Retrofit API to retrieve a png image

Question

Hi I am new to Retrofit framework for Android. I could get JSON responses from REST services using it but I don\'t know how to download a png using retrofit. I am trying to

Answer 1

Details

• Android studio 3.1.4
• Kotlin 1.2.60
• Retrofit 2.4.0
• checked in minSdkVersion 19

Solution

object RetrofitImage

object RetrofitImage {

    private fun provideRetrofit(): Retrofit {
        return Retrofit.Builder().baseUrl("https://google.com").build()
    }

    private interface API {
        @GET
        fun getImageData(@Url url: String): Call
    }

    private val api : API by lazy  { provideRetrofit().create(API::class.java) }

    fun getBitmapFrom(url: String, onComplete: (Bitmap?) -> Unit) {

        api.getImageData(url).enqueue(object : retrofit2.Callback {

            override fun onFailure(call: Call?, t: Throwable?) {
                onComplete(null)
            }

            override fun onResponse(call: Call?, response: Response?) {
                if (response == null || !response.isSuccessful || response.body() == null || response.errorBody() != null) {
                    onComplete(null)
                    return
                }
                val bytes = response.body()!!.bytes()
                onComplete(BitmapFactory.decodeByteArray(bytes, 0, bytes.size))
            }
        })
    }
}

Usage 1

RetrofitImage.getBitmapFrom(ANY_URL_STRING) {
   // "it" - your bitmap
   print("$it")
}

Usage 2

Extension for ImageView

fun ImageView.setBitmapFrom(url: String) {
    val imageView = this
    RetrofitImage.getBitmapFrom(url) {
        val bitmap: Bitmap?
        bitmap = if (it != null) it else {
            // create empty bitmap
            val w = 1
            val h = 1
            val conf = Bitmap.Config.ARGB_8888
            Bitmap.createBitmap(w, h, conf)
        }

        Looper.getMainLooper().run {
            imageView.setImageBitmap(bitmap!!)
        }
    }
}

Usage of the extension

imageView?.setBitmapFrom(ANY_URL_STRING)