Paint着色器一

参考资料：http://blog.csdn.net/aigestudio/article/details/41799811

Paint有很多重要的方法，之前的颜色过滤器、过渡模式，这里开始Shader着色器

着色器有很5种，这里介绍第一种BitmapShader

1、BitmapShader简介

　　画布上在绘制时，使用一张图片，来设置不同的模式来着色，图片的起点则是0，0。模式有三种分别是：Shader.TileMode.CLAMP,Shader.TileMode.MIRROR,Shader.TileMode.REPEAT

　　tile[taɪl] 瓦片，TileMode平铺模式　　clamp[klæmp]堆高、夹住　　mirror[ˈmɪrə(r)]镜子，反射　　repeat[rɪˈpi:t]重复

　　边缘拉伸，y轴边缘像素复制，再x轴边缘像素复制

public class ShaderView extends View{

    private Paint mPaint;

    public ShaderView(Context context, AttributeSet attrs) {
        super(context, attrs);

        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG|Paint.DITHER_FLAG);
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.b);
        // BitmapShader是先应用了Y轴的模式而X轴是后应用的
        mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));

    }

    @Override
    protected void onDraw(Canvas canvas) {

        canvas.drawRect(100, 100, 600, 600, mPaint);
    }
}

　　

　　上下左右镜像

public class ShaderView extends View{

    private Paint mPaint;

    public ShaderView(Context context, AttributeSet attrs) {
        super(context, attrs);

        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG|Paint.DITHER_FLAG);
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.b);
        // BitmapShader是先应用了Y轴的模式而X轴是后应用的
        mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.MIRROR, Shader.TileMode.MIRROR));

    }

    @Override
    protected void onDraw(Canvas canvas) {

        canvas.drawRect(100, 100, 600, 600, mPaint);
    }
}

　　

　　上下左右重复

public class ShaderView extends View{

    private Paint mPaint;

    public ShaderView(Context context, AttributeSet attrs) {
        super(context, attrs);

        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG|Paint.DITHER_FLAG);
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.b);
        // BitmapShader是先应用了Y轴的模式而X轴是后应用的
        mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT));

    }

    @Override
    protected void onDraw(Canvas canvas) {

        canvas.drawRect(100, 100, 600, 600, mPaint);
    }
}

　　

 

2、BitmapShader应用

　　绘制只显示圆圈的内容，随手指拖动显示

public class BrickView extends View {

    private Paint mFillPaint, mStrokePaint;
    private BitmapShader mBitmapShader;

    private float posX, posY;

    public BrickView(Context context, AttributeSet attrs) {
        super(context, attrs);

        mStrokePaint = new Paint(Paint.ANTI_ALIAS_FLAG|Paint.DITHER_FLAG);
        mStrokePaint.setColor(0xFF000000);
        mStrokePaint.setStyle(Paint.Style.STROKE);
        mStrokePaint.setStrokeWidth(5);

        mFillPaint = new Paint();

        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.b);
        mBitmapShader = new BitmapShader(bitmap, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);
        mFillPaint.setShader(mBitmapShader);
    }


    @Override
    protected void onDraw(Canvas canvas) {

        canvas.drawColor(Color.DKGRAY);
        canvas.drawCircle(posX, posY, 80, mFillPaint);
        canvas.drawCircle(posX, posY, 80, mStrokePaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if(event.getAction() == MotionEvent.ACTION_MOVE){
            posX = event.getX();
            posY = event.getY();

            invalidate();
        }
        return true;
    }
}