ImageView缩放不起作用

Question

I googled this question but didn't fond answer for me.

This is my ImageView :

And this this ImageView in xml:

<ImageView
      android:id="@+id/stock_cover"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:adjustViewBounds="true"                        
      android:src="@drawable/place_holder16_9" />

How I can scale this image like on example image?

PS This image I download from internet.

UPD 1. ImageLoader code added.

DisplayImageOptions options = new DisplayImageOptions.Builder()
            .showImageForEmptyUri(R.drawable.place_holder16_9)
            .cacheInMemory(true)
            .cacheOnDisk(true)
            .build();
ImageLoader.getInstance().displayImage(promo.getImageBigUrl(), mCoverImageView, options);

Answer 1

Sorry, but you cannot make it bigger as you use this:

  android:layout_width="match_parent"

It already means "take how much width as you can". As your width has the maximum value, your image height also takes a maximum value.

You can check it by using:

android:scaleX="3"
android:scaleY="3"

It should make it bigger three times. If it won't work use:

android:scaleX="0.2"
android:scaleY="0.2"

It should make it smaller five times. I'm pretty sure that it would work

Hope it help

Answer 2

Set LayoutParams from code.

ImageView image = new ImageView(this);
image.setImageResource(getResources().getIdentifier('file_name', "drawable", getPackageName()));
image.setAdjustViewBounds(true);
image.setScaleType(ImageView.ScaleType.CENTER_CROP);
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
image.setLayoutParams(layoutParams);
parent.addView(image);

It's a known issue with ImageView, which won't upscale small images.

Answer 3

Try this code:

private void scaleImage(ImageView view, int boundBoxInDp)
{
    // Get the ImageView and its bitmap
    Drawable drawing = view.getDrawable();
    Bitmap bitmap = ((BitmapDrawable)drawing).getBitmap();

    // Get current dimensions
    int width = bitmap.getWidth();
    int height = bitmap.getHeight();

    // Determine how much to scale: the dimension requiring less scaling is
    // closer to the its side. This way the image always stays inside your
    // bounding box AND either x/y axis touches it.
    float xScale = ((float) boundBoxInDp) / width;
    float yScale = ((float) boundBoxInDp) / height;
    float scale = (xScale <= yScale) ? xScale : yScale;

    // Create a matrix for the scaling and add the scaling data
    Matrix matrix = new Matrix();
    matrix.postScale(scale, scale);

    // Create a new bitmap and convert it to a format understood by the        ImageView
    Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
    BitmapDrawable result = new BitmapDrawable(scaledBitmap);
    width = scaledBitmap.getWidth();
    height = scaledBitmap.getHeight();

    // Apply the scaled bitmap
    view.setImageDrawable(result);

    // Now change ImageView's dimensions to match the scaled image
    LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) view.getLayoutParams();
    params.width = width;
    params.height = height;
    view.setLayoutParams(params);
}

private int dpToPx(int dp)
{
    float density = getApplicationContext().getResources().getDisplayMetrics().density;
    return Math.round((float)dp * density);
}

Answer 4

You can set Bitmap as background.

// Load image, decode it to Bitmap and return Bitmap to callback 
imageLoader.loadImage(imageUri, new SimpleImageLoadingListener() { 
    @Override 
    public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
        // Do whatever you want with Bitmap 
        mCoverImageView.setBackground(new BitmapDrawable(getResources(), bitmap));
    } 
}); 

Reference Link

Answer 5

Try using ScaleType attribute for your ImageView in your xml. For example

android:scaleType="centerCrop".