How to resolve the algorithm Colour pinstripe/Printer step by step in the Go programming language
How to resolve the algorithm Colour pinstripe/Printer step by step in the Go programming language
Table of Contents
Problem Statement
The task is to create 1 point wide colour vertical pinstripes with a sufficient number of pinstripes to span the entire width of the colour graphics printer. The pinstripes should alternate between each individual cartridge ink and ink pair and black and white pinstripes should be included. A typical pinstripe sequence woud be black, red, green, blue, magenta, cyan, yellow, white. After the first inch of printing, we switch to a wider 2 pixel wide vertical pinstripe pattern. and to 3 point wide vertical for the next inch, and then 4 point wide, etc. This trend continues for the entire length of the page (or for 12 inches of run length in the case of a printer using continuous roll stationery). After printing the test pattern the page is ejected (or the test pattern is rolled clear of the printer enclosure, in the case of continuous roll printers). Note that it is an acceptable solution to use the smallest marks that the language provides, rather than working at native printer resolution, where this is not achievable from within the language. Optionally, on systems where the printer resolution cannot be determined, it is permissible to prompt the user for printer resolution, and to calculate point size based on user input, enabling fractional point sizes to be used.
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Colour pinstripe/Printer step by step in the Go programming language
This Go program creates a colorful pinstripe pattern and saves it as a PNG image. It also attempts to open the image using the default image viewer on the user's system. A breakdown of the code:
-
Creating the Context:
dc := gg.NewContext(842, 595)
creates a new graphics context with a width of 842 and a height of 595. This context is used for drawing the pinstripe pattern.
-
Drawing the Pinstripe Pattern:
- The
pinstripe
function generates the pinstripe pattern using a loop to draw rectangles of different colors and sizes. - The
palette
variable contains an array of eight hex color strings, representing different colors. - The loop iterates over the palette, drawing rectangles with a width equal to the value of
b
(which ranges from 1 to 11) and a height equal to the height of the context divided by 7.
- The
-
Saving the Image:
dc.SavePNG("color_pinstripe.png")
saves the current graphics context as a PNG image file named "color_pinstripe.png".
-
Opening the Image in Default Viewer:
- The program attempts to open the saved image using the default image viewer on the user's system.
- If the operating system is Windows, it uses the
mspaint
command. Otherwise, it uses thelp
command (which is usually used for printing).
-
Error Handling:
- If there is an error running the command to open the image, the program prints the error and exits using
log.Fatal
.
- If there is an error running the command to open the image, the program prints the error and exits using
Source code in the go programming language
package main
import (
"github.com/fogleman/gg"
"log"
"os/exec"
"runtime"
)
var palette = [8]string{
"000000", // black
"FF0000", // red
"00FF00", // green
"0000FF", // blue
"FF00FF", // magenta
"00FFFF", // cyan
"FFFF00", // yellow
"FFFFFF", // white
}
func pinstripe(dc *gg.Context) {
w := dc.Width()
h := dc.Height() / 7
for b := 1; b <= 11; b++ {
for x, ci := 0, 0; x < w; x, ci = x+b, ci+1 {
dc.SetHexColor(palette[ci%8])
y := h * (b - 1)
dc.DrawRectangle(float64(x), float64(y), float64(b), float64(h))
dc.Fill()
}
}
}
func main() {
dc := gg.NewContext(842, 595)
pinstripe(dc)
fileName := "color_pinstripe.png"
dc.SavePNG(fileName)
var cmd *exec.Cmd
if runtime.GOOS == "windows" {
cmd = exec.Command("mspaint", "/pt", fileName)
} else {
cmd = exec.Command("lp", fileName)
}
if err := cmd.Run(); err != nil {
log.Fatal(err)
}
}
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