自绘制View---------左右滑动刻度调频View

代码中使用自定义View：

private SeekView mSeekView = null;
......
mSeekView = new SeekView(this, mHandler);
RelativeLayout rela = (RelativeLayout)findViewById(R.id.seek_part);
rela.addView(mSeekView);

重写View如下：

package com.mediatek.fmradio;

import java.util.StringTokenizer;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.Path;
import android.graphics.Shader;
import android.graphics.Typeface;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.format.Time;
import android.util.AttributeSet;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;

public class SeekView extends View {

    private static final String TAG = "SeekView";

    private final Paint mPaint = new Paint();
    private final double FM_STATION_FIELD = 108.0 - 87.5;
    private final double FM_STATION_MIN = 87.5;
    private final double FM_STATION_MAX = 108.0;
    private Bitmap mBitmapSlider;
    private Bitmap mBitmapSliderPress;
    private String mStrStationValue;
    private float mFloatStationValue;
    private float mOffSet;
    private float mSliderLength;
    private float mSliderMargin;
    private boolean mBoolClickPress;
    private Handler mHandler;
    Message mMessage;
    Bundle mBundle;

    public SeekView(Context context) {
        super(context);
    }

    public SeekView(Context context, final Handler mHandler) {
        super(context);
        this.mHandler = mHandler;
        mBundle = new Bundle();
        mSliderLength = 0;
        mSliderMargin = (float) context.getResources().getDimension(R.dimen.slider_margin);
        mBitmapSlider = BitmapFactory.decodeResource(context.getResources(), R.drawable.indicator);
        mBitmapSliderPress = BitmapFactory.decodeResource(context.getResources(), R.drawable.indicator_pressed);
        if (null != mBitmapSlider) {
            mSliderMargin = mSliderMargin + mBitmapSlider.getWidth() / 2;
        }
        mBoolClickPress = false;
        mStrStationValue = "87.5";
        mFloatStationValue = 87.5f;
    }

    public static float dip2px(Context context, float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (dpValue * scale + 0.5f);
    }

    public static float px2dip(Context context, float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (pxValue / scale + 0.5f);
    }

    public SeekView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SeekView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public String getStationValue() {
        return this.mStrStationValue;
    }

    public float getFloatStationValue() {
        return this.mFloatStationValue;
    }

    public void setStationValue(String st_v) {
        this.mStrStationValue = st_v;
        this.mFloatStationValue = Float.parseFloat(mStrStationValue);
        updateSeekView();
    }

    public void setStationValue(float st_v) {
        this.mFloatStationValue = st_v;
        this.mStrStationValue = Float.toString(this.mFloatStationValue);
        updateSeekView();
    }

    public void updateSeekView() {
        this.invalidate();
    }

    @Override
    public void onDraw(Canvas canvas) {
        float viewWidth = (float) getWidth();
        if (viewWidth == 0) {
            return;
        }
        if (mFloatStationValue < FM_STATION_MIN || mFloatStationValue > FM_STATION_MAX) {
            return;
        }
        mSliderLength = getWidth() - mSliderMargin * 2;
        mOffSet = (float) ((mFloatStationValue - 87.5) * mSliderLength / (108.0 - 87.5));

        canvas.drawBitmap(mBoolClickPress ? mBitmapSliderPress : mBitmapSlider,
                mSliderMargin - mBitmapSlider.getWidth() / 2 + mOffSet, getTop(), mPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float mX = event.getX();
        float mY = event.getY();
        if (mY < getTop() || mY > getBottom()) {
            return false;
        }
        mSliderLength = getWidth() - mSliderMargin * 2;
        mOffSet = (float) ((mFloatStationValue - 87.5) * mSliderLength / (108.0 - 87.5));
        if (mY > getTop() && mY < (getTop() + mBitmapSlider.getHeight())
                && mX > (mSliderMargin + mOffSet - mBitmapSlider.getWidth() / 2)
                && mX < (mSliderMargin + mOffSet + mBitmapSlider.getWidth() / 2)) {
            mBoolClickPress = true;
        }
        if (event.getAction() == MotionEvent.ACTION_UP) {
            mBoolClickPress = false;
        }
        if (mX < mSliderMargin) {
            mOffSet = 0;
        } else if (mX > (getRight() - mSliderMargin)){
            mOffSet = mSliderLength;
        } else {
            mOffSet = mX - mSliderMargin;
        }
        mFloatStationValue = (float) (mOffSet * (108.0 - 87.5) / mSliderLength + 87.5);

        mBundle.putInt(FmRadioListener.KEY_STATION_VALUE, (int) ((mFloatStationValue) * 10));
        mMessage = new Message();
        mMessage.what = FmRadioListener.MSGID_MOVE_FINISHED;
        mMessage.setData(mBundle);
        mHandler.sendMessage(mMessage);

        this.invalidate();
        return true;
    }
}