I am trying to figure out if I can use JSON as a color-picker for a drawing app.
Published: 2023-05-11 10:20:59

As the title says, I am trying to figure out if I can use JSON to pick colors from, in order, to fulfill the phase-1 final assignment for an HTTP API that includes, at least, 5 elements in an array with 3 attributes.

By having primary and secondary colors, I would have 6 elements (red, yellow, blue, orange, green and violet) in an array. Its attributes would be:

1. color name 
2. color image
3. color group (primary or secondary)

And, it would be displayed on the screen as a single page drawing app using HTML and Javascript. 

My app will be, called "!ward," which is "draw!" backwards. Clever, ha?

Unfortunately, what isn't clever is that implementing it is not as straightforward as I had thought. I might not have the time, nor knowledge to implement the necessary work-around. But, according to my research, 

> One way to implement a color picker on HTML canvas is to use `getImageData` to get the pixel color under the mouse cursor. This can be achieved by first drawing a gradient on the canvas, and then using `getImageData` to get the color at the mouse position. Here's an example:

```
const canvas = document.getElementById('myCanvas');
const ctx = canvas.getContext('2d');
const gradient = ctx.createLinearGradient(0, 0, canvas.width, 0);
gradient.addColorStop(0, 'red');
gradient.addColorStop(0.2, 'orange');
gradient.addColorStop(0.4, 'yellow');
gradient.addColorStop(0.6, 'green');
gradient.addColorStop(0.8, 'blue');
gradient.addColorStop(1, 'purple');
ctx.fillStyle = gradient;
ctx.fillRect(0, 0, canvas.width, canvas.height);

canvas.addEventListener('click', function(event) {
  const x = event.pageX - canvas.offsetLeft;
  const y = event.pageY - canvas.offsetTop;
  const imageData = ctx.getImageData(x, y, 1, 1);
  const color = `rgb(\${imageData.data[0]}, \${imageData.data[1]}, \${imageData.data[2]})`;
  console.log(color);
});
```

> Another way to implement a color picker on HTML canvas is to draw a color palette image on the canvas, and then use `getImageData` to get the pixel color under the mouse cursor. Here's an example:

```
const canvas = document.getElementById('myCanvas');
const ctx = canvas.getContext('2d');
const image = new Image();
image.src = 'color-palette.png';
image.onload = function() {
  ctx.drawImage(image, 0, 0);
};

canvas.addEventListener('click', function(event) {
  const x = event.pageX - canvas.offsetLeft;
  const y = event.pageY - canvas.offsetTop;
  const imageData = ctx.getImageData(x, y, 1, 1);
  const color = `rgb(\${imageData.data[0]}, \${imageData.data[1]}, \${imageData.data[2]})`;
  console.log(color);
})
```

> In both examples, the `rgb` value of the pixel under the mouse cursor is obtained using `getImageData`, and can be used to set the fill/stroke color of shapes drawn on the canvas.
> JSON can be used to store and retrieve colors in these examples. For example, if you want to store the color selected by the user in a JSON object, you could do something like this:

```
let selectedColor = { r: 255, g: 0, b: 0 }; // initial color is red

canvas.addEventListener('click', function(event) {
  const x = event.pageX - canvas.offsetLeft;
  const y = event.pageY - canvas.offsetTop;
  const imageData = ctx.getImageData(x, y, 1, 1);
  selectedColor.r = imageData.data[0];
  selectedColor.g = imageData.data[1];
  selectedColor.b = imageData.data[2];
  console.log(selectedColor);
});
```

> This would update the `selectedColor` object with the `rgb` values of the pixel under the mouse cursor every time the user clicks on the canvas.

My challenge will be to try to make the JSON color-picker work. But, in case, I can't do it in time, I have code using HTML and Javascript for a simple drawing app.

In conclusion, I have found that my original idea was flawed. Even, if I can get a JSON color-picker to work, it would be clunky compared to what I already have working. Even, though there are many different ways to write code, I feel that the simplest, easiest, most elegant way is the best way. In this regard, a JSON color-picker would simply not be used outside of fulfilling some checkbox that needed to be checked.