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64f7f1d662
Composites an overlay image with alpha channel into the input image (which must have alpha channel) using ‘over’ alpha compositing blend mode. This API requires both images to have the same dimensions. References: - http://en.wikipedia.org/wiki/Alpha_compositing#Alpha_blending - https://github.com/jcupitt/ruby-vips/issues/28#issuecomment-9014826 See #97.
87 lines
3.4 KiB
Markdown
Executable File
87 lines
3.4 KiB
Markdown
Executable File
# Contributing to sharp
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Hello, thank you for your interest in helping!
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## Submit a new bug report
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Please create a [new issue](https://github.com/lovell/sharp/issues/new) containing the steps to reproduce the problem.
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New bugs are assigned a `triage` label whilst under investigation.
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If you're having problems with `npm install sharp`, please include the output of the following commands, perhaps as a [gist](https://gist.github.com/):
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```sh
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vips -v
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pkg-config --print-provides vips
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npm install --verbose sharp
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```
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## Submit a new feature request
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If a [similar request](https://github.com/lovell/sharp/labels/enhancement) exists, it's probably fastest to add a comment to it about your requirement.
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Implementation is usually straightforward if _libvips_ [already supports](http://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/ch03.html) the feature you need.
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## Submit a Pull Request to fix a bug
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Thank you! To prevent the problem occurring again, please add unit tests that would have failed.
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Please select the `master` branch as the destination for your Pull Request so your fix can be included in the next minor release.
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Please squash your changes into a single commit using a command like `git rebase -i upstream/master`.
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To test C++ changes, you can compile the module using `npm install` and then run the tests using `npm test`.
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## Submit a Pull Request with a new feature
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Please add JavaScript [unit tests](https://github.com/lovell/sharp/tree/master/test/unit) to cover your new feature. A test coverage report for the JavaScript code is generated in the `coverage/lcov-report` directory.
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You deserve to add your details to the [list of contributors](https://github.com/lovell/sharp/blob/master/package.json#L5).
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Any change that modifies the existing public API should be added to the relevant work-in-progress branch for inclusion in the next major release.
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| Release | WIP branch |
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| ------: | :--------- |
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| v0.11.0 | knife |
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| v0.12.0 | look |
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| v0.13.0 | mind |
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Please squash your changes into a single commit using a command like `git rebase -i upstream/<wip-branch>`.
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### Add a new public method
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The API tries to be as fluent as possible. Image processing concepts follow the naming conventions from _libvips_ and, to a lesser extent, _ImageMagick_.
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Most methods have optional parameters and assume sensible defaults. Methods with mandatory parameters often have names like `doSomethingWith(X)`.
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Please ensure backwards compatibility where possible. Methods to modify previously default behaviour often have names like `withoutOptionY()` or `withExtraZ()`.
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Feel free to create a [new issue](https://github.com/lovell/sharp/issues/new) to gather feedback on a potential API change.
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### Remove an existing public method
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A method to be removed should be deprecated in the next major version then removed in the following major version.
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By way of example, the [bilinearInterpolation method](https://github.com/lovell/sharp/blob/v0.6.0/index.js#L155) present in v0.5.0 was deprecated in v0.6.0 and removed in v0.7.0.
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## Run the tests
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### Functional tests and static code analysis
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```sh
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npm test
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```
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### Memory leak tests
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Requires _valgrind_.
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```sh
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cd sharp/test/leak
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./leak.sh
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```
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## Finally
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Please feel free to ask any questions via a [new issue](https://github.com/lovell/sharp/issues/new) or contact me by [e-mail](https://github.com/lovell/sharp/blob/master/package.json#L4).
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