我遇到一个问题，我在 View 寻呼机内有一个表面 View 。一切都呈现良好，直到我按下其中一个选项卡。 View 寻呼机滚动，但下一个屏幕上的页面被压扁。
如果我退出应用程序并返回，第二页将呈现正常。然后，如果我按返回到第一个，它会再次被挤压。
我根本不知道布局的哪一部分出了问题，据我所知，表面 View 的实际高度没有改变，就像我在表面 View 它总是返回相同的值。
这是我的 View 寻呼机类:
public class PendulumViewPager extends ViewPager {
public PendulumViewPager(Context context) {
super(context);
}
public PendulumViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
return false;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return false;
}
这是添加到 View 寻呼机的 fragment :
public class SurfacePanelFragment extends Fragment{
private int TYPE = 1;
private SurfacePanel panel;
public void setType(int type){
TYPE = type;
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_surface_panel, container, false);
panel = view.findViewById(R.id.canvas);
panel.setType(TYPE);
return view;
}
public void startStopPendulum(ImageButton view){
panel.startStop(view);
}
public void stopPendulum(){
panel.stop();
}
@Override
public void onResume() {
if(getUserVisibleHint()) {
panel.delayStartThread();
((MainActivity)getActivity()).getStopButton().setImageDrawable(getContext().getResources().getDrawable(R.drawable.ic_pause_white_48dp));
}
super.onResume();
}
@Override
public void onPause() {
panel.terminate();
super.onPause();
}
public void stopRendering(){
panel.stopRendering();
}
public void startRendering(){
panel.startRendering();
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if(panel != null) {
if (isVisibleToUser) {
panel.delayStartThread();
((MainActivity)getActivity()).getStopButton().setImageDrawable(getContext().getResources().getDrawable(R.drawable.ic_pause_white_48dp));
Log.i("WP", String.valueOf(panel.getHeight()));
} else {
panel.terminate();
}
}
}
这是主要 Activity :
public class MainActivity extends AppCompatActivity {
private PendulumViewPager pager;
private ArrayList<SurfacePanelFragment> fragments = new ArrayList<SurfacePanelFragment>(2);
private ImageButton stopButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
pager = findViewById(R.id.view_pager);
pager.setAdapter(new FragmentStatePagerAdapter(getSupportFragmentManager()) {
@Override
public Fragment getItem(int position) {
SurfacePanelFragment frag = new SurfacePanelFragment();
switch (position) {
case 0:
frag.setType(SurfacePanel.SINGLE_PENDULUM);
fragments.add(0, frag);
return frag;
case 1:
frag.setType(SurfacePanel.DOUBLE_PENDULUM);
fragments.add(1, frag);
return frag;
default:
return null;
}
}
@Override
public int getCount() {
return 2;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position){
case 0: return "Single";
case 1: return "Double";
default: return "";
}
}
});
TabLayout pagerTabs = findViewById(R.id.pager_tabs);
pagerTabs.setTabGravity(TabLayout.GRAVITY_FILL);
pagerTabs.setupWithViewPager(pager);
stopButton = findViewById(R.id.stop_button);
stopButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startStopCurrentPendulum((ImageButton) view);
}
});
ImageButton helpButton = findViewById(R.id.help_button);
helpButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startHelpActivity();
}
});
}
private void startStopCurrentPendulum(ImageButton view) {
fragments.get(pager.getCurrentItem()).startStopPendulum(view);
}
public ImageButton getStopButton(){
return stopButton;
}
private void startHelpActivity(){
Intent intent = new Intent(this, HelpActivity.class);
startActivity(intent);
}
这是 SurfacePanel 类
public class SurfacePanel extends SurfaceView implements SurfaceHolder.Callback {
public static final int SINGLE_PENDULUM = 1;
public static final int DOUBLE_PENDULUM = 2;
private int TYPE = 1;
private PendulumThread _thread;
private boolean needToStartThread = false;
private SurfaceHolder holder;
public SurfacePanel(Context context, AttributeSet attrSet) {
super(context, attrSet);
SurfaceHolder holder = getHolder();
holder.addCallback(this);
}
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
Log.i("WP", String.valueOf(this.getHeight()));
this.holder = surfaceHolder;
if(needToStartThread){
startThread();
needToStartThread = false;
}
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
if(_thread != null) {
try {
_thread.terminate();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
this.holder = null;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (_thread != null) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
_thread.click(event);
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
_thread.updatePos(event);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
_thread.unclick();
}
}
return true;
}
public void startStop(ImageView button) {
if(_thread != null){
if(_thread.isPRunning()){
button.setImageDrawable(getContext().getResources().getDrawable(R.drawable.ic_play_arrow_white_48dp));
_thread.pStop();
}else{
button.setImageDrawable(getContext().getResources().getDrawable(R.drawable.ic_pause_white_48dp));
_thread.pStart();
}
}
}
public void start(){
if(_thread != null){
_thread.pStart();
}
}
public void stop(){
if(_thread != null){
_thread.pStop();
}
}
public void stopRendering(){
if(_thread != null){
Log.i("WP", "A");
_thread.stopRendering();
}
}
public void startRendering(){
if(_thread != null){
Log.i("WP", "D");
_thread.startRendering();
}
}
public void terminate(){
if(_thread != null){
try {
_thread.terminate();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private void startThread(){
if(_thread == null || !_thread.isAlive()) {
switch (TYPE) {
case SurfacePanel.SINGLE_PENDULUM:
_thread = new SinglePendulumThread(holder, getWidth(), getHeight(), getContext());
_thread.pStart();
_thread.start();
break;
case SurfacePanel.DOUBLE_PENDULUM:
_thread = new DoublePendulumThread(holder, getWidth(), getHeight(), getContext());
_thread.pStart();
_thread.start();
break;
default:
_thread = new SinglePendulumThread(holder, getWidth(), getHeight(), getContext());
_thread.pStart();
_thread.start();
break;
}
}
}
public void delayStartThread(){
if(holder == null) {
needToStartThread = true;
}else{
startThread();
}
}
public void setType(int type){
TYPE = type;
}
这是表面面板 fragment ，表面面板 View 位于
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<com.astarphysics.wikidpendulum.SurfacePanel
android:id="@+id/canvas"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteX="8dp"
tools:layout_editor_absoluteY="8dp" />
</RelativeLayout>
这是单摆线
public class SinglePendulumThread extends PendulumThread{
private SurfaceHolder holder;
private Paint paint;
private int backgroundColor;
private int width;
private Context context;
private boolean clicked = false;
private static final double g = 9.81;
private final int RADIUS;
private int length;
private double theta = Math.PI/8;
private double thetaV = 0;
SinglePendulumThread(SurfaceHolder holder, int width, int height, Context context){
this.holder = holder;
this.context = context;
int bobColor = context.getResources().getColor(R.color.colorBob);
int shadowColor = context.getResources().getColor(R.color.shadowColor);
backgroundColor = context.getResources().getColor(R.color.backgroundColor);
paint = new Paint();
paint.setColor(bobColor);
paint.setShadowLayer(5, -1, 2, shadowColor);
this.width = width;
RADIUS = dpToPx(20);
length = dpToPx(200);
}
protected void update(){
if(pRunning && !clicked) {
thetaV += (-1 * g * Math.sin(theta)) / length;
theta += thetaV * (40 * Math.pow(10, -2));
}
}
protected void render(){
Canvas canvas = holder.lockCanvas();
canvas.drawColor(backgroundColor);
canvas.drawLine(width / 2, 0, (float) ((width / 2) + (length * Math.sin(theta))), (float) (length * Math.cos(theta)), paint);
canvas.drawCircle((int) Math.round((width / 2) + (length * Math.sin(theta))), (int) Math.round(length * Math.cos(theta)), RADIUS, paint);
holder.unlockCanvasAndPost(canvas);
}
@Override
void click(MotionEvent e) {
clicked = true;
updatePos(e);
}
@Override
void updatePos(MotionEvent e){
length = (int)Math.round(Math.sqrt((Math.abs(e.getX()-(width/2))*Math.abs(e.getX()-(width/2)))+(e.getY()*e.getY())));
theta = Integer.signum(Math.round((e.getX()-(width/2))))*Math.asin((Math.abs(e.getX()-(width/2))/length));
}
@Override
void unclick() {
this.resetForPStart();
clicked = false;
}
private void resetForPStart(){
thetaV = 0;
}
private int dpToPx(int dp) {
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
return Math.round(dp * (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));
}
这是双摆线:
public class DoublePendulumThread extends PendulumThread {
private SurfaceHolder holder;
private Paint paint;
private int backgroundColor;
private int width;
private int height;
private Context context;
private boolean clicked1 = false;
private boolean clicked2 = false;
private final int RADIUS;
private final double m1 = 3;
private final double m2 = 3;
private static final double g = 9.81;
private double l1;
private double l2;
private double[] state = new double[4];
private double[] dydt = new double[4];
private double[] prev = new double[4];
private double[] midpt = new double[4];
private static final double h = 0.5;
private static final double DIMENSION = 4;
private static final double HALF = h/2;
private static final double THIRD = h/3;
private static final double SIXTH = h/6;
DoublePendulumThread(SurfaceHolder holder, int width, int height, Context context){
this.holder = holder;
this.context = context;
this.width = width;
this.height = height;
//Setting sizes that require Context to be set
RADIUS = dpToPx(20);
l1 = dpToPx(150);
l2 = dpToPx(150);
state[0] = Math.PI/8;
//Setting up paints for rendering on Canvas
int bobColor = context.getResources().getColor(R.color.colorBob);
int shadowColor = context.getResources().getColor(R.color.shadowColor);
backgroundColor = context.getResources().getColor(R.color.backgroundColor);
paint = new Paint();
paint.setColor(bobColor);
paint.setShadowLayer(5, -1, 2, shadowColor);
}
/*
Evaluates derivatives for Runge-Kutta.
*/
private void loadDys(double[] y){
dydt[0] = y[2]; //Theta1
dydt[1] = y[3]; //Theta2
dydt[2] = ( -1*g*(2*m1 + m2)*sin(y[0]) - m2*g*sin(y[0] - 2*y[1]) - 2*sin(y[0] - y[1])*m2*(y[3]*y[3]*l2 + y[2]*y[2]*l1*cos(y[0] - y[1])) ) / (l1*(2*m1 + m2 - m2*cos(2*y[0]-2*y[1])));
dydt[3] = (2*sin(y[0] - y[1])*(y[2]*y[2]*l1*(m1+m2) + g*(m1+m2)*cos(y[0]) + y[3]*y[3]*l2*m2*cos(y[0]-y[1]))) / (l2*(2*m1 + m2 - m2*cos(2*y[0]-2*y[1])));
}
/*
Each time update is run one iteration of the Runge-Kutta method takes place, with time step h.
*/
protected void update(){
if(pRunning && !clicked1 && !clicked2) {
for (int i = 0; i < DIMENSION; i++) {
midpt[i] = state[i];
prev[i] = state[i];
}
loadDys(midpt);
for (int i = 0; i < DIMENSION; i++) {
state[i] += SIXTH * dydt[i];
midpt[i] = prev[i] + HALF * dydt[i];
}
loadDys(midpt);
for (int i = 0; i < DIMENSION; i++) {
state[i] += THIRD * dydt[i];
midpt[i] = prev[i] + HALF * dydt[i];
}
loadDys(midpt);
for (int i = 0; i < DIMENSION; i++) {
state[i] += THIRD * dydt[i];
midpt[i] = prev[i] + h * dydt[i];
}
loadDys(midpt);
for (int i = 0; i < DIMENSION; i++) {
state[i] += SIXTH * dydt[i];
}
}else if(pRunning && clicked1) {
state[3] += (-1 * g * Math.sin(state[1])) / l2;
state[3] = state[3] * 0.9;
state[1] += state[3] * (40 * Math.pow(10, -2));
}
}
protected void render(){
Canvas canvas = holder.lockCanvas();
canvas.drawColor(backgroundColor);
canvas.drawLine(width / 2, height/4, (float) ((width / 2) + (l1 * Math.sin(state[0]))), (float) (height/4 + l1 * Math.cos(state[0])), paint);
canvas.drawLine((float) ((width / 2) + (l1 * Math.sin(state[0]))), (float) (height/4 + l1 * Math.cos(state[0])), (float) ((width / 2) + (l1 * Math.sin(state[0])) + (l2 * Math.sin(state[1]))), (float) (height/4 + l1 * Math.cos(state[0]) + l2 * Math.cos(state[1])), paint);
canvas.drawCircle((float) ((width / 2) + (l1 * Math.sin(state[0]))), (float) (height/4 + l1 * Math.cos(state[0])), RADIUS, paint);
canvas.drawCircle((float) ((width / 2) + (l1 * Math.sin(state[0])) + (l2 * Math.sin(state[1]))), (float) (height/4 + l1 * Math.cos(state[0]) + l2 * Math.cos(state[1])), RADIUS, paint);
holder.unlockCanvasAndPost(canvas);
}
void updatePos(MotionEvent e){
if(clicked1){
l1 = (int)Math.round(Math.sqrt(((e.getX()-(width/2))*(e.getX()-(width/2)))+((e.getY()-height/4)*(e.getY()-height/4))));
if(e.getY() - height/4 < 0) {
if (Math.round(e.getX() - width / 2) == 0) {
state[0] = Math.PI;
} else {
state[0] = Integer.signum(Math.round((e.getX() - (width / 2)))) * Math.acos((Math.abs(e.getX() - (width / 2)) / l1)) + Integer.signum(Math.round((e.getX() - (width / 2)))) * Math.PI / 2;
}
}else if(Math.round(e.getY() - (height/4)) == 0){
state[0] = Integer.signum(Math.round(e.getX() - (width/2))) * Math.PI / 2;
}else{
state[0] = Math.asin((e.getX()-(width/2))/l1);
}
}else if(clicked2){
l2 = (int)Math.round(Math.sqrt(((e.getX()-((width / 2) + (l1 * Math.sin(state[0]))))*(e.getX()-((width / 2) + (l1 * Math.sin(state[0])))))+((e.getY()-(height/4 + l1 * Math.cos(state[0])))*(e.getY()-(height/4 + l1 * Math.cos(state[0]))))));
if(e.getY() - (height/4 + l1 * Math.cos(state[0])) < 0){
if(Math.round(e.getX() - ((width/2) + l1*sin(state[0]))) == 0){
state[1] = Math.PI;
}else {
state[1] = Integer.signum((int) Math.round((e.getX() - ((width / 2) + (l1 * Math.sin(state[0])))))) * Math.acos((Math.abs(e.getX() - ((width / 2) + (l1 * Math.sin(state[0])))) / l2)) + Integer.signum((int) Math.round((e.getX() - ((width / 2) + (l1 * Math.sin(state[0])))))) * Math.PI / 2;
}
}else if(Math.round(e.getY() - (height/4 + l1 * Math.cos(state[0]))) == 0) {
state[1] = Integer.signum((int) Math.round(e.getX() - ((width/2) + l1*sin(state[0])))) * Math.PI / 2;
}else{
state[1] = Math.asin((e.getX()-((width / 2) + (l1 * Math.sin(state[0]))))/l2);
}
}
}
void click(MotionEvent e){
if((e.getX() - ((width / 2) + (l1 * Math.sin(state[0])) + (l2 * Math.sin(state[1]))))*(e.getX() - ((width / 2) + (l1 * Math.sin(state[0])) + (l2 * Math.sin(state[1])))) + (e.getY() - (height/4 + l1 * Math.cos(state[0]) + l2 * Math.cos(state[1])))*(e.getY() - (height/4 + l1 * Math.cos(state[0]) + l2 * Math.cos(state[1]))) <= RADIUS*RADIUS){
clicked2 = true;
}else {
clicked1 = true;
}
updatePos(e);
}
void unclick(){
if(clicked1 || clicked2) {
state[2] = 0;
state[3] = 0;
for (int i = 0; i < DIMENSION; i++) {
dydt[i] = 0;
midpt[i] = 0;
prev[i] = 0;
}
clicked1 = false;
clicked2 = false;
}
}
private int dpToPx(int dp) {
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
return Math.round(dp * (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));
}
private static double sin(double x){
return Math.sin(x);
}
private static double cos(double x){
return Math.cos(x);
}
这是将 fragment 嵌入到 View 分页器中的主要 Activity 。
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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="com.astarphysics.wikidpendulum.MainActivity"
>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
<com.astarphysics.wikidpendulum.PendulumViewPager
android:id="@+id/view_pager"
android:layout_width="0dp"
android:layout_height="0dp"
tools:layout_constraintTop_creator="1"
tools:layout_constraintRight_creator="1"
tools:layout_constraintBottom_creator="1"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintRight_toRightOf="parent"
android:layout_marginTop="8dp"
tools:layout_constraintLeft_creator="1"
android:layout_marginBottom="8dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp">
</com.astarphysics.wikidpendulum.PendulumViewPager>
</android.support.constraint.ConstraintLayout>
<android.support.design.widget.AppBarLayout
android:layout_height="wrap_content"
android:layout_width="match_parent">
<android.support.v7.widget.Toolbar
app:layout_scrollFlags="enterAlways"
android:id="@+id/toolbar"
android:layout_height="192dp"
android:layout_width="match_parent"
app:contentInsetLeft="0dp"
app:contentInsetStart="0dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="144dp">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:padding="10dp">
<android.support.v7.widget.AppCompatImageButton
android:id="@+id/stop_button"
android:layout_width="48dp"
android:layout_height="48dp"
app:srcCompat="@drawable/ic_pause_white_48dp"
android:background="?attr/selectableItemBackgroundBorderless"
android:layout_marginRight="10dp"
android:layout_marginEnd="10dp"/>
<android.support.v7.widget.AppCompatImageButton
android:id="@+id/help_button"
android:layout_width="48dp"
android:layout_height="48dp"
app:srcCompat="@drawable/ic_help_white_48dp"
android:background="?attr/selectableItemBackgroundBorderless" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<ImageView
android:layout_width="80dp"
android:layout_height="80dp"
android:src="@drawable/icon"/>
<TextView
android:layout_width="150dp"
android:layout_height="wrap_content"
android:text="@string/app_name"
android:gravity="center"
android:textSize="24sp"
android:fontFamily="sans-serif-smallcaps"
android:textColor="@color/textColor"/>
</LinearLayout>
</RelativeLayout>
<android.support.design.widget.TabLayout
android:id="@+id/pager_tabs"
android:layout_width="match_parent"
android:layout_height="48dp">
</android.support.design.widget.TabLayout>
</LinearLayout>
</android.support.v7.widget.Toolbar>
</android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>
如果您认为是其他内容，那么我可以添加代码。
谢谢。
最佳答案
仅更改 ViewPager 中的页面不会强制 fragment 经历其生命周期或导致重新创建 SurfaceView。点击 recents 或 home 然后返回应用程序确实会导致 SurfaceView 被重新创建，这似乎解决了您所遇到的问题看见了。
如果问题是与您的布局相关的微妙问题，我建议您尽可能简化它。我重新设计了两个主要布局以简化它们，如下所示。如果您决定走这条路线，您可能需要更改主布局中的一些内容才能按照您想要的方式调整大小/位置。您不必进行任何结构性更改。
如果上述方法不起作用，可以尝试的其他方法是在为 API 26+ 选择 fragment 时强制重新创建 fragment 。这将强制重新实例化 fragment 和布局，并应该纠正问题。
如果新布局有效，那就最好了；如果您必须在选择选项卡时重新创建，这只是一种解决方法。如果您发现根本问题是什么，请将其发布到此处。我有兴趣知道它是什么。也许这个问题的另一位读者可以深入了解它。
pendulum_layout.xml
<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"
android:orientation="vertical"
tools:context=".MainActivity">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="144dp"
app:contentInsetLeft="0dp"
app:contentInsetStart="0dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:padding="10dp">
<android.support.v7.widget.AppCompatImageButton
android:id="@+id/stop_button"
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:background="?attr/selectableItemBackgroundBorderless"
app:srcCompat="@drawable/ic_pause_white_48dp" />
<android.support.v7.widget.AppCompatImageButton
android:id="@+id/help_button"
android:layout_width="48dp"
android:layout_height="48dp"
android:background="?attr/selectableItemBackgroundBorderless"
app:srcCompat="@drawable/ic_help_white_48dp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<ImageView
android:layout_width="80dp"
android:layout_height="80dp"
android:src="@drawable/icon" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-smallcaps"
android:gravity="center"
android:text="@string/app_name"
android:textColor="#FF000000"
android:textSize="24sp" />
</LinearLayout>
</RelativeLayout>
</android.support.v7.widget.Toolbar>
<com.example.viewpagerbase.PendulumViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.TabLayout
android:id="@+id/pager_tabs"
android:layout_width="match_parent"
android:layout_height="48dp" />
</com.example.viewpagerbase.PendulumViewPager>
</LinearLayout>
fragment_main.xml
<com.example.viewpagerbase.MySurfaceView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/surfaceView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
这是在选择时强制创建新 fragment 的一种方法。如果您在网上搜索，还有其他方法可用。
将以下内容添加到您的 ViewPager 中并从每个构造函数中调用。这将为 API 26+ 设置页面监听器。只要选择不同的页面，此监听器就会触发。
private void init() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
return;
}
addOnPageChangeListener(new OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
MainActivity.SectionsPagerAdapter adapter =
// Your adapter name goes here
((MainActivity.SectionsPagerAdapter) getAdapter());
adapter.invalidateFragment(position);
}
@Override
public void onPageScrollStateChanged(int position) {
}
});
}
将以下内容添加到您的适配器:
private List<SurfacePanelFragment> fragments = new ArrayList<>(PAGE_COUNT);
@Override
public SurfacePanelFragment getItem(int position) {
if (fragments.get(position) == null) {
fragments.set(position, SurfacePanelFragment.newInstance());
}
return fragments.get(position);
}
@Override
public int getItemPosition(Object object) {
return (fragments.contains(object)) ? POSITION_UNCHANGED : POSITION_NONE;
}
public void invalidateFragment(int position) {
fragments.set(position, null);
notifyDataSetChanged();
}
private static final int PAGE_COUNT = 2;
关于java - Surface View 被挤压在 View 寻呼机内，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46595326/