在Android中实现滑块(SeekBar)

Question

我想实现一个滑块,它基本上是两条线,一条垂直线和一条水平线,穿过触摸屏幕的地方.我设法做了一个,但我必须提出问题:

1. 滑块不是很平滑,当我移动手指时有轻微的延迟
2. 如果我放置两个滑块,它不是多点触控,我想同时使用它们

这是代码:

public class Slider extends View {

    private Controller controller = new Controller();
    private boolean initialisedSlider;
    private int sliderWidth, sliderHeight;
    private Point pointStart;
    private Paint white;
    private int mode;

    final static int VERTICAL = 0, HORIZONTAL = 1, BOTH = 2;

    public Slider(Context context) {
        super(context);
        setFocusable(true);    
        // TODO Auto-generated constructor stub
    }
    public Slider(Context context, AttributeSet attrs) {
        super(context, attrs);     
        setFocusable(true);    
        pointStart = new Point();
        initialisedSlider = false;   
        mode = Slider.BOTH;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if(!initialisedSlider) {
            initialisedSlider = true;
            sliderWidth = getMeasuredWidth();
            sliderHeight = getMeasuredHeight();

            pointStart.x = (int)(sliderWidth/2.0);
            pointStart.y = (int)(sliderHeight/2.0);
            controller = new Controller(pointStart, 3);

            white = new Paint();
            white.setColor(0xFFFFFFFF);
        }

        canvas.drawLine(controller.getCoordX(),0,
                        controller.getCoordX(),sliderHeight, 
                        white);
        canvas.drawLine(0, controller.getCoordY(), 
                        sliderWidth, controller.getCoordY(), 
                        white);

    }

    public boolean onTouchEvent(MotionEvent event) {
        int eventaction = event.getAction();     
        int X = (int)event.getX(); 
        int Y = (int)event.getY(); 
        switch (eventaction) { 
        case MotionEvent.ACTION_DOWN:
            if(isInBounds(X,Y)) {
                updateController(X, Y);
            }
            break;
        case MotionEvent.ACTION_MOVE:
            if(isInBounds(X,Y)) {
                updateController(X, Y);
            }
            break;
        case MotionEvent.ACTION_UP:
            if(isInBounds(X,Y)) {
                updateController(X, Y);
            }
            break;
        }
        invalidate();  
        return true; 
    }

    private boolean isInBounds(int x, int y) {
        return ((x<=(sliderWidth)) && (x>=(0)) 
                 && (y<=(sliderHeight)) && (y>=(0)));
    }
    private void updateController(int x, int y) {
        switch(mode) {
        case Slider.HORIZONTAL:
            controller.setCoordX(x);
            break;
        case Slider.VERTICAL:
            controller.setCoordY(y);
            break;
        case Slider.BOTH:
            controller.setCoordX(x);
            controller.setCoordY(y);
            break;
        }
    }

    private class Controller {
        private int coordX, coordY;
        Controller() {

        }
        Controller(Point point, int width) {
            setCoordX(point.x);
            setCoordY(point.y);
        }
        public void setCoordX(int coordX) {
            this.coordX = coordX;
        }
        public int getCoordX() {
            return coordX;
        }
        public void setCoordY(int coordY) {
            this.coordY = coordY;
        }
        public int getCoordY() {
            return coordY;
        }
    }
}

和XML文件:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <com.android.lasttest.Slider 
        android:id="@+id/slider"
        android:layout_width="100dp" 
        android:layout_height="100dp" 
        android:layout_gravity="center_horizontal" 
        android:adjustViewBounds="true"/>
    <com.android.lasttest.Slider 
        android:id="@+id/slider"
        android:layout_width="150dp" 
        android:layout_height="150dp" 
        android:layout_gravity="center_horizontal" 
        android:adjustViewBounds="true"/>
    <com.android.lasttest.Slider 
        android:id="@+id/slider"
        android:layout_width="200dp" 
        android:layout_height="200dp" 
        android:layout_gravity="center_horizontal" 
        android:adjustViewBounds="true"/>

</LinearLayout>

Answer 1

Android提供水平滑块

• http://developer.android.com/reference/android/widget/SeekBar.html

并实现OnSeekBarChangeListener

• http://developer.android.com/reference/android/widget/SeekBar.OnSeekBarChangeListener.html

如果您想要垂直Seekbar,请点击此链接

• http://hoodaandroid.blogspot.in/2012/10/vertical-seek-bar-or-slider-in-android.html

Answer 2

如何实现SeekBar

将SeekBar添加到您的布局中

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

    <TextView
        android:id="@+id/textView"
        android:layout_margin="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <SeekBar
        android:id="@+id/seekBar"
        android:max="100"
        android:progress="50"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

笔记

• max是搜索栏可以达到的最高值.默认是100.最低限度是0.xml min值仅可从API 26获得,但您可以通过编程方式将0-100范围转换为早期版本所需的范围.
• progress 是滑块点的初始位置(称为"拇指").
• 对于垂直SeekBar使用android:rotation="270".

听取代码的变化

public class MainActivity extends AppCompatActivity {

    TextView tvProgressLabel;

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

        // set a change listener on the SeekBar
        SeekBar seekBar = findViewById(R.id.seekBar);
        seekBar.setOnSeekBarChangeListener(seekBarChangeListener);

        int progress = seekBar.getProgress();
        tvProgressLabel = findViewById(R.id.textView);
        tvProgressLabel.setText("Progress: " + progress);
    }

    SeekBar.OnSeekBarChangeListener seekBarChangeListener = new SeekBar.OnSeekBarChangeListener() {

        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            // updated continuously as the user slides the thumb
            tvProgressLabel.setText("Progress: " + progress);
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {
            // called when the user first touches the SeekBar
        }

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            // called after the user finishes moving the SeekBar
        }
    };
}

笔记

• 如果您在用户移动搜索栏时不需要进行任何更新,那么您只需更新用户界面即可onStopTrackingTouch.

也可以看看

• 在Android Studio中使用示例的SeekBar教程

Answer 3

对于未来的读者！

从材料组件 android 1.2.0-alpha01 开始，你有slider组件

前任：

<com.google.android.material.slider.Slider
        android:id="@+id/slider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:valueFrom="20f"
        android:valueTo="70f"
        android:stepSize="10" />

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