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Tuan Thanh Tan
Tuan Thanh Tan

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My fourth accepted PR on github hacktoberfest

Hello every, my name is Dustin. I'd like to talk about my experience of solving another issue on github that are labelled as hacktoberfest 2021.

Reasons

The reason behind why I chose this project is so interesting and written completely in Javascript.

Fourth pull request

My fouth pull request was pretty hard and took me nearly 2 days to finish it.

The project can be found here
My pull request can be found here

Detail

The issue was about using control z to undo previous changes. It was quite simple and easy to understand what the project owner is asking but coding is absolutely the opposite. It got me a few hours to finish everything and push it to github, but unfortunately that is not what the project owner is looking for. What I did was that I had an array of history. So each layer will have their own history. If user clicks on a layer, and hit control z, I would undo changes on that layer. That also sounded correct to me but it didn't to project owner. His idea was that I had to have 1 history to store every change happening in all layers.

For example, I change X and then add a new layer, and then change X on that layer. If I control z it will change X back to 0, and control z again, it will remove the second layer.

So it means that I had to completely change my code and started again. It took me another few hours to figure it out but I got to say that it's not that much code as I thought.

Luckily, he also has comments on type so that as beginners who want to contribute to the code can easily understand which one is which.

This is what I have when a key is clicked

document.addEventListener('keydown', (e) => {
  if (e.ctrlKey && e.key === 'z' && history.isAvailableToPop()) {
    let current = history.pop();
    // also delete layer by looping through the history
    // check if there is any current.position in the array
    if (history.isLastOne(current.position)) {
      const layerToDelete = controller.getLayer(current.position);
      if (layerToDelete.locked) return;
      const radio = current.input;
      const sibling = radio.closest('.layer').nextElementSibling;
      /** @type {HTMLInputElement} */
      const nextRadio = sibling.querySelector('input[name="layer"]');
      nextRadio.checked = true;
      selectLayer(layers.get(nextRadio));

      controller.delete(layerToDelete);
      radio.closest('.layer').remove();
      history.decreasePosition();
    } else if (current.position !== history.getLast().position) {
      current = history.getLastOfPosition(current.position);
      const position = current.position;

      selectLayer(current.layer);

      const layer = controller.getLayer(position);

      Object.assign(layer, current.layer);
      cancelAnimationFrame(lastHandle);
      lastHandle = requestAnimationFrame(() => {
        updatePreview(current.input);
        controller.draw(layer);
      });
    } else {
      const position = history.getLast().position;

      selectLayer(history.getLast().layer);

      const layer = controller.getLayer(position);

      Object.assign(layer, history.getLast().layer);
      cancelAnimationFrame(lastHandle);
      lastHandle = requestAnimationFrame(() => {
        updatePreview(history.getLast().input);
        controller.draw(layer);
      });
    }
  }
});
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Tingwei

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