Android ImageView adjusting parent's height and fitting width

问题

Update : I solved this issue by using the method described in this answer

I\'m a bit stuck with this issue, which I think should be pretty simple.

So my app downloads an image, and renders the bitmap in an ImageView, a child element of a RelativeLayout. I would like the ImageView to fit the parent width, and to adapt it\'s size to keep the aspect ratio.

Here is my XML :

<?xml version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
android:orientation=\"vertical\"
android:layout_width=\"fill_parent\"
android:layout_height=\"fill_parent\"
>
<RelativeLayout android:id=\"@+id/banner\" android:layout_width=\"fill_parent\" android:layout_height=\"wrap_content\"></RelativeLayout>
<TextView  
android:layout_width=\"fill_parent\" 
android:layout_height=\"wrap_content\" 
android:text=\"@string/hello\"
/>
</LinearLayout>

And the code :

public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


    RelativeLayout banner = (RelativeLayout) findViewById(R.id.banner);
    ImageView imgV = new ImageView(this);

    imgV.setScaleType(ImageView.ScaleType.CENTER_CROP);
    // I tried all the scale types : CENTER_INSIDE : same effect, FIT_CENTER : same effect... 

    imgV.setBackgroundColor(0x00FFFF00);

    imgV.setAdjustViewBounds(Color.BLUE);


    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

    banner.addView(imgV,params);

    // Some code downloading the image stream

    bitmap = BitmapFactory.decodeStream(stream);


    imgV.setImageBitmap(bitmap);

    }

Desired :

Result :

回答1:

Thanks to @Julien and @js. Here is complete solution of ImageView that will stretch bitmap height preserving aspect ratio even if bitmap is smaller than ImageView.

public class ResizableImageView extends ImageView {

    public ResizableImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override 
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
         Drawable d = getDrawable();

         if(d!=null){
                 // ceil not round - avoid thin vertical gaps along the left/right edges
                 int width = MeasureSpec.getSize(widthMeasureSpec);
                 int height = (int) Math.ceil((float) width * (float) d.getIntrinsicHeight() / (float) d.getIntrinsicWidth());
                 setMeasuredDimension(width, height);
         }else{
                 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
         }
    }

}

You can use this class in your xml layouts instead ImageView.

<com.example.ResizableImageView
    android:id="@+id/banner"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:src="@drawable/banner" />

回答2:

You're probably looking for android:adjustViewBounds="true" in xml or imageView.setAdjustViewBounds(true) in Java.

回答3:

As I mentioned in a comment, I subclassed the ImageView. I found my code, here you go :

    protected class ResizableImageView extends ImageView
    {

        private Bitmap mBitmap;

        // Constructor

        public ResizableImageView(Context context)
        {
            super(context);
        }


        // Overriden methods


          @Override 
          protected void onMeasure(int widthMeasureSpec,
                  int heightMeasureSpec) {
              if(mBitmap != null)
              {
                    int width = MeasureSpec.getSize(widthMeasureSpec);
                    int height = width * mBitmap.getHeight() / mBitmap.getWidth();
                    setMeasuredDimension(width, height);

              } 
              else
              {
                  super.onMeasure(widthMeasureSpec,
                          heightMeasureSpec);
              }
              }

            @Override
            public void setImageBitmap(Bitmap bitmap)
            {
                mBitmap = bitmap;
                 super.setImageBitmap(bitmap);
            }

    }

回答4:

I think you should change your imgV width to "match_parent"

You should change the scale type to imgV.setScaleType(ImageView.ScaleType.CENTER_INSIDE);

回答5:

I made a slight change to @Seraphim S's solution to account for cases where the image may be wide, and the view's bounds also wide (for example, rotating the device to landscape mode).

public class ResizableImageView extends ImageView {
    public ResizableImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Drawable d = getDrawable();

        if (d != null) {

            int width = MeasureSpec.getSize(widthMeasureSpec);
            int height = MeasureSpec.getSize(heightMeasureSpec);

            if (width >= height) {
                width = (int) Math.ceil((float) height * (float) d.getIntrinsicWidth() / (float) d.getIntrinsicHeight());
            } else {
                height = (int) Math.ceil((float) width * (float) d.getIntrinsicHeight() / (float) d.getIntrinsicWidth());
            }

            setMeasuredDimension(width, height);
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
}

来源：https://stackoverflow.com/questions/5554682/android-imageview-adjusting-parents-height-and-fitting-width