刮刮乐效果

BitmapShader+ path  实现“”刮刮乐“”效果

 步骤：准备一张尺寸不小于view 的图片，这样shader 不会使用填充模式

package boyikia.com.thumbsview;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.graphics.Shader;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

/**
 * @des :
 * @author: lht
 * @time : 2019/3/26 22:20
 */
public class TelescopeView extends View {
    private Paint mPaint;
    private Bitmap mbitmap;
    private int startX=-1,startY=-1;
    private  boolean isDown;
    private Path mPath=new Path();
    public TelescopeView(Context context) {
        super(context);
        initView();
    }

    public TelescopeView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    public TelescopeView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView();
    }

    private void initView() {
        setLayerType(LAYER_TYPE_SOFTWARE, null);
        mPaint = new Paint();
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(20);
        mbitmap = BitmapFactory.decodeResource(getResources(), R.drawable.timg);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(startX!=-1&&startY!=-1){
            mPaint.setShader(new BitmapShader(mbitmap, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT));
            if(isDown){
                mPath.moveTo(startX,startY);
            }else{
                mPath.lineTo(startX,startY);
            }
            canvas.drawPath(mPath,mPaint);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                isDown=true;
                startX= (int) event.getX();
                startY= (int) event.getY();
                postInvalidate();
                return  true;
            case MotionEvent.ACTION_MOVE:
                isDown=false;
                startX= (int) event.getX();
                startY= (int) event.getY();
                postInvalidate();

                break;
            case MotionEvent.ACTION_UP:
                break;

        }
        return super.onTouchEvent(event);
    }
}