在 Android 中单击时放大图像视图

Question

我现在使用毕加索有一段时间了，我对它非常满意。 但是我需要放大毕加索从firebase加载的imageview的图像。 下面的代码位于在 MainActivity.java 中调用的 adapter.java

UserRef = FirebaseDatabase.getInstance().getReference().child("user").child(fromUserID);
        UserRef.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                String senderName = snapshot.child("name").getValue().toString();
                String userid = fromUserID;
                if (snapshot.hasChild("avata")){
                 final String receiverImage = snapshot.child("avata").getValue().toString();

                        if (fromUserID.equals(messageSenderId)) {
                            messageViewholder.senderMessageName.setVisibility(View.VISIBLE);
                            messageViewholder.senderImageView.setVisibility(View.VISIBLE);

                            if (fromMessageType.equals("text")) {
                                messageViewholder.senderMessageText.setVisibility(View.VISIBLE);
                                messageViewholder.senderMessageText.setText(messages.getMessage());
                            }else if (fromMessageType.equals("image")) {
                                messageViewholder.senderMessageImage.setVisibility(View.VISIBLE);
                                Picasso.get().load(messages.getMessage()).into(messageViewholder.senderMessageImage);

                            }

这是xml

   <ImageView
        android:id="@+id/receiver_message_image"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_toEndOf="@id/receiver_image"
        android:layout_below="@id/receiver_message_name"
        android:layout_marginStart="5dp"
        android:visibility="gone"
        android:adjustViewBounds="true"
        android:layout_marginEnd="20dp" />

Answer 1

您可以使用ScaleGestureDetector来检测已发生的特定手势事件。 它还可以让您根据手势放大和缩小。 在此示例中，我使用viewBinding将 XML 布局映射到 Java。

XML 布局

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/symatech_logo"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

Java 代码

   public class EnlargeImageViewWhenClicked extends AppCompatActivity {

    EnlargeImageViewBinding enlargeImageViewBinding;
    ScaleGestureDetector scaleGestureDetector;
    float factor = 1.5f;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        enlargeImageViewBinding = EnlargeImageViewBinding.inflate(getLayoutInflater());
        setContentView(enlargeImageViewBinding.getRoot()); // Setting up the view

        scaleGestureDetector = new ScaleGestureDetector(this, new Listerner()); // Creating the ScaleGestureDetector object.
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        scaleGestureDetector.onTouchEvent(event);
        return super.onTouchEvent(event);
    }

    private class Listerner extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScale(ScaleGestureDetector scaleGestureDetector) {
            factor *= scaleGestureDetector.getScaleFactor(); // The scaling factor from the previous scale event being applied to the current event.
            factor = Math.max(0.5f, Math.min(factor, 5.0f));
            enlargeImageViewBinding.imageView.setScaleY(factor);
            enlargeImageViewBinding.imageView.setScaleX(factor);
            return true;
        }
    }
}

在我放大之前

放大后

我当然希望这会有所帮助！

Answer 2

考虑将 ImageView(messageViewholder.senderMessageImage) 置于 ScaleGestureDetector.SimpleOnScaleGestureListener 中的 onScale 函数，就像我给出的示例一样。 像这样的东西（您可能需要编辑代码以适合您的情况。也不要忘记获取其余代码，即初始化ScaleGestureDetector并覆盖onTouchEvent函数）

 private class Listerner extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScale(ScaleGestureDetector scaleGestureDetector) {
            factor *= scaleGestureDetector.getScaleFactor(); // The scaling factor from the previous scale event being applied to the current event.
            factor = Math.max(0.5f, Math.min(factor, 5.0f));
            **messageViewholder.senderMessageImage**.setScaleY(factor);
            **messageViewholder.senderMessageImage**.setScaleX(factor);
            return true;
        }
    }