Android : downloaded Image set in ImageView smaller than same sized image from bundle

Question

I am rather confused.

I have an App which has a matrix of nine imagebuttons 3 x 3

The centre button has a logo which is loaded from a resource ID R.drawable.logo and the others are initialised to "no image yet" images. All images are 86 x 86 and set from the screen builder tool.

When the user logs in, one or more of the surrounding 8 images will be downloaded from the web. They are mainly 86x86 as well.

The downloaded images come up appx half size in x and y directions compared to the pre-set images.

Images are examined and known to be 86 x 86 once downloaded by examining bitmapFactory options object.

Images downloaded by two different methods in this page... How to load an ImageView by URL in Android?

what is your question? I'm assuming you want them to be 86x86. You have to change the scaleType attribute on your ImageView for the images to scale in a desirable way for you — dymmeh, Mar 05 '12 at 17:09
The question is WHY images set in the layout file appear a different size from images downloaded and set using either setImageBitmap or setImageDrawable and how I can ensure that all images are rendered to the same size more or less — Dave Appleton, Mar 05 '12 at 17:13

David · Answer 1 · 2016-04-11T12:07:07.220

An image pulled from resources will get up-scaled if one cannot be found for the target device's density dpi. For example, if you are on a device that is DisplayMetrics.DENSITY_HIGH (hdpi) but you only have the image in /res/drawable-mdpi that image will be automatically up-scaled when you retrieve it via something like getDrawable().

However, with a downloaded image the system does not know which density the image is designed for because it is not contained in a resource folder which specifies its density, so scaling cannot be done automatically. You must define the density manually using BitmapFactory.Options. Consider the following function:

/**
 * Downloads an image for a specified density DPI.
 * @param context the current application context
 * @param url the url of the image to download
 * @param imgDensity the density DPI the image is designed for (DisplayMetrics.DENSITY_MEDIUM, DisplayMetrics.DENSITY_HIGH, etc.)
 * @return the downloaded image as a Bitmap
 */
public static Bitmap loadBitmap(Context context, String url, int imgDensity) {
    DisplayMetrics metrics = context.getResources().getDisplayMetrics();
    BitmapFactory.Options options = new BitmapFactory.Options();

    // This defines the density DPI the image is designed for.
    options.inDensity = imgDensity;

    // These define the density DPI you would like the image to be scaled to (if necessary).
    options.inScreenDensity = metrics.densityDpi;
    options.inTargetDensity = metrics.densityDpi;

    try {
        // Download image
        InputStream is = new java.net.URL(url).openStream();
        return BitmapFactory.decodeStream(is, null, options);
    }
    catch(Exception ex) {
        // Handle error
    }

    return null;
}

So if your image at the specified URL is designed for an mdpi screen, you would pass DisplayMetrics.DENSITY_MEDIUM for the imgDensity parameter. If the current context has a larger density DPI (such as DisplayMetrics.DENSITY_HIGH), the image will be up-scaled accordingly.

score 0 · Answer 2 · answered Mar 05 '12 at 18:26

0

Add android:scaleType="fitXY" to the ImageView. This would always render the image within the specified border.

answered Mar 05 '12 at 18:26

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Android : downloaded Image set in ImageView smaller than same sized image from bundle

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