标签：imp rac 使用 scrollto activity top width 修改 ...
View滑动的基本思想:当点击事件传到View时,系统记下触摸点的坐标,手指移动时系统记下触摸后的坐标并计算出偏移量,然后根据偏移量修正View坐标.
实现View滑动共有6种方法:layout()方法,offsetTopAndBottom(),LayoutParams,动画,scrollTo与scrollBy,以及Scroller.
一.layout()
import ...; public class CustomView extends View { private int lastX; private int lastY; public CustomView(Context context) { super(context); } public CustomView(Context context, AttributeSet attrs) { super(context, attrs); } public CustomView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } public CustomView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); } @Override public boolean onTouchEvent(MotionEvent event) {
int x = (int) event.getX(); int y = (int) event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN:
//获取手指按下时,触摸点位置 lastX = x; lastY = y; break; case MotionEvent.ACTION_MOVE:
//获取移动后触摸点位置,计算偏移量 int offsetX = x - lastX; int offsetY = y - lastY;
//修改View的left,top,right,bottom属性重新放置View layout(getLeft() + offsetX, getTop() + offsetY, getRight() + offsetX, getBottom() + offsetY); break; } return true; } }
然后在布局文件中引用就好了:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" android:orientation="vertical" > <com.example.scroll_test.CustomView android:layout_width="80dp" android:layout_height="80dp" android:background="@color/colorAccent" /> </LinearLayout>
二.offsetLeftandRight
这种方法与Layout()方法相似,只需将ACTION_MOVE修改成以下代码:
case MotionEvent.ACTION_MOVE: int offsetX = x - lastX; int offsetY = y - lastY; offsetLeftAndRight(offsetX); offsetTopAndBottom(offsetY); break; }
三.LayoutParams(改变布局参数)
通过LayoutParams改变View的布局参数,从而达到修改View位置的效果.
将ACTION_MOVE修改成以下代码:
case MotionEvent.ACTION_MOVE: int offsetX = x - lastX; int offsetY = y - lastY;
LinearLayout.LayoutParams layoutParams= (LinearLayout.LayoutParams) getLayoutParams(); layoutParams.leftMargin=getLeft() + offsetX; layoutParams.topMargin=getTop() + offsetY; setLayoutParams(layoutParams); break; }
由于父控件是LinearLayout,所以用到了LineatLayout.LayoutParams.如果是RelativeLayout,则要使用RelativeLayot.LayoutParams.还可以用ViewGroup.MarginLayoutParams来实现:
ViewGroup.MarginLayoutParams layoutParams= (LinearLayout.LayoutParams) getLayoutParams(); layoutParams.leftMargin=getLeft() + offsetX; layoutParams.topMargin=getTop() + offsetY; setLayoutParams(layoutParams);
标签：imp rac 使用 scrollto activity top width 修改 ...
原文地址：https://www.cnblogs.com/adressian/p/10771040.html
