实现在Android的滑块

本文介绍了实现在Android的滑块的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我想实现一个滑块，这基本上是两条线，一纵一横，道口，屏幕被触摸。我已成功地使一个，但我要的问题：

I want to implement a slider, which is basically two lines, one vertical and one horizontal, crossing where the screen is touched. I have managed to make one but I have to issues:

在滑块不是很顺利，有当我移动手指有轻微的延迟
如果我把两个滑块它没有多点触控，而且我想同时使用两者

下面是code：

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>

感谢您圣诞快乐！

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