字型滾動選擇器,當滾動到某個字型時,直接改變對應的字型,首先看一下滾動選擇器

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.Paint.FontMetricsInt;
import android.graphics.Paint.Style;
import android.graphics.Typeface;
import
 
 android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;

/**
 *
 * 滾動選擇器
 */
public class PolaroidPickerView extends View
{


    public
 
 static final String TAG = "PolaroidPickerView";
    /**
     * text之間間距和minTextSize之比
     */
    public static final float MARGIN_ALPHA = 2.0f;
    /**
     * 自動回滾到中間的速度
     */
    public static final float SPEED = 2;

    public static final String ABCDEFG_TEXT = "PickView";


    private ArrayList<Typeface> mTypefaceList;
    /**
     * 選中的位置，這個位置是mTypefaceList的中心位置，一直不變
     */
 

    private int mCurrentSelected;
    private Paint mPaint;

    private float mMaxTextSize = 30;
    private float mMinTextSize = 20;

    private float mMaxTextAlpha = 255;
    private float mMinTextAlpha = 120;

    private int mColorText = 0x333333;

    private int mViewHeight;
    private int mViewWidth;

    private float mLastDownY;
    /**
     * 滑動的距離
     */
    private float mMoveLen = 0;
    private boolean isInit = false;
    private onSelectListener mSelectListener;
    private Timer timer;
    private MyTimerTask mTask;

    Handler updateHandler = new Handler()
    {
        @Override
        public void handleMessage(Message msg)
        {
            if (Math.abs(mMoveLen) < SPEED)
            {
                mMoveLen = 0;
                if (mTask != null)
                {
                    mTask.cancel();
                    mTask = null;
                    performSelect();
                }
            } else
                //  // 這裡mMoveLen / Math.abs(mMoveLen)是為了保有mMoveLen的正負號，以實現上滾或下滾
                mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;
            invalidate();
        }

    };

    public PolaroidPickerView(Context context)
    {
        super(context);

        init();
    }

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

    public void setOnSelectListener(onSelectListener listener)
    {
        mSelectListener = listener;
    }

    private void performSelect()
    {
        if (mSelectListener != null)
            mSelectListener.onSelect(mTypefaceList.get(mCurrentSelected));
    }


    public void setSelected(int selected)
    {
        mCurrentSelected = selected;
    }

    private void moveHeadToTail()
    {
        Typeface head = mTypefaceList.get(0);
        mTypefaceList.remove(0);
        mTypefaceList.add(head);
    }

    private void moveTailToHead()
    {
        Typeface tail = mTypefaceList.get(mTypefaceList.size() - 1);
        mTypefaceList.remove(mTypefaceList.size() - 1);
        mTypefaceList.add(0, tail);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mViewHeight = getMeasuredHeight();
        mViewWidth = getMeasuredWidth();
        // 按照View的高度計算字型大小
        mMaxTextSize = mViewHeight / 5.0f;
        mMinTextSize = mMaxTextSize / 2f;
        isInit = true;
        invalidate();
    }

    private void init()
    {
        timer = new Timer();
         //初始化字型資料  這裡我們可以設定成String,從而設計文字滾動選擇器,文字選擇器mList = new mList<String>();
        mTypefaceList = new ArrayList<Typeface>();
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStyle(Style.FILL);
        mPaint.setTextAlign(Align.CENTER);
        mPaint.setColor(mColorText);
//        Typeface tf = Typeface.createFromAsset(this.getContext().getAssets(),
//                "fonts/FasterOne-Regular.ttf");
//        mPaint.setTypeface(tf);
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);
        // 根據index繪製view
        if (isInit)
            drawData(canvas);
    }

    private void drawData(Canvas canvas)
    {
        // 先繪製選中的text再往上往下繪製其餘的text
        float scale = parabola(mViewHeight / 4.0f, mMoveLen);
        float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
        mPaint.setTextSize(size);

        mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
        // text居中繪製，注意baseline的計算才能達到居中，y值是text中心座標
        float x = (float) (mViewWidth / 2.0);
        float y = (float) (mViewHeight / 2.0 + mMoveLen);
        FontMetricsInt fmi = mPaint.getFontMetricsInt();
        float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
        //設定畫筆字型  文字滾動選擇器不需要設定字型 
// canvas.drawText(mList.get(mCurrentSelected),x,baseline,mPaint);
mPaint.setTypeface(mTypefaceList.get(mCurrentSelected));
        //設定selected顏色
//        mPaint.setColor(getResources().getColor(R.color.edit_font_color));
        mPaint.setColor(Color.RED);
        //畫內容,  文字選擇器只需要直接畫內容,
        canvas.drawText(PolaroidPickerView.ABCDEFG_TEXT, x, baseline, mPaint);
        //繪製上方data
        for (int i = 1; (mCurrentSelected - i) >= 0; i++)
        {
            drawOtherText(canvas, i, -1);
        }
        // 繪製下方data
        for (int i = 1; (mCurrentSelected + i) < mTypefaceList.size(); i++)
        {
            drawOtherText(canvas, i, 1);
        }

    }

    /**
     * @param canvas
     * @param position
     *            距離mCurrentSelected的差值
     * @param type
     *            1表示向下繪製，-1表示向上繪製
     */
    private void drawOtherText(Canvas canvas, int position, int type)
    {
        float d = (float) (MARGIN_ALPHA * mMinTextSize * position + type
                * mMoveLen);
        float scale = parabola(mViewHeight / 4.0f, d);
        float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;   
        mPaint.setTextSize(size);
        mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
        //設定normal顏色
//        mPaint.setColor(getResources().getColor(R.color.black));
        mPaint.setColor(Color.WHITE);
        float y = (float) (mViewHeight / 2.0 + type * d);
        FontMetricsInt fmi = mPaint.getFontMetricsInt();
        float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
        //設定其他的字型顯示並畫出來
        mPaint.setTypeface(mTypefaceList.get(mCurrentSelected + type * position));
        canvas.drawText(PolaroidPickerView.ABCDEFG_TEXT,
                (float) (mViewWidth / 2.0), baseline, mPaint);
    }

    /**
     * 拋物線
     * 
     * @param zero
     *           零點座標
     * @param x
     *            偏移量
     * @return scale
     */
    private float parabola(float zero, float x)
    {
        float f = (float) (1 - Math.pow(x / zero, 2));
        return f < 0 ? 0 : f;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event)
    {
        switch (event.getActionMasked())
        {
        case MotionEvent.ACTION_DOWN:
            doDown(event);
            break;
        case MotionEvent.ACTION_MOVE:
            doMove(event);
            break;
        case MotionEvent.ACTION_UP:
            doUp(event);
            break;
        }
        return true;
    }

    private void doDown(MotionEvent event)
    {
        if (mTask != null)
        {
            mTask.cancel();
            mTask = null;
        }
        mLastDownY = event.getY();
    }

    private void doMove(MotionEvent event)
    {

        mMoveLen += (event.getY() - mLastDownY);

        if (mMoveLen > MARGIN_ALPHA * mMinTextSize / 2)
        {
            // 往下滑超過離開距離
            moveTailToHead();
            mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;
        } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2)
        {
            // 往上滑超過離開距離
            moveHeadToTail();
            mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;
        }

        mLastDownY = event.getY();
        invalidate();
    }

    private void doUp(MotionEvent event)
    {
        // 擡起手後mCurrentSelected的位置由當前位置move到中間選中位置
        if (Math.abs(mMoveLen) < 0.0001)
        {
            mMoveLen = 0;
            return;
        }
        if (mTask != null)
        {
            mTask.cancel();
            mTask = null;
        }
        mTask = new MyTimerTask(updateHandler);
        timer.schedule(mTask, 0, 10);
    }

    public ArrayList<Typeface> getTypefaceList() {
        return mTypefaceList;
    }

    public void setTypefaceList(ArrayList<Typeface> mTypefaceList) {
        this.mTypefaceList = mTypefaceList;
        mCurrentSelected = mTypefaceList.size() / 2;
        invalidate();
    }

    class MyTimerTask extends TimerTask
    {
        Handler handler;

        public MyTimerTask(Handler handler)
        {
            this.handler = handler;
        }

        @Override
        public void run()
        {
            handler.sendMessage(handler.obtainMessage());
        }

    }

    public interface onSelectListener
    {
        void onSelect(Typeface typeface);
    }

    public int getCurSeleceted(){
        return mCurrentSelected;
    }
}

呼叫並設定字型給對應的文字

    /**
     * 初始化字型
     */
    private void initData() {
        mFonts.add(Typeface.DEFAULT);
        String[] listName;
        try {
            listName = mPolaroidActivity.getAssets().list("fonts");
            for (String fontname : listName) {
                mFonts.add(Typeface.createFromAsset(mPolaroidActivity.getAssets(), "fonts/"
                        + fontname));
            }
        } catch (Exception e) {
            // TODO: handle exception
        }
    }

  inflater.inflate(R.layout.polaroid_fragment_font_style, mFl);
            PolaroidPickerView pickerView = (PolaroidPickerView) mFl.findViewById(R.id.polaroid_fragment_font_style_pickerview);
            //給滾動選擇器設定字型,文字選擇器直接設定文字即可
        pickerView.setTypefaceList(mFonts);
        pickerView.setOnSelectListener(new PolaroidPickerView.onSelectListener() {
            @Override
            public void onSelect(Typeface typeface) {
                mPolaroidActivity.getEt().setTypeface(typeface);
            }
        });