A set of Picasso Transformation Examples

CircleTransformation.java

package co.kaush.mystarterapp.myappmodule.ui.transformations;

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Shader;

import com.squareup.picasso.Transformation;

public class CircleTransformation
    implements Transformation {

    @Override
    public Bitmap transform(Bitmap sourceBitmap) {

        int smallerOfHeightAndWidth = Math.min(sourceBitmap.getHeight(), sourceBitmap.getWidth());
        int x_firstSourcePixel = (sourceBitmap.getWidth() - smallerOfHeightAndWidth) / 2;
        int y_firstSourcePixel = (sourceBitmap.getHeight() - smallerOfHeightAndWidth) / 2;
        float radius = smallerOfHeightAndWidth / 2f;

        Bitmap sourceBitmapSquare = Bitmap.createBitmap(sourceBitmap,
                                                        x_firstSourcePixel,
                                                        y_firstSourcePixel,
                                                        smallerOfHeightAndWidth,
                                                        smallerOfHeightAndWidth);
        // recycle original bitmap if it's not the same as we no longer need it
        if (sourceBitmapSquare != sourceBitmap) {
            sourceBitmap.recycle();
        }

        // create the output bitmap structure
        Bitmap outputBitmap = Bitmap.createBitmap(smallerOfHeightAndWidth,
                                                  smallerOfHeightAndWidth,
                                                  sourceBitmap.getConfig());

        // prepare canvas + paint with all ingredients
        BitmapShader shader = new BitmapShader(sourceBitmapSquare,
                                               Shader.TileMode.CLAMP,
                                               Shader.TileMode.CLAMP);
        Canvas canvas = new Canvas(outputBitmap);
        Paint paint = new Paint();
        paint.setShader(shader);
        paint.setAntiAlias(true);

        canvas.drawCircle(radius, radius, radius, paint);

        // recycle sourceBitmapSquare as we no longer need it
        sourceBitmapSquare.recycle();

        return outputBitmap;
    }

    @Override
    public String key() {
        return "co.kaush.mystarterapp.myappmodule.ui.transformations.CircleTransformation";
    }
}

VignetteTransformation.java

package co.kaush.mystarterapp.myappmodule.ui.transformations;

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ComposeShader;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.Shader;

import com.squareup.picasso.Transformation;

public class VignetteTransformation
    implements Transformation {

    private final TYPE _type;

    public enum TYPE {BOTTOM, TOP}

    public VignetteTransformation(TYPE type) {
        _type = type;
    }

    @Override
    public Bitmap transform(Bitmap source) {

        // create the output bitmap structure
        Bitmap outputBitmap = Bitmap.createBitmap(source.getWidth(),
                                                  source.getHeight(),
                                                  source.getConfig());

        // prepare canvas + paint with all ingredients
        ComposeShader composeShader = _getVignetteShader(source);
        Canvas canvas = new Canvas(outputBitmap);
        Paint paint = new Paint();
        paint.setShader(composeShader);
        paint.setAntiAlias(true);

        // paint on canvas which holds to be rendered bitmap
        canvas.drawPaint(paint);

        // recycle the original bitmap which we no longer require
        source.recycle();

        return outputBitmap;
    }

    @Override
    public String key() {
        return "co.kaush.mystarterapp.myappmodule.ui.transformations.VignetteTransformation";
    }

    private ComposeShader _getVignetteShader(Bitmap source) {// create the bitmap shader
        // create a bitmap shader
        Shader bitmapShader = new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);

        // create the linear gradient shader
        Shader linearGradientShader = _getLinearGradient(source);

        // create a shader that combines both effects
        return new ComposeShader(bitmapShader, linearGradientShader, PorterDuff.Mode.DST_OUT);
    }

    private LinearGradient _getLinearGradient(Bitmap source) {

        int x0 = 0, y0 = 0,
            x1 = 0, y1 = source.getHeight(),
            // The colors here are actually irrelevant
            fromColor = Color.RED,             // This translates to the image showing
            toColor = Color.TRANSPARENT;       // This translates to background color

        switch (_type) {
            case BOTTOM:
                fromColor = Color.TRANSPARENT;
                toColor = Color.RED;
                break;
        }

        return new LinearGradient(x0, y0, x1, y1, fromColor, toColor, Shader.TileMode.MIRROR);
    }
}