![]() So the r,g,b,a values of the upper-leftmost pixel are represented by the first four indices in the array. Furthermore, each pixel is represented with integers in four spots in the array (for red, green, blue and alpha values). It represents each pixel in the image going across the rows from left to right, starting in the upper left corner. The image is two-dimensional, but the data array is one-dimensional (flat). ![]() Figuring out the correct position is tricky, though. Setting the color of a particular pixel is conceptually simple: simply put that color data into the image data array at the right spot. By manipulating the elements of that array, it’s possible to set pixel color values that can then be rendered using putImageData. createImageData generates a Uint8ClampedArray that represents the pixels in the canvas. To do this we use the companion methods createImageData and putImageData. We’ll eventually use it to draw the entire color wheel, but the first step is figuring out how to instruct it to draw basic color data, pixel by pixel. I’ve identified the HTML5 element as our first building block. Find out hwo to map colors to specific angles around the circle.Refine our drawing so that we restrict the pixels to a circle.Figure out how to just draw something (in this post it will be a red square). ![]() In the case of this post the steps will be: When faced with any new programming challenge, it’s critical to break it down into smaller steps that are more approachable-by building those and layering them atop each other it’s possible to achieve our more ambitious overall goal. Our goal: Render a color wheel like Apple’s HSL color picker picture here
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