Image Resizing

[onur-ozkan]

According to docs, there is a Resize function that changes image dimensions based on scale ratio. But what if I want to change dimensions by giving width and height values, which function should I use?

[onur-ozkan]

I try

net-vips/samples/NetVips.Samples/Samples/Thumbnail.cs

Line 12 in b1585c9

var image = Image.Thumbnail(Filename, 300, height: 300);

that one but the output's height is not correct.

[kleisauke]

Did you see #71 (comment)?

[lofcz]

This: ThumbnailImage(w, h, size: "force");

[onur-ozkan]

This: ThumbnailImage(w, h, size: "force");

Thanks!

[kleisauke]

I'd avoid ThumbnailImage, if possible. It can't do any of the shrink-on-load tricks, so it's much, much slower. The "force" parameter (VIPS_SIZE_FORCE) breaks aspect ratio, so I can't recommend that either.

[Darkle]

I'd avoid ThumbnailImage, if possible. It can't do any of the shrink-on-load tricks, so it's much, much slower. The "force" parameter (VIPS_SIZE_FORCE) breaks aspect ratio, so I can't recommend that either.

What would be the thing to use in its place?

Oh wait, I see in the examples that it mentions to use ThumbnailBuffer: https://github.com/kleisauke/net-vips/blob/master/samples/NetVips.Samples/Samples/ThumbnailPipeline.cs#L211

[kleisauke]

What would be the thing to use in its place?

You can use the various Image.Thumbnail* functions for this. For example:

-using var image = Image.NewFromFile(Filename, access: Enums.Access.Sequential);
-
 // `vips_thumbnail` resize behavior is based on a square bounding box.
 // To resize along a specific axis, pass a huge value to the opposite axis.
 // See: https://github.com/libvips/libvips/pull/1639
-using var thumb = image.ThumbnailImage(300, height: 10000000);
+using var thumb = Image.Thumbnail(Filename, 300, height: 10000000);
 thumb.WriteToFile("thumbnail.jpg");

-using var image = Image.NewFromBuffer(Buffer, access: Enums.Access.Sequential);
-using var thumb = image.ThumbnailImage(300, height: 10000000);
+using var thumb = Image.ThumbnailBuffer(Buffer, 300, height: 10000000);
 thumb.WriteToFile("thumbnail.jpg");

-using var image = Image.NewFromStream(Stream, access: Enums.Access.Sequential);
-using var thumb = image.ThumbnailImage(300, height: 10000000);
+using var thumb = Image.ThumbnailStream(Stream, 300, height: 10000000);
 thumb.WriteToFile("thumbnail.jpg");