LinearGradient线型渐变效果

 public LinearGradient(float x0, float y0, float x1, float y1, int[] colors, float[] positions, TileMode tile) {
        throw new RuntimeException("Stub!");
    }

    public LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1, TileMode tile) {
        throw new RuntimeException("Stub!");
    }

x0,y0是起始 的渐变点坐标,x1 ,y1 是结束渐变点坐标,color0是起始颜色,color1是终止颜色,tile填充模式,colors是对应的颜色数值,position与渐变颜色相对应,取值是0到1 的float类型数据,表示每种颜色在整条渐变线中的百分比位置

示例代码:

package com.loaderman.customviewdemo;

import android.content.Context;
import android.graphics.*;
import android.util.AttributeSet;
import android.view.View;


public class LinearGradientView extends View {
    private Paint mPaint;

    public LinearGradientView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setLayerType(LAYER_TYPE_SOFTWARE, null);
        mPaint = new Paint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        /**
         * 双色渐变
         */
//        mPaint.setShader(new LinearGradient(0,getHeight()/2,getWidth(),getHeight()/2,0xffff0000,0xff00ff00, Shader.TileMode.CLAMP));
//        canvas.drawRect(0,0,getWidth(),getHeight(),mPaint);

        /**
         * 多色渐变
         */
        int[] colors = {0xffff0000,0xff00ff00,0xff0000ff,0xffffff00,0xff00ffff};
        float[]  pos = {0f,0.2f,0.4f,0.6f,1.0f};
        LinearGradient multiGradient = new LinearGradient(0,getHeight()/2,getWidth(),getHeight()/2,colors,pos, Shader.TileMode.CLAMP);
        mPaint.setShader(multiGradient);
        canvas.drawRect(0,0,getWidth(),getHeight(),mPaint);

        /**
         * 多色渐变文字
         */
//        int[] colors = {0xffff0000, 0xff00ff00, 0xff0000ff, 0xffffff00, 0xff00ffff};
//        float[] pos = {0f, 0.2f, 0.4f, 0.6f, 1.0f};
//        LinearGradient multiGradient = new LinearGradient(0, 0, getWidth()/2, getHeight()/2, colors, pos, Shader.TileMode.MIRROR);
//        mPaint.setShader(multiGradient);
//        mPaint.setTextSize(50);
//        canvas.drawText("欢迎学习", 0, getHeight()/2, mPaint);

    }
}

package com.loaderman.customviewdemo;

import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.*;
import android.util.AttributeSet;
import android.widget.TextView;


public class ShimmerTextView extends TextView {
    private Paint mPaint;
    private int mDx;
    private LinearGradient mLinearGradient;

    public ShimmerTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint = getPaint();
        int length = (int) mPaint.measureText(getText().toString());
        createAnim(length);
        createLinearGradient(length);
    }

    private void createAnim(int length) {
        ValueAnimator animator = ValueAnimator.ofInt(0, 2 * length);
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            public void onAnimationUpdate(ValueAnimator animation) {
                mDx = (Integer) animation.getAnimatedValue();
                postInvalidate();
            }
        });
        animator.setRepeatMode(ValueAnimator.RESTART);
        animator.setRepeatCount(ValueAnimator.INFINITE);
        animator.setDuration(2000);
        animator.start();
    }

    private void createLinearGradient(int length) {
        mLinearGradient = new LinearGradient(-length, 0, 0, 0, new int[]{
                getCurrentTextColor(), 0xff00ff00, getCurrentTextColor()
        },
                new float[]{
                        0,
                        0.5f,
                        1
                },
                Shader.TileMode.CLAMP
        );
    }


    @Override
    protected void onDraw(Canvas canvas) {

        Matrix matrix = new Matrix();
        matrix.setTranslate(mDx, 0);
        mLinearGradient.setLocalMatrix(matrix);
        mPaint.setShader(mLinearGradient);

        super.onDraw(canvas);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="center"
    android:background="@android:color/white"
    android:gravity="center"
    android:orientation="vertical">

    <com.loaderman.customviewdemo.LinearGradientView
        android:layout_width="match_parent"
        android:layout_height="200dp" />

    <com.loaderman.customviewdemo.ShimmerTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="嗯哈 loaderman" />
</LinearLayout>

效果: