Android TextView文本过长时渐隐显示

最简单的方式实现TextView文字过长渐隐，效果如下图：

  

具体实现如下：

package com.example.picturetest.textview;

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

/**
 * 
 * @author ZH-SW-Wangxi
 * @time 2018-4-16
 * @function 过长渐隐
 */

public class TextViewGradient extends TextView {
	/** 开始渐隐长度 */
	private float mGradientScope = 200;
	/** 渲染，主要实现api */
	private Shader shader_horizontal;

	public TextViewGradient(Context context) {
		this(context, null);
	}

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

	/** 设置渐隐长度 */
	public void setGradientScope(float gradientScope) {
		this.mGradientScope = gradientScope;
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
	}

	@Override
	protected void onLayout(boolean changed, int left, int top, int right,
			int bottom) {
		super.onLayout(changed, left, top, right, bottom);
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);
		if (getMeasuredWidth() > mGradientScope) {
			shader_horizontal = new LinearGradient(0, 0, mGradientScope, 0,
					Color.parseColor("#ff0375b2"), Color.TRANSPARENT,
					Shader.TileMode.CLAMP);
		} else {
			shader_horizontal = new LinearGradient(0, 0, mGradientScope, 0,
					Color.parseColor("#ff0375b2"), Color.TRANSPARENT,
					Shader.TileMode.CLAMP);
		}
	}

	@Override
	protected void onDraw(Canvas canvas) {
		getPaint().setShader(shader_horizontal);
		Paint.FontMetrics metrics = getPaint().getFontMetrics();
		float dy = -(metrics.descent + metrics.ascent) / 2;
		float y = getMeasuredHeight() / 2 + dy;
		canvas.drawText((String) getText(), 0, y, getPaint());
	}
}

xml用法和原生TextView一样

代码设置一下需要渐变的长度

mTvGradient = (TextViewGradient) findViewById(R.id.tv_gradient);
mTvGradient.setGradientScope(300);
mTvGradient.setText("文字过长渐隐文字过长渐隐");