">

    <SeekBar
        android:id="@+id/seekBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:max="255"  
        android:progress="255"
        android:padding="10dp"/>
    <TextView
        android:id="@+id/seekBar_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="透明度：255"
        android:padding="20dp"/>

    <ImageView
        android:id="@+id/chapter3_imageView"
        android:layout_width="wrap_content"
        android:layout_height="472dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="30dp"
        android:layout_marginBottom="70dp"
        android:layout_gravity="center_horizontal"
        android:scaleType="fitCenter"  />
 
</LinearLayout>

Java活动文件(ClearActivity)：

import android.app.ActionBar;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;

import org.opencv.android.Utils;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Scalar;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

import java.io.ByteArrayOutputStream;
import java.util.Random;

public class ClearActivity extends Activity 

    private SeekBar seekBar;
    private TextView tv;
    private ImageView imageView;
    private Bitmap bm;
    private Data application;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.clear_activity);
        
        application = (Data)getApplicationContext();//保存全局变量
        Bitmap bm = application.getBitmap_edit();//得到具体的全局变量
        
        ImageView iv = (ImageView)this.findViewById(R.id.chapter3_imageView);
        iv.setImageBitmap(bm);//为ImageView设置图片
        init();
    

    private void init() 
        imageView = (ImageView) findViewById(R.id.chapter3_imageView);
        seekBar = (SeekBar) findViewById(R.id.seekBar);//得到Seek bar
        tv = (TextView) findViewById(R.id.seekBar_tv); //得到TextView
        //为滑动条Seekbar添加事件监听
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() 
            @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) 
            	//滑动时，执行此函数
               //progress为当前滑动条的进度
                imageView.setImageAlpha(progress);//根据滑动条进度改变图片的透明度
                progress = progress-255;
                tv.setText("透明度："+ progress );// 当进度条改变时，改变文本框的显示内容
            

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) 
            //开始滑动时，执行此函数
            Toast.makeText(ClearActivity.this,"开始滑动",Toast.LENGTH_SHORT).show();
            

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) 
            //结束滑动时，执行此函数
            Toast.makeText(ClearActivity.this,"结束滑动",Toast.LENGTH_SHORT).show();
            
        );