Standard library · Machine learning

image

Reading, editing and saving images, and writing text on them.

import image

On this page

Types
Constants and variables
Functions

This package works with images without any outside library: it reads and writes PNG, JPEG and BMP. It also reads and writes WebP, both lossy and lossless. From a GIF it reads the first frame, and it saves an image in a GIF with at most 256 colors. Open and Save work the format out from the content or the extension. Drawing, resizing, cropping, rotating and filters such as blurring and sharpening are all there.

For text, read a TrueType font with LoadFont and write with DrawTextStyled; Persian and Arabic text is shaped and laid out right to left on its own. For building social media images automatically, DrawTextFitBox finds the size that fits. The font example needs a font file and on the site it is only checked.

Types

`Image`

struct Image

An 8 bit RGBA image.

Name	Type	Description
`width`	`int = 0`	The width in pixels.
`height`	`int = 0`	The height.
`pixels`	`void*`	The pixels, four bytes each, row by row.

image-Draw.salam

import image
import os

func main:
    mut img := image.New(8, 6)
    println img.width, img.height, image.IsEmpty(img), image.InBounds(img, 7, 5), image.InBounds(img, 8, 0)
    image.Fill(img, image.RGB(255, 255, 255))
    image.FillHex(img, "#202040")
    image.SetPixel(img, 0, 0, image.RGB(255, 0, 0))
    image.BlendPixel(img, 1, 0, image.RGBA(255, 255, 255, 128))
    println image.ToHex(image.GetPixel(img, 0, 0)), image.ToHex(image.GetPixel(img, 1, 0)), image.ToHexRGB(image.GetPixel(img, 2, 0))
    image.DrawLine(img, 0, 5, 7, 5, image.Gray(200))
    image.DrawRect(img, 1, 1, 4, 3, image.ParseHex("#ffcc00"))
    image.DrawRectFilled(img, 2, 2, 2, 1, image.ParseHex("#00ff00"))
    image.DrawCircle(img, 6, 2, 1, image.Gray(255))
    image.DrawCircleFilled(img, 6, 2, 0, image.Gray(10))
    println image.ToHexRGB(image.GetPixel(img, 3, 2)), image.ToHexRGB(image.GetPixel(img, 4, 5))

    color := image.ParseHex("#336699")
    println color.r, color.g, color.b, color.a, image.Luminance(color)
    println image.Equals(color, image.RGB(51, 102, 153)), image.ToHex(image.Blend(color, image.RGBA(255, 255, 255, 0)))
    println image.ToHexRGB(image.LerpColor(image.Gray(0), image.Gray(200), 0.5))

    mut labelled := image.NewFilled(40, 10, image.Gray(0))
    image.DrawText(labelled, 1, 1, "SALAM", image.Gray(255), 1)
    println image.TextWidth("SALAM", 1), image.FontWidth, image.FontHeight

    dir := os.TempDir()
    println image.Save(img, dir + "/salam_en.png"), image.SavePNG(img, dir + "/salam2_en.png"), image.SaveBMP(img, dir + "/salam_en.bmp"), image.SaveJPEG(img, dir + "/salam_en.jpg", 90)
    println image.SaveQuality(img, dir + "/salam2_en.jpg", 50), image.SaveWebP(img, dir + "/salam_en.webp")
    mut ok := false
    read := image.Open(dir + "/salam_en.png", ok)
    println ok, read.width, image.Equals(image.GetPixel(read, 0, 0), image.GetPixel(img, 0, 0))
    png := image.OpenPNG(dir + "/salam2_en.png", ok)
    bmp := image.OpenBMP(dir + "/salam_en.bmp", ok)
    jpg := image.OpenJPEG(dir + "/salam_en.jpg", ok)
    println ok, png.width, bmp.height, jpg.width
    println image.FormatFromExt("a.jpeg") == image.FormatJPEG, image.FormatFromExt("a.png") == image.FormatPNG, image.FormatFromExt("a.txt") == image.FormatUnknown

    buf := image.EncodePNG(img)
    println image.DetectFormat(buf.data, buf.len) == image.FormatPNG, image.IsWebP(buf.data, buf.len)
    from_buf := image.DecodePNG(buf.data, buf.len, ok)
    generic := image.Decode(buf.data, buf.len, ok)
    println ok, from_buf.width, generic.height
    b := image.EncodeBMP(img)
    b2 := image.DecodeBMP(b.data, b.len, ok)
    j := image.EncodeJPEG(img, 80)
    j2 := image.DecodeJPEG(j.data, j.len, ok)
    println image.DetectFormat(b.data, b.len) == image.FormatBMP, image.DetectFormat(j.data, j.len) == image.FormatJPEG, b2.width, j2.width
    any := image.Encode(img, image.FormatBMP, 90)
    web := image.EncodeWebP(img)
    lossy := image.EncodeWebPQuality(img, 75)
    println any.len == b.len, web.len > 0, image.FormatWebP
    clear := image.NewFilled(1, 1, image.RGBA(0, 0, 0, 0))
    println image.ToHex(image.GetPixel(image.FlattenAlpha(clear, image.Gray(255)), 0, 0))
    converted := image.Convert(img, image.FormatJPEG)
    println converted.width
    webp := image.DecodeWebP(web.data, web.len, ok)
    println ok, webp.width, image.Equals(image.GetPixel(webp, 1, 0), image.GetPixel(img, 1, 0))
    webp3 := image.DecodeWebP(lossy.data, lossy.len, ok)
    println ok, webp3.width, webp3.height
    webp2 := image.OpenWebP(dir + "/salam_en.webp", ok)
    println image.SaveGIF(img, dir + "/salam_en.gif"), image.FormatFromExt("a.gif") == image.FormatGIF
    gif := image.OpenGIF(dir + "/salam_en.gif", ok)
    g := image.EncodeGIF(img)
    gif2 := image.DecodeGIF(g.data, g.len, ok)
    println ok, gif.width, gif2.height, image.IsGIF(g.data, g.len), image.Equals(image.GetPixel(gif, 0, 0), image.GetPixel(img, 0, 0))
    println ok, webp2.height
    mut copy := image.Clone(img)
    image.Free(copy)
    image.Free(img)
end

Output8 6 false true false #ff0000ff #8f8f9fff #202040 #00ff00 #c8c8c8 51 102 153 255 92 true #336699ff #646464 30 5 7 true true true true true true true 8 true true 8 6 8 true true true true false true 8 6 true true 8 8 true true 4 #ffffffff 8 true 8 true true 8 6 true true true 8 6 true true true 6

`Color`

struct Color

One color.

Name	Type	Description
`r`	`u8 = 0`	Red, 0 to 255.
`g`	`u8 = 0`	Green.
`b`	`u8 = 0`	Blue.
`a`	`u8 = 255`	Alpha, that is opacity; 255 is fully opaque.

The example for this item is shown with the ones above: image-Draw.salam

`Font`

struct Font

A TrueType or OpenType font.

Name	Type	Description
`data`	`void*`	The file's bytes.
`size`	`int = 0`	The size of the data.
`units_per_em`	`int = 0`	The units per em.
`num_glyphs`	`int = 0`	The number of glyphs.
`ascent`	`int = 0`	The ascent.
`descent`	`int = 0`	The descent.
`line_gap`	`int = 0`	The line gap.
`glyf`	`int = 0`	Where the glyf table is.
`glyf_len`	`int = 0`	The length of the glyf table.
`loca`	`int = 0`	Where the loca table is.
`loca_len`	`int = 0`	The length of the loca table.
`hmtx`	`int = 0`	Where the hmtx table is.
`kern`	`int = 0`	Where the kern table is.
`cmap_sub`	`int = 0`	Where the cmap subtable is.
`cmap_symbol`	`bool = false`	The cmap is a symbol one.
`num_hmetrics`	`int = 0`	The number of horizontal metrics.
`loca_long`	`bool = false`	The loca is the long one.
`ok`	`bool = false`	It was read correctly.

The example for this item is shown with the ones above: image-Draw.salam

`Histogram`

struct Histogram

A histogram: how many pixels have each value from 0 to 255.

Name	Type	Description
`r`	`void*`	The red histogram.
`g`	`void*`	The green histogram.
`b`	`void*`	The blue histogram.
`luma`	`void*`	The brightness histogram.

image-Edit.salam

import image

func size(name: str, img: image.Image):
    println name, "" + img.width + "x" + img.height
end

func main:
    mut img := image.NewFilled(8, 4, image.Gray(100))
    image.SetPixel(img, 0, 0, image.RGB(255, 0, 0))
    size("nearest", image.ResizeNearestNeighbor(img, 4, 2))
    size("bilinear", image.ResizeBilinearFilter(img, 16, 8))
    size("resize", image.Resize(img, 2, 2, image.ResizeBilinear))
    size("near", image.Resize(img, 2, 2, image.ResizeNearest))
    size("scale", image.Scale(img, 0.5))
    size("crop", image.Crop(img, 2, 1, 3, 2))
    clockwise := image.RotateCW(img)
    size("clockwise", clockwise)
    println image.ToHexRGB(image.GetPixel(clockwise, 3, 0))
    size("counterclockwise", image.RotateCCW(img))
    println image.ToHexRGB(image.GetPixel(image.Rotate180(img), 7, 3))
    println image.ToHexRGB(image.GetPixel(image.FlipHorizontal(img), 7, 0)), image.ToHexRGB(image.GetPixel(image.FlipVertical(img), 0, 3))
    size("fit", image.ResizeFit(img, 4, 4))
    size("fill", image.ResizeFill(img, 4, 4))
    size("thumbnail", image.Thumbnail(img, 2))

    mut c := image.NewFilled(2, 1, image.RGB(200, 100, 50))
    image.Grayscale(c)
    println image.ToHexRGB(image.GetPixel(c, 0, 0))
    image.Invert(c)
    image.Brightness(c, 10)
    image.Contrast(c, 1.5)
    println image.ToHexRGB(image.GetPixel(c, 0, 0))
    image.Threshold(c, 128)
    println image.ToHexRGB(image.GetPixel(c, 0, 0))
    mut dot := image.NewFilled(5, 5, image.Gray(0))
    image.SetPixel(dot, 2, 2, image.Gray(255))
    blurred := image.Blurred(dot, 1)
    println image.GetPixel(blurred, 2, 2).r < 255, image.GetPixel(blurred, 1, 2).r > 0
    println image.GetPixel(image.Sharpened(dot, 1.0), 2, 2).r
    mut base := image.NewFilled(2, 2, image.Gray(0))
    image.Overlay(base, image.NewFilled(1, 1, image.Gray(200)), 1, 1, 0.5)
    println image.ToHexRGB(image.GetPixel(base, 1, 1)), image.ToHexRGB(image.GetPixel(base, 0, 0))

    mut hist := image.ComputeHistogram(dot)
    println image.HistogramGet(hist.luma, 0), image.HistogramGet(hist.luma, 255), image.HistogramGet(hist.r, 255), image.HistogramGet(hist.g, 0), image.HistogramGet(hist.b, 0)
    image.HistogramFree(hist)
    black := image.NewFilled(5, 5, image.Gray(0))
    diff := image.Diff(dot, black)
    println image.GetPixel(diff, 2, 2).r, image.GetPixel(diff, 0, 0).r
    println (image.MeanAbsError(dot, black) * 100.0 + 0.5) as i64, (image.PSNR(dot, black) + 0.5) as i64
end

Outputnearest 4x2 bilinear 16x8 resize 2x2 near 2x2 scale 4x2 crop 3x2 clockwise 4x8 #ff0000 counterclockwise 4x8 #ff0000 #ff0000 #ff0000 fit 4x4 fill 4x4 thumbnail 2x1 #7c7c7c #939393 #ffffff true true 251 #636363 #000000 24 1 1 24 24 255 0 1020 14

`TextStyle`

struct TextStyle

A text style.

Name	Type	Description
`size`	`f64 = 16`	The size in pixels.
`rotate`	`f64 = 0`	The rotation in degrees.
`skew`	`f64 = 0`	The skew.
`tracking`	`f64 = 0`	The space added between the characters.
`kern`	`bool = true`	Adjust the spacing of pairs.
`dir`	`int = 0`	The direction, one of the `TextDir...` constants.
`shape`	`bool = true`	Join the Persian and Arabic letters into their connected shapes.

image-Font.salam

import image
import io

func main:
    println image.FindSystemFont(), image.FindArabicFont()
    mut ok := false
    mut font := image.LoadSystemFont(ok)
    if not ok:
        font = image.LoadFont("Vazirmatn-Regular.ttf", ok)
    end
    if not ok:
        println "no font was found"
        ret
    end
    println image.FontValid(font), image.UnitsPerEm(font), image.NumGlyphs(font)
    size := 32.0
    println image.ScaleFactor(font, size), image.AscentPixels(font, size), image.DescentPixels(font, size), image.LineHeightPixels(font, size)
    a := image.GlyphIndex(font, 65)
    v := image.GlyphIndex(font, 86)
    println image.GlyphAdvance(font, a), image.KernAdvance(font, a, v), image.GlyphHasOutline(font, a)
    mut x0 := 0
    mut y0 := 0
    mut x1 := 0
    mut y1 := 0
    println image.GlyphBox(font, a, x0, y0, x1, y1), x1 - x0, y1 - y0

    mut img := image.NewFilled(400, 120, image.Gray(255))
    black := image.Gray(0)
    _ := image.DrawTextTTF(img, 10.0, 40.0, "Salam", black, font, size)
    println image.TextWidthTTF(font, "Salam", size)
    style := image.TextStyle { size = 28.0, tracking = 1.0, kern = true, dir = image.TextDirAuto, shape = true }
    _ := image.DrawTextStyled(img, 10.0, 80.0, "سلام دنیا", black, font, style)
    println image.TextWidthStyled(font, "سلام دنیا", style), image.TextInkWidth(font, "سلام", style), image.TextInkHeight(font, "سلام", style)
    mut width := 0.0
    mut height := 0.0
    println image.TextInkSize(font, "سلام", style, width, height), width, height
    mut a0 := 0.0
    mut b0 := 0.0
    mut a1 := 0.0
    mut b1 := 0.0
    println image.TextBounds(font, "سلام", style, a0, b0, a1, b1)
    println image.FitSizeToWidth(font, "سلام", style, 200.0, 96.0), image.FitSizeToBox(font, "سلام", style, 200.0, 50.0, 96.0)
    _ := image.DrawGlyphStyled(img, a, 300.0, 40.0, black, font, style)
    _ := image.DrawCodepointStyled(img, 1600, 340.0, 40.0, black, font, style)
    _ := image.DrawTextCentered(img, 200.0, 60.0, "middle", black, font, style)
    _ := image.DrawTextCenteredIn(img, "middle", black, font, style)
    _ := image.DrawTextInBox(img, 0.0, 0.0, 200.0, 60.0, "box", black, font, style, image.TextAlignRight, image.TextVAlignMiddle)
    _ := image.DrawTextFitBox(img, 0.0, 60.0, 200.0, 60.0, "fit", black, font, style, 0.8, 64.0)
    _ := image.DrawTextFitImage(img, "سلام", black, font, style, 0.9, 120.0)
    println image.TextAlignLeft, image.TextAlignCenter, image.TextVAlignTop, image.TextVAlignBottom, image.TextVAlignBaseline
    _ := image.Save(img, "salam-text-en.png")

    data := io.ReadFile("Vazirmatn-Regular.ttf")
    mut f2 := image.ParseFont(data as void*, data.len(), ok)
    mut f3 := image.ParseFontIndex(data as void*, data.len(), 0, ok)
    mut f4 := image.LoadFontIndex("NotoSansCJK.ttc", 0, ok)
    println image.IsCFFFont(data as void*, data.len())
    image.FreeFont(f2)
    image.FreeFont(f3)
    image.FreeFont(f4)
    image.FreeFont(font)
    image.Free(img)
end

Constants and variables

`ResizeNearest`

const ResizeNearest: i32 = 0

Resizing method: nearest neighbor, sharp and fast.

The example for this item is shown with the ones above: image-Edit.salam

`ResizeBilinear`

const ResizeBilinear: i32 = 1

Resizing method: bilinear, smooth.

The example for this item is shown with the ones above: image-Edit.salam

`TextAlignLeft`

const TextAlignLeft: i32 = 0

Horizontal alignment: left.

The example for this item is shown with the ones above: image-Font.salam

`TextAlignCenter`

const TextAlignCenter: i32 = 1

Horizontal alignment: center.

The example for this item is shown with the ones above: image-Font.salam

`TextAlignRight`

const TextAlignRight: i32 = 2

Horizontal alignment: right.

The example for this item is shown with the ones above: image-Font.salam

`TextVAlignTop`

const TextVAlignTop: i32 = 0

Vertical alignment: top.

The example for this item is shown with the ones above: image-Font.salam

`TextVAlignMiddle`

const TextVAlignMiddle: i32 = 1

Vertical alignment: middle.

The example for this item is shown with the ones above: image-Font.salam

`TextVAlignBottom`

const TextVAlignBottom: i32 = 2

Vertical alignment: bottom.

The example for this item is shown with the ones above: image-Font.salam

`TextVAlignBaseline`

const TextVAlignBaseline: i32 = 3

Vertical alignment: the baseline.

The example for this item is shown with the ones above: image-Font.salam

`TextDirAuto`

const TextDirAuto: i32 = 0

Text direction: automatic, from the first letter.

image-Bidi.salam

import image

func main:
    println image.IsRTLText("سلام"), image.IsRTLText("hello")
    println image.BaseDirection("سلام hello") == image.TextDirRTL, image.BaseDirection("hello سلام") == image.TextDirLTR
    println image.TextDirAuto
    visual := image.ToVisualOrder("abc", image.TextDirLTR)
    println visual
    shaped := image.ShapeArabic("سلام")
    println shaped.len() > 0, shaped != "سلام"
    println image.ToVisualOrder("سلام", image.TextDirRTL) != "سلام"
end

Outputtrue false true true 0 abc true true true

`TextDirLTR`

const TextDirLTR: i32 = 1

Direction: left to right.

The example for this item is shown with the ones above: image-Bidi.salam

`TextDirRTL`

const TextDirRTL: i32 = 2

Direction: right to left.

The example for this item is shown with the ones above: image-Bidi.salam

`FormatUnknown`

const FormatUnknown: i32 = 0

Format: unknown.

The example for this item is shown with the ones above: image-Draw.salam

`FormatPNG`

const FormatPNG: i32 = 1

Format: PNG.

The example for this item is shown with the ones above: image-Draw.salam

`FormatBMP`

const FormatBMP: i32 = 2

Format: BMP.

The example for this item is shown with the ones above: image-Draw.salam

`FormatJPEG`

const FormatJPEG: i32 = 3

Format: JPEG.

The example for this item is shown with the ones above: image-Draw.salam

`FormatWebP`

const FormatWebP: i32 = 4

Format: WebP.

The example for this item is shown with the ones above: image-Draw.salam

`FormatGIF`

const FormatGIF: i32 = 5

Format: GIF.

The example for this item is shown with the ones above: image-Draw.salam

`FontWidth`

const FontWidth: i32 = 5

The width of each character of the pixel font.

The example for this item is shown with the ones above: image-Draw.salam

`FontHeight`

const FontHeight: i32 = 7

The height of the pixel font.

The example for this item is shown with the ones above: image-Draw.salam

Functions

`IsWebP`

func IsWebP(p: void*, n: int): bool

The bytes are WebP.

The example for this item is shown with the ones above: image-Draw.salam

`SaveWebP`

func SaveWebP(img: Image, path: str): bool

Saves the image in a lossless WebP file; it returns true if the writing worked.

The example for this item is shown with the ones above: image-Draw.salam

`OpenWebP`

func OpenWebP(path: str, ok &: bool): Image

Reads a WebP file, both lossy and lossless.

The example for this item is shown with the ones above: image-Draw.salam

`EncodePNG`

func EncodePNG(img: Image): compress.ByteBuf

The image as PNG.

The example for this item is shown with the ones above: image-Draw.salam

`SavePNG`

func SavePNG(img: Image, path: str): bool

Saves a PNG.

The example for this item is shown with the ones above: image-Draw.salam

`DecodePNG`

func DecodePNG(p: void*, n: int, ok &: bool): Image

Reads a PNG from bytes: every bit depth from 1 to 16, palette and gray images, tRNS transparency and interlaced PNG. 16 bits comes down to 8 by rounding. A file with a broken signature or CRC is refused.

The example for this item is shown with the ones above: image-Draw.salam

`OpenPNG`

func OpenPNG(path: str, ok &: bool): Image

Reads a PNG file.

The example for this item is shown with the ones above: image-Draw.salam

`TextBounds`

func TextBounds(f: Font, text: str, st: TextStyle, x0 &: f64, y0 &: f64, x1 &: f64, y1 &: f64): bool

The ink box of a text.

The example for this item is shown with the ones above: image-Font.salam

`TextInkWidth`

func TextInkWidth(f: Font, text: str, st: TextStyle): f64

The ink width.

The example for this item is shown with the ones above: image-Font.salam

`TextInkHeight`

func TextInkHeight(f: Font, text: str, st: TextStyle): f64

The ink height.

The example for this item is shown with the ones above: image-Font.salam

`TextInkSize`

func TextInkSize(f: Font, text: str, st: TextStyle, w &: f64, h &: f64): bool

The ink width and height.

The example for this item is shown with the ones above: image-Font.salam

`FitSizeToWidth`

func FitSizeToWidth(f: Font, text: str, st: TextStyle, target_w: f64, max_size: f64): f64

The largest size at which the text fits in a width.

The example for this item is shown with the ones above: image-Font.salam

`FitSizeToBox`

func FitSizeToBox(f: Font, text: str, st: TextStyle, target_w: f64, target_h: f64, max_size: f64): f64

The largest size at which the text fits in a box.

The example for this item is shown with the ones above: image-Font.salam

`RGB`

func RGB(r: int, g: int, b: int): Color

A color from red, green and blue.

The example for this item is shown with the ones above: image-Draw.salam

`RGBA`

func RGBA(r: int, g: int, b: int, a: int): Color

A color with alpha.

The example for this item is shown with the ones above: image-Draw.salam

`Gray`

func Gray(v: int): Color

A gray with one value.

The example for this item is shown with the ones above: image-Draw.salam

`Equals`

func Equals(a: Color, b: Color): bool

The two colors are the same.

The example for this item is shown with the ones above: image-Draw.salam

`Luminance`

func Luminance(c: Color): int

A color's perceived brightness, 0 to 255.

The example for this item is shown with the ones above: image-Draw.salam

`ParseHex`

func ParseHex(hex: str): Color

A color from hex, with three, six or eight digits.

The example for this item is shown with the ones above: image-Draw.salam

`ToHex`

func ToHex(c: Color): str

Hex with alpha, like #336699ff.

The example for this item is shown with the ones above: image-Draw.salam

`ToHexRGB`

func ToHexRGB(c: Color): str

Hex without alpha.

The example for this item is shown with the ones above: image-Draw.salam

`Blend`

func Blend(dst: Color, src: Color): Color

Blends the source color with its alpha onto the destination.

The example for this item is shown with the ones above: image-Draw.salam

`LerpColor`

func LerpColor(a: Color, b: Color, t: f64): Color

A linear interpolation of two colors.

The example for this item is shown with the ones above: image-Draw.salam

`EncodeBMP`

func EncodeBMP(img: Image): compress.ByteBuf

Encodes the image as a 32 bit BMP with a version 5 header, so the transparency is seen in other programs too.

The example for this item is shown with the ones above: image-Draw.salam

`SaveBMP`

func SaveBMP(img: Image, path: str): bool

Saves a BMP.

The example for this item is shown with the ones above: image-Draw.salam

`DecodeBMP`

func DecodeBMP(p: void*, n: int, ok &: bool): Image

Reads a BMP from bytes: 1 to 8 bit palette, RLE, 16, 24 and 32 bit with color masks, OS/2 and Windows headers and a BMP with a JPEG or a PNG inside. The pixels RLE does not write stay transparent.

The example for this item is shown with the ones above: image-Draw.salam

`OpenBMP`

func OpenBMP(path: str, ok &: bool): Image

Reads a BMP file.

The example for this item is shown with the ones above: image-Draw.salam

`ResizeNearestNeighbor`

func ResizeNearestNeighbor(img: Image, new_width: int, new_height: int): Image

Resizing with the nearest neighbor.

The example for this item is shown with the ones above: image-Edit.salam

`ResizeBilinearFilter`

func ResizeBilinearFilter(img: Image, new_width: int, new_height: int): Image

Bilinear resizing.

The example for this item is shown with the ones above: image-Edit.salam

`Resize`

func Resize(img: Image, new_width: int, new_height: int, method: int): Image

Resizing with a method.

The example for this item is shown with the ones above: image-Edit.salam

`Scale`

func Scale(img: Image, factor: f64): Image

Growing or shrinking by a factor.

The example for this item is shown with the ones above: image-Edit.salam

`Crop`

func Crop(img: Image, x: int, y: int, w: int, h: int): Image

Cuts a rectangle out.

The example for this item is shown with the ones above: image-Edit.salam

`RotateCW`

func RotateCW(img: Image): Image

A ninety degree clockwise turn.

The example for this item is shown with the ones above: image-Edit.salam

`RotateCCW`

func RotateCCW(img: Image): Image

A ninety degree counterclockwise turn.

The example for this item is shown with the ones above: image-Edit.salam

`Rotate180`

func Rotate180(img: Image): Image

A hundred and eighty degree turn.

The example for this item is shown with the ones above: image-Edit.salam

`FlipHorizontal`

func FlipHorizontal(img: Image): Image

A horizontal mirror.

The example for this item is shown with the ones above: image-Edit.salam

`FlipVertical`

func FlipVertical(img: Image): Image

A vertical mirror.

The example for this item is shown with the ones above: image-Edit.salam

`ResizeFit`

func ResizeFit(img: Image, box_w: int, box_h: int): Image

The whole image inside a box keeping its ratio, centered with a transparent edge; the output is the size of the box.

The example for this item is shown with the ones above: image-Edit.salam

`ResizeFill`

func ResizeFill(img: Image, box_w: int, box_h: int): Image

Fills the box keeping the ratio and cuts the rest off.

The example for this item is shown with the ones above: image-Edit.salam

`Thumbnail`

func Thumbnail(img: Image, max_size: int): Image

A small image whose longest side is at most this; a smaller image is left alone.

The example for this item is shown with the ones above: image-Edit.salam

`DrawLine`

func DrawLine(img &: Image, x0: int, y0: int, x1: int, y1: int, c: Color)

A line.

The example for this item is shown with the ones above: image-Draw.salam

`DrawRect`

func DrawRect(img &: Image, x: int, y: int, w: int, h: int, c: Color)

An empty rectangle.

The example for this item is shown with the ones above: image-Draw.salam

`DrawRectFilled`

func DrawRectFilled(img &: Image, x: int, y: int, w: int, h: int, c: Color)

A filled rectangle.

The example for this item is shown with the ones above: image-Draw.salam

`DrawCircle`

func DrawCircle(img &: Image, cx: int, cy: int, radius: int, c: Color)

An empty circle.

The example for this item is shown with the ones above: image-Draw.salam

`DrawCircleFilled`

func DrawCircleFilled(img &: Image, cx: int, cy: int, radius: int, c: Color)

A filled circle.

The example for this item is shown with the ones above: image-Draw.salam

`Grayscale`

func Grayscale(img &: Image)

Makes it gray in place.

The example for this item is shown with the ones above: image-Edit.salam

`Invert`

func Invert(img &: Image)

Inverts the colors in place.

The example for this item is shown with the ones above: image-Edit.salam

`Brightness`

func Brightness(img &: Image, delta: int)

Makes it lighter or darker in place.

The example for this item is shown with the ones above: image-Edit.salam

`Contrast`

func Contrast(img &: Image, factor: f64)

Changes the contrast by a factor in place.

The example for this item is shown with the ones above: image-Edit.salam

`Threshold`

func Threshold(img &: Image, level: int)

Black and white with a threshold, in place.

The example for this item is shown with the ones above: image-Edit.salam

`Blurred`

func Blurred(img: Image, radius: int): Image

A blurred version with a radius.

The example for this item is shown with the ones above: image-Edit.salam

`Sharpened`

func Sharpened(img: Image, amount: f64): Image

A sharper version.

The example for this item is shown with the ones above: image-Edit.salam

`Overlay`

func Overlay(base &: Image, mark: Image, x: int, y: int, opacity: f64)

Puts another image on top with an opacity; a watermark, for instance.

The example for this item is shown with the ones above: image-Edit.salam

`ScaleFactor`

func ScaleFactor(f: Font, size: f64): f64

The factor that turns font units into pixels at a size.

The example for this item is shown with the ones above: image-Font.salam

`AscentPixels`

func AscentPixels(f: Font, size: f64): f64

The ascent in pixels.

The example for this item is shown with the ones above: image-Font.salam

`DescentPixels`

func DescentPixels(f: Font, size: f64): f64

The descent in pixels; negative.

The example for this item is shown with the ones above: image-Font.salam

`LineHeightPixels`

func LineHeightPixels(f: Font, size: f64): f64

The line height in pixels.

The example for this item is shown with the ones above: image-Font.salam

`GlyphAdvance`

func GlyphAdvance(f: Font, glyph: int): int

A glyph's advance in font units.

The example for this item is shown with the ones above: image-Font.salam

`KernAdvance`

func KernAdvance(f: Font, glyph1: int, glyph2: int): int

The spacing adjustment of two glyphs, like AV.

The example for this item is shown with the ones above: image-Font.salam

`DecodeWebP`

func DecodeWebP(p: void*, n: int, ok &: bool): Image

Reads WebP from bytes, both lossy and lossless, with the transparency. From an animated WebP it returns the first frame. For broken data, ok becomes false.

The example for this item is shown with the ones above: image-Draw.salam

`EncodeWebP`

func EncodeWebP(img: Image): compress.ByteBuf

Encodes the image as lossless WebP; every pixel's color and alpha stays exact. For an empty image, or one larger than 16384 pixels, it returns an empty buffer.

The example for this item is shown with the ones above: image-Draw.salam

`EncodeWebPQuality`

func EncodeWebPQuality(img: Image, quality: int): compress.ByteBuf

Encodes the image as WebP with a quality from 0 to 100; quality 100 is the lossless WebP and anything lower makes a lossy WebP, which is much smaller for a photo. The transparency stays exact either way.

The example for this item is shown with the ones above: image-Draw.salam

`DrawTextCentered`

func DrawTextCentered(img &: Image, cx: f64, cy: f64, text: str, col: Color, f: Font, st: TextStyle): f64

Text centered on a point.

The example for this item is shown with the ones above: image-Font.salam

`DrawTextCenteredIn`

func DrawTextCenteredIn(img &: Image, text: str, col: Color, f: Font, st: TextStyle): f64

Text in the middle of the image.

The example for this item is shown with the ones above: image-Font.salam

`DrawTextInBox`

func DrawTextInBox(img &: Image, x: f64, y: f64, w: f64, h: f64, text: str, col: Color, f: Font, st: TextStyle, halign: int, valign: int): f64

Text in a box with a horizontal and a vertical alignment.

The example for this item is shown with the ones above: image-Font.salam

`DrawTextFitBox`

func DrawTextFitBox(img &: Image, x: f64, y: f64, w: f64, h: f64, text: str, col: Color, f: Font, st: TextStyle, fill: f64, max_size: f64): f64

Writes the text at the largest size that fits in a box, for titles and labels.

The example for this item is shown with the ones above: image-Font.salam

`DrawTextFitImage`

func DrawTextFitImage(img &: Image, text: str, col: Color, f: Font, st: TextStyle, fill: f64, max_size: f64): f64

Writes the text at the largest size over the whole image.

The example for this item is shown with the ones above: image-Font.salam

`IsGIF`

func IsGIF(p: void*, n: int): bool

The bytes are GIF.

The example for this item is shown with the ones above: image-Draw.salam

`DecodeGIF`

func DecodeGIF(p: void*, n: int, ok &: bool): Image

Reads a GIF from bytes. From an animated GIF it returns the first frame, and the transparent pixels get an alpha of zero. For broken data, ok becomes false.

The example for this item is shown with the ones above: image-Draw.salam

`OpenGIF`

func OpenGIF(path: str, ok &: bool): Image

Reads a GIF file.

The example for this item is shown with the ones above: image-Draw.salam

`EncodeGIF`

func EncodeGIF(img: Image): compress.ByteBuf

Encodes the image as GIF. If the image has 256 colors or fewer the colors stay exact; otherwise the best 256 colors are picked and put in their place with error diffusion. Pixels with an alpha below 128 become transparent.

The example for this item is shown with the ones above: image-Draw.salam

`SaveGIF`

func SaveGIF(img: Image, path: str): bool

Saves the image in a GIF file; it returns true if the writing worked.

The example for this item is shown with the ones above: image-Draw.salam

`New`

func New(width: int, height: int): Image

A new transparent image.

The example for this item is shown with the ones above: image-Draw.salam

`NewFilled`

func NewFilled(width: int, height: int, c: Color): Image

An image filled with one color.

The example for this item is shown with the ones above: image-Draw.salam

`Free`

func Free(img &: Image)

Frees the image.

The example for this item is shown with the ones above: image-Draw.salam

`Clone`

func Clone(img: Image): Image

An independent copy.

The example for this item is shown with the ones above: image-Draw.salam

`IsEmpty`

func IsEmpty(img: Image): bool

The image has no pixels.

The example for this item is shown with the ones above: image-Draw.salam

`InBounds`

func InBounds(img: Image, x: int, y: int): bool

The point is inside the image.

The example for this item is shown with the ones above: image-Draw.salam

`GetPixel`

func GetPixel(img: Image, x: int, y: int): Color

A pixel's color.

The example for this item is shown with the ones above: image-Draw.salam

`SetPixel`

func SetPixel(img &: Image, x: int, y: int, c: Color)

Sets a pixel's color.

The example for this item is shown with the ones above: image-Draw.salam

`BlendPixel`

func BlendPixel(img &: Image, x: int, y: int, c: Color)

Blends a color with its alpha onto a pixel.

The example for this item is shown with the ones above: image-Draw.salam

`Fill`

func Fill(img &: Image, c: Color)

Makes everything one color.

The example for this item is shown with the ones above: image-Draw.salam

`FillHex`

func FillHex(img &: Image, hex: str)

Fills everything with a hex color, like #202040.

The example for this item is shown with the ones above: image-Draw.salam

`ParseFontIndex`

func ParseFontIndex(p: void*, n: int, index: int, ok &: bool): Font

Font number i of a TTC collection.

The example for this item is shown with the ones above: image-Font.salam

`ParseFont`

func ParseFont(p: void*, n: int, ok &: bool): Font

A font from bytes.

The example for this item is shown with the ones above: image-Font.salam

`LoadFont`

func LoadFont(path: str, ok &: bool): Font

A font from a .ttf or .otf file.

The example for this item is shown with the ones above: image-Font.salam

`LoadFontIndex`

func LoadFontIndex(path: str, index: int, ok &: bool): Font

Font number i of a TTC file.

The example for this item is shown with the ones above: image-Font.salam

`FreeFont`

func FreeFont(f &: Font)

Frees the font.

The example for this item is shown with the ones above: image-Font.salam

`FontValid`

func FontValid(f: Font): bool

The font is valid.

The example for this item is shown with the ones above: image-Font.salam

`IsCFFFont`

func IsCFFFont(p: void*, n: int): bool

The font has CFF outlines; that kind is not supported.

The example for this item is shown with the ones above: image-Font.salam

`UnitsPerEm`

func UnitsPerEm(f: Font): int

The units per em.

The example for this item is shown with the ones above: image-Font.salam

`NumGlyphs`

func NumGlyphs(f: Font): int

The number of glyphs.

The example for this item is shown with the ones above: image-Font.salam

`EncodeJPEG`

func EncodeJPEG(img: Image, quality: int): compress.ByteBuf

The image as JPEG with a quality from 1 to 100.

The example for this item is shown with the ones above: image-Draw.salam

`SaveJPEG`

func SaveJPEG(img: Image, path: str, quality: int): bool

Saves a JPEG.

The example for this item is shown with the ones above: image-Draw.salam

`DecodeJPEG`

func DecodeJPEG(p: void*, n: int, ok &: bool): Image

Reads a JPEG from bytes: baseline and progressive JPEG, gray, color and CMYK, with any chroma subsampling. The pixels are the ones libjpeg gives.

The example for this item is shown with the ones above: image-Draw.salam

`OpenJPEG`

func OpenJPEG(path: str, ok &: bool): Image

Reads a JPEG file.

The example for this item is shown with the ones above: image-Draw.salam

`GlyphIndex`

func GlyphIndex(f: Font, codepoint: int): int

The glyph number for a Unicode code point.

The example for this item is shown with the ones above: image-Font.salam

`ComputeHistogram`

func ComputeHistogram(img: Image): Histogram

The image's histogram.

The example for this item is shown with the ones above: image-Edit.salam

`HistogramGet`

func HistogramGet(channel: void*, bucket: int): int

How many have one value in one channel.

The example for this item is shown with the ones above: image-Edit.salam

`HistogramFree`

func HistogramFree(h &: Histogram)

Frees it.

The example for this item is shown with the ones above: image-Edit.salam

`Diff`

func Diff(a: Image, b: Image): Image

The absolute pixel by pixel difference.

The example for this item is shown with the ones above: image-Edit.salam

`MeanAbsError`

func MeanAbsError(a: Image, b: Image): f64

The mean absolute error of two images.

The example for this item is shown with the ones above: image-Edit.salam

`PSNR`

func PSNR(a: Image, b: Image): f64

The signal to noise ratio in decibels; higher means more alike.

The example for this item is shown with the ones above: image-Edit.salam

`DrawGlyphStyled`

func DrawGlyphStyled(img &: Image, glyph: int, x: f64, y: f64, col: Color, f: Font, st: TextStyle)

One glyph by its number.

The example for this item is shown with the ones above: image-Font.salam

`DrawCodepointStyled`

func DrawCodepointStyled(img &: Image, codepoint: int, x: f64, y: f64, col: Color, f: Font, st: TextStyle): f64

One glyph by its code point.

The example for this item is shown with the ones above: image-Font.salam

`DrawTextStyled`

func DrawTextStyled(img &: Image, x: f64, y: f64, text: str, col: Color, f: Font, st: TextStyle): f64

Text with a style; Persian is shaped and laid out right to left.

The example for this item is shown with the ones above: image-Font.salam

`DrawTextTTF`

func DrawTextTTF(img &: Image, x: f64, y: f64, text: str, col: Color, f: Font, size: f64): f64

Text with a font and a size; it returns the advance.

The example for this item is shown with the ones above: image-Font.salam

`TextWidthStyled`

func TextWidthStyled(f: Font, text: str, st: TextStyle): f64

The width of a text with a style.

The example for this item is shown with the ones above: image-Font.salam

`TextWidthTTF`

func TextWidthTTF(f: Font, text: str, size: f64): f64

The width of a text in a font.

The example for this item is shown with the ones above: image-Font.salam

`FindSystemFont`

func FindSystemFont(): str

The path of a system font.

The example for this item is shown with the ones above: image-Font.salam

`FindArabicFont`

func FindArabicFont(): str

The path of a font with Arabic and Persian letters.

The example for this item is shown with the ones above: image-Font.salam

`LoadSystemFont`

func LoadSystemFont(ok &: bool): Font

Loads a system font.

The example for this item is shown with the ones above: image-Font.salam

`ShapeArabic`

func ShapeArabic(text: str): str

Turns the Persian and Arabic letters into their connected initial, medial and final shapes.

The example for this item is shown with the ones above: image-Bidi.salam

`IsRTLText`

func IsRTLText(text: str): bool

The text has a right to left character.

The example for this item is shown with the ones above: image-Bidi.salam

`BaseDirection`

func BaseDirection(text: str): int

A text's base direction from its first strong letter, by the Unicode bidirectional algorithm.

The example for this item is shown with the ones above: image-Bidi.salam

`ToVisualOrder`

func ToVisualOrder(text: str, dir: int): str

Puts the text in display order, for drawing.

The example for this item is shown with the ones above: image-Bidi.salam

`DetectFormat`

func DetectFormat(p: void*, n: int): int

Works the format out from the first bytes.

The example for this item is shown with the ones above: image-Draw.salam

`FormatFromExt`

func FormatFromExt(path: str): int

The format from a file extension.

The example for this item is shown with the ones above: image-Draw.salam

`Decode`

func Decode(p: void*, n: int, ok &: bool): Image

Reads any supported format from bytes.

The example for this item is shown with the ones above: image-Draw.salam

`Open`

func Open(path: str, ok &: bool): Image

Reads any supported format from a file.

The example for this item is shown with the ones above: image-Draw.salam

`FlattenAlpha`

func FlattenAlpha(img: Image, bg: Color): Image

Flattens the transparency onto a background color, before saving a JPEG.

The example for this item is shown with the ones above: image-Draw.salam

`Convert`

func Convert(img: Image, format: int): Image

Prepares the image for a format; for JPEG it takes the transparency away.

The example for this item is shown with the ones above: image-Draw.salam

`Encode`

func Encode(img: Image, format: int, quality: int): compress.ByteBuf

Turns the image into bytes in a format with a quality.

The example for this item is shown with the ones above: image-Draw.salam

`SaveQuality`

func SaveQuality(img: Image, path: str, quality: int): bool

Saves with a quality; the format comes from the extension. For WebP, quality 100 is lossless and anything lower is lossy.

The example for this item is shown with the ones above: image-Draw.salam

`Save`

func Save(img: Image, path: str): bool

Saves; the format comes from the file extension. JPEG and WebP are saved at quality 90.

The example for this item is shown with the ones above: image-Draw.salam

`GlyphBox`

func GlyphBox(f: Font, glyph: int, x0 &: int, y0 &: int, x1 &: int, y1 &: int): bool

A glyph's box in font units.

The example for this item is shown with the ones above: image-Font.salam

`GlyphHasOutline`

func GlyphHasOutline(f: Font, glyph: int): bool

The glyph has an outline; it is not a space.

The example for this item is shown with the ones above: image-Font.salam

`DrawText`

func DrawText(img &: Image, x: int, y: int, text: str, c: Color, scale: int)

Text with the simple pixel font and a magnification factor; it needs no font file and is only for Latin characters.

The example for this item is shown with the ones above: image-Draw.salam

`TextWidth`

func TextWidth(text: str, scale: int): int

The width of a text in the pixel font.

The example for this item is shown with the ones above: image-Draw.salam