拖动条(SeekBar)使用

李小白是一只喵

发布于 2020-04-23 15:20:48

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发布于 2020-04-23 15:20:48

文章被收录于专栏：算法微时光算法微时光

SeekBar

SeekBar 是水平进度条 ProgressBar 的间接子类，相当于一个可以拖动的水平进度条。

使用时需要在xml文件中添加:

   <SeekBar
        android:id="@+id/seekBar1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"/>

基本使用方式和进度条差不多.

使用实例

activity_main.xml文件:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView"/>

    <SeekBar
        android:id="@+id/seekBar1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="89dp"
        android:layout_marginBottom="385dp"
        android:max="100"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView1"
        tools:layout_editor_absoluteX="0dp" />

</android.support.constraint.ConstraintLayout>

代码文件:

package com.example.user.seekbar;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.SeekBar;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

    private TextView textView;
    private SeekBar seekBar;

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

        textView = (TextView)findViewById(R.id.textView1);
        seekBar = (SeekBar)findViewById(R.id.seekBar1);

        textView.setText("当前进度为：" + "0%");
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener(){
            /*拖动条停止拖动时调用 */
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
            }
            /*拖动条开始拖动时调用*/
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
            }
            /* 拖动条进度改变时调用*/
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                textView.setText("当前进度为：" + progress + "%");
            }
        });

    }
}

实例效果:

使用SeekBar改变图片透明度

activity_main.xml文件:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="400dp"
        android:layout_height="400dp"
        android:src="@drawable/ppp"/>


    <SeekBar
        android:id="@+id/seekBar1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="89dp"
        android:layout_marginBottom="385dp"
        android:max="100"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView1"
        app:layout_constraintVertical_bias="0.28"
        tools:layout_editor_absoluteX="0dp" />

</android.support.constraint.ConstraintLayout>

代码文件:

package com.example.user.seekbar;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.SeekBar;
import android.widget.ImageView;


public class MainActivity extends AppCompatActivity {

    private ImageView imageView;
    private SeekBar seekBar;

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

        imageView = (ImageView)findViewById(R.id.imageView1);
        seekBar = (SeekBar)findViewById(R.id.seekBar1);

        seekBar.setMax(255);
        imageView.setImageAlpha(255);
        seekBar.setProgress(255);

        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener(){
            /*拖动条停止拖动时调用 */
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
            }
            /*拖动条开始拖动时调用*/
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
            }
            /* 拖动条进度改变时调用*/
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                imageView.setImageAlpha(progress);
            }
        });

    }
}

执行效果: