How to implement image rotation and flipping in Golang

Golang's method of rotating and flipping images

In image processing, it is often necessary to rotate and flip images. This article will introduce how to use Golang to rotate and flip images, and provide corresponding code examples.

First, we need to import the two packages image and image/draw:

import (
    "image"
    "image/draw"
)

Next, we define a function RotateImage Used to implement image rotation:

func RotateImage(src image.Image, angle float64) *image.RGBA {
    //计算旋转后的图片尺寸
    bounds := src.Bounds()
    width := bounds.Max.X - bounds.Min.X
    height := bounds.Max.Y - bounds.Min.Y
    offsetX := float64(width) / 2
    offsetY := float64(height) / 2

    //创建旋转后的图片
    rotateImg := image.NewRGBA(bounds)
    rotateImgRect := rotateImg.Bounds()

    //根据旋转角度计算旋转后每个像素的位置
    for x := rotateImgRect.Min.X; x < rotateImgRect.Max.X; x++ {
        for y := rotateImgRect.Min.Y; y < rotateImgRect.Max.Y; y++ {
            px := float64(x) - offsetX
            py := float64(y) - offsetY
            rotX := float64(px)*math.Cos(angle) - float64(py)*math.Sin(angle)
            rotY := float64(px)*math.Sin(angle) + float64(py)*math.Cos(angle)
            rotX += offsetX
            rotY += offsetY

            //获取旋转后位置对应的原图像素
            if rotX >= 0 && rotX < float64(width) && rotY >= 0 && rotY < float64(height) {
                rotateImg.Set(x, y, src.At(int(rotX), int(rotY)))
            }
        }
    }
    return rotateImg
}

The above function accepts two parameters, src represents the source image, and angle represents the angle of rotation. The function first calculates the size of the rotated image and creates a new RGBA image to store the rotated result.

Then, two nested loops are used to traverse each pixel position after rotation, calculate its corresponding position in the original image, and obtain the pixel value at that position. Finally set that pixel value into the rotated image.

Next, we define a function FlipImage to implement image flipping:

func FlipImage(src image.Image) *image.RGBA {
    //计算翻转后的图片尺寸
    bounds := src.Bounds()
    width := bounds.Max.X - bounds.Min.X
    height := bounds.Max.Y - bounds.Min.Y

    //创建翻转后的图片
    flipImg := image.NewRGBA(bounds)
    flipImgRect := flipImg.Bounds()

    //翻转画布
    draw.Draw(flipImg, flipImgRect, src, bounds.Min, draw.Src)

    //水平翻转
    for x := flipImgRect.Min.X; x < flipImgRect.Max.X; x++ {
        for y := flipImgRect.Min.Y; y < flipImgRect.Max.Y; y++ {
            flipX := flipImgRect.Max.X - x - 1
            flipImg.Set(flipX, y, flipImg.At(x, y))
        }
    }
    return flipImg
}

The above code first calculates the size of the flipped image and creates a new RGBA image using To store the result after flipping. Then draw the source image into the flipped image through the draw.Draw() function.

Finally, each pixel position is traversed through two nested loops, flipped horizontally, and set into the flipped image.

Next we write the main function to test the above code:

func main() {
    //读取原始图片
    file, _ := os.Open("source.png")
    defer file.Close()
    src, _, _ := image.Decode(file)

    //旋转图片
    rotateImg := RotateImage(src, math.Pi/4)
    rotateFile, _ := os.Create("rotate.png")
    defer rotateFile.Close()
    png.Encode(rotateFile, rotateImg)

    //翻转图片
    flipImg := FlipImage(src)
    flipFile, _ := os.Create("flip.png")
    defer flipFile.Close()
    png.Encode(flipFile, flipImg)
}

The above code first reads the original image through the image.Decode() function, and then calls ## The #RotateImage() function and the FlipImage() function perform rotation and flip operations respectively. Finally, the result is saved to the file through the png.Encode() function.

Through the above code examples, we can use Golang to implement image rotation and flipping operations. These operations are often used in image processing and are also very helpful for the realization of some special effects. I hope this article can help you understand and use Golang for image processing.

The above is the detailed content of How to implement image rotation and flipping in Golang. For more information, please follow other related articles on the PHP Chinese website!