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

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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

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