Rgb 565 Pdf to Image - xamarin

Question

I am trying to convert a PDF page to an image, to create thumbnails. This is the code that I am using:
PdfRenderer pdfRenderer = new PdfRenderer(GetSeekableFileDescriptor(filePath));
var appDirectory = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments);
string fileName = System.IO.Path.GetFileNameWithoutExtension(filePath);
string directoryPath = System.IO.Path.Combine(appDirectory, "thumbnailsTemp", System.IO.Path.GetFileNameWithoutExtension(fileName));
if (!Directory.Exists(directoryPath))
{
Directory.CreateDirectory(directoryPath);
int pageCount = pdfRenderer.PageCount;
for (int i = 0; i < pageCount; i++)
{
Page page = pdfRenderer.OpenPage(i);
Android.Graphics.Bitmap bmp = Android.Graphics.Bitmap.CreateBitmap(page.Width, page.Height, Android.Graphics.Bitmap.Config.Rgb565 or Argb8888);
page.Render(bmp, null, null, PdfRenderMode.ForDisplay);
try
{
using (FileStream output = new FileStream(System.IO.Path.Combine(directoryPath, fileName + "Thumbnails" + i + ".png"), FileMode.Create))
{
bmp.Compress(Android.Graphics.Bitmap.CompressFormat.Png, 100, output);
}
page.Close();
}
catch (Exception ex)
{
//TODO -- GERER CETTE EXPEXPTION
throw new Exception();
}
}
return directoryPath;
}
I tried with ARGB 8888 and that was a success. But the rendering time was too slow for big PDF files. This is why I tried to improve it by changing the format to RGB 565. But my app is crashing with this Execption:
Unsuported pixel format
Any idea to fix this, or how to render a PDF to a bitmap faster? I was looking on google but didn't find a solution related to my code.
UPDATE
I did this but know, my app is crashing at this line of code :
await Task.Run(() =>
{
bytes = page.AsPNG(72);
});
My class :
public async Task<string> GetBitmaps(string filePath)
{
//TODO -- WORK ON THIS
PdfRenderer pdfRenderer = new PdfRenderer(GetSeekableFileDescriptor(filePath));
var appDirectory = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments);
string fileName = System.IO.Path.GetFileNameWithoutExtension(filePath);
string directoryPath = System.IO.Path.Combine(appDirectory, "thumbnailsTemp", System.IO.Path.GetFileNameWithoutExtension(fileName));
var stream = new MemoryStream();
using (Stream resourceStream = new FileStream(filePath, FileMode.Open))
{
resourceStream.CopyTo(stream);
}
for (int i = 0; i < pdfRenderer.PageCount; i++)
{
TallComponents.PDF.Rasterizer.Page page = new TallComponents.PDF.Rasterizer.Page(stream, i);
byte[] bytes = null;
await Task.Run(() =>
{
bytes = page.AsPNG(72);
});
using (FileStream output = new FileStream(System.IO.Path.Combine(directoryPath, fileName + "Thumbnails" + i + ".png"), FileMode.Create, FileAccess.Write))
{
output.Write(bytes, 0, bytes.Length);
}
}
return directoryPath;
}

Answer 1

you could draw a PDF page in app by converting a PDF page to a bitmap,here the PDF document itself is embedded as a resource.
var assembly = Assembly.GetExecutingAssembly();
var stream = new MemoryStream();
using (Stream resourceStream = assembly.GetManifestResourceStream("DrawPdf.Android.tiger.pdf"))
{
resourceStream.CopyTo(stream);
}
Page page = new Page(stream, 0);
// render PDF Page object to a Bitmap
byte[] bytes = null;
await Task.Run(() =>
{
bytes = page.AsPNG(72);
});
Bitmap bmp = global::Android.Graphics.BitmapFactory.DecodeByteArray(bytes, 0, bytes.Length);