viewgroup实现item拖动效果

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wx5aae83353cec4 2022-11-29 09:58:47 博主文章分类：android高级开发

文章标签 ide i++ 自定义 文章分类 运维

网络上关于GridView可拖动的例子已经不少了，包括带动画不带动画的都有一堆，但几乎都是通过继承Android原生控件GridView来扩展的，当然这种实现方式是很容易联想到的，也是最容易实现的。我随便百度了一下，就有一个：http://zhangcb666.blog.163.com/blog/static/4696352920124221043837/，大家可以参考一下，我这里就不赘述了。

今天跟大家分享另外一种方式，通过继承ViewGroup来实现，我们都知道，ViewGroup可以填充很多个View，因此，我觉得可以类似把GridView的每一个Item填充到我们自定义的ViewGroup中，然后监听长按时间，实现拖动的效果，同时加上动画效果，个人感觉比网上其他实现方式更加简洁和美观，唯一的缺点就是：没有setAdapter的函数，添加的item，需要我们手动add到ViewGroup中，如果item不是特别复杂和繁多，个人觉得也不算什么问题。好了，废话不多说，我们先来看看效果图，第一张是静态效果，第二张是拖动时的效果图。

viewgroup实现item拖动效果_自定义

viewgroup实现item拖动效果_ide_02

其实代码也是很简单的，总共就两个类：一个自定义控件DragGridView，还有一个使用的例子MainActivity。

我们先来看看DragGridView的代码部分：

[java] view plain copy

/**
* 另外一种方式实现动画可拖动item的GridView
*
* @author way
*
*/
public class DragGridView extends ViewGroup implements
View.OnClickListener, View.OnLongClickListener {
// layout vars
public static float
protected int colCount, childSize, padding, dpi, scroll = 0;
protected float lastDelta = 0;
protected Handler handler = new
// dragging vars
protected int dragged = -1, lastX = -1, lastY = -1, lastTarget = -1;
protected boolean enabled = true, touching = false;
// anim vars
public static int animT = 150;
protected ArrayList<Integer> newPositions = new
// listeners
protected
protected
private
/**
* 拖动item的接口
*/
public interface
public abstract void onRearrange(int oldIndex, int
}
// CONSTRUCTOR AND HELPERS
public
super(context, attrs);
setListeners();
handler.removeCallbacks(updateTask);
500);
true);
new
((Activity) context).getWindowManager().getDefaultDisplay()
.getMetrics(metrics);
dpi = metrics.densityDpi;
}
protected void
this);
super.setOnClickListener(this);
this);
}
@Override
public void
secondaryOnClickListener = l;
}
protected Runnable updateTask = new
public void
if (dragged != -1) {
if (lastY < padding * 3 && scroll > 0)
20;
else if (lastY > getBottom() - getTop() - (padding * 3)
&& scroll < getMaxScroll())
20;
else if (lastDelta != 0
scroll += lastDelta;
9;
if (Math.abs(lastDelta) < .25)
0;
}
clampScroll();
true, getLeft(), getTop(), getRight(), getBottom());
this, 25);
}
};
@Override
public void
super.addView(child);
1);
};
@Override
public void removeViewAt(int
super.removeViewAt(index);
newPositions.remove(index);
};
// LAYOUT
@Override
protected void onLayout(boolean changed, int l, int t, int r, int
// compute width of view, in dp
float
// determine number of columns, at least 2
2;
int sub = 240;
280;
while (w > 0) {
colCount++;
w -= sub;
40;
}
// determine childSize and padding, in px
childSize = (r - l) / colCount;
childSize = Math.round(childSize * childRatio);
1);
for (int i = 0; i < getChildCount(); i++)
if
Point xy = getCoorFromIndex(i);
getChildAt(i).layout(xy.x, xy.y, xy.x + childSize,
xy.y + childSize);
}
}
@Override
protected int getChildDrawingOrder(int childCount, int
if (dragged == -1)
return
else if (i == childCount - 1)
return
else if
return i + 1;
return
}
public int getIndexFromCoor(int x, int
int
if (col == -1 || row == -1) // touch is between columns or rows
return -1;
int
if
return -1;
return
}
protected int getColOrRowFromCoor(int
coor -= padding;
for (int i = 0; coor > 0; i++) {
if
return
coor -= (childSize + padding);
}
return -1;
}
protected int getTargetFromCoor(int x, int
if (getColOrRowFromCoor(y + scroll) == -1) // touch is between rows
return -1;
// if (getIndexFromCoor(x, y) != -1) //touch on top of another visual
// return -1;
int leftPos = getIndexFromCoor(x - (childSize / 4), y);
int rightPos = getIndexFromCoor(x + (childSize / 4), y);
if (leftPos == -1 && rightPos == -1) // touch is in the middle of
// nowhere
return -1;
if (leftPos == rightPos) // touch is in the middle of a visual
return -1;
int target = -1;
if (rightPos > -1)
target = rightPos;
else if (leftPos > -1)
1;
if
return target - 1;
// Toast.makeText(getContext(), "Target: " + target + ".",
// Toast.LENGTH_SHORT).show();
return
}
protected Point getCoorFromIndex(int
int
int
return new
+ (childSize + padding) * row - scroll);
}
public int
for (int i = 0; i < getChildCount(); i++)
if
return
return -1;
}
// EVENT HANDLERS
public void
if
if (secondaryOnClickListener != null)
secondaryOnClickListener.onClick(view);
if (onItemClickListener != null && getLastIndex() != -1)
null,
getChildAt(getLastIndex()), getLastIndex(),
getLastIndex() / colCount);
}
}
public boolean
if
return false;
int
if (index != -1) {
dragged = index;
animateDragged();
return true;
}
return false;
}
public boolean
int
switch
case
true;
int) event.getX();
int) event.getY();
true;
break;
case
int delta = lastY - (int) event.getY();
if (dragged != -1) {
// change draw location of dragged visual
int x = (int) event.getX(), y = (int) event.getY();
int l = x - (3 * childSize / 4), t = y - (3 * childSize / 4);
3 / 2),
3 / 2));
// check for new target hover
int
if
if (target != -1) {
animateGap(target);
lastTarget = target;
}
}
else
scroll += delta;
clampScroll();
if (Math.abs(delta) > 2)
false;
true, getLeft(), getTop(), getRight(), getBottom());
}
int) event.getX();
int) event.getY();
lastDelta = delta;
break;
case
if (dragged != -1) {
View v = getChildAt(dragged);
if (lastTarget != -1)
reorderChildren();
else
Point xy = getCoorFromIndex(dragged);
v.layout(xy.x, xy.y, xy.x + childSize, xy.y + childSize);
}
v.clearAnimation();
if (v instanceof
255);
1;
1;
}
false;
break;
}
if (dragged != -1)
return true;
return false;
}
// EVENT HELPERS
protected void
View v = getChildAt(dragged);
int x = getCoorFromIndex(dragged).x + childSize / 2, y = getCoorFromIndex(dragged).y
2;
int l = x - (3 * childSize / 4), t = y - (3 * childSize / 4);
3 / 2), t + (childSize * 3 / 2));
new AnimationSet(true);
new ScaleAnimation(.667f, 1, .667f, 1,
3 / 4, childSize * 3 / 4);
scale.setDuration(animT);
new AlphaAnimation(1, .5f);
alpha.setDuration(animT);
animSet.addAnimation(scale);
animSet.addAnimation(alpha);
true);
true);
v.clearAnimation();
v.startAnimation(animSet);
}
protected void animateGap(int
for (int i = 0; i < getChildCount(); i++) {
View v = getChildAt(i);
if
continue;
int
if (dragged < target && i >= dragged + 1
newPos--;
else if
newPos++;
// animate
int
if (newPositions.get(i) != -1)
oldPos = newPositions.get(i);
if
continue;
Point oldXY = getCoorFromIndex(oldPos);
Point newXY = getCoorFromIndex(newPos);
new
- v.getTop());
new
- v.getTop());
new
Animation.ABSOLUTE, oldOffset.x, Animation.ABSOLUTE,
newOffset.x, Animation.ABSOLUTE, oldOffset.y,
Animation.ABSOLUTE, newOffset.y);
translate.setDuration(animT);
true);
true);
v.clearAnimation();
v.startAnimation(translate);
newPositions.set(i, newPos);
}
}
protected void
// FIGURE OUT HOW TO REORDER CHILDREN WITHOUT REMOVING THEM ALL AND
// RECONSTRUCTING THE LIST!!!
if (onRearrangeListener != null)
onRearrangeListener.onRearrange(dragged, lastTarget);
new
for (int i = 0; i < getChildCount(); i++) {
getChildAt(i).clearAnimation();
children.add(getChildAt(i));
}
removeAllViews();
while
if (lastTarget == children.size()) // dragged and dropped to the
// right of the last element
{
children.add(children.remove(dragged));
dragged = lastTarget;
else if (dragged < lastTarget) // shift to the right
{
1);
dragged++;
else if (dragged > lastTarget) // shift to the left
{
1);
dragged--;
}
for (int i = 0; i < children.size(); i++) {
1);
addView(children.get(i));
}
true, getLeft(), getTop(), getRight(), getBottom());
}
public void
0;
}
public void
scroll = Integer.MAX_VALUE;
clampScroll();
}
protected void
int stretch = 3, overreach = getHeight() / 2;
int
0);
if
scroll = -overreach;
0;
else if
scroll = max + overreach;
0;
else if (scroll < 0) {
if
0;
else if
scroll -= scroll / stretch;
else if
if
scroll = max;
else if
scroll += (max - scroll) / stretch;
}
}
protected int
int rowCount = (int) Math.ceil((double) getChildCount() / colCount), max = rowCount
1) * padding - getHeight();
return
}
public int
return
}
// OTHER METHODS
public void
this.onRearrangeListener = l;
}
public void
this.onItemClickListener = l;
}
}