topics/ui/multi-window.jd

page.title=H tr a ca s
page.metaDescription=H tr mi trong Android N  hin th nhiu hn mt ng dng cng lc.
page.keywords="multi-window", "android N", "split screen", "free-form"

@jd:body

<div id="tb-wrapper">
  <div id="tb">
    <h2>Trong ti liu ny</h2>
      <ol>
        <li><a href="#overview">Tng quan</a></li>
        <li><a href="#lifecycle">Vng i a ca s</a></li>
        <li><a href="#configuring">Cu hnh ng dng ca bn cho Ch
              a ca s</a></li>
        <li><a href="#running">Chy ng dng ca bn trong Ch  a ca s</a></li>
        <li><a href="#testing">Kim th H tr a ca s ca ng dng ca bn</a></li>
      </ol>
    <h2>Xem thm</h2>
      <ol>
        <li><a class="external-link" href="https://github.com/googlesamples/android-MultiWindowPlayground">ng dng mu Multi-Windows
          Playground</a></li>
      </ol>
  </div>
</div>

<p>
  Android N thm h tr cho hin th ng thi nhiu hn mt ng dng
  vo cng mt thi im. Trn thit b cm tay, hai ng dng c th chy song song hoc
  trn di nhau trong ch  <em>chia mn hnh</em>. Trn thit b TV, ng dng c th
  s dng ch  <em>nh trong nh</em>  tip tc pht li video trong khi ngi dng
  ang tng tc vi ng dng khc.
</p>

<p>
  Nu bn dng ng dng ca bn bng N Preview SDK, bn c th cu hnh cch ng dng ca bn
  x l hin th a ca s. V d, bn c th quy nh
  cc kch thc ti thiu cho php ca hot ng ca bn. Bn cng c th v hiu ha hin th a ca s cho
  ng dng ca bn, m bo rng h thng ch hin th ng dng ca bn trong ch
   ton mn hnh.
</p>

<h2 id="overview">Tng quan</h2>

<p>
  Android N cho php mt vi ng dng chia s mn hnh ngay lp tc. V
  d, ngi dng c th chia i mn hnh ra, xem mt trang web  bn tri mn hnh
  trong khi ang to email  bn phi mn hnh. Tri nghim ny ca ngi dng ph thuc vo
  thit b:
</p>

<ul>
  <li>Thit b cm tay ang chy Android N c ch
  chia mn hnh. Trong ch  ny, h thng s lp y mn hnh bng hai ng dng
  song song nhau hoc trn di. Ngi dng c th ko ng chia
  phn tch hai ng dng  hin th mt ng dng rng hn v ng dng cn li nh i.
  </li>

  <li>Trn Trnh pht Nexus ang chy Android N, cc ng dng c th t t chng
  vo trong <a href="picture-in-picture.html">ch  nh trong nh</a>, cho php
  cc ng dng ny tip tc hin th ni dung khi ngi dng duyt web hoc tng tc vi
  ng dng khc.
  </li>

  <li>Cc nh sn xut thit b c kch c ln hn c th chn kch hot ch
  hnh dng t do, trong  ngi dng c th t do thay i kch thc mi hot ng. Nu
  nh sn xut  kch hot tnh nng ny, ngoi
  ch  chia mn hnh, thit b s cn c ch  hnh dng t do.
  </li>
</ul>

<img src="{@docRoot}images/android-7.0/mw-splitscreen.png" alt="" width="650" srcset="{@docRoot}images/android-7.0/mw-splitscreen.png 1x,
    {@docRoot}images/android-7.0/mw-splitscreen_2x.png 2x," id="img-split-screen" />
<p class="img-caption">
  <strong>Hnh 1.</strong> Hai ng dng chy trong ch  chia mn hnh.
</p>

<p>
  Ngi dng c th chuyn vo trong ch  a ca s bng cc cch sau:
</p>

<ul>
  <li>Nu ngi dng m mn hnh <a href="{@docRoot}guide/components/recents.html">Overview
  </a> v thc hin nhn gi
  tiu  ca hot ng, h c th ko hot ng  n phn c t sng ca
  mn hnh  t hot ng  vo trong ch  a ca s.
  </li>

  <li>Nu ngi dng thc hin nhn gi nt Overview, thit b s t
  hot ng hin ti vo trong ch  a ca s, v m mn hnh Overview
  cho php ngi dng chn mt hot ng khc  chia s mn hnh.
  </li>
</ul>

<p>
  Ngi dng c th <a href="{@docRoot}guide/topics/ui/drag-drop.html">ko v
  th</a> t mt hot ng sang mt hot ng khc trong khi cc hot ng ny vn ang chia s
  cng mt mn hnh. (Trc , ngi dng ch c th ko v th d liu trong mt hot ng
  n l.)
</p>

<h2 id="lifecycle">Vng i a ca s</h2>

<p>
  Ch  a ca s khng thay i <a href="{@docRoot}training/basics/activity-lifecycle/index.html">vng i
  ca hot ng</a>.
</p>

<p>
  Trong ch  a ca s, ch hot ng m ngi dng  tng tc gn y nht
  mi hot ng trong khong thi gian xc nh. Hot ng ny c cn nhc <em> trn cng</em>.
  Tt c cc hot ng khc s  trong tnh trng tm dng, ngay c khi chng vn hin th.
  Tuy nhin, h thng s cp mc u tin cao hn cho hot ng b tm dng nhng vn hin th ny
  so vi cc hot ng khng hin th. Nu ngi dng tng tc vi mt trong nhng
  hot ng b tm dng, hot ng  s c tip tc, v hot ng trn cng trc
  s b tm dng.
</p>

<p class="note">
  <strong>Lu :</strong> Trong ch  a ca s, mt ng dng c th trong trng thi
  tm dng v vn hin th vi ngi dng. ng dng c th cn tip tc
  cc hot ng ca n thm ch trong khi amg b tm dng. V d, mt ng dng pht video ang  trong
  ch  tm dng nhng vn hin th th s tip tc hin th video ca n. V l do
  ny, chng ti  ngh cc hot ng pht video <em>khng</em> tm dng
  video trong trnh x l{@link android.app.Activity#onPause onPause()}.
  Thay vo , cc ng dng nn tm dng video trong {@link android.app.Activity#onStop
  onStop()}, v tip tc pht li trong {@link android.app.Activity#onStart
  onStart()}.
</p>

<p>
  Khi ngi dng t mt ng dng vo trong ch  a ca s, h thng s thng bo v
  hot ng thay i cu hnh , nh c quy nh trong <a href="{@docRoot}guide/topics/resources/runtime-changes.html">X l Thay i
  Thi gian chy</a>. V c bn, thay i ny c ng  v vng i hot ng tng t
  v khi h thng thng bo cho ng dng rng thit b  chuyn
  t ch  hng dc sang ch  ngang, ngoi tr trng hp cc kch thc ca thit b
   c thay i thay v ch b hon i. Nh  tho lun trong phn <a href="{@docRoot}guide/topics/resources/runtime-changes.html">X l Thay i
  Thi gian chy</a>, hot ng ca bn c th t x l thay i cu hnh ny, hoc n
  c th cho php h thng hy hot ng ny v to li n vi
  cc kch thc mi.
</p>

<p>
  Nu ngi dng thay i kch thc ca mt ca s v lm n rng hn  bt k kch thc no,
  h thng s thay i kch thc ca hot ng  khp vi hnh ng ca ngi dng v pht hnh <a href="{@docRoot}guide/topics/resources/runtime-changes.html">cc thay i thi gian chy</a>
  nu cn. Nu ng dng b tr li trong khi v cc vng mi c hin th,
  h thng s tm thi lp y cc vng  bng mt mu c quy nh bi thuc tnh {@link
  android.R.attr#windowBackground windowBackground} hoc bng thuc tnh kiu
  <code>windowBackgroundFallback</code> mc nh.
</p>

<h2 id="configuring">Cu hnh ng dng ca bn cho Ch  a ca s</h2>

<p>
  Nu ng dng ca bn nhm n Android N, bn c th cu hnh cch thc v
  liu cc hot ng ca ng dng c h tr hin th a ca s khng. Bn c th t
  cc thuc tnh trong bn k khai ca bn  kim sot c kch c v b tr.
  Ci t thuc tnh ca hot ng gc s p dng cho tt c cc hot ng
  nm trong ngn xp hot ng ca n.
</p>

<p class="note">
  <strong>Lu :</strong> Nu bn dng mt ng dng a hng bng phin bn
   SDK thp hn Android N, v ngi dng s dng ng dng  trong
  ch  a ca s, h thng s bt buc thay i kch thc ca ng dng . H thng s hin th mt
  hp hi thoi cnh bo ngi dng rng ng dng ny c th c hnh vi khng nh k vng. H thng
  <em>khng</em> thay i kch c ca ng dng c hng c nh; nu
  ngi dng c m mt ng dng c hng c nh di ch  a ca s,
  ng dng ny s chim ton b mn hnh.
</p>

<h4 id="resizeableActivity">android:resizeableActivity</h4>
<p>
  t thuc tnh ny trong <code>&lt;activity&gt;</code> ca bn k khai ca bn hoc node
  <code>&lt;application&gt;</code>  kch hot hoc v hiu ha hin th
  a ca s:
</p>

<pre>
android:resizeableActivity=["true" | "false"]
</pre>

<p>
  Nu thuc tnh ny c t thnh true, hot ng c th c khi chy trong
 ch  chia mn hnh v hnh dng t do. Nu thuc tnh ny c t thnh false,
  hot ng s khng h tr ch  a ca s. Nu gi tr ny l false, v
  ngi dng c khi chy hot ng trong ch  a ca s, hot ng  s
  chim ton mn hnh.
</p>

<p>
  Nu ng dng ca bn nhm n Android N, nhng bn cha quy nh gi tr
  cho thuc tnh ny, gi tr ca thuc tnh s mc nh t l true.
</p>

<h4 id="supportsPictureInPicture">android:supportsPictureInPicture</h4>

<p>
  t thuc tnh ny trong node <code>&lt;activity&gt;</code> ca bn k khai ca bn
  cho bit liu hot ng ny c h tr hin th nh trong nh hay khng. Thuc tnh
  ny c b qua nu <code>android:resizeableActivity</code> l false.
</p>

<pre>
android:supportsPictureInPicture=["true" | "false"]
</pre>

<h3 id="layout">Thuc tnh b tr</h3>

<p>
  Vi Android N, phn t bn k khai <code>&lt;layout&gt;</code>
  c h tr mt s thuc tnh s nh hng n cch hot ng c hnh vi nh th no trong
  ch  a ca s:
</p>

<dl>
  <dt>
    <code>android:defaultWidth</code>
  </dt>

  <dd>
    Chiu rng mc nh ca hot ng khi c khi chy trong ch  hnh dng t do.
  </dd>

  <dt>
    <code>android:defaultHeight</code>
  </dt>

  <dd>
    Chiu cao mc nh ca hot ng khi c khi chy trong ch  hnh dng t do.
  </dd>

  <dt>
    <code>android:gravity</code>
  </dt>

  <dd>
    V tr ban u ca hot ng khi c khi chy trong ch  hnh dng t do. Xem tham chiu
    {@link android.view.Gravity} v cc gi tr ph hp.
  </dd>

  <dt>
    <code>android:minimalSize</code>
  </dt>

  <dd>
    Chiu cao v chiu rng ti thiu cho hot ng trong c ch  chia mn hnh
    v ch  hnh dng t do. Nu ngi dng di chuyn thanh phn chia trong ch  chia mn hnh
     lm cho hot ng nh hn mc ti thiu quy nh, h thng s ct xn
    hot ng  thnh kch c m ngi dng yu cu.
  </dd>
</dl>

<p>
  V d, on m sau y s cho bit cch quy nh kch thc v v tr mc nh
   ca mt hot ng v kch thc ti thiu ca n, khi hot ng c hin th trong
  ch  hnh dng t do:
</p>

<pre>
&lt;activity android:name=".MyActivity"&gt;
    &lt;layout android:defaultHeight="500dp"
          android:defaultWidth="600dp"
          android:gravity="top|end"
          android:minimalSize="450dp" /&gt;
&lt;/activity&gt;
</pre>

<h2 id="running">Chy ng dng ca bn trong Ch  a ca s</h2>

<p>
  Android N c tnh nng mi  h tr cc ng dng c th chy
  trong ch  a ca s.
</p>

<h3 id="disabled-features">Cc tnh nng b v hiu ha trong Ch  a ca s</h3>

<p>
  Mt s tnh nng b v hiu ha hoc b qua khi mt thit b ang  ch
  a ca s bi cc tnh nng ny khng c  ngha i vi mt hot ng c th ang chia s
  mn hnh thit b vi cc hot ng hoc ng dng khc. Cc tnh nng  bao gm:

<ul>
  <li>V d, mt vi ty chn ty chnh <a href="{@docRoot}training/system-ui/index.html">System UI</a>
  s b v hiu ha, ng dng khng th n thanh trng thi
  nu chng ang chy trong ch  ton mn hnh.
  </li>

  <li>H thng s b qua cc thay i i vi thuc tnh <code><a href=
  "{@docRoot}guide/topics/manifest/activity-element.html#screen"
  >android:screenOrientation</a></code>.
  </li>
</ul>

<h3 id="change-notification">Thng bo v truy vn thay i a ca s</h3>

<p>
  Cc phng thc mi sau y  c thm vo lp {@link android.app.Activity}
   h tr hin th a ca s.  bit chi tit v mi phng thc, xem
  <a href="{@docRoot}preview/setup-sdk.html#docs-dl">Tham chiu N Preview SDK</a>.
</p>

<dl>
  <dt>
    <code>Activity.inMultiWindow()</code>
  </dt>

  <dd>
    Lnh gi  tm hiu xem hot ng c ang  ch  a ca s hay khng.
  </dd>

  <dt>
    <code>Activity.inPictureInPicture()</code>
  </dt>

  <dd>
    Lnh gi  tm hiu xem hot ng c ang  ch  nh trong nh hay khng.

    <p class="note">
      <strong>Lu :</strong> Ch  nh trong nh l trng hp c bit
      ca ch  a ca s. Nu <code>myActivity.inPictureInPicture()</code>
      tr v l true, th <code>myActivity.inMultiWindow()</code> cng tr v l
      true.
    </p>
  </dd>

  <dt>
    <code>Activity.onMultiWindowChanged()</code>
  </dt>

  <dd>
    H thng s gi phng thc ny bt c khi no hot ng i vo trong hay ra ngoi
    ch  a ca s. H thng s chuyn cho phng thc gi tr true nu
    hot ng ang i vo ch  a ca s, v false nu hot ng
    ang ri ch  a ca s.
  </dd>

  <dt>
    <code>Activity.onPictureInPictureChanged()</code>
  </dt>

  <dd>
    H thng s gi phng thc ny bt c khi no hot ng i vo trong hay ra ngoi
    ch  nh trong nh. H thng s chuyn cho phng thc mt gi tr true nu
    hot ng ang i vo ch  nh trong nh, v false nu hot ng
    ang ri ch  nh trong nh.
  </dd>
</dl>

<p>
  Cng c cc phin bn {@link android.app.Fragment} ca tng phng thc
  ny, v d nh <code>Fragment.inMultiWindow()</code>.
</p>

<h3 id="entering-pip">Vo ch  nh trong nh</h3>

<p>
   t mt hot ng vo trong ch  nh trong nh, hy gi phng thc mi
  <code>Activity.enterPictureInPicture()</code>. Phng thc ny s khng c nh hng nu
  thit b khng h tr ch  nh trong nh.  bit thm thng tin,
  hy xem ti liu <a href="picture-in-picture.html">nh trong nh</a>.
</p>

<h3 id="launch">Khi chy Hot ng Mi trong Ch  a ca s</h3>

<p>
  Khi bn khi chy mt hot ng mi, bn c th gi  cho h thng rng hot ng
  mi s c hin th lin k hot ng hin ti, nu c th.  thc hin iu
  ny, hy dng c
  <code>Intent.FLAG_ACTIVITY_LAUNCH_TO_ADJACENT</code>. Vic chuyn
  c ny yu cu hnh vi sau:
</p>

<ul>
  <li>Nu thit b ang  ch  chia mn hnh, h thng s c to ra
  hot ng mi bn cnh hot ng  khi chy n, v vy hai hot ng ny
  s chia s cng mt mn hnh. H thng khng c m bo c th lm c iu ny, nhng n
 lm cho cc hot ng  lin k nhau nu c th.
  </li>

  <li>Nu thit b khng  ch  chia mn hnh, c ny s khng c tc dng.
  </li>
</ul>

<p>
  Nu thit b ang  ch  hnh dng t do v bn ang khi chy mt hot ng mi, bn c th
  quy nh kch thc ca hot ng mi v v tr mn hnh bng cch gi
  <code>ActivityOptions.setLaunchBounds()</code>. Phng thc ny s khng c nh hng nu
  thit b khng  ch  a ca s.
</p>

<p class="note">
  <strong>Lu :</strong> Nu bn khi chy mt hot ng trong mt ngn xp tc v, hot ng
  ny s thay th hot ng trn mn hnh, k tha tt c cc thuc tnh a ca s
  ca n. Nu bn mun khi chy hot ng mi di dng mt ca s
  ring trong ch  a ca s, bn phi khi chy n trong mt ngn xp tc v mi.
</p>

<h3 id="dnd">H tr ko v th</h3>

<p>
  Ngi dng c th <a href="{@docRoot}guide/topics/ui/drag-drop.html">ko v
  th</a> d liu t mt hot ng ny sang mt hot ng khc trong khi cc hot ng ny vn ang
  chia s cng mt mn hnh. (Trc , ngi dng ch c th ko v th d liu trong mt
  hot ng n l.) V l do ny, bn c th mun thm tnh nng ko v th
  vo ng dng ca bn nu ng dng ca bn hin khng h tr tnh nng ny.
</p>

<p>
  N Preview SDK m rng gi <a href="{@docRoot}reference/android/view/package-summary.html"><code>android.view</code></a>
   h tr ko v th gia cc ng dng.  bit chi tit v cc lp v phng thc
  sau, hy xem <a href="{@docRoot}preview/setup-sdk.html#docs-dl">Tham chiu N
  Preview SDK</a>.
</p>

<dl>
  <dt>
    <code>android.view.DropPermissions</code>
  </dt>

  <dd>
    i tng m thng bo chu trch nhim v vic quy nh cc quyn cp cho ng dng
    nhn c thao tc th.
  </dd>

  <dt>
    <code>View.startDragAndDrop()</code>
  </dt>

  <dd>
    B danh mi cho {@link android.view.View#startDrag View.startDrag()}.
    kch hot ko v th gia cc hot ng, hy chuyn c mi
    <code>View.DRAG_FLAG_GLOBAL</code>. Nu bn cn cp quyn URI cho
    hot ng ca i tng nhn, hy chuyn cc c mi
    <code>View.DRAG_FLAG_GLOBAL_URI_READ</code> hoc
    <code>View.DRAG_FLAG_GLOBAL_URI_WRITE</code>, nu ph hp.
  </dd>

  <dt>
    <code>View.cancelDragAndDrop()</code>
  </dt>

  <dd>
    Hy thao tc ko hin ang din ra. Ch c th c gi bng
    ng dng  khi ngun thao tc ko .
  </dd>

  <dt>
    <code>View.updateDragShadow()</code>
  </dt>

  <dd>
    Thay th bng ko cho thao tc ko hin ang din ra. Ch c th
    c gi bng ng dng  khi ngun thao tc ko .
  </dd>

  <dt>
    <code>Activity.requestDropPermissions()</code>
  </dt>

  <dd>
    Yu cu cc quyn cho URI ni dung  chuyn vi {@link
    android.content.ClipData} c cha trong {@link android.view.DragEvent}.
  </dd>
</dl>

<h2 id="testing">Kim th H tr a ca s ca ng dng ca bn</h2>

<p>
  D cho bn c cp nht ng dng ca mnh ln Android N hay khng, bn cng nn
  xc minh cch thit b c hnh vi nh th no trong ch  a ca s trong trng hp ngi dng c khi chy n
   ch  a ca s trn thit b chy Android N.
</p>

<h3 id="configuring">Cu hnh Thit b Kim th</h3>

<p>
  Nu bn ci t Android N trn thit b, ch  chia mn hnh
  s c t ng h tr.
</p>

<h3 id="test-non-n">Nu ng dng ca bn khng c dng bng N Preview SDK</h3>

<p>
  Nu bn dng ng dng ca mnh bng N Preview SDK, v ngi dng c s dng ng dng ny
  trong ch  a ca s, h thng s bt buc thay i kch thc ca ng dng  tr khi ng dng ny
  khai bo hng c nh.
</p>

<p>
  Nu ng dng khng khai bo hng c nh, bn nn khi chy ng dng ca bn
  trn thit b ang chy Android N v c t ng dng vo trong
  ch  chia mn hnh. Xc minh rng tri nghim ngi dng l
  chp nhn c khi ng dng b bt buc thay i kch c.
</p>

<p>
  Nu ng dng khai bo hng c nh, bn nn c t ng dng vo trong
  ch  a ca s. Xc minh xem khi bn lm nh vy, ng dng vn gi
   ch  ton mn hnh.
</p>

<h3 id="test-mw">Nu bn h tr ch  a ca s</h3>

<p>
  Nu bn dng ng dng ca bn bng N Preview SDK v cha v hiu ha
  h tr a ca s, hy xc minh hnh vi sau di ch  chia mn hnh
  v ch  hnh dng t do.
</p>

<ul>
  <li>Khi chy ng dng trong ch  ton mn hnh, ri chuyn sang ch  a ca s bng cch
  nhn gi nt Overview. Xc minh rng ng dng  chuyn i ng cch.
  </li>

  <li>Khi chy ng dng trc tip trong ch  a ca s, v xc thc rng ng dng ny
  khi chy ng cch. Bn c th khi chy ng dng trong ch  a ca s bng cch nhn vo nt
  Overview, ri nhn gi vo thanh tiu  ca ng dng ca bn v ko n
  n mt trong nhng vng c t sng trn mn hnh.
  </li>

  <li>Thay i kch thc ng dng ca bn trong ch  chia mn hnh bng cch ko ng phn chia.
  Xc minh rng ng dng thay i kch thc m khng b li, v cc phn t UI cn thit
  vn hin th.
  </li>

  <li>Nu bn  quy nh cc kch c ti thiu cho ng dng ca bn, hy c thay i kch thc ca ng dng
  sao cho nh hn cc kch thc  quy nh . Xc minh rng bn khng th thay i kch c ca ng dng
  nh hn kch c ti thiu  quy nh.
  </li>

  <li>Thng qua tt c cc bi kim th, hy xc minh rng hiu nng ca ng dng ca bn l c th chp nhn c. V
  d, xc minh rng s khng b tr qu lu  cp nht UI sau khi
  ng dng b thay i kch thc.
  </li>
</ul>

<h4 id="test-checklist">Danh sch kim th</h4>

<p>
   xc minh hiu nng ng dng ca bn trong ch  a ca s, hy th cc thao tc
  sau. Bn nn th cc thao tc ny trong c ch  chia mn hnh v
  ch  a ca s, tr khi c lu  khc.
</p>

<ul>
  <li>Vo v ri ch  a ca s.
  </li>

  <li>Hy chuyn t ng dng ca bn sang ng dng khc, v xc minh rng ng dng c hnh vi
  ng cch trong khi n hin th nhng khng hot ng. V d nu ng dng ca bn ang
  pht video, hy xc minh rng video tip tc pht trong khi ngi dng ang
  tng tc vi mt ng dng khc.
  </li>

  <li>Trong ch  chia mn hnh, hy th di chuyn thanh phn chia  lm cho ng dng ca bn
  rng hn v nh hn. Th cc thao tc ny trong c cu hnh song song v
  trn di. Xc minh rng ng dng khng b treo,
  cc chc nng thit yu vn hin th, v thao tc thay i kch c khng qu
   lu.
  </li>

  <li>Thc hin mt vi thao tc thay i kch c ni tip nhau tht nhanh. Xc minh rng ng dng
  ca bn khng b li hoc b r r b nh.  bit thng tin v kim tra vic s dng b nh ca
  ng dng, xem <a href="{@docRoot}tools/debugging/debugging-memory.html">
  Kim tra S dng RAM ca bn</a>.
  </li>

  <li>S dng ng dng ca bn nh thng thng trong mt s cu hnh ca s khc nhau, v
  xc minh rng ng dng c hnh vi bnh thng. Xc minh rng c th c c cc ch v
  cc phn t UI khng qu nh  tng tc vi chng.
  </li>
</ul>

<h3 id="test-disabled-mw">Nu bn  v hiu ha h tr a ca s</h3>

<p>
  Nu bn  v hiu ha h tr a ca s bng cch t
  <code>android:resizableActivity="false"</code>, bn nn khi chy ng dng ca mnh trn
  thit b chy Android N v c t ng dng ny vo trong
  c ch  hnh dng t do v ch  chia mn hnh. Xc minh xem khi bn lm nh vy, ng dng vn gi
   ch  ton mn hnh.
</p>