彩色跑马灯TextView

利用android中的LinearGradient,来实现滚动的颜色,其实就是一个矩阵在跑

package com.minami.qtest1;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.widget.TextView;

public class RainbowTextView extends TextView {
private int mViewWidth=0;
private float mTranslate = 0;
private Paint mPaint;
private LinearGradient mLinearGradient;
private Matrix mMatrix;

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

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

public RainbowTextView(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);
//初始化渲染器
if (mViewWidth == 0) {
mViewWidth = getMeasuredWidth();
if (mViewWidth > 0) {
mPaint = getPaint();
mLinearGradient = new LinearGradient(0, 0, mViewWidth, 0, new int[]{Color.RED, Color.GREEN, Color.YELLOW},
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);
}
}
}