image pixelization utilizes the bitmap scaling operations built into the framework. - Android Graphics

Android examples for Graphics:Bitmap Effect

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Description

image pixelization utilizes the bitmap scaling operations built into the framework.

Demo Code


//package com.java2s;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.os.Build;

public class Main {
    /**//from   ww w  .j  av  a 2  s.  c  om
     * This method of image pixelization utilizes the bitmap scaling operations built
     * into the framework. By downscaling the bitmap and upscaling it back to its
     * original size (while setting the filter flag to false), the same effect can be
     * achieved with much better performance.
     */
    public static BitmapDrawable builtInPixelization(Context context,
            float pixelizationFactor, Bitmap bitmap) {

        int width = bitmap.getWidth();
        int height = bitmap.getHeight();

        int downScaleFactorWidth = (int) (pixelizationFactor * width);
        downScaleFactorWidth = downScaleFactorWidth > 0 ? downScaleFactorWidth
                : 1;
        int downScaleFactorHeight = (int) (pixelizationFactor * height);
        downScaleFactorHeight = downScaleFactorHeight > 0 ? downScaleFactorHeight
                : 1;

        int downScaledWidth = width / downScaleFactorWidth;
        int downScaledHeight = height / downScaleFactorHeight;

        Bitmap pixelatedBitmap = Bitmap.createScaledBitmap(bitmap,
                downScaledWidth, downScaledHeight, false);

        /* Bitmap's createScaledBitmap method has a filter parameter that can be set to either
         * true or false in order to specify either bilinear filtering or point sampling
         * respectively when the bitmap is scaled up or now.
         *
         * Similarly, a BitmapDrawable also has a flag to specify the same thing. When the
         * BitmapDrawable is applied to an ImageView that has some scaleType, the filtering
         * flag is taken into consideration. However, for optimization purposes, this flag was
         * ignored in BitmapDrawables before Jelly Bean MR1.
         *
         * Here, it is important to note that prior to JBMR1, two bitmap scaling operations
         * are required to achieve the pixelization effect. Otherwise, a BitmapDrawable
         * can be created corresponding to the downscaled bitmap such that when it is
         * upscaled to fit the ImageView, the upscaling operation is a lot faster since
         * it uses internal optimizations to fit the ImageView.
         * */
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            BitmapDrawable bitmapDrawable = new BitmapDrawable(
                    context.getResources(), pixelatedBitmap);
            bitmapDrawable.setFilterBitmap(false);
            return bitmapDrawable;
        } else {
            Bitmap upscaled = Bitmap.createScaledBitmap(pixelatedBitmap,
                    width, height, false);
            return new BitmapDrawable(context.getResources(), upscaled);
        }
    }
}

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