trim does not work as expected when using with joinChannel

[deepakg202]

Are you using the latest version? Is the version currently in use as reported by npm ls sharp the same as the latest version as reported by npm view sharp dist-tags.latest?

Yes

What are the steps to reproduce?
I am trying to apply a b/w mask to an image and trim the transparent area. These are the input image and the mask.
Image
Mask
This is the code I am using:

const sharp = require('sharp');
const fs = require('fs');

applyMaskAndTrim = async (image, mask) => {
    await sharp(image).joinChannel(mask).trim(10).toFile('output.png');
}

(async () => {
    var imageFile = fs.readFileSync("image.jpg");
    var maskFile = fs.readFileSync("mask.png");

    await applyMaskAndTrim(imageFile, maskFile);
    console.log("Done");
})();

What is the expected behaviour?
The expected output should be Expected Image
But I get this Output Image
However I get the correct output when using joinChannel and trim separately on separate files.

Are you able to provide a minimal, standalone code sample, without other dependencies, that demonstrates this problem?
See code sample above

Are you able to provide a sample image that helps explain the problem?
See above images

What is the output of running npx envinfo --binaries --system?

  System:
    OS: Windows 10 10.0.22000
    CPU: (8) x64 Intel(R) Core(TM) i5-10210U CPU @ 1.60GHz
    Memory: 2.43 GB / 7.83 GB
  Binaries:
    Node: 14.17.5 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.15 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 6.14.14 - C:\Program Files\nodejs\npm.CMD

[lovell]

Hi, yes, you'll need to split these operations into two pipelines, as the trim will always occur first. You might also run into #2166.

[deepakg202]

@lovell Thank you for the quick response.
Is there any other alternative to make the process faster as it adds additional time to encode the image twice.

[lovell]

As an intermediate image format, you could use either raw pixel data or png with a compressionLevel of 0.

[lovell]

I hope this information helped. Please feel free to re-open with more details if further assistance is required.