Short version:
http://stackoverflow.com/questions/7535503/mono-for-android-exit-code-255-on-bitmapfactory-decodestream/7590929#7590929
Long version:
We map every Java method which takes e.g. java.io.InputStream to a
System.IO.Stream, and provide an "Adapter" which subclasses System.IO.Stream
and invokes the corresponding InputStream methods. Ditto for OutputStream, etc.
However, one thing we didn't realize until this week is that Java and C# have
different conventions for "end-of-stream" (EOS) -- Java uses -1, while C# uses
0.
So what would frequently happen (such as your test cases) is that you'd call
the bound method, which would return a Stream, and then invoke another Java
method. This would result in e.g. BitmapDrawable.createFromStream() doing a
Java->Managed->Java transition for the .read() method, and because of the
"mismatch" of EOS conventions, things would go "weird" (e.g. the Java stream
would return 0, which C# code would interpret as EOS, when it actually meant
"no data right now, try again later.")
This will be fixed in the 1.9.1 release. In the meantime, try going through a
MemoryStream + byte[], as I suggest in the above stack overflow answer.
- Jon
On Sep 29, 2011, at 12:30 PM, John Heerman wrote:
> Hello,
>
> I've run across a problem trying to retrieve an image from the web and
> decode the stream or byte array into a bitmap/drawable resource. Each
> one of the tests below fail when I try to invoke the static
> BitmapFactory or BitmapDrawable class. I'm running my tests in
> MonoDevelop on Mac OSX Lion targeting API Level 8 with Mono for
> Android 1.2.
>
> The exception I receive for test 1:
> System.NullReferenceException: Object reference not set to an instance
> of an object
> at Android.Runtime.JNIEnv.get_Handle () [0x00014] in
> /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:33
> at Android.Runtime.JNIEnv.get_Env () [0x00000] in /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:24
> at Android.Runtime.JNIEnv.FindClass (System.String classname)
> [0x00000] in /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:145
> at Android.Graphics.BitmapFactory..cctor () [0x00000] in <filename unknown>:0
>
>
> The exception I receive for test 2:
> System.NullReferenceException: Object reference not set to an instance
> of an object
> at Android.Runtime.JNIEnv.get_Handle () [0x00014] in
> /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:33
> at Android.Runtime.JNIEnv.get_Env () [0x00000] in /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:24
> at Android.Runtime.JNIEnv.FindClass (System.String classname)
> [0x00000] in /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:145
> at Android.Graphics.BitmapFactory..cctor () [0x00000] in <filename unknown>:0
>
> The exception I receive for test 3:
> System.NullReferenceException: Object reference not set to an instance
> of an object
> at Android.Runtime.JNIEnv.get_Handle () [0x00014] in
> /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:33
> at Android.Runtime.JNIEnv.get_Env () [0x00000] in /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:24
> at Android.Runtime.JNIEnv.FindClass (System.String classname)
> [0x00000] in /Volumes/Macintosh
> HD/Users/jon/Development/xamarin/monodroid/Mono.Android/src/Runtime/JNIEnv.cs:145
> at Android.Graphics.Drawables.Drawable..cctor () [0x00000] in
> <filename unknown>:0
>
> Any help would be greatly appreciated.
>
> Regards,
> John
>
> //////////////////////////////////////////////////////////
>
> using System;
> using System.Net;
>
> using Android.Graphics;
> using Android.Graphics.Drawables;
>
> using NUnit.Framework;
>
> namespace App.Shared.Test
> {
> [TestFixture]
> public class ImageTest
> {
> private string url =
> "http://www.google.com/intl/en_com/images/srpr/logo3w.png";;
>
> [Test]
> public void TestStreamWithBitmapFactory()
> {
> try
> {
> System.IO.Stream stream = new
> WebClient().OpenRead(url);
> var bitmap = BitmapFactory.DecodeStream(stream);
> Assert.IsNotNull(bitmap);
> }
> catch (Exception ex)
> {
> Console.WriteLine(ex.InnerException);
> Assert.Fail(ex.InnerException.ToString());
> }
>
> }
>
> [Test]
> public void TestBytesWithBitmapFactory()
> {
> try
> {
> byte[] bytes = new
> WebClient().DownloadData(url);
> var bitmap =
> BitmapFactory.DecodeByteArray(bytes, 0, bytes.Length);
> Assert.IsNotNull(bitmap);
> }
> catch (Exception ex)
> {
> Console.WriteLine(ex.InnerException);
> Assert.Fail(ex.InnerException.ToString());
> }
> }
>
> [Test]
> public void TestStreamWithBitmapDrawable()
> {
> try
> {
> System.IO.Stream stream = new
> WebClient().OpenRead(url);
> var bitmap =
> BitmapDrawable.CreateFromStream(stream, "src");
> Assert.IsNotNull(bitmap);
> }
> catch (Exception ex)
> {
> Console.WriteLine(ex.InnerException);
> Assert.Fail(ex.InnerException.ToString());
> }
> }
> }
> }
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![http://www.google.com/intl/en_com/images/srpr/logo3w.png"](https://www.google.com/intl/en_com/images/srpr/logo3w.png"){kind=link}