protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Set our view from the "main" layout resource:
SetContentView(Resource.Layout.pdf_paging_activity);
// Get our RecyclerView layout:
mRecyclerView = FindViewById <RecyclerView>(Resource.Id.recyclerView);
btnPrev = FindViewById <Button>(Resource.Id.button_prev);
btnPrev.Text = "Prev";
btnPrev.Click += BtnPrev_Click;
btnNext = FindViewById <Button>(Resource.Id.button_next);
btnNext.Text = "Next";
btnNext.Click += BtnNext_Click;
textPageCurrent = FindViewById <TextView>(Resource.Id.text_page_current);
// Use the built-in linear layout manager:
mLayoutManager = new LinearLayoutManager(this);
// Plug the layout manager into the RecyclerView:
mRecyclerView.SetLayoutManager(mLayoutManager);
// Get screen width for bitmap sizing
screenWidth = Resources.DisplayMetrics.WidthPixels;
// Set up pdf bitmap adapter
pages = new List <Bitmap>();
mAdapter = new PdfBitmapAdapter(pages);
mRecyclerView.SetAdapter(mAdapter);
// Register the item click handler (below) with the adapter:
mAdapter.ItemClick += OnItemClick;
RenderPages();
}
void RenderPages()
{
Stream inputStream = Assets.Open(fileName);
using (var outputStream = this.OpenFileOutput("_sample.pdf", Android.Content.FileCreationMode.Private))
{
inputStream.CopyTo(outputStream);
}
var fileStreamPath = this.GetFileStreamPath("_sample.pdf");
MemoryStream m_memoryStream = new MemoryStream();
File.OpenRead(fileStreamPath.AbsolutePath).CopyTo(m_memoryStream);
var renderer = new PdfRenderer(ParcelFileDescriptor.Open(fileStreamPath, ParcelFileMode.ReadOnly));
var screenWidth = Resources.DisplayMetrics.WidthPixels;
// render all pages
pageCount = renderer.PageCount;
for (int i = 0; i < pageCount; i++)
{
page = renderer.OpenPage(i);
// create bitmap at appropriate size
var ratio = (float)page.Height / page.Width;
var newHeight = screenWidth * ratio;
bitmap = Bitmap.CreateBitmap(screenWidth, (int)newHeight, Bitmap.Config.Argb8888);
// render PDF page to bitmap
page.Render(bitmap, null, null, PdfRenderMode.ForDisplay);
// add bitmap to list
pages.Add(bitmap);
// close the page
page.Close();
// if free memory is less than the size of two page bitmaps and we still have pages left to load
// we'll stop loading and then display a message about downloading the full doc
// * this catch doesn't seem to work on Android O but it worked on a Nexus 5 running Android M, apparently Android O changes some memory handling
Debug.WriteLine("\nMemory usage " + i + "\n" + "Bitmap Byte Count: " + bitmap.ByteCount + "\nMemory Available: " + MemoryAvailable());
if (bitmap.ByteCount * 2 > MemoryAvailable() && i < pageCount - 1)
{
lowMemory = true;
break;
}
}
// close the renderer
renderer.Close();
// Create an adapter for the RecyclerView, and pass it the
// data set (the bitmap list) to manage:
mAdapter = new PdfBitmapAdapter(pages);
// Register the item click handler (below) with the adapter:
mAdapter.ItemClick += OnItemClick;
// Plug the adapter into the RecyclerView:
mRecyclerView.SetAdapter(mAdapter);
if (lowMemory)
{
try
{
AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.SetTitle("Out Of Memory");
alert.SetMessage("You are only viewing " + pages.Count + " out of " + pageCount + " pages.");
alert.SetPositiveButton("OK", (senderAlert, args) => { });
Dialog dialog = alert.Create();
dialog.Show();
}
catch (Exception e)
{
Debug.WriteLine("Exception: " + e.Message);
}
}
}