chaquo之Kotlin接收Python返回的Bitmap

• Python生成图片流

import io
import matplotlib.pyplot as plt

def plot(x, y):
    xa = [float(word) for word in x.split()]
    ya = [float(word) for word in y.split()]

    fig, ax = plt.subplots()
    ax.plot(xa, ya)

    f = io.BytesIO()
    plt.savefig(f, format="png")
    return f.getvalue()

• Kotlin接收处理图片流并将其展示在ImageView上

package com.chaquo.myapplication

import android.content.Context
import android.graphics.BitmapFactory
import android.os.Bundle
import android.view.inputmethod.InputMethodManager
import android.widget.Button
import android.widget.EditText
import android.widget.ImageView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.chaquo.python.PyException
import com.chaquo.python.Python
import com.chaquo.python.android.AndroidPlatform

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        if (! Python.isStarted()) {
            Python.start(AndroidPlatform(this))
        }
        val py = Python.getInstance()
        val module = py.getModule("plot")

        findViewById<Button>(R.id.button).setOnClickListener {
            try {
                val bytes = module.callAttr("plot",
                                            findViewById<EditText>(R.id.etX).text.toString(),
                                            findViewById<EditText>(R.id.etY).text.toString())
                    .toJava(ByteArray::class.java)
                val bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.size)
                findViewById<ImageView>(R.id.imageView).setImageBitmap(bitmap)

                currentFocus?.let {
                    (getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager)
                        .hideSoftInputFromWindow(it.windowToken, 0)
                }
            } catch (e: PyException) {
                Toast.makeText(this, e.message, Toast.LENGTH_LONG).show()
            }
        }
    }
}