Android自定义橡皮擦效果

本文实例为大家分享了android自定义橡皮擦效果，使用贝塞尔曲线处理曲线转折处

public class picfingertotest extends view {

  private paint paint;
  private bitmap decoderesourcesrc;
  private bitmap createbitmapdst;
  // 手指路径，使用贝塞尔路线
  private path path;
  private float perx;
  private float pery;

  public picfingertotest(context context, attributeset attrs) {
    super(context, attrs);
    // 1、设置禁用硬件设置
    setlayertype(view.layer_type_software, null);

    // 2、设置手指画笔
    paint = new paint();
    paint.setantialias(true);
    paint.setcolor(color.red);
    paint.setstyle(paint.style.stroke);
    paint.setstrokewidth(45);

    // 3、生成图像手指源目标
    // 源
    decoderesourcesrc = bitmapfactory.decoderesource(getresources(), r.drawable.welcome, null);
    // 目标
    createbitmapdst = bitmap.createbitmap(decoderesourcesrc.getwidth(), decoderesourcesrc.getheight(),
        config.argb_8888);
    path = new path();

  }

  @override
  protected void ondraw(canvas canvas) {
    super.ondraw(canvas);
    // 分层绘制
    int savelayer = canvas.savelayer(0, 0, getwidth(), getheight(), null,canvas.all_save_flag);

    // 把手指轨迹划到目标路径上
    canvas canvas2 = new canvas(createbitmapdst);
    canvas2.drawpath(path, paint);

    // 把目标图像画到画布上
    canvas.drawbitmap(createbitmapdst, 0, 0, paint);

    // 计算源图像区域

    paint.setxfermode(new porterduffxfermode(mode.src_out));
    canvas.drawbitmap(decoderesourcesrc, 0, 0, paint);

    paint.setxfermode(null);
    canvas.restoretocount(savelayer);

  }

  //使用贝塞尔曲线，使折线过度圆滑
  @override
  public boolean ontouchevent(motionevent event) {

    switch (event.getaction()) {
    // 记录手指触摸的初始化位置
    case motionevent.action_down:

      path.moveto(event.getx(), event.gety());

      perx = event.getx();
      pery = event.gety();

      return true;

    case motionevent.action_move:

      float endx = (perx + event.getx()) / 2;
      float endy = (pery + event.gety()) / 2;

      path.quadto(perx, pery, endx, endy);
      perx = event.getx();
      pery = event.gety();
      postinvalidate();

      break;
    case motionevent.action_up:

      break;

    default:
      break;
    }

    return super.ontouchevent(event);
  }

}

小编再为大家补充一段代码：android橡皮擦擦图片功能

public void oncreate() {
  //底边图片
  imageview ivtop = (imageview) findviewbyid(r.id.iv_top);
 
  options opts = new options(); //图片加载器，用于配置一些缩放比例，和像素单位
  opts.insamplesize = 2; //制定加载器把原图片的宽高缩放到2/1的效果加载
  //获得外层图片,decoderesource方法默认获得的像素单位是rgb(red,green,blue),argb(alpha,red,green,blue)
  bitmap topimage = bitmapfactory.decoderesources( getresource(),r.drawable.top, opts);
 
  //创建一张空白图片，并且把图片想读单位指定为:argb
  bitmap blank = bitmap.createbitmap(topimage.getwidth(), topimage.getheight, config.argb_4444);
 
  //把上边的topimage画到空白图片上
  canvas canvas = new canvas(blank);
  //把topimage画到空白图片上但是像素单位变成argb()
  canvas.drawbitmap(topimage, 0, 0, null);
  ivtop.setimagebitmap(blank);
}
 
class myontouchlistoner implements ontouchlistener {
 
  @override pulic boolean ontouch(view v, motionevent event) {
    //是否是移动的事件
    if (event.getaction() == motionevent.action_move) {
      //获得按下坐标
      int x = (int) event.getx();
      int y = (int) event.gety();
 
      for (int i = x - 10; i < x + 10; i++) {
        for (int j = y - 10; j < y + 10; j++) {
          //防止超出边界
          if (j >= 0 && blank.getheight() && i >= 0 && i < blank.getwidth()) {
            blank.setpixel(i, j, color.transparent);
          }
        }
      }
      //修改后的图片设置给imageview
      ivtop.setimagebitmap(blank);
    }
 
    return true; //true 消耗掉这次触摸事件.false 不消耗
  }
 
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。