屏幕上显示的图像-Android Studio

Question

For some reason when I set the x coordinate to screen_width - image_width, the image is displayed off the screen. The same scenario occurs with the y coordinate. Here is my code.

public class MainActivity extends AppCompatActivity {

    ImageView image;
    float height;
    float width;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        height = displayMetrics.heightPixels;
        width = displayMetrics.widthPixels;

        image.setImageResource(R.drawable.pigeon);
        image.setX(width - image.getMeasuredWidth());

In this case the image, which is a pigeon, is not displayed on the screen. And I expect it to be displayed so that the right border of the pigeon touches the right border of the screen.

Edit: It's not that I just want to position the image and be done with it. I want to be able to move the image to precise coordinates while the app is running, such as when a mouse click occurs.

Answer 1

One way to align the image right is to use the XML layout. This is the easiest method.

Assuming you have an ImageView inside a RelativeLayout you can use the `layout_alignParentRight' attribute as follows:

<?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:id="@+id/view"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal"
    tools:context=".MainActivity">
    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:contentDescription="@string/image_name"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        />
</RelativeLayout>

The layout_alignParentEnd attribute is an alternative for layout_alignParentRight for right to left language script. For a LinearLayout you can use layout_gravity attribute. Also, ensure that your ImageView is wrap_content and not match_parent in which case the image will expand to fill the entire ImageView .

If you want to do it programmatically, you can do it in the following manner:

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = findViewById(R.id.imageView);
        imageView.setImageResource(R.drawable.pigeon);
        RelativeLayout.LayoutParams params = new 
        RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, 
        RelativeLayout.LayoutParams.WRAP_CONTENT);
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        imageView.setLayoutParams(params);
    }

Here we are aligning the child view of RelativeLayout right by adding the align right rule and then setting that layout parameter for the Image View . This can also be done for LinearLayout using layout_gravity feature.

I have tested this code for a sample image. Hope this solves your problem.