文字霓虹灯效果

新建LinearGradientTextView，继承TextView，重写onSizeChanged和onDraw。

public class LinearGradientTextView extends TextView {

    private int mViewWidth;

    private Paint mPaint;

    private LinearGradient mLinearGradient;

    private Matrix mMatrix;

    private int mTranslate;

    public LinearGradientTextView(Context context) {

        super(context);

    }

    public LinearGradientTextView(Context context, AttributeSet attrs) {

        super(context, attrs);

    }

    public LinearGradientTextView(Context context, AttributeSet attrs, int defStyleAttr) {

        super(context, attrs, defStyleAttr);

    }

    @Override

    protected void onSizeChanged(int w, int h, int oldw, int oldh) {

        super.onSizeChanged(w, h, oldw, oldh);

        if (mViewWidth == 0) {

            mViewWidth = getMeasuredWidth();

            if (mViewWidth > 0) {

                mPaint = getPaint();

                mLinearGradient = new LinearGradient(0, 0, mViewWidth, 0,

                        new int[]{Color.BLUE, Color.GRAY, Color.RED, Color.GREEN}, null, Shader.TileMode.MIRROR);

                mPaint.setShader(mLinearGradient);

                mMatrix = new Matrix();

            }

        }

    }

    @Override

    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);

        if (mMatrix != null) {

            mTranslate += mViewWidth / 5;

            if (mTranslate > 2 * mViewWidth) {

                mTranslate = -mViewWidth;

            }

            mMatrix.setTranslate(mTranslate, 0);

            mLinearGradient.setLocalMatrix(mMatrix);

            postInvalidateDelayed(100);

        }

    }

}

LinearGradient有两个构造函数：
public LinearGradient(float x0, float y0, float x1, float y1, int[] colors, float[] positions,Shader.TileMode tile)
参数:
float x0: 渐变起始点x坐标
float y0:渐变起始点y坐标
float x1:渐变结束点x坐标
float y1:渐变结束点y坐标
int[] colors:颜色 的int 数组
float[] positions: 相对位置的颜色数组,可为null, 若为null,可为null,颜色沿渐变线均匀分布
Shader.TileMode tile: 渲染器平铺模式

<com.wuxiaolong.apksample.LinearGradientTextView

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_gravity="center"

        android:gravity="center"

        android:text="测试文字一闪一闪"

        android:textSize="30sp" />

转自:http://wuxiaolong.me/2015/11/16/LinearGradientTextView/