在特定时间段内为Android着色TextView

问题描述

是否可以在特定时间段内为 TextView 或 Android 中的其他文本着色。因此，它将以全白色文本开始，然后着色从左向右移动并在一定的持续时间。

例如，如果 duration 为 10 ，则整行应为彩色 10 秒，但它也应该以相同的速度移动。

Is there a way to color text in TextView or something else in Android during certain time period. So it would start off with fully white text and then the coloring would move from left to right and fill it up during a certain duration.
So for example if the duration would be 10 then the whole line should be color in 10 seconds, but it should also move with the same pace.

看起来像这样：

有一种方法可以在 IOS 和 CATextLayer ，但是我还没有找到在 Android上实现此目标的方法。

There is a way to do it on IOS with CATextLayer, but I haven't yet found a way to do it on Android.

推荐答案

我去年刚刚创建了一个自定义TextView，这是我的课程

I'm just creating a self-defined TextView in last year,here is my class

public class AKChangeColorTextView extends TextView {
    public AKChangeColorTextView(Context context) {
        this(context,null);
    }
    String TAG = "AKChangeColorTextView";
    public AKChangeColorTextView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }

    RectF mRectF;
    float mX;
    float mY;
    public AKChangeColorTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setColor(Color.BLUE);
        PorterDuffXfermode mode = new PorterDuffXfermode(PorterDuff.Mode.SRC_IN);
        mPaint.setXfermode(mode);
        float x = 60;
        float y = 10;
        mY =    0;
        mRectF = new RectF(x, y, x + 50, y + 50);
        mTPaint = getPaint();
        mX = 0;
    }

    Paint mPaint;
    TextPaint mTPaint;
    Bitmap shadowBitmap ;
    Rect bounds = new Rect();
    Canvas textCanvas;

    @Override
    protected void onDraw(Canvas canvas) {
//        super.onDraw(canvas);
        if (shadowBitmap == null) {
            shadowBitmap = Bitmap.createBitmap(getMeasuredWidth(),getMeasuredHeight(), Bitmap.Config.ARGB_8888);
        }
        if (textCanvas == null) {
            textCanvas = new Canvas(shadowBitmap);
        }
        textCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
        if (mTPaint == null) {
            mTPaint = getPaint();
        }
        String content  = getText().toString();
        mTPaint.getTextBounds(content,0,content.length(),bounds);
        textCanvas.drawText(content,0,bounds.height(),mTPaint);
        mRectF.set(colorLeft,mY,colorRight,mY+bounds.height()+10);
        textCanvas.drawRect(mRectF,mPaint);
        canvas.drawBitmap(shadowBitmap,0,0,null);
    }
    float colorLeft;
    float colorRight;
    public void setXOffset(float left,float right){
        colorLeft = left;
        colorRight = right;
        invalidate();
    }

}

我的演示代码：

class MainActivity : AppCompatActivity() {
    val TAG = "MainActivity"
    lateinit var countDownTimer:CountDownTimer
    var currentOffsetx = 0
    var textWidth = 0
    var isIncrease = true
    lateinit var txt:AKChangeColorTextView
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setSupportActionBar(toolbar)
        (findViewById<View>(R.id.tv_hello) as AKChangeColorTextView).apply{
            txt = this
        }

        countDownTimer = object:CountDownTimer(300000,200){
            override fun onFinish() {
            }

            override fun onTick(millisUntilFinished: Long) {
                if (textWidth == 0) {
                    textWidth = txt.width
                }
                if (currentOffsetx <= textWidth) {
                    if (isIncrease) {
                        currentOffsetx += 10
                        currentOffsetx = min(currentOffsetx, textWidth)
                    } else {
                        currentOffsetx -= 10
                        currentOffsetx = max(currentOffsetx, 0)
                    }
                }
                if (currentOffsetx == textWidth) {
                    isIncrease = false
                }else if (currentOffsetx == 0) {
                    isIncrease = true
                }
                txt.setXOffset(0f,currentOffsetx.toFloat())
                Log.w(TAG,"check current tick:$millisUntilFinished,offsetx:$currentOffsetx,txtWidth:$textWidth")
            }
        }
        countDownTimer.start()
    }

}

我的xml布局：

<com.example.administrator.myapplication.AKChangeColorTextView
            android:id="@+id/tv_hello"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="I Found a Love For Aolphn"
            android:textColor="#000000"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent"/>

以下是效果

这篇关于在特定时间段内为Android着色TextView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！