如何为jpg添加透明填充并将其另存为具有透明性的png? [英] How to add transparent padding to a jpg and save it as png with transparency?

问题描述

SixLabors ImageSharp的文档非常有限，大多数Google搜索都指向GitHub，但这不是很有帮助.

The documentation for SixLabors ImageSharp is very limited, and most google searches leads to GitHub, which is not very helpful.

如何上载jpg，.Mutate并使用透明填充并将其另存为png并具有透明性?

How can I upload a jpg, .Mutate it with transparent padding and save it as a png with transparency?

这是我到目前为止的代码.如果上传的图片是png，则可以使用透明填充，但是jpgs可以使用黑色填充:

This is the code I have so far. If the uploaded image is a png, transparent padding works, but jpgs get black padding:

private static void ResizeAndSavePhoto(Image<Rgba32> img, string path, int squareSize)
{
    Configuration.Default.ImageFormatsManager.SetEncoder(PngFormat.Instance, new PngEncoder()
    {
        ColorType = PngColorType.RgbWithAlpha
    });
    img.Mutate(x =>
        x.Resize(new ResizeOptions
        {
            Size = new Size(squareSize, squareSize),
            Mode = ResizeMode.Pad
        }).BackgroundColor(new Rgba32(255, 255, 255, 0))
        );
    img.Save(path);
    return;
}

.SaveAsPng()需要一个文件流，但是我有一个Image<Rgba32>和一个路径...

.SaveAsPng() takes a filestream, but I have an Image<Rgba32> and a path...

推荐答案

您可以通过SaveAsPng明确地另存为png，将路径扩展名设置为.png，或将IImageEncoder传递给Save方法

You can explicitly save as a png via SaveAsPng, set the path extensions to .png, or pass an IImageEncoder to the Save methods.

您可以在 https://docs.sixlabors.com/api/中找到API文档. index.html

private static void ResizeAndSavePhoto(Image<Rgba32> img, string path, int squareSize)
{
    img.Mutate(x =>
        x.Resize(new ResizeOptions
        {
            Size = new Size(squareSize, squareSize),
            Mode = ResizeMode.Pad
        }).BackgroundColor(new Rgba32(255, 255, 255, 0)));

    // The following demonstrates how to force png encoding with a path.
    img.Save(Path.ChangeExtension(path, ".jpg"))

    img.Save(path, new PngEncoder());
}

此外，如果保存到流中.

Additionally, if saving to a stream.

img.SaveAsPng(path);

这篇关于如何为jpg添加透明填充并将其另存为具有透明性的png?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！