Android 自定义View TextView变色字体

先上效果图 

https://img-blog.csdnimg.cn/95edc6546012472eb2411d07a334817b.jpeg

https://img-blog.csdnimg.cn/0dd4d09175f94148af4748334e1a490a.jpeg

先上自定义view

public  class FontColorView extends androidx.appcompat.widget.AppCompatTextView {
    private int sameColor= Color.BLACK;
    private int changeColor=Color.GREEN;
    private Paint mSamePaint ;
    private Paint mChangePaint ;
    public FontColorView(Context context) {
        this(context,null);
    }
    public FontColorView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs,0);
    }
    public FontColorView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.FontColorView);
        sameColor = array.getColor(R.styleable.FontColorView_sameColor,sameColor);
        changeColor = array.getColor(R.styleable.FontColorView_changeColor,changeColor);
        array.recycle();
        initSamePaint();
        initChangePaint();
    }
    private void  initSamePaint(){
        mSamePaint = new Paint();
        mSamePaint.setColor(sameColor);
        mSamePaint.setAntiAlias(true);
        mSamePaint.setTextSize(getTextSize()); // 获取到文字大小
    }
    private void  initChangePaint(){
        mChangePaint = new Paint();
        mChangePaint.setColor(changeColor);
        mChangePaint.setAntiAlias(true);
        mChangePaint.setTextSize(getTextSize()); // 获取到文字大小
    }
    private float mCurrentPro = 0.5F;
    public void setmCurrentPro(float mCurrentPro) {
        this.mCurrentPro = mCurrentPro;
        invalidate();
    }
    public enum DirectionEnum{
        TOLEFT,
        TORIGHT
    }
    private DirectionEnum directionEnum ;
    public void setDirectionEnum(DirectionEnum directionEnum) {
        this.directionEnum = directionEnum;
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.save();   // 保存下 画布  后面执行裁剪操作
        int middle = (int) (mCurrentPro*getWidth()); // 计算中间值
        if(directionEnum ==DirectionEnum.TORIGHT){
            drawText(0,middle,canvas,mChangePaint);
            drawText(middle,getWidth(),canvas,mSamePaint);
        }else {
            drawText(getWidth()-middle,getWidth(),canvas,mChangePaint);
            drawText(0,getWidth()-middle,canvas,mSamePaint);
        }


    }
    private void  drawText(int start ,int end ,Canvas canvas,Paint mPaint){
        canvas.save();
        Rect mClipRect = new Rect(start,0,end,getHeight()) ;
        canvas.clipRect(mClipRect);   // 裁剪区域
        String str = getText().toString() ;// 获取到文本
        Rect boundsRect = new Rect() ;
        mPaint.getTextBounds(str,0,str.length(),boundsRect);
        int x =  getWidth()/2-boundsRect.width()/2;
        Paint.FontMetricsInt fontMetricsInt = mPaint.getFontMetricsInt();//获取到文本的基线
        int baseLine = ( fontMetricsInt.bottom-fontMetricsInt.top)/2-fontMetricsInt.descent;
        int y = getHeight()/2+baseLine ;
        canvas.drawText(str,x,y,mPaint);
        canvas.restore();
    }
}

接下来是自定义属性文件

<declare-styleable name="FontColorView">
    <attr name="sameColor" format="color"/>
    <attr name="changeColor" format="color"/>

</declare-styleable>

效果测试方法

public void changeColor(View view) {

    if(isShow){
        isShow = false;
        font_view_tv.setDirectionEnum(FontColorView.DirectionEnum.TORIGHT);
        ValueAnimator  valueAnimator =  ObjectAnimator.ofFloat(0,1);
        valueAnimator.setDuration(1000);
        valueAnimator.addUpdateListener(animation -> {
            float sds  = (float) animation.getAnimatedValue();
            font_view_tv.setmCurrentPro(sds);
        });
                valueAnimator.start();
    }else {
        isShow = true ;
        font_view_tv.setDirectionEnum(FontColorView.DirectionEnum.TOLEFT);
        ValueAnimator  valueAnimator =  ObjectAnimator.ofFloat(0,1);
        valueAnimator.setDuration(1000);
        valueAnimator.addUpdateListener(animation -> {
            float sds  = (float) animation.getAnimatedValue();
            font_view_tv.setmCurrentPro(sds);
        });
        valueAnimator.start();
    }


}