resize: withoutEnlargement: Height disregarded when cover && width > original width

[BrychanOdlum]

What are the steps to reproduce?

1. Take an image of dimensions 1500 x 1000.

await Sharp.file(imageData)
  .resize({ width: 1750, height: 250, fit: 'cover', withoutEnlargement: true });

What is the expected behaviour?
An image of 1500 x 250.

Instead we get an image of 1500 x 1000.

Example code:
https://github.com/BrychanOdlum/Sharp-BugExample/blob/master/main.js
https://github.com/BrychanOdlum/Sharp-BugExample (has input & output image in repo)

What is the output of running npx envinfo --binaries --languages --system --utilities?
System:
OS: macOS 10.15
CPU: (8) x64 Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
Memory: 232.27 MB / 16.00 GB
Shell: 5.7.1 - /bin/zsh
Binaries:
Node: 12.11.0 - ~/.nvm/versions/node/v12.11.0/bin/node
Yarn: 1.17.3 - /usr/local/bin/yarn
npm: 6.11.3 - ~/.nvm/versions/node/v12.11.0/bin/npm
Utilities:
CMake: 3.15.4 - /usr/local/bin/cmake
Make: 3.81 - /usr/bin/make
GCC: 4.2.1 - /usr/bin/gcc
Git: 2.21.0 - /usr/bin/git
Clang: 1100.0.33.8 - /usr/bin/clang
Subversion: 1.12.2 - /usr/local/bin/svn
Languages:
Bash: 3.2.57 - /bin/bash
Go: 1.12.6 - /usr/local/go/bin/go
Java: 1.8.0_161 - /usr/bin/javac
Perl: 5.30.0 - /usr/local/bin/perl
PHP: 7.3.8 - /usr/bin/php
Python: 2.7.16 - /usr/local/bin/python
Python3: 3.7.5 - /usr/local/bin/python3
Ruby: 2.6.3 - /usr/bin/ruby

[BrychanOdlum]

At the surface it looks as if this here is the culprit:

sharp/src/pipeline.cc

Lines 226 to 237 in 755a0ca

	if (baton->withoutEnlargement) {
	if (inputWidth < baton->width || inputHeight < baton->height) {
	xfactor = 1.0;
	yfactor = 1.0;
	xshrink = 1;
	yshrink = 1;
	xresidual = 1.0;
	yresidual = 1.0;
	baton->width = inputWidth;
	baton->height = inputHeight;
	}
	}

Might changing that to something like this instead do the trick?

      if (baton->withoutEnlargement) {
        if (inputWidth < baton->width) {
          xfactor = 1.0;
          xshrink = 1;
          xresidual = 1.0;
          baton->width = inputWidth;
        }

        if (inputHeight < baton->height) {
          yfactor = 1.0;
          yshrink = 1;
          yresidual = 1.0;
          baton->height = inputHeight;
        }
      }

[lovell]

Hi Brychan, this is a nice bug, rather amazing it took this long for someone to find so thank you for reporting it!

I think the proposal above might impact the aspect ratio; the following alternative could also work:

- if (baton->withoutEnlargement) { 
+ if (baton->withoutEnlargement && baton->width > inputWidth && baton->height > inputHeight) {

Happy to accept a PR with a fix and your example scenario as a new test case to prevent this occurring again, if you're able.

[lovell]

v0.24.0 is now available. Thanks for both reporting and fixing this!