7.5. SeekBar (拖动条)
- 掌握拖动条：SeekBar的主要作用
- 掌握SeekBar组件的事件处理操作
- 可以使用SeekBar组件控制手机屏幕的亮度。
| public class SeekBarextends AbsSeekBar
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范例一:简单拖动
配置：
| <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <SeekBar android:id="@+id/seekbar" android:layout_width="fill_parent" android:layout_height="wrap_content" /> <TextView android:id="@+id/text" android:layout_width="fill_parent" android:layout_height="wrap_content"/> </LinearLayout> |
Activity:
| package com.makyan.demo; import android.app.Activity; import android.os.Bundle; import android.text.method.ScrollingMovementMethod; import android.widget.SeekBar; import android.widget.TextView; public class SeekBarActivity extends Activity { private SeekBar seekbar = null; private TextView text = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); super.setContentView(R.layout.activity_seek_bar); seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件 text = (TextView) super.findViewById(R.id.text); // 取得组件 text.setMovementMethod(ScrollingMovementMethod.getInstance()); // 文本组件的内容可以滚动 seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl()); } private class OnSeekBarChangeListenerImpl implements SeekBar.OnSeekBarChangeListener { @Override public void onStartTrackingTouch(SeekBar seekBar) { SeekBarActivity.this.text.append("*** 开始拖动，当前值：" + seekBar.getProgress() + "\n"); } @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { SeekBarActivity.this.text.append("*** 正在拖动，当前值：" + seekBar.getProgress() + "\n"); } @Override public void onStopTrackingTouch(SeekBar seekBar) { SeekBarActivity.this.text.append("*** 停止拖动，当前值：" + seekBar.getProgress() + "\n"); } } } |
演示效果：
范例二：拖动显示图片
配置：
| <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <ImageView android:id="@+id/pic" android:src="@drawable/pic_0" android:layout_width="fill_parent" android:layout_height="wrap_content"/> <SeekBar android:id="@+id/seekbar" android:layout_width="fill_parent" android:layout_height="wrap_content" /> </LinearLayout> |
Activity:
| package com.makyan.demo; import android.app.Activity; import android.os.Bundle; import android.widget.ImageView; import android.widget.SeekBar; public class SeekBarActivity extends Activity { private SeekBar seekbar = null; private ImageView pic = null; private int picData[] = new int[] { R.drawable.pic_0, R.drawable.pic_1, R.drawable.pic_2, R.drawable.pic_3, R.drawable.pic_4, R.drawable.pic_5, R.drawable.pic_6, R.drawable.pic_7, R.drawable.pic_8, R.drawable.pic_9 }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); super.setContentView(R.layout.activity_seek_bar); seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件 pic = (ImageView) super.findViewById(R.id.pic); // 取得组件 seekbar.setMax(9); // 0 ~ 9的范围 seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl()); } private class OnSeekBarChangeListenerImpl implements SeekBar.OnSeekBarChangeListener { @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) { pic.setImageResource(SeekBarActivity.this.picData[seekBar.getProgress()]);// 设置显示图片 } @Override public void onStopTrackingTouch(SeekBar seekBar) { } } } |
演示效果：
范例三：改变屏幕亮度
WindowManager.LayoutParams layoutParams = super.getWindow().getAttributes() ;
// 取得屏幕的属性
配置：
| <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <ImageView android:id="@+id/pic" android:src="@drawable/android_book" android:layout_width="fill_parent" android:layout_height="wrap_content"/> <SeekBar android:id="@+id/seekbar" android:layout_width="fill_parent" android:layout_height="wrap_content" /> </LinearLayout> |
Activity:
| package com.makyan.demo; import android.app.Activity; import android.os.Bundle; import android.view.WindowManager; import android.widget.SeekBar; public class SeekBarActivity extends Activity { private SeekBar seekbar = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); super.setContentView(R.layout.activity_seek_bar); seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件 seekbar.setMax(100); seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl()); } private class OnSeekBarChangeListenerImpl implements SeekBar.OnSeekBarChangeListener { @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { setScreenBrightness((float) seekBar.getProgress() / 100); } @Override public void onStopTrackingTouch(SeekBar seekBar) { } } private void setScreenBrightness(float num) { // 0 ~ 1表示亮度 WindowManager.LayoutParams layoutParams = super.getWindow().getAttributes() ; // 取得屏幕的属性 layoutParams.screenBrightness = num ; // 设置屏幕亮度 super.getWindow().setAttributes(layoutParams) ; // 重新设置窗口的属性 } } |
演示效果就不贴了，很简单。