Android渲染器Shader：梯度渐变扫描渲染器SweepGradient（二）


Android渲染器Shader：梯度渐变扫描渲染器SweepGradient（二）

附录文章1介绍了线性渐变渲染器。

Android的SweepGradient梯度渐变扫描，重点是在构造SweepGradient的中心点选择。我写一个例子。

package zhangphil.demo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.SweepGradient;
import android.util.AttributeSet;
import android.view.View;

/**
* Created by Phil on 2016/7/25.
*/

public class SweepGradientView extends View {

private Paint mPaint = null;

// 梯度渐变扫描渲染
private SweepGradient mSweepGradient = null;

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

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

mSweepGradient = new SweepGradient(this.getWidth() / 2, this.getHeight() / 2, new int[]{Color.TRANSPARENT, Color.RED, Color.TRANSPARENT, Color.YELLOW, Color.BLUE}, null);
mPaint = new Paint();
mPaint.setAntiAlias(true);

mPaint.setShader(mSweepGradient);

canvas.drawCircle(this.getWidth() / 2, this.getHeight() / 2, 300, mPaint);
}
}

SweepGradientView直接像附录文章1那样在上层的activity里面new出来一个对象，然后setContentView进去即可。

代码运行结果：



附录文章：

1，《Android渲染器Shader：LinearGradient（一）》链接：http://blog.csdn.net/zhangphil/article/details/52004027