Golang image manipulation: learn how to scale and rotate images

Golang Image Operation: Learn how to scale and rotate images

In modern software development, image processing is a common requirement. Whether it is for website UI design or mobile application graphic display, we often need to scale and rotate images to meet our needs. In this article, we will learn how to use Golang to perform image scaling and rotation operations, and attach corresponding code examples.

In order to perform image processing, we first need to import Golang's image and draw packages. Use the following command to import these two packages:

import (
    "image"
    "image/draw"
)

Next, we need to load an image. Golang provides an image package to easily manipulate images. We can use the image.Decode function to decode the image file into an image.Image object, as shown below:

file, _ := os.Open("image.jpg")
defer file.Close()

img, _, _ := image.Decode(file)

Now, we have successfully loaded an image, next we will Learn how to resize images. The way to scale an image is to create a new canvas and draw the scaled image on it. We can use the draw.ApproxBiLinear.Scale function to implement the scaling operation. The code example is as follows:

scaledWidth := 500
scaledHeight := 500

scaledImg := image.NewRGBA(image.Rect(0, 0, scaledWidth, scaledHeight))
draw.ApproxBiLinear.Scale(scaledImg, scaledImg.Bounds(), img, img.Bounds(), draw.Src, nil)

In the above example, we created a new canvas with a size of 500x500 pixels and used draw.ApproxBiLinear.ScaleThe function draws the original image to a new canvas. This function will automatically scale the image according to the size of the target canvas. Through the draw.Src parameter we can specify the algorithm for drawing the image.

Next, we will learn how to rotate images. To rotate an image, you need to use Golang’s draw.Rotate function. This function can rotate the image around a specified angle. The code example is as follows:

angle := 45

rotatedImg := image.NewRGBA(image.Rect(0, 0, img.Bounds().Max.X, img.Bounds().Max.Y))
draw.Rotate(rotatedImg, img.Bounds(), img, img.Bounds().Max, float64(angle)*math.Pi/180)

In the above example, we create a new canvas with the same dimensions as the original image and use the draw.Rotate function to draw the original image to the new canvas superior. By adjusting the angle parameter, we can specify the angle of rotation.

So far, we have learned how to use Golang to scale and rotate images. Through these simple code examples, we can easily handle various image manipulation needs in our own projects. Of course, Golang's image and draw packages also provide more powerful image processing functions, such as cropping, drawing graphics, etc. Readers can continue to learn in depth to meet more image processing needs.

I hope this article can help readers in need and improve their skills in Golang image processing. If you have any questions or suggestions, please leave a message to communicate. Thanks!

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