Save as extensions

[pekspro]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

This add several methods for saving images. Id addresses #1255.

There were no unit test for the existing extensions so I did not ceate anyone for this either. But I did make sure that all extensions for all file formats produced identical files with this code:

using SixLabors.ImageSharp;
using System;
using System.IO;
using System.Threading.Tasks;

namespace ConsoleAppImageSharpTester
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var img = Image.Load(@"testimage.png");

            Directory.CreateDirectory(@".\test");

            {
                img.SaveAsTga(@".\test\norm_name.tga");
                img.SaveAsTga(@".\test\norm_name_enc.tga", new SixLabors.ImageSharp.Formats.Tga.TgaEncoder());
                await img.SaveAsTgaAsync(@".\test\async_name.tga");
                await img.SaveAsTgaAsync(@".\test\async_name_enc.tga", new SixLabors.ImageSharp.Formats.Tga.TgaEncoder());
                using var f1 = new FileStream(@".\test\norm_stream.tga", FileMode.OpenOrCreate);
                img.SaveAsTga(f1);
                using var f2 = new FileStream(@".\test\norm_stream_enc.tga", FileMode.OpenOrCreate);
                img.SaveAsTga(f2, new SixLabors.ImageSharp.Formats.Tga.TgaEncoder());
                using var f3 = new FileStream(@".\test\async_stream.tga", FileMode.OpenOrCreate);
                await img.SaveAsTgaAsync(f3);
                using var f4 = new FileStream(@".\test\async_stream_enc.tga", FileMode.OpenOrCreate);
                await img.SaveAsTgaAsync(f4, new SixLabors.ImageSharp.Formats.Tga.TgaEncoder());
            }


            {
                img.SaveAsPng(@".\test\norm_name.png");
                img.SaveAsPng(@".\test\norm_name_enc.png", new SixLabors.ImageSharp.Formats.Png.PngEncoder());
                await img.SaveAsPngAsync(@".\test\async_name.png");
                await img.SaveAsPngAsync(@".\test\async_name_enc.png", new SixLabors.ImageSharp.Formats.Png.PngEncoder());
                using var f1 = new FileStream(@".\test\norm_stream.png", FileMode.OpenOrCreate);
                img.SaveAsPng(f1);
                using var f2 = new FileStream(@".\test\norm_stream_enc.png", FileMode.OpenOrCreate);
                img.SaveAsPng(f2, new SixLabors.ImageSharp.Formats.Png.PngEncoder());
                using var f3 = new FileStream(@".\test\async_stream.png", FileMode.OpenOrCreate);
                await img.SaveAsPngAsync(f3);
                using var f4 = new FileStream(@".\test\async_stream_enc.png", FileMode.OpenOrCreate);
                await img.SaveAsPngAsync(f4, new SixLabors.ImageSharp.Formats.Png.PngEncoder());
            }
        

            {
                img.SaveAsBmp(@".\test\norm_name.bmp");
                img.SaveAsBmp(@".\test\norm_name_enc.bmp", new SixLabors.ImageSharp.Formats.Bmp.BmpEncoder());
                await img.SaveAsBmpAsync(@".\test\async_name.bmp");
                await img.SaveAsBmpAsync(@".\test\async_name_enc.bmp", new SixLabors.ImageSharp.Formats.Bmp.BmpEncoder());
                using var f1 = new FileStream(@".\test\norm_stream.bmp", FileMode.OpenOrCreate);
                img.SaveAsBmp(f1);
                using var f2 = new FileStream(@".\test\norm_stream_enc.bmp", FileMode.OpenOrCreate);
                img.SaveAsBmp(f2, new SixLabors.ImageSharp.Formats.Bmp.BmpEncoder());
                using var f3 = new FileStream(@".\test\async_stream.bmp", FileMode.OpenOrCreate);
                await img.SaveAsBmpAsync(f3);
                using var f4 = new FileStream(@".\test\async_stream_enc.bmp", FileMode.OpenOrCreate);
                await img.SaveAsBmpAsync(f4, new SixLabors.ImageSharp.Formats.Bmp.BmpEncoder());
            }


            {
                img.SaveAsGif(@".\test\norm_name.gif");
                img.SaveAsGif(@".\test\norm_name_enc.gif", new SixLabors.ImageSharp.Formats.Gif.GifEncoder());
                await img.SaveAsGifAsync(@".\test\async_name.gif");
                await img.SaveAsGifAsync(@".\test\async_name_enc.gif", new SixLabors.ImageSharp.Formats.Gif.GifEncoder());
                using var f1 = new FileStream(@".\test\norm_stream.gif", FileMode.OpenOrCreate);
                img.SaveAsGif(f1);
                using var f2 = new FileStream(@".\test\norm_stream_enc.gif", FileMode.OpenOrCreate);
                img.SaveAsGif(f2, new SixLabors.ImageSharp.Formats.Gif.GifEncoder());
                using var f3 = new FileStream(@".\test\async_stream.gif", FileMode.OpenOrCreate);
                await img.SaveAsGifAsync(f3);
                using var f4 = new FileStream(@".\test\async_stream_enc.gif", FileMode.OpenOrCreate);
                await img.SaveAsGifAsync(f4, new SixLabors.ImageSharp.Formats.Gif.GifEncoder());
            }


            {
                img.SaveAsJpeg(@".\test\norm_name.jpg");
                img.SaveAsJpeg(@".\test\norm_name_enc.jpg", new SixLabors.ImageSharp.Formats.Jpeg.JpegEncoder());
                await img.SaveAsJpegAsync(@".\test\async_name.jpg");
                await img.SaveAsJpegAsync(@".\test\async_name_enc.jpg", new SixLabors.ImageSharp.Formats.Jpeg.JpegEncoder());
                using var f1 = new FileStream(@".\test\norm_stream.jpg", FileMode.OpenOrCreate);
                img.SaveAsJpeg(f1);
                using var f2 = new FileStream(@".\test\norm_stream_enc.jpg", FileMode.OpenOrCreate);
                img.SaveAsJpeg(f2, new SixLabors.ImageSharp.Formats.Jpeg.JpegEncoder());
                using var f3 = new FileStream(@".\test\async_stream.jpg", FileMode.OpenOrCreate);
                await img.SaveAsJpegAsync(f3);
                using var f4 = new FileStream(@".\test\async_stream_enc.jpg", FileMode.OpenOrCreate);
                await img.SaveAsJpegAsync(f4, new SixLabors.ImageSharp.Formats.Jpeg.JpegEncoder());
            }



        }
    }
}

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #1256 into master will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1256      +/-   ##
==========================================
+ Coverage   82.61%   82.68%   +0.07%     
==========================================
  Files         697      697              
  Lines       30529    30589      +60     
  Branches     3445     3460      +15     
==========================================
+ Hits        25221    25294      +73     
+ Misses       4603     4593      -10     
+ Partials      705      702       -3     

Flag	Coverage Δ
#unittests	82.68% <100.00%> (+0.07%)	⬆️

Impacted Files	Coverage Δ
src/ImageSharp/Formats/Bmp/ImageExtensions.cs	100.00% <100.00%> (ø)
src/ImageSharp/Formats/Gif/ImageExtensions.cs	100.00% <100.00%> (ø)
src/ImageSharp/Formats/Jpeg/ImageExtensions.cs	100.00% <100.00%> (ø)
src/ImageSharp/Formats/Png/ImageExtensions.cs	100.00% <100.00%> (ø)
src/ImageSharp/Formats/Tga/ImageExtensions.cs	100.00% <100.00%> (ø)
src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs	96.85% <0.00%> (+1.88%)	⬆️
src/ImageSharp/Formats/Tga/TgaEncoderCore.cs	99.35% <0.00%> (+1.94%)	⬆️
src/ImageSharp/Formats/Gif/GifFormat.cs	100.00% <0.00%> (+11.11%)	⬆️
src/ImageSharp/Formats/Bmp/BmpFormat.cs	100.00% <0.00%> (+12.50%)	⬆️
src/ImageSharp/Formats/Jpeg/JpegFormat.cs	100.00% <0.00%> (+12.50%)	⬆️
... and 2 more

---

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[antonfirsov]

Good job, looks good after a quick review! Thanks!

It's not your fault that there is no existing precedent to extensively test this type of boilerplate, but I'm a bit hesitant if it's ok to add this huge amount of uncovered methods.

@pekspro if I provide some guidance are you OK with adding the tests as well?

[pekspro]

Sure @antonfirsov, I would like to see some unit test too on this :-) Just give me some guidance and I fix it :-)

As I see it, it would be nice if the extension methods worked with an interface instead of Image. But it is quit trick right now because of lines like this:

   encoder ?? source.GetConfiguration().ImageFormatsManager.FindEncoder(BmpFormat.Instance));

GetConfiguration does not return an interface, and ImageFormatsManager is also not an interface.

[pekspro]

@antonfirsov , what if I created unit test like this?

    public class BmpImageExtensions
    {
        [Fact]
        public async Task SaveAsBmpAsync_Path()
        {
            string dir = TestEnvironment.CreateOutputDirectory(nameof(BmpImageExtensions));
            string file = Path.Combine(dir, "SaveAsBmpAsync_Path.bmp");

            using (var image = new Image<Rgba32>(10, 10))
            {
                await image.SaveAsBmpAsync(file);
            }

            using (Image.Load(file, out IImageFormat mime))
            {
                Assert.Equal("image/bmp", mime.DefaultMimeType);
            }
        }

        [Fact]
        public async Task SaveAsBmpAsync_Path_Encoder()
        {
            string dir = TestEnvironment.CreateOutputDirectory(nameof(BmpImageExtensions));
            string file = Path.Combine(dir, "SaveAsBmpAsync_Path_Encooder.bmp");

            using (var image = new Image<Rgba32>(10, 10))
            {
                await image.SaveAsBmpAsync(file, new BmpEncoder());
            }

            using (Image.Load(file, out IImageFormat mime))
            {
                Assert.Equal("image/bmp", mime.DefaultMimeType);
            }
        }

        [Fact]
        public async Task SaveAsBmpAsync_Stream()
        {
            using var memoryStream = new MemoryStream();

            using (var image = new Image<Rgba32>(10, 10))
            {
                await image.SaveAsBmpAsync(memoryStream);
            }

            memoryStream.Position = 0;

            using (Image.Load(memoryStream, out IImageFormat mime))
            {
                Assert.Equal("image/bmp", mime.DefaultMimeType);
            }
        }

        [Fact]
        public async Task SaveAsBmpAsync_Stream_Encoder()
        {
            using var memoryStream = new MemoryStream();

            using (var image = new Image<Rgba32>(10, 10))
            {
                await image.SaveAsBmpAsync(memoryStream, new BmpEncoder());
            }

            memoryStream.Position = 0;

            using (Image.Load(memoryStream, out IImageFormat mime))
            {
                Assert.Equal("image/bmp", mime.DefaultMimeType);
            }
        }
    }

[antonfirsov]

@pekspro perfect, thanks! Go ahead!

[JimBobSquarePants]

Perfect @pekspro Thanks so much for doing this!