At least render something when progressive.

This allows parsing of the broken eof images. The non-progressive
renders perfectly, the progressive appears to not render the final
scan.... or something.

src/ImageSharp.Formats.Jpeg/Components/Decoder/JpegScanDecoder.cs

@@ -356,12 +356,22 @@ namespace ImageSharp.Formats.Jpg
                         throw new ImageFormatException("Excessive DC component");
                     }
 
+                    // TODO: Handle the EOFException and piece together the final progressive scan.
+                    try
+                    {
                         int deltaDC = decoder.Bits.ReceiveExtend(value, decoder);
                         this.pointers.Dc[compIndex] += deltaDC;
 
                         // b[0] = dc[compIndex] << al;
                         Block8x8F.SetScalarAt(b, 0, this.pointers.Dc[compIndex] << this.al);
                     }
+                    catch (JpegDecoderCore.EOFException)
+                    {
+                        // Do something clever here. I'm just undoing ReceiveExtend
+                        decoder.Bits.UnreadBits += value;
+                        decoder.Bits.Mask >>= value;
+                    }
+                }
 
                 if (zig <= this.zigEnd && this.eobRun > 0)
                 {
@@ -383,7 +393,20 @@ namespace ImageSharp.Formats.Jpg
                                 break;
                             }
 
-                            int ac = decoder.Bits.ReceiveExtend(val1, decoder);
+                            int ac; // = decoder.Bits.ReceiveExtend(val1, decoder);
+
+                            // TODO: Handle the EOFException and piece together the final progressive scan.
+                            try
+                            {
+                                ac = decoder.Bits.ReceiveExtend(val1, decoder);
+                            }
+                            catch (JpegDecoderCore.EOFException)
+                            {
+                                // Do something clever here. I'm just undoing ReceiveExtend
+                                decoder.Bits.UnreadBits += val1;
+                                decoder.Bits.Mask >>= val1;
+                                break;
+                            }
 
                             // b[Unzig[zig]] = ac << al;
                             Block8x8F.SetScalarAt(b, this.pointers.Unzig[zig], ac << this.al);

src/ImageSharp.Formats.Jpeg/JpegDecoderCore.cs

@@ -186,11 +186,9 @@ namespace ImageSharp.Formats
                 throw new ImageFormatException("Missing SOI marker.");
             }
 
-            // Process the remaining segments until the End Of Image marker.
+            while (true)
-            bool processBytes = true;
+            {
-
+                try
-            // we can't currently short circute progressive images so don't try.
-            while (processBytes)
                 {
                     this.ReadFull(this.Temp, 0, 2);
                     while (this.Temp[0] != 0xff)
@@ -297,14 +295,7 @@ namespace ImageSharp.Formats
                                 return;
                             }
 
-                        // when this is a progressive image this gets called a number of times
-                        // need to know how many times this should be called in total.
                             this.ProcessStartOfScan(remaining);
-                        if (!this.IsProgressive)
-                        {
-                            // if this is not a progressive image we can stop processing bytes as we now have the image data.
-                            processBytes = false;
-                        }
 
                             break;
                         case JpegConstants.Markers.DRI:
@@ -346,6 +337,13 @@ namespace ImageSharp.Formats
                             break;
                     }
                 }
+                catch (EOFException)
+                {
+                    // For non-progressive images this is a simple way to handle a missing EOI
+                    // TODO: For progressive we still have to handle the exception within JpegScanDecoder to include last scan
+                    break;
+                }
+            }
 
             if (this.grayImage.IsInitialized)
             {

tests/ImageSharp.Tests/FileTestBase.cs

@@ -22,9 +22,11 @@ namespace ImageSharp.Tests
             // TestFile.Create(TestImages.Png.Pd), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Jpeg.Floorplan), // Perf: Enable for local testing only
             TestFile.Create(TestImages.Jpeg.Calliphora),
+            // TestFile.Create(TestImages.Jpeg.BadEOF), // Perf: Enable for local testing only
+            // TestFile.Create(TestImages.Jpeg.BadEOFProgressive),
             // TestFile.Create(TestImages.Jpeg.Ycck), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Jpeg.Cmyk), // Perf: Enable for local testing only
-            TestFile.Create(TestImages.Jpeg.Turtle),
+            // TestFile.Create(TestImages.Jpeg.Turtle), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Jpeg.Fb), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Jpeg.Progress), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Jpeg.GammaDalaiLamaGray), // Perf: Enable for local testing only
@@ -33,7 +35,7 @@ namespace ImageSharp.Tests
             // TestFile.Create(TestImages.Png.Blur), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Png.Indexed), // Perf: Enable for local testing only
             TestFile.Create(TestImages.Png.Splash),
-            TestFile.Create(TestImages.Png.Powerpoint),
+            // TestFile.Create(TestImages.Png.Powerpoint), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Png.SplashInterlaced), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Png.Interlaced), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Png.Filter0), // Perf: Enable for local testing only

tests/ImageSharp.Tests/TestImages.cs

@@ -52,6 +52,7 @@ namespace ImageSharp.Tests
             public const string Hiyamugi = "Jpg/Hiyamugi.jpg";
 
             public const string BadEOF = "Jpg/badeof.jpg";
+            public const string BadEOFProgressive = "Jpg/badeofprog.jpg";
             public const string Snake = "Jpg/Snake.jpg";
             public const string Lake = "Jpg/Lake.jpg";