Examples of how to display images in Golang

With the rapid development of computers and the Internet, most application software requires the medium of images to complete certain functions. In programming languages, various APIs and functions are provided to process images.

Golang is a new programming language designed for developing efficient, reliable and simple software. Although it is a relatively new language, it has become the language of choice in an increasing number of applications. This article will introduce how to display images in Golang.

1. Import related libraries

Before we start processing images, we need to import related libraries. In Golang, we use the image and image/png packages to display images in png format, and use image/jpeg to display images in jpeg format. Here is the code for importing the library:

import (
    "fmt"
    "image"
    "image/png"
    "image/jpeg"
    "os"
)

2. Reading pictures

Reading pictures is the first step to display pictures. In Golang, we can use the image.Decode() function to read images from files. This function returns an image.Image interface, which represents the image. The following is the code for reading images in png format:

file, err := os.Open("image.png")
if err != nil {
    panic(err)
}
defer file.Close()

img, err := png.Decode(file)
if err != nil {
    panic(err)
}

If you want to display images in jpeg format, just replace png.Decode(file) with jpeg.Decode( file).

3. Create Window

Once we have the image, we need to display it on the screen. In Golang, we can create windows using the gonum.org/v1/plot/vg package. The following is the code to create a window:

import (
    "gonum.org/v1/plot/vg"
)

// 设置窗口大小
width := 600
height := 800

canvas := vg.NewScaledCanvas(vg.Length(width), vg.Length(height))

We can set the window size by modifying width and height.

4. Draw the image

Once we have the canvas, we can use the DrawImage() function to draw the image to the canvas. The following is the code to draw the picture:

import (
    "gonum.org/v1/plot/vg/draw"
)

// 计算图片的位置
x := vg.Points(0)
y := vg.Points(0)

// 将图片绘制到画布上
draw.CropTop(draw.CropRight(draw.CropBottom(draw.CropLeft(canvas, x), y), vg.Length(img.Bounds().Max.X)), vg.Length(img.Bounds().Max.Y)), img)

To draw the picture, we need to specify the position of the picture. In this example, we draw the image in the upper left corner of the canvas and then draw the entire image.

5. Display window

Finally, we need to display our window. The following is the code to display the window:

import (
    "github.com/go-gl/glfw/v3.2/glfw"
)

// 创建窗口并显示
window := glfw.NewWindow(width, height, "My Window", nil, nil)
window.SetTitle("Display Image Demo")

// 显示画布
window.SetSizeCallback(func(w *glfw.Window, width int, height int) {
    canvas.SetCanvasSize(vg.Length(width), vg.Length(height))
})

window.MakeContextCurrent()
for !window.ShouldClose() {
    window.SwapBuffers()
    glfw.PollEvents()
}

To display the window, we use glfw to create the window and draw the canvas to the window. Finally, we use window.ShouldClose() to check if the window needs to be closed.

Summary

The above is the entire process of how to display images in Golang. With a few simple steps, we can use Golang to display images in png or jpeg format. This article is just a simple demonstration, more complex operations can be achieved using this process. I hope that through this article you can have a deeper understanding of how Golang processes images.

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