【Kotlin】Day3 ( Intent + ImageButton )

各種筆記…

• /res/mipmap-* 這類資料夾裡面，負責放 icon
• /res/drawable  當中放入其它素材
• 按鈕點擊下去後
  因為會用到 Camera 所以需要 runtime permission
  記住要把 「需要permission的動作放在else裡面」 不然他在一面請求你的permission時就會先做下面的事情所以就會Crash了~QQ

  if(ContextCompat.checkSelfPermission(MainActivity_Context, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED){
      requests_for_permission(CAMERA_REQUEST_CODE)
  }else{
      val intent= Intent(MediaStore.ACTION_IMAGE_CAPTURE)
      startActivityForResult(intent, CAMERA_REQUEST_CODE)
  }

• 想要讓人只能從檔案管理中選擇圖片時
  然後回傳時

  val intent:Intent = Intent(Intent.ACTION_GET_CONTENT)
  intent.setType("image/*")
  startActivityForResult(intent, FILESYS_REQUEST_CODE)

• 從檔案管理那邊拿到之後還要經過轉換才能變成Bitmap

  // 接下來用當時RequestCode來判斷怎麼處理回傳的資料
  // 用 When == Switch
  when(requestCode){
      CAMERA_REQUEST_CODE -> {
          if (resultCode == Activity.RESULT_OK && data != null){
              displayImage(data.extras.get("data") as Bitmap)
          }
      }
  
      FILESYS_REQUEST_CODE -> {
          if(resultCode == Activity.RESULT_OK && data != null){
              val resolver = this.contentResolver
              val bitmap = MediaStore.Images.Media.getBitmap(resolver, data?.data)
              displayImage(bitmap)
          }
      }
  }

  fun displayImage(img: Bitmap){
      this.imageView.setImageBitmap(img)
  }

• 拿到 Permission之後要做的事情

  override fun onRequestPermissionsResult(requestCode: Int, permissions: Array, grantResults: IntArray) {
      super.onRequestPermissionsResult(requestCode, permissions, grantResults)
      when(requestCode){
          CAMERA_REQUEST_CODE -> {
              if((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)){
                  Toast.makeText(this, "CAMERA 成功~", Toast.LENGTH_LONG)
              }
          }
      }
  }