Chapter 9 Multimedia

notice

basis

Android 8.0 introduced the concept of notification channels, and each notification must belong to a corresponding channel. Such as private messages, news, likes and so on

// Create channel
val notificationManager = getSystemService(NOTIFICATION_SERVICE) as NotificationManager
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    notificationManager.createNotificationChannel(
      	// Channel ID, channel name (shown to the user, Settings and long press notification can be seen), notification importance level
        NotificationChannel(
            "like"."Thumb up", NotificationManager.IMPORTANCE_DEFAULT
        )
    )
}
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Create a notification:

// Use NotificationCompat to ensure that all Android versions behave the same. "like" is the notification channel
val build = NotificationCompat.Builder(this."like")
    .setContentTitle("This is content title")
    .setContentText("This is content text")
    .setSmallIcon(R.drawable.apple_pic)
    .setLargeIcon(
        BitmapFactory.decodeResource(resources, R.drawable.ic_launcher_foreground)
    )
    .build()
// 1 is the id. Make sure you specify a different ID for each notification
notificationManager1.notify(1, build)
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PandingIntent

Similar to intents in name, pendingIntents tend to execute an action at the right time.

PendingIntent provides several static methods for retrieving PendingIntent instances. You can use either the getActivity() method, getBroadcast() method, or getService() method as required.

val intent = Intent(this, Chapter9Activity::class.java)
// The second parameter is usually 0, the third parameter is Intent, and the fourth parameter is usually 0
val pendingIntent = PendingIntent.getActivity(this.0, intent, 0)

val build = NotificationCompat.Builder(this."like")
    .setContentTitle("This is content title")
    .setContentText("This is content text")
    .setSmallIcon(R.drawable.apple_pic)
    .setLargeIcon(
        BitmapFactory.decodeResource(resources, R.drawable.ic_launcher_foreground)
    )
		// Set PendingIntent and click on the effect
    .setContentIntent(pendingIntent)
		// Click and the icon disappears
    .setAutoCancel(true)
    .build()
notificationManager1.notify(1, build)
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Cancellation notice:

val notificationManager = getSystemService(NOTIFICATION_SERVICE) as NotificationManager
// Cancel notification. Id is the id when sending
notificationManager.cancel(1)
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The advanced

Display long text

val build = NotificationCompat.Builder(this."like")... .setStyle(NotificationCompat.BigTextStyle().bigText(The Recently used App screen (also known as the overview screen, recent Task list, or Recently used Apps) is a system-level interface that lists activities and tasks that have been recently visited. The user can browse through the list and select the task to resume, or slide out to remove the task from the list.))... .build()Copy the code

Displays a larger image

val build = NotificationCompat.Builder(this."like")... .setStyle(NotificationCompat.BigPictureStyle().bigPicture(BitmapFactory.decodeResource(resources, R.drawable.banana_pic))) ... .build()Copy the code

Notification importance Level

See the notification Settings in Settings for details

Call the camera and album

Calling the Camera

package com.youngly.firstlineofcode.chapter9

import android.app.Activity
import android.content.Intent
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.Matrix
import android.media.ExifInterface
import android.net.Uri
import android.os.Build
import android.os.Bundle
import android.provider.MediaStore
import android.view.View
import android.view.View.OnClickListener
import android.widget.ImageView
import android.widget.TextView
import androidx.core.content.FileProvider
import com.youngly.firstlineofcode.BaseActivity
import com.youngly.firstlineofcode.R
import java.io.File

class CameraActivity : BaseActivity(), OnClickListener {
    private val takePhotoCode = 1
    private lateinit var imageView: ImageView
    private lateinit var outputImage: File
    private lateinit var imageUri: Uri

    override fun onCreate(savedInstanceState: Bundle?). {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_camera)
        imageView = findViewById(R.id.imageView)
        findViewById<TextView>(R.id.takePhoto).setOnClickListener(this)}override fun onClick(v: View?). {
        ExternalCacheDir /sdcard/Android/data/
          
           /cache
          
        // You do not need to apply for SD permission to read or write storage areas associated with applications
        outputImage = File(externalCacheDir, "camara_image.jpg")
        if (outputImage.exists()) {
            outputImage.delete()
        }
        outputImage.createNewFile()
        // Starting with Android 7.0, it is considered unsafe to use urIs directly from local real paths.
        imageUri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            // The second argument can be any unique string
            FileProvider.getUriForFile(
                this."com.youngly.firstlineofcode.fileprovider",
                outputImage
            )
        } else {
            // Convert the File object to the Uri object
            Uri.fromFile(outputImage)
        }
        val intent = Intent("android.media.action.IMAGE_CAPTURE")
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri)
        startActivityForResult(intent, takePhotoCode)
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int.data: Intent?). {
        super.onActivityResult(requestCode, resultCode, data)
        when (requestCode) {
            takePhotoCode -> {
                if (resultCode == Activity.RESULT_OK) {
                    val bitmap =
                        BitmapFactory.decodeStream(contentResolver.openInputStream(imageUri))
                    imageView.setImageBitmap(rotateIfRequired(bitmap))
                }
            }
        }
    }

    private fun rotateIfRequired(bitmap: Bitmap): Bitmap {
        val exifInterface = ExifInterface(outputImage.path)
        val orientation = exifInterface.getAttributeInt(
            ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL
        )
        return when (orientation) {
            ExifInterface.ORIENTATION_ROTATE_90 -> rotateBitmap(bitmap, 90)
            ExifInterface.ORIENTATION_ROTATE_180 -> rotateBitmap(bitmap, 180)
            ExifInterface.ORIENTATION_ROTATE_270 -> rotateBitmap(bitmap, 270)
            else -> bitmap
        }
    }

    private fun rotateBitmap(bitmap: Bitmap, degree: Int): Bitmap {
        val matrix = Matrix()
        matrix.postRotate(degree.toFloat())
        val createBitmap =
            Bitmap.createBitmap(bitmap, 0.0, bitmap.width, bitmap.height, matrix, true)
        // Recycle bitmaps that are no longer needed
        bitmap.recycle()
        return createBitmap
    }
}
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// Add the following configuration to manifest.xml<provider
    android:name="androidx.core.content.FileProvider"
    android:authorities="com.youngly.firstlineofcode.fileprovider"
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/file_paths" />
</provider>
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Create the file_paths.xml file


          <paths xmlns:android="http://schemas.android.com/apk/res/android">/ / the name arbitrarily<external-path name="camara_image.jpg" path="/" /></paths>
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Select the file from the album

val intent = Intent(Intent.ACTION_OPEN_DOCUMENT)
intent.addCategory(Intent.CATEGORY_OPENABLE)
intent.type = "image/*"
startActivityForResult(intent, fromAlbum)
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if (resultCode == Activity.RESULT_OK && data! =null) {
    data.data? .let {val bitmapFromUri = getBitmapFromUri(it)
        imageView.setImageBitmap(bitmapFromUri)
    }
}
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private fun getBitmapFromUri(uri: Uri)  = contentResolver.openFileDescriptor(uri, "r")? .use { BitmapFactory.decodeFileDescriptor(it.fileDescriptor) }Copy the code

Playing multimedia Files

package com.youngly.firstlineofcode.chapter9

import android.media.MediaPlayer
import android.net.Uri
import android.os.Bundle
import android.provider.MediaStore
import android.view.View
import android.widget.VideoView
import com.youngly.firstlineofcode.BaseActivity
import com.youngly.firstlineofcode.R

class MediaActivity : BaseActivity() {
    private val mediaPlayer = MediaPlayer()
    private lateinit var videoView:VideoView

    override fun onCreate(savedInstanceState: Bundle?). {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_media)
        videoView = findViewById<VideoView>(R.id.videoView)
        initMediaPlayer()
    }

    private fun initMediaPlayer(a) {
        val openFd = assets.openFd("Jacky Cheung - Trouble song.mp3")
        mediaPlayer.setDataSource(openFd.fileDescriptor, openFd.startOffset, openFd.length)
        mediaPlayer.prepare()

        val parse = Uri.parse("android.resource:://$packageName/${R.raw.screen}")
        videoView.setVideoURI(parse)
    }

    fun start(view: View) {
        if(! mediaPlayer.isPlaying) { mediaPlayer.start() } }fun pause(view: View) {
        if (mediaPlayer.isPlaying) {
            mediaPlayer.pause()
        }
    }
    fun stop(view: View) {
        if (mediaPlayer.isPlaying) {
            mediaPlayer.stop()
        }
    }

    fun vStart(view: View) {
        if(! videoView.isPlaying) { videoView.start() } }fun vPause(view: View) {
        if (videoView.isPlaying) {
            videoView.pause()
        }
    }
    fun vStop(view: View) {
        if (videoView.isPlaying) {
            videoView.resume()
        }
    }

    override fun onDestroy(a) {
        super.onDestroy()
      	// Release resources
        mediaPlayer.stop()
        mediaPlayer.release()
        videoView.suspend()}}Copy the code

Kotlin classroom

Infix function
```
infix fun String.beginWith(prefix:String)= startsWith(prefix)
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```
```
if ("hello" beginWith "1") {
  // todo
}
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```
The Infix function allows us to remove computer-specific syntax such as decimals, parentheses, and so on from function calls.

Limitations:
1. Cannot be defined as a top-level function. It must be a member function of a class or can be defined as an extension function to a class
2. The infix function must accept only one function

Chapter 9 Multimedia

Chapter 9 Multimedia

notice

basis

The advanced

Call the camera and album

Calling the Camera

Playing multimedia Files

Kotlin classroom

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