path BimapShader

渲染 Shader：

BimapShader位图的图像渲染器

LinearGradient线性渲染

RadialGradient环形渲染

SweepGradient梯度渲染(扫描渲染)

ComposeShader组合渲染

利用bitmapshader我们可以实现圆形等一些列的不规则的突破

/**
 * TileMode.CLAMP 拉伸最后一个像素去铺满剩下的地方
 * TileMode.MIRROR 通过镜像翻转铺满剩下的地方。
 * TileMode.REPEAT 重复图片平铺整个画面（电脑设置壁纸）
 */

bitmapShader = new BitmapShader(bitmap, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);

可以利用矩阵对bitmrpshader实现平移  旋转  缩放等一些列操作

        width = bitmap.getWidth();
        height = bitmap.getHeight();
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        Matrix matrix = new Matrix();
        matrix.setScale(bitmapRadius * 2.0f / width, bitmapRadius * 2.0f / height);
        bitmapShader.setLocalMatrix(matrix);
最后设置shader

 paint.setShader(bitmapShader);
最后在ondraw中进行绘制

canvas.drawCircle(bitmapRadius, bitmapRadius, bitmapRadius, paint);
关于描边

        strokePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        strokePaint.setColor(Color.RED);
        strokePaint.setStrokeWidth(5);
        strokePaint.setStyle(Paint.Style.STROKE);
        canvas.drawCircle(bitmapRadius, bitmapRadius, bitmapRadius, strokePaint);

我们还可以利用shapeDrawable去实现圆形图片

        ShapeDrawable shapeDrawable = new ShapeDrawable(new OvalShape());
        shapeDrawable.getPaint().setShader(bitmapShader);
        shapeDrawable.setBounds(0, 0, bitmapRadius * 2, bitmapRadius * 2);
        shapeDrawable.draw(canvas);

完整代码如下

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RadialGradient;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.view.View;

/**
 * Created by qianxin on 16/11/24.
 */

public class MyPathShader extends View {

    private Bitmap bitmap;
    private Paint paint;
    private BitmapShader bitmapShader;
    private int width;
    private int height;

    private int bitmapRadius = 100;

    private Paint strokePaint;


    private int[] colors = {Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW};

    private RadialGradient radialGradient;


    public MyPathShader(Context context) {
        super(context);
        bitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.zsh)).getBitmap();


        strokePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        strokePaint.setColor(Color.RED);
        strokePaint.setStrokeWidth(5);
        strokePaint.setStyle(Paint.Style.STROKE);


        bitmapShader = new BitmapShader(bitmap, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);

        width = bitmap.getWidth();
        height = bitmap.getHeight();
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        Matrix matrix = new Matrix();
        matrix.setScale(bitmapRadius * 2.0f / width, bitmapRadius * 2.0f / height);
        bitmapShader.setLocalMatrix(matrix);
        //将图片根据控件的尺寸进行缩放
        paint.setShader(bitmapShader);
    }

    /**
     * TileMode.CLAMP 拉伸最后一个像素去铺满剩下的地方
     * TileMode.MIRROR 通过镜像翻转铺满剩下的地方。
     * TileMode.REPEAT 重复图片平铺整个画面（电脑设置壁纸）
     */

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

        canvas.drawColor(Color.WHITE);

         canvas.drawCircle(bitmapRadius, bitmapRadius, bitmapRadius, paint);

        canvas.drawCircle(bitmapRadius, bitmapRadius, bitmapRadius, strokePaint);


        //用shapeDrawable也可以实现
        ShapeDrawable shapeDrawable = new ShapeDrawable(new OvalShape());
        shapeDrawable.getPaint().setShader(bitmapShader);
        shapeDrawable.setBounds(0, 0, bitmapRadius * 2, bitmapRadius * 2);
        shapeDrawable.draw(canvas);
        canvas.drawCircle(bitmapRadius, bitmapRadius, bitmapRadius, strokePaint);

        radialGradient = new RadialGradient(300, 300, 50, colors, null, Shader.TileMode.MIRROR);
        paint.setShader(radialGradient);
        canvas.drawCircle(300, 300, 150, paint);
    }
}