自定义放大/缩小按钮不能同时工作

Question

I am making buttons to zoom in/out on an image view. The zoom in button works correctly. However, once I add the zoom out button, the zoom in button ceases to work and it zooms in on the image.

I have tried switching the variable names to make sure they're initialized correctly. Once I delete the zoom out button and its function, the zoom in button works correctly. It is only the zoom out button function that makes the zoom in button break.

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_camera2_video,container,false);
}

@Override
public void onViewCreated(final View view, Bundle savedInstanceState) {
    mTextureView = view.findViewById(R.id.texture);
    mButtonVideo = view.findViewById(R.id.video);

    mZoomIn = view.findViewById(R.id.zoomIn);
    mZoomOut = view.findViewById(R.id.zoomOut);
    img = view.findViewById(R.id.imageView1);

    mButtonVideo.setOnClickListener(this);
    mZoomIn.setOnClickListener(this);
    mZoomOut.setOnClickListener(this);
}

@Override
public void onClick(View view) {
    switch (view.getId()) {
        case R.id.video: {
            if (mIsRecordingVideo) {
                stopRecordingVideo();
            } else {
                startRecordingVideo();
            }
            break;
        }

        // Zoom In
        case R.id.zoomIn: {
            float x = img.getScaleX();
            float y = img.getScaleY();

            img.setScaleX(x + 1);
            img.setScaleY(y + 1);
        }

        // Zoom Out
        case R.id.zoomOut: {
            float x = img.getScaleX();
            float y = img.getScaleY();

            img.setScaleX(x - 1);
            img.setScaleY(y - 1);
        }
    }
}


<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.example.android.camera2video.AutoFitTextureView
        android:id="@+id/texture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true" />

    <ImageButton
        android:id="@+id/zoomIn"
        android:layout_width="49dp"
        android:layout_height="46dp"
        android:layout_above="@+id/zoomOut"
        android:layout_alignStart="@+id/texture"
        android:layout_alignEnd="@+id/zoomOut"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:layout_marginBottom="0dp"
        android:contentDescription="@string/zoom_in"
        android:src="@drawable/ic_zoom_in_black_24dp" />

    <ImageButton
        android:id="@+id/zoomOut"
        android:layout_width="49dp"
        android:layout_height="46dp"
        android:layout_above="@+id/change_screen_brightness_seekbar"
        android:layout_alignStart="@+id/texture"
        android:layout_alignEnd="@+id/video"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:layout_marginBottom="0dp"
        android:contentDescription="@string/zoom_out"
        android:src="@drawable/ic_zoom_out_black_24dp" />

    <ImageView
        android:contentDescription="@string/reticle"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:id="@+id/imageView1"
        android:src="@drawable/reticle"
        android:layout_height="wrap_content">

    </ImageView>
</RelativeLayout>

Both the buttons appear on the screen. When I have just the zoom in button, the image view will zoom in as expected. But once I add the function to make the zoom out button work, it looks like the image will zoom out/disappear, then reappear and begin zooming in. The zoom in button stops working too.

Answer 1

You are experiencing "fall-through" in your switch because you don't have a break before case R.id.zoomOut: . This means that the program is moving on to the next case , which in your case is the "zoom out" functionality. You aren't seeing any effect because that cancels out the "zoom in" functionality.

It is a good practice to add the break after the last case to avoid just this sort of error.