桌面小部件

技术概述

用来自定义安卓的桌面小部件，实现桌面组件的定制化，也方便用户快速获取信息。难点在于组件的绘制过程不能进行耗时操作，以及周期性的更新问题。

技术详述

动态获取权限

override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        //是否获取到权限
        if(grantResults[0] == PackageManager.PERMISSION_GRANTED){
            GlobalScope.launch {
                initData()
                withContext(Dispatchers.Main){
                    btn_quit.visibility = View.VISIBLE
                }
            }
        }
    }

获取数据信息,并进行筛选

for (t in TimeLineApi.getTimeLine().result){
            max = if(max > t.seasons.size)max else t.seasons.size
        }

        for (i in 0 until  (7*max)){
            animeList.add(Season(i,"","","","",""))
        }

        var num = 0
        for (t in TimeLineApi.getTimeLine().result){
            if(t.day_of_week == 1)
                flag = true
            ///...
            if(num == 7)
                break
        }

在service层，进行桌面组件itemd绘制

override fun getViewAt(position: Int): RemoteViews? {
            val views =
                RemoteViews(mContext.packageName, R.layout.item_grid_layout)
            if (position < 7){
                views.setTextViewText(R.id.tv_title, weekday[position])
                views.setViewVisibility(R.id.iv_pic,View.GONE)
                views.setViewVisibility(R.id.tv_time,View.GONE)
            }else {
                if (animeList[position-7].title.isNullOrEmpty() || animeList[position-7].square_cover.isNullOrEmpty()){
                    views.setViewVisibility(R.id.ll_item,View.GONE)
                    return views
                }
                views.setTextViewText(R.id.tv_title, animeList[position-7].title)
                views.setTextViewText(R.id.tv_time,animeList[position-7].pub_time)
                var dir = if (Environment.getExternalStorageState() == Environment.MEDIA_MOUNTED)
                    Environment.getExternalStorageDirectory().absolutePath;
                else
                    Environment.getRootDirectory().absolutePath
                var title = rename(animeList[position-7].title!!)
                val fs = FileInputStream("$dir/bilibiliWidgt/$title.jpg")
                var bitmap = BitmapFactory.decodeStream(fs)
                bitmap = Bitmap.createBitmap(bitmap)
                views.setImageViewBitmap(R.id.iv_pic,bitmap)
            }
            return views
        }

技术使用中遇到的问题和解决过程。

原来是在service层通过url进行图片的绘制，但是一直为加载中。因为无法在service层进行数据请求获取图片，所以就打算先把图片缓存到本地，再通过本地资源来加载图片得以解决。

参考文献

《Android开发艺术探索》