Android移动View的几种方式
概述
View位置的变化和触控操作都涉及到MotionEvent类，MotionEvent中封装了一些与触摸相关的东西,比如触摸事件Action,触摸坐标等。移动View无疑就是改变其位置，通常有以下几种方式。
onTouchEvent
在View 类中,我们知道有一个layout方法是给View定位的 ,结合onTouchEvent方法 ,我们可以很好的实现一个View的移动.
int lastX, lastY; @Override
public boolean onTouchEvent(MotionEvent event) { int rawX = (int) event.getRawX(); int rawY = (int) event.getRawY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN:
lastX = rawX;
lastY = rawY; break; case MotionEvent.ACTION_MOVE: int offsetX = rawX - lastX; int offsetY = rawY - lastY;
layout(getLeft()+offsetX,
getTop()+offsetY,
getRight()+offsetX,
getBottom()+offsetY);
lastX = rawX;
lastY = rawY; break;
} return true;
}12345678910111213141516171819202122232425262728293031323334
这里面使用了绝对坐标,使用绝对坐标的时候,需要在每次ACTION_MOVE后重新设置初始坐标.
offsetLeftAndRight()
使用offsetLeftAndRight();offsetTopAndBottom();方法,通过设置偏移量来滑动View
int lastX, lastY; @Override
public boolean onTouchEvent(MotionEvent event) { int rawX = (int) event.getRawX(); int rawY = (int) event.getRawY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN:
lastX = rawX;
lastY = rawY; break; case MotionEvent.ACTION_MOVE: int offsetX = rawX - lastX; int offsetY = rawY - lastY; //layout(getLeft()+offsetX,
// getTop()+offsetY,
// getRight()+offsetX,
// getBottom()+offsetY);
offsetLeftAndRight(offsetX);
offsetTopAndBottom(offsetY);
lastX = rawX;
lastY = rawY; break;
} return true;
}12345678910111213141516171819202122232425262728293031323334353637
LayoutParams
LayoutParams，使用LayoutParams滑动View，通过改变布局参数来达到滑动View的目的.
int lastX, lastY; @Override
public boolean onTouchEvent(MotionEvent event) { int rawX = (int) event.getRawX(); int rawY = (int) event.getRawY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN:
lastX = rawX;
lastY = rawY; break; case MotionEvent.ACTION_MOVE: int offsetX = rawX - lastX; int offsetY = rawY - lastY; // layout(getLeft()+offsetX,
// getTop()+offsetY,
// getRight()+offsetX,
// getBottom()+offsetY);// offsetLeftAndRight(offsetX);// offsetTopAndBottom(offsetY);
ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) getLayoutParams();
layoutParams.leftMargin = getLeft() + offsetX ;
layoutParams.topMargin = getTop() +offsetY;
setLayoutParams(layoutParams);
lastX = rawX;
lastY = rawY; break;
} return true;
}123456789101112131415161718192021222324252627282930313233343536373839404142
ScrollTo() ScrollBy()
使用ScrollTo() 和ScrollBy() 方法来改变View 的位置.
int lastX, lastY; @Override
public boolean onTouchEvent(MotionEvent event) { int rawX = (int) event.getRawX(); int rawY = (int) event.getRawY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN:
lastX = rawX;
lastY = rawY; break; case MotionEvent.ACTION_MOVE: int offsetX = rawX - lastX; int offsetY = rawY - lastY; // layout(getLeft()+offsetX,
// getTop()+offsetY,
// getRight()+offsetX,
// getBottom()+offsetY);// offsetLeftAndRight(offsetX);// offsetTopAndBottom(offsetY);// ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) getLayoutParams();// layoutParams.leftMargin = getLeft() + offsetX ;// layoutParams.topMargin = getTop() +offsetY;// setLayoutParams(layoutParams);
((View) getParent()).scrollBy( -offsetX, -offsetY);
lastX = rawX;
lastY = rawY; break;
} return true;
}123456789101112131415161718192021222324252627282930313233343536373839404142434445
这里需要注意的是
1.首先我们的ScrollTo() and ScrollBy()方法移动的是View的Content
2.我们移动的是画布,因此需要设置相反的值,才能让View 跟随手指移动.
Scroller
使用Scroller类来移动View,与ScrollBy()方法关系紧密,ScrollBy()移动是瞬时完成,Scroller类在ACTION_MOVE中对偏移量进行划分,达到平滑效果.我们需要三个步骤
mScroller = new Scroller(context);1
@Override
public void computeScroll() { super.computeScroll(); if (mScroller.computeScrollOffset()) {
((View) getParent()).scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
invalidate();
}
}12345678
case MotionEvent.ACTION_UP: ViewGroup viewGroup = (ViewGroup) getParent(); mScroller.startScroll(viewGroup.getScrollX(),viewGroup.getScrollY(),-viewGroup.getScrollX(),-viewGroup.getScrollY()); invalidate(); break;1234567
Property Animation
通过 属性动画对View位置对改变
int w = text.getWidth(); int screenW = UiUtil.getScreenWidth(); int transX = screenW - w; ObjectAnimator transAnim = ObjectAnimator.ofFloat(text, "translationX", 0, transX);1234
ViewDragHelper
使用v4包中的ViewDragHelper能很好的实现View的滑动和事件分发,典型谷歌官方的 Drawerlayout
实例：ViewDragHelper实现QQ侧滑效果DragLayout[github]