Now this is just a simple "Paint App" but upon this same logic a lot of complex software can be developed.
Go through the following exercise, keep it simple, and take it as it comes:
2) Build a "Paint App" with the ability to alter resolution by mutating the app.resW & app.resH variables.
3) The display should represent a 2d array named matrix.
4) Compound loops should be used to iterate through the matrix/multidimensional-array.
Here is the code we have:
To view it in the browser:
Now let me narrate each line of code so we can learn it better:
First of all there is the HTML label, it covers most of the HTML & CSS generation process of our code.
There is a class named pixels which belongs to each individual pixel on our canvas, it makes our pixels square shaped. Now in modern day an actual pixel is one of those really small squares on the screen, however back in the day those squares used to be gigantic like the ones in our app, our browser may crash if we try to generate a 1px², 600px*800px canvas, so instead we are generating a 10px²,30px*30px canvas.
There is a hover pseudo-class on pixels, this highlights (in red) the pixel to show the user which pixel their identifier/cursor is targeting.
There is a class named on which changes the color of a white pixel to a black pixel giving the user the ability to draw and write on the canvas with black color.
There is a divider with id "display" this will clench all our pixels within itself.This concludes the HTML label portion of our code.
Then on line #19 we have an object named "app", in this object we are plotting some vital policies of our app, we have the width and the amount of pixels assembled in each row of pixels in our app's canvas established in the resW property, and we have the height and the amount of pixels assembled in each column of pixels in our app's canvas established in the resH property. Finally we have the method that toggles a pixel between black and white colors so we can draw upon our canvas. To this point we are just storing data that is a prerequisite to spreading out a mutable canvas.
Then on lines #29 to #33 we have a variable named "matrix", this is a record of each pixel in our canvas, if we ever need to export our drawings into a separate file to save them we will actually be saving a 2-dimentional matrix of pixel data. This code narrates like this "Declare a variable named matrix, in this variable we have an array with (resH) amount of members, within this array all members are arrays, each of the latter array has (resW) amount of members, each of these members are an empty-string".
Now from line #35 to #47 we have a two-way loop that extracts each pixel data from our matrix and directs it towards display on lines #39 to #41; Now on lines #43 to #46 we are placing/spreading each pixel to its proper place. The row & col variables on lines #36 & #37 are index numbers and are used as co-ordinates for pixels. The code narrates like this "Extract the 1st pixel from the matrix and spread it on (#display) canvas, give this pixel the class
pixels and the ability to toggle between black and white colors when clicked; place this pixel on co-ordinates (x, y) where x equals 10 times its vertical placement in the matrix and y equals 10 times its horizontal placement in the matrix".
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