前言
最近做了个滑动选择的小控件，拿出来给大家分享一下，先上图
运行效果
实现步骤
这里分解为3个动作:down、move、up来进行分析，博主文采不好，大家直接看流程图吧！！
代码分析
前置知识
1、这个地方使用的是recyclerview的代码，使用recyclerview只能使用linearlayoutmanager,listview的运行效果稍微要比recyclerview差一些
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//这里使用dispatchtouchevent，因为ontouchevent容易被ontouchlistener截取
@override
public boolean dispatchtouchevent(motionevent ev) {
layoutmanager manager = getlayoutmanager();
//获取第一个和最后一个显示的item对应的相对position
if (manager instanceof linearlayoutmanager) {
mfirstvisibleposition = ((linearlayoutmanager) manager).findfirstvisibleitemposition();
mlastvisibleposition = ((linearlayoutmanager) manager).findlastvisibleitemposition();
}
switch (ev.getaction()) {
case motionevent.action_down:
//获取按下时的位置,x,y
int startx = (int) ev.getx();
int starty = (int) ev.gety();
int prex = startx;
mprey = starty;
mprefirstvisibleposition = mfirstvisibleposition;
mpreposition = mstartposition = pointtoposition(startx, starty);
if (mstartposition > -1) {
//获取当前item的view
view child = getchildat(mstartposition);
if (null != child) {
//获取响应域，一般响应域里面就是一个checkbox
view tmpcheckboxcontainer = child.findviewwithtag("checkbox_layout");
if (null != tmpcheckboxcontainer && tmpcheckboxcontainer.getvisibility() == visible) {
mcheckboxwidth = tmpcheckboxcontainer.getwidth();
//获取响应域的范围，一定要用这种获取绝对位置的方式，不然会受到padding或者是margin的影响
int[] location = new int[2];
tmpcheckboxcontainer.getlocationonscreen(location);
mcheckboxx = location[0];
//判断按下的位置是否是在响应域内
if (startx >= mcheckboxx && startx <= (mcheckboxx + mcheckboxwidth)) {
log.d(log_tag, "dispatchtouchevent() down mstartposition: " + mstartposition);
//设置截取事件的标志位
misneedscrollcheck = true;
//设置为第一次滑动，这是用作判断折返的
misfirstmove = true;
setstartcheckboxstate();
//截获checkbox的点击事件，防止两次选中
return true;
} else {
misneedscrollcheck = false;
}
} else {
misneedscrollcheck = false;
log.e(log_tag, "dispatchtouchevent() ", new throwable("cannot get checkboxcontainer!"));
}
} else {
log.e(log_tag, "dispatchtouchevent() ", new throwable("cannot get item view!"));
}
}
break;
case motionevent.action_move:
//获取当前位置
int currentx = (int) ev.getx();
int currenty = (int) ev.gety();
//获取当前的item
int currentposition = pointtoposition(currentx, currenty);
//判断是否允许滑动选中
if (misneedscrollcheck && -1 != mfirstvisibleposition && -1 != mlastvisibleposition && -1 != currentposition) {
//判断是否在下一个item的像英语
if ((currentposition + mfirstvisibleposition) != (mpreposition + mprefirstvisibleposition) &&
currentx >= mcheckboxx && currentx <= (mcheckboxx + mcheckboxwidth)) {
log.i(log_tag, "********************************** dispatchtouchevent() ********************************");
log.d(log_tag, "dispatchtouchevent() move mcurrentposition: " + currentposition);
log.d(log_tag, "dispatchtouchevent() move mfirstvisibleposition: " + mfirstvisibleposition);
log.d(log_tag, "dispatchtouchevent() move mpreposition: " + mpreposition);
log.d(log_tag, "dispatchtouchevent() move mprefirstvisibleposition: " + mprefirstvisibleposition);
log.i(log_tag, "********************************** dispatchtouchevent() ********************************");
//折返回来时要改变前一个的checkbox的状态
if (misfirstmove) {
misfirstmove = false;
if (currenty >= mprey) {
mupordown = false;
} else {
mupordown = true;
}
} else {
if ((currentposition + mfirstvisibleposition) > (mpreposition + mprefirstvisibleposition) && mupordown) {
changecheckboxstate(mpreposition);
mupordown = false;
} else if ((currentposition + mfirstvisibleposition) < (mpreposition + mprefirstvisibleposition) && !mupordown) {
changecheckboxstate(mpreposition);
mupordown = true;
}
}
changecheckboxstate(currentposition);
}
//判断是否是在最后一个item上滑动，如果是则进行自动向下滑动，如果是在第一个上下滑动，则自动向上滑动
//log.d(log_tag, "dispatchtouchevent() move: " + (mlastvisibleposition - mcurrentposition - mfirstvisibleposition));
if ((mlastvisibleposition - mfirstvisibleposition - currentposition) < 1 && currenty > mprey) {
//自动向下滑
log.d(log_tag, "dispatchtouchevent() move mcount: " + mcount);
view child = getchildat(currentposition);
if (null != child && 0 == mcount % 5) {
scrolltoposition(mlastvisibleposition + 1);
}
mcount++;
} else if (currentposition < 2 && currenty < mprey) {
//自动向上滑
view child = getchildat(currentposition);
log.d(log_tag, "dispatchtouchevent() move mcount: " + mcount);
//mcount用于降低滑动的频率，频率太快容易滑动的看不清楚
if (null != child && 0 == mcount % 5) {
scrolltoposition(mfirstvisibleposition - 1);
}
mcount++;
}
mprey = currenty;
mpreposition = currentposition;
mprefirstvisibleposition = mfirstvisibleposition;
return true;
}
break;
case motionevent.action_up:
if (misneedscrollcheck) {
mcount = 0;
return false;
}
break;
}
return super.dispatchtouchevent(ev);
}
其他的代码片段
//改变开始的checkbox状态
private void setstartcheckboxstate() {
view child = getchildat(mstartposition);
if (null != child) {
viewgroup checkboxcontainer = (viewgroup) child.findviewwithtag("checkbox_layout");
if (null != checkboxcontainer) {
checkbox checkbox = (checkbox) checkboxcontainer.getchildat(0);
if (null != checkbox && checkbox.getvisibility() == visible) {
checkbox.toggle();
}
}
}
}
//判断当前item的position，相对位置
private int pointtoposition(int x, int y) {
rect frame = mtouchframe;
if (frame == null) {
mtouchframe = new rect();
frame = mtouchframe;
}
final int count = getchildcount();
for (int i = count - 1; i >= 0; i--) {
final view child = getchildat(i);
if (child.getvisibility() == view.visible) {
child.gethitrect(frame);
if (frame.contains(x, y)) {
return i;
}
}
}
return -1;
}
//改变position的选中状态
public void changecheckboxstate(int position) {
if (position < 0 || position >= getchildcount()) {
return;
}
view child = getchildat(position);
if (null != child) {
viewgroup checkboxlayout = (viewgroup) child.findviewwithtag("checkbox_layout");
if (null != checkboxlayout && checkboxlayout.getvisibility() == visible) {
checkbox checkbox = (checkbox) checkboxlayout.getchildat(0);
if (null != checkbox) {
log.d(log_tag, "changecheckboxstate() selectcheckbox: " + position);
//checkbox.performclick();
checkbox.toggle();
//checkbox.setclickable(false);
//checkbox.callonclick();
}
}
}
}
项目源码：
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移动技术网。
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