From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/go/image%2Fdraw%2Findex.html | 85 ++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 devdocs/go/image%2Fdraw%2Findex.html (limited to 'devdocs/go/image%2Fdraw%2Findex.html') diff --git a/devdocs/go/image%2Fdraw%2Findex.html b/devdocs/go/image%2Fdraw%2Findex.html new file mode 100644 index 00000000..b44b2f3c --- /dev/null +++ b/devdocs/go/image%2Fdraw%2Findex.html @@ -0,0 +1,85 @@ +

Package draw

Overview

Package draw provides image composition functions.

+

See "The Go image/draw package" for an introduction to this package: https://golang.org/doc/articles/image_draw.html

Index

Examples

Drawer (FloydSteinberg)

Package files

draw.go

func Draw 

func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op)

Draw calls DrawMask with a nil mask.

+

func DrawMask 

func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)

DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.

+

type Drawer 1.2

Drawer contains the Draw method.

+
type Drawer interface {
+    // Draw aligns r.Min in dst with sp in src and then replaces the
+    // rectangle r in dst with the result of drawing src on dst.
+    Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
+}

FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error diffusion.

+
var FloydSteinberg Drawer = floydSteinberg{}

Example (FloydSteinberg) +

Code:

+const width = 130
+const height = 50
+
+im := image.NewGray(image.Rectangle{Max: image.Point{X: width, Y: height}})
+for x := 0; x < width; x++ {
+    for y := 0; y < height; y++ {
+        dist := math.Sqrt(math.Pow(float64(x-width/2), 2)/3+math.Pow(float64(y-height/2), 2)) / (height / 1.5) * 255
+        var gray uint8
+        if dist > 255 {
+            gray = 255
+        } else {
+            gray = uint8(dist)
+        }
+        im.SetGray(x, y, color.Gray{Y: 255 - gray})
+    }
+}
+pi := image.NewPaletted(im.Bounds(), []color.Color{
+    color.Gray{Y: 255},
+    color.Gray{Y: 160},
+    color.Gray{Y: 70},
+    color.Gray{Y: 35},
+    color.Gray{Y: 0},
+})
+
+draw.FloydSteinberg.Draw(pi, im.Bounds(), im, image.Point{})
+shade := []string{" ", "░", "▒", "▓", "█"}
+for i, p := range pi.Pix {
+    fmt.Print(shade[p])
+    if (i+1)%width == 0 {
+        fmt.Print("\n")
+    }
+}
+

type Image

Image is an image.Image with a Set method to change a single pixel.

+
type Image interface {
+    image.Image
+    Set(x, y int, c color.Color)
+}

type Op

Op is a Porter-Duff compositing operator.

+
type Op int
const (
+    // Over specifies ``(src in mask) over dst''.
+    Over Op = iota
+    // Src specifies ``src in mask''.
+    Src
+)

func (Op) Draw 1.2 

func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)

Draw implements the Drawer interface by calling the Draw function with this Op.

+

type Quantizer 1.2

Quantizer produces a palette for an image.

+
type Quantizer interface {
+    // Quantize appends up to cap(p) - len(p) colors to p and returns the
+    // updated palette suitable for converting m to a paletted image.
+    Quantize(p color.Palette, m image.Image) color.Palette
+}

type RGBA64Image 1.17

RGBA64Image extends both the Image and image.RGBA64Image interfaces with a SetRGBA64 method to change a single pixel. SetRGBA64 is equivalent to calling Set, but it can avoid allocations from converting concrete color types to the color.Color interface type.

+
type RGBA64Image interface {
+    image.RGBA64Image
+    Set(x, y int, c color.Color)
+    SetRGBA64(x, y int, c color.RGBA64)
+}
+

+ © Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
+ http://golang.org/pkg/image/draw/ +

+
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