golang font settings

Go language is an open source programming language launched by Google in 2009. Its main features are simplicity, speed and efficiency, which make it the language of choice for many developers. In the Go language, we can easily use font settings to render and display text. In this article, we will introduce some commonly used golang font setting methods.

1. Load font

First, we need to load the font file. Generally, the file name of the font file ends with ".ttf" or ".otf". In Go language, we can use the truetype.Parse function in the "github.com/golang/freetype/truetype" package to load font files. Its usage is as follows:

fontFile, err := os.Open("path/to/font.ttf")
if err != nil {
    log.Fatal(err)
}
defer fontFile.Close()

fontBytes, err := ioutil.ReadAll(fontFile)
if err != nil {
    log.Fatal(err)
}

font, err := truetype.Parse(fontBytes)
if err != nil {
    log.Fatal(err)
}

In the above code, "path/to/font.ttf" is the path to the font file. First, we open the font file, then read the contents of the font file and use the truetype.Parse function to parse the font file into a font object "font".

2. Set the font size

Setting the font size is also very simple. First, we need to define a freetype.Context object. It contains a Canvas object for drawing text, font objects and some other settings. Then, we pass the font object to the Context object by setting the Font property of freetype.Context.

The following is an example:

import (
    "image"
    "image/color"
    "golang.org/x/image/font"
    "golang.org/x/image/font/gofont/goregular"
    "golang.org/x/image/font/gofont/gosmallcaps"
    "golang.org/x/image/math/fixed"
)

func main() {
    bounds := image.Rect(0, 0, 1024, 768)
    img := image.NewGray(bounds)
    ctx := freetype.NewContext()
    ctx.SetDPI(72)
    ctx.SetFont(font.Font{})
    ctx.SetFontSize(14)
    ctx.SetClip(img.Bounds())
    ctx.SetDst(img)
    ctx.SetSrc(image.NewUniform(color.Black))

    pt := freetype.Pt(50, 50)
    _, err := ctx.DrawString("Hello, world!", pt)
    if err != nil {
        log.Println(err)
    }
}

In the above code, we use the image.NewGray function to create a new grayscale image, and create a new Context through the freetype.NewContext function object. Then, we set the font using the ctx.SetFont function. The parameter of this function is an object that implements the Font interface in the image/font package. In this example, we use a font object of type font.Face. Finally, we draw a piece of text using the ctx.DrawString function.

3. Set the font style

Setting the font style is also very simple. We can use the font.FaceOptions object to set the style of the font. Here is an example:

import (
    "github.com/golang/freetype"
    "github.com/golang/freetype/truetype"
    "golang.org/x/image/font"
)

func main() {
    fontFile, err := os.Open("path/to/font.ttf")
    if err != nil {
        log.Fatalf("failed to open font file: %v", err)
    }
    
    defer fontFile.Close()
    
    fontBytes, err := ioutil.ReadAll(fontFile)
    if err != nil {
        log.Fatalf("failed to read font file: %v", err)
    }
    
    font, err := truetype.Parse(fontBytes)
    if err != nil {
        log.Fatalf("failed to parse font: %v", err)
    }
    
    size := 24.0
    
    ctx := freetype.NewContext()
    ctx.SetDPI(72)
    ctx.SetFont(font)
    
    var hinting font.Hinting
    ctx.SetHinting(hinting)

    faceOptions := truetype.Options{
        Size: size,
        DPI: 72,
        Hinting: hinting,
    }
    
    boldFont := truetype.NewFace(font, &faceOptions)
    
    italicFaceOptions := faceOptions
    italicFaceOptions.FauxBold = true
    italicFaceOptions.FauxItalic = true
    italicFaceOptions.Size = size + 6
    
    italicBoldFont := truetype.NewFace(font, &italicFaceOptions)
}

In the above code, we defined two variables faceOptions and italicFaceOptions, which are used to set the font style. Then, we call the truetyp.NewFace function to create the boldFont and italicBoldFont font variables.

Through these methods, we can easily set the font size and style, making our program more creative and beautiful.

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