保存位图Android 8时图像名称和类型错误 [英] Wrong image name and type when saving bitmap Android 8

问题描述

我有一个有趣的功能，可以将位图另存为PNG或JPG(两者均无法正常工作)，但是好像使用的内容值无法正常工作.

I have a fun that saves bitmap as PNG or JPG (both not working), but seems like using content values not working as expected.

1. 文件名不正确.
2. 文件类型不正确.

我想念什么? 在Android 10上有效，但在Android 8上无效

What am I missing ? Works on Android 10, but not working on Android 8

fun Bitmap.save(context: Context) {
    val contentResolver = context.contentResolver

    val contentValues = ContentValues().apply {
        put(MediaStore.MediaColumns.DISPLAY_NAME, "test.png")
        put(MediaStore.MediaColumns.TITLE, "test")
        put(MediaStore.MediaColumns.MIME_TYPE, "image/png")
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
            put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_PICTURES)
            put(MediaStore.MediaColumns.IS_PENDING, 1)
        }
    }

    val contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI
    val uri = contentResolver.insert(contentUri, contentValues)
    if (uri != null) {
        try {
            contentResolver.openFileDescriptor(uri, "w", null)?.use {
                if (it.fileDescriptor != null) {
                    with(FileOutputStream(it.fileDescriptor)) {
                        compress(
                            Bitmap.CompressFormat.PNG,
                            DEFAULT_IMAGE_QUALITY,
                            this
                        )
                        flush()
                        close()
                    }
                }
            }
        } catch (e: Exception) {
            e.printStackTrace()
        }

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
            contentValues.clear()
            contentValues.put(MediaStore.MediaColumns.IS_PENDING, 0)
            contentResolver.update(uri, contentValues, null, null)
        }

        MediaScannerConnection.scanFile(context, arrayOf(uri.toString()), null, null)
    }
    recycle()
}

实际文件名为 1592205828045 (带有时间戳)

Actual file name is 1592205828045 (some timestamp)

实际文件类型为 jpg 和 0B -由于未正确保存?

Actual file type is jpg with 0B - as it was not saved properly ?

推荐答案

您正在创建文件，但仍需要向其中写入Bitmap:

You are creating the file, but you still need to write your Bitmap to it:

fun Bitmap.save(context: Context) {

    ...

    val bitmap = this
    val maxImageQuality = 100

    val uri = contentResolver.insert(contentUri, contentValues)
    if (uri != null) {
        try {
            contentResolver.openFileDescriptor(uri, "w", null)?.use {
                if (it.fileDescriptor != null) {
                    with(FileOutputStream(it.fileDescriptor)) {
                        bitmap.compress(
                            Bitmap.CompressFormat.PNG,
                            maxImageQuality, this
                        )
                        flush()
                        close()
                    }
                }
            }
        } catch (e: Exception) {
            e.printStackTrace()
        }

        // release pending status of the file
        contentValues.clear()
        contentValues.put(MediaStore.Images.Media.IS_PENDING, 0)
        contentResolver.update(uri, contentValues, null, null)

        // notify media scanner there's a new picture
        MediaScannerConnection.scanFile(context, arrayOf(uri.toString()), null, null)
    }
    // don't forget to recycle the bitmap when you don't need it any longer
    bitmap.recycle()
}

这篇关于保存位图Android 8时图像名称和类型错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！