Android自定义一个图形单点移动缩小的效果

先给大家展示下效果图，如果大家感觉不错，请参考实现代码

效果图如下所示：

代码如下所示：

public class mainactivity extends activity {
  view view;
  public static final int drag = 1;
  public static final int scale = 2;
  int mode = 1;
  int height = 10, width = 10;
  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    getwindow().requestfeature(window.feature_no_title);
    setcontentview(r.layout.activity_main);
    view = findviewbyid(r.id.view);
  }
  float length = 1;
  // 重写
  @override
  public boolean ontouchevent(motionevent event) {
    int x = (int) event.getx();
    int y = (int) event.gety();
    // 多指触控
    switch (event.getaction() & event.getactionmasked()) {
    case motionevent.action_down:
      mode = drag;
      break;
    case motionevent.action_pointer_down:
      log.e("tag", "多指移动");
      mode = scale;
      // 两个手指开始的长度是多少呢？
      length = calc(event);
      break;
    case motionevent.action_up:
      length = 1;
      break;
    case motionevent.action_move:
      if (mode == drag) {
        // 1. 单个手指
        framelayout.layoutparams params = new framelayout.layoutparams(
            width, height);
        params.setmargins(x, y, 0, 0);
        view.setlayoutparams(params);
      } else {
        // 2. 两个手指
        float beilv = calc(event) / length;
        width = (int) (view.getwidth() * beilv);
        height = (int) (view.getheight() * beilv);
        log.e("tag", beilv + " " + width + " " + height);
        framelayout.layoutparams params = (layoutparams) view
            .getlayoutparams();
        params.width = width;
        params.height = height;
        view.setlayoutparams(params);
      }
      break;
    }
    return true;
  }
  // 类 ponint
  public float calc(motionevent event) {
    float x1 = event.getx();
    float y1 = event.gety();
    float x2 = event.getx(1);
    float y2 = event.gety(1);
    return (float) math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
  }
}

xml类

<framelayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context="com.example.lesson6_work1.mainactivity" >
  <view
    android:id="@+id/view"
    android:layout_width="30dp"
    android:layout_height="30dp"
    android:background="@drawable/oval" />
</framelayout>

自己在shape中定义的一个圆的oval.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval">
  <solid android:color="@android:color/holo_red_dark"/>
</shape>

用自定义view的方式实现单点触控时拖动图片，跟着拖动点走

qiuview 类

public class qiuview extends view {
  paint paint = new paint();
  pointf point = new pointf();
  public qiuview(context context) {
    super(context);
    paint.setcolor(color.red);
    paint.setantialias(true);
    paint.setdither(true);
  }
  @override
  protected void ondraw(canvas canvas) {
    super.ondraw(canvas);
    canvas.drawcircle(point.x, point.y, 50, paint);
  }
  //  触摸事件
  @override
  public boolean ontouchevent(motionevent event) {
    if (event.getaction() == motionevent.action_move) {
      point.set(event.getx(), event.gety());
      invalidate();
    }
    return true;
  }
}

总结

以上所述是小编给大家介绍的android自定义一个图形单点移动缩小的效果，希望对大家有所帮助