gg

package module
v1.1.3 Latest Latest
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 Go to latest Published: Jul 13, 2024 License: MIT Imports: 26 Imported by: 57

README

Go Graphics

gg is a library for rendering 2D graphics in pure Go.

Stars

Installation

go get -u github.com/FloatTech/gg

Alternatively, you may use gopkg.in to grab a specific major-version:

go get -u github.com/FloatTech/gg.v1

Documentation

Hello, Circle!

Look how easy!

package main

import "github.com/FloatTech/gg"

func main() {
    dc := gg.NewContext(1000, 1000)
    dc.DrawCircle(500, 500, 400)
    dc.SetRGB(0, 0, 0)
    dc.Fill()
    dc.SavePNG("out.png")
}

Examples

There are lots of examples included. They're mostly for testing the code, but they're good for learning, too.

Examples

Creating Contexts

There are a few ways of creating a context.

NewContext(width, height int) *Context
NewContextForImage(im image.Image) *Context
NewContextForRGBA(im *image.RGBA) *Context

Drawing Functions

Ever used a graphics library that didn't have functions for drawing rectangles or circles? What a pain!

DrawPoint(x, y, r float64)
DrawLine(x1, y1, x2, y2 float64)
DrawRectangle(x, y, w, h float64)
DrawRoundedRectangle(x, y, w, h, r float64)
DrawCircle(x, y, r float64)
DrawArc(x, y, r, angle1, angle2 float64)
DrawEllipse(x, y, rx, ry float64)
DrawEllipticalArc(x, y, rx, ry, angle1, angle2 float64)
DrawRegularPolygon(n int, x, y, r, rotation float64)
DrawImage(im image.Image, x, y int)
DrawImageAnchored(im image.Image, x, y int, ax, ay float64)
SetPixel(x, y int)

MoveTo(x, y float64)
LineTo(x, y float64)
QuadraticTo(x1, y1, x2, y2 float64)
CubicTo(x1, y1, x2, y2, x3, y3 float64)
ClosePath()
ClearPath()
NewSubPath()

Clear()
Stroke()
Fill()
StrokePreserve()
FillPreserve()

It is often desired to center an image at a point. Use DrawImageAnchored with ax and ay set to 0.5 to do this. Use 0 to left or top align. Use 1 to right or bottom align. DrawStringAnchored does the same for text, so you don't need to call MeasureString yourself.

Text Functions

It will even do word wrap for you!

DrawString(s string, x, y float64)
DrawStringAnchored(s string, x, y, ax, ay float64)
DrawStringWrapped(s string, x, y, ax, ay, width, lineSpacing float64, align Align)
MeasureString(s string) (w, h float64)
MeasureMultilineString(s string, lineSpacing float64) (w, h float64)
WordWrap(s string, w float64) []string
SetFontFace(fontFace font.Face)
LoadFontFace(path string, points float64) error

Color Functions

Colors can be set in several different ways for your convenience.

SetRGB(r, g, b float64)
SetRGBA(r, g, b, a float64)
SetRGB255(r, g, b int)
SetRGBA255(r, g, b, a int)
SetColor(c color.Color)
SetHexColor(x string)

Stroke & Fill Options

SetLineWidth(lineWidth float64)
SetLineCap(lineCap LineCap)
SetLineJoin(lineJoin LineJoin)
SetDash(dashes ...float64)
SetDashOffset(offset float64)
SetFillRule(fillRule FillRule)

Gradients & Patterns

gg supports linear, radial and conic gradients and surface patterns. You can also implement your own patterns.

SetFillStyle(pattern Pattern)
SetStrokeStyle(pattern Pattern)
NewSolidPattern(color color.Color)
NewLinearGradient(x0, y0, x1, y1 float64)
NewRadialGradient(x0, y0, r0, x1, y1, r1 float64)
NewConicGradient(cx, cy, deg float64)
NewSurfacePattern(im image.Image, op RepeatOp)

Transformation Functions

Identity()
Translate(x, y float64)
Scale(x, y float64)
Rotate(angle float64)
Shear(x, y float64)
ScaleAbout(sx, sy, x, y float64)
RotateAbout(angle, x, y float64)
ShearAbout(sx, sy, x, y float64)
TransformPoint(x, y float64) (tx, ty float64)
InvertY()

It is often desired to rotate or scale about a point that is not the origin. The functions RotateAbout, ScaleAbout, ShearAbout are provided as a convenience.

InvertY is provided in case Y should increase from bottom to top vs. the default top to bottom.

Stack Functions

Save and restore the state of the context. These can be nested.

Push()
Pop()

Clipping Functions

Use clipping regions to restrict drawing operations to an area that you defined using paths.

Clip()
ClipPreserve()
ResetClip()
AsMask() *image.Alpha
SetMask(mask *image.Alpha)
InvertMask()

Helper Functions

Sometimes you just don't want to write these yourself.

Radians(degrees float64) float64
Degrees(radians float64) float64
LoadImage(path string) (image.Image, error)
LoadPNG(path string) (image.Image, error)
SavePNG(path string, im image.Image) error

Separator

Another Example

See the output of this example below.

package main

import "github.com/FloatTech/gg"

func main() {
	const S = 1024
	dc := gg.NewContext(S, S)
	dc.SetRGBA(0, 0, 0, 0.1)
	for i := 0; i < 360; i += 15 {
		dc.Push()
		dc.RotateAbout(gg.Radians(float64(i)), S/2, S/2)
		dc.DrawEllipse(S/2, S/2, S*7/16, S/8)
		dc.Fill()
		dc.Pop()
	}
	dc.SavePNG("out.png")
}

Ellipses

Documentation

Overview

Package gg provides a simple API for rendering 2D graphics in pure Go.

包 gg 提供了一个简单的API，用于在纯Go中渲染二维图形。

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Degrees 

func Degrees(radians float64) float64

角度

func GetWH 

func GetWH(path string) (int, int, error)

解析图片的宽高信息

func ImageToNRGBA 

func ImageToNRGBA(src image.Image) *image.NRGBA

image.Image 转为 image.NRGBA

func ImageToNRGBA64 

func ImageToNRGBA64(src image.Image) *image.NRGBA64

image.Image 转为 *image.NRGBA64

func ImageToRGBA 

func ImageToRGBA(src image.Image) *image.RGBA

image.Image 转为 image.RGBA

func ImageToRGBA64 

func ImageToRGBA64(src image.Image) *image.RGBA64

image.Image 转为 image.RGBA64

func LoadFontFace 

func LoadFontFace(path string, points float64) (face font.Face, err error)

LoadFontFace is a helper function to load the specified font file with the specified point size. Note that the returned `font.Face` objects are not thread safe and cannot be used in parallel across goroutines. You can usually just use the Context.LoadFontFace function instead of this package-level function.

LoadFontFace 是一个辅助函数，用于加载指定点大小的指定字体文件。 请注意，返回的 `font.Face` 对象不是线程安全的，不能跨 goroutine 并行使用。 您通常可以只使用 Context.LoadFontFace 函数而不是这个包级函数。

func LoadImage 

func LoadImage(path string) (image.Image, error)

加载指定路径的图像

func LoadJPG 

func LoadJPG(path string) (image.Image, error)

加载指定路径的 JPG 图像

func LoadPNG 

func LoadPNG(path string) (image.Image, error)

加载指定路径的 PNG 图像

func ParseFontFace added in v1.1.0 

func ParseFontFace(b []byte, points float64) (face font.Face, err error)

ParseFontFace 是一个辅助函数，用于加载指定点大小的指定字体文件。 请注意，返回的 `font.Face` 对象不是线程安全的，不能跨 goroutine 并行使用。 您通常可以只使用 Context.LoadFontFace 函数而不是这个包级函数。

func ParseHexColor 

func ParseHexColor(x string) (r, g, b, a int)

解析十六进制颜色

func Radians 

func Radians(degrees float64) float64

弧度

func SaveJPG 

func SaveJPG(path string, im image.Image, quality int) error

保存 JPG 图像

func SavePNG 

func SavePNG(path string, im image.Image) error

保存 PNG 图像

func TakeColor added in v1.1.3 

func TakeColor(img image.Image, k int) []color.RGBA

Takecolor 实现基于k-means算法的图像取色算法

Types

type Align 

type Align int
const (
	AlignLeft Align = iota
	AlignCenter
	AlignRight
)

type Context 

type Context struct {
	// contains filtered or unexported fields
}

func NewContext 

func NewContext(width, height int) *Context

NewContext creates a new image.RGBA with the specified width and height and prepares a context for rendering onto that image.

创建一个具有指定宽度和高度的新 image.RGBA 并准备渲染到该图像上的上下文。

func NewContextForImage 

func NewContextForImage(im image.Image) *Context

NewContextForImage copies the specified image into a new image.RGBA and prepares a context for rendering onto that image.

将指定图像复制到一个新的 image.RGBA 并准备渲染到该图像上的上下文。

func NewContextForRGBA 

func NewContextForRGBA(im *image.RGBA) *Context

NewContextForRGBA prepares a context for rendering onto the specified image. No copy is made.

准备渲染到指定图像的上下文。没有复制。

func (*Context) AsMask 

func (dc *Context) AsMask() *image.Alpha

AsMask returns an *image.Alpha representing the alpha channel of this context. This can be useful for advanced clipping operations where you first render the mask geometry and then use it as a mask.

返回一个 *image.Alpha 表示此上下文的 Alpha 通道。 这对于您首先渲染蒙版几何图形然后将其用作蒙版的高级裁剪操作很有用。

func (*Context) Brightness added in v1.1.1 

func (dc *Context) Brightness(per int)

Brightness 调整亮度 范围：±100%

func (*Context) Clear 

func (dc *Context) Clear()

Clear fills the entire image with the current color.

用当前颜色填充整个图像。

func (*Context) ClearPath 

func (dc *Context) ClearPath()

ClearPath clears the current path. There is no current point after this operation.

清除当前路径。 此操作后没有当前点。

func (*Context) Clip 

func (dc *Context) Clip()

Clip updates the clipping region by intersecting the current clipping region with the current path as it would be filled by dc.Fill(). The path is cleared after this operation.

通过与当前的相交来更新剪辑区域 使用当前路径剪切区域，因为它将由 dc.Fill() 填充。 此操作后路径被清除。

func (*Context) ClipPreserve 

func (dc *Context) ClipPreserve()

ClipPreserve updates the clipping region by intersecting the current clipping region with the current path as it would be filled by dc.Fill(). The path is preserved after this operation.

通过将当前剪辑区域与当前路径相交来更新剪辑区域，因为它将由 dc.Fill() 填充。 此操作后将保留路径。

func (*Context) ClosePath 

func (dc *Context) ClosePath()

ClosePath adds a line segment from the current point to the beginning of the current subpath. If there is no current point, this is a no-op.

添加从当前点到当前子路径开头的线段。 如果没有当前点，这是一个空操作。

func (*Context) Contrast added in v1.1.1 

func (dc *Context) Contrast(per int)

Contrast 调整对比度 范围：±100%

func (*Context) CubicTo 

func (dc *Context) CubicTo(x1, y1, x2, y2, x3, y3 float64)

CubicTo adds a cubic bezier curve to the current path starting at the current point. If there is no current point, it first performs MoveTo(x1, y1). Because freetype/raster does not support cubic beziers, this is emulated with many small line segments.

向当前路径添加一条三次贝塞尔曲线，从 当前点。 如果没有当前点，则首先执行 MoveTo(x1, y1) 因为 freetype/raster 不支持三次贝塞尔曲线， 这是用许多小线段模拟的。

func (*Context) DrawArc 

func (dc *Context) DrawArc(x, y, r, angle1, angle2 float64)

绘制弧线

func (*Context) DrawCircle 

func (dc *Context) DrawCircle(x, y, r float64)

绘制圆圈

func (*Context) DrawEllipse 

func (dc *Context) DrawEllipse(x, y, rx, ry float64)

绘制椭圆

func (*Context) DrawEllipticalArc 

func (dc *Context) DrawEllipticalArc(x, y, rx, ry, angle1, angle2 float64)

绘制椭圆弧

func (*Context) DrawImage 

func (dc *Context) DrawImage(im image.Image, x, y int)

DrawImage draws the specified image at the specified point.

在指定点绘制指定图像。

func (*Context) DrawImageAnchored 

func (dc *Context) DrawImageAnchored(im image.Image, x, y int, ax, ay float64)

DrawImageAnchored draws the specified image at the specified anchor point. The anchor point is x - w * ax, y - h * ay, where w, h is the size of the image. Use ax=0.5, ay=0.5 to center the image at the specified point.

在指定锚点处绘制指定图像。 锚点是x - w * ax, y - h * ay，其中w, h是图像的大小。 使用 ax=0.5, ay=0.5 使图像在指定点居中。

func (*Context) DrawLine 

func (dc *Context) DrawLine(x1, y1, x2, y2 float64)

绘制一条线

func (*Context) DrawPoint 

func (dc *Context) DrawPoint(x, y, r float64)

DrawPoint is like DrawCircle but ensures that a circle of the specified size is drawn regardless of the current transformation matrix. The position is still transformed, but not the shape of the point.

DrawPoint 与 DrawCircle 类似，但确保绘制指定大小的圆，而不管当前的变换矩阵如何。 位置仍然被改变，但不是点的形状。

func (*Context) DrawRectangle 

func (dc *Context) DrawRectangle(x, y, w, h float64)

绘制一个矩形 以x, y 坐标为起点进行绘制

func (*Context) DrawRegularPolygon 

func (dc *Context) DrawRegularPolygon(n int, x, y, r, rotation float64)

绘制正多边形

func (*Context) DrawRoundedRectangle 

func (dc *Context) DrawRoundedRectangle(x, y, w, h, r float64)

绘制一个圆角矩形 以x, y 坐标为起点进行绘制

func (*Context) DrawString 

func (dc *Context) DrawString(s string, x, y float64)

DrawString draws the specified text at the specified point.

在指定锚点绘制文本， x 为宽度的起点 y 为高度的终点

func (*Context) DrawStringAnchored 

func (dc *Context) DrawStringAnchored(s string, x, y, ax, ay float64)

DrawStringAnchored draws the specified text at the specified anchor point. The anchor point is x - w * ax, y - h * ay, where w, h is the size of the text. Use ax=0.5, ay=0.5 to center the text at the specified point.

在指定锚点处绘制指定文本。 锚点是 x - w * ax, y - h * ay，其中 w, h 是文本的大小。 使用 ax=0.5, ay=0.5 使文本在指定点居中。

func (*Context) DrawStringWrapped 

func (dc *Context) DrawStringWrapped(s string, x, y, ax, ay, width, lineSpacing float64, align Align)

DrawStringWrapped word-wraps the specified string to the given max width and then draws it at the specified anchor point using the given line spacing and text alignment.

将指定的字符串换行到给定的最大宽度， 然后使用给定的行距和文本对齐在指定的锚点处绘制它。

func (*Context) EncodeJPG 

func (dc *Context) EncodeJPG(w io.Writer, o *jpeg.Options) error

EncodeJPG encodes the image as a JPG and writes it to the provided io.Writer in JPEG 4:2:0 baseline format with the given options. Default parameters are used if a nil *jpeg.Options is passed.

将图像编码为JPG，并将其写入提供的 io.Writer 在 JPEG 4:2:0 基线格式中，使用给定选项。 如果为nil，则使用默认参数 *jpeg.Options 进行传递

func (*Context) EncodePNG 

func (dc *Context) EncodePNG(w io.Writer) error

EncodePNG encodes the image as a PNG and writes it to the provided io.Writer.

将图像编码为 PNG 并将其写入提供的 io.Writer

func (*Context) Fill 

func (dc *Context) Fill()

Fill fills the current path with the current color. Open subpaths are implicity closed. The path is cleared after this operation.

用当前颜色填充当前路径。 打开的子路径是隐式关闭的。 此操作后路径被清除。

func (*Context) FillPreserve 

func (dc *Context) FillPreserve()

FillPreserve fills the current path with the current color. Open subpaths are implicity closed. The path is preserved after this operation.

用当前颜色填充当前路径。 打开的子路径是隐式关闭的。 此操作后将保留路径。

func (*Context) FontHeight 

func (dc *Context) FontHeight() float64

返回字体高度

func (*Context) GetCurrentPoint 

func (dc *Context) GetCurrentPoint() (Point, bool)

GetCurrentPoint will return the current point and if there is a current point. The point will have been transformed by the context's transformation matrix.

返回当前点，如果存在当前点。 该点将通过上下文的变换矩阵进行变换。

func (*Context) H 

func (dc *Context) H() int

H 返回图像的高度 (以像素为单位)

func (*Context) Hash added in v1.1.0 

func (dc *Context) Hash() [md5.Size]byte

Hash 计算已绘制图片的md5

func (*Context) Height 

func (dc *Context) Height() int

Height returns the height of the image in pixels.

返回图像的高度（以像素为单位）

func (*Context) Identity 

func (dc *Context) Identity()

Identity resets the current transformation matrix to the identity matrix. This results in no translating, scaling, rotating, or shearing.

将当前变换矩阵重置为单位矩阵。 这不会导致平移、缩放、旋转或剪切。

func (*Context) Image 

func (dc *Context) Image() image.Image

Image returns the image that has been drawn by this context.

返回在此上下文中绘制的图像。

func (*Context) InvertMask 

func (dc *Context) InvertMask()

InvertMask inverts the alpha values in the current clipping mask such that a fully transparent region becomes fully opaque and vice versa.

反转当前剪贴蒙版中的 alpha 值，使完全透明的区域变得完全不透明，反之亦然。

func (*Context) InvertY 

func (dc *Context) InvertY()

InvertY flips the Y axis so that Y grows from bottom to top and Y=0 is at the bottom of the image.

反转Y轴，使Y从下到上增长，Y=0 位于图像的底部。

func (*Context) LineTo 

func (dc *Context) LineTo(x, y float64)

LineTo adds a line segment to the current path starting at the current point. If there is no current point, it is equivalent to MoveTo(x, y)

从当前点开始向当前路径添加一条线段。 如果没有当前点，则等价于 MoveTo(x, y)

func (*Context) LoadFontFace 

func (dc *Context) LoadFontFace(path string, points float64) error

Load the font from the specified path

加载指定路径的字体

func (*Context) LoadImage 

func (dc *Context) LoadImage(path string, x, y int) error

加载指定路径的图像并设定像素坐标

func (*Context) MeasureMultilineString 

func (dc *Context) MeasureMultilineString(s string, lineSpacing float64) (width, height float64)

具有度量多行字符串的公式

func (*Context) MeasureString 

func (dc *Context) MeasureString(s string) (w, h float64)

MeasureString returns the rendered width and height of the specified text given the current font face.

返回给定当前字体的指定文本的渲染宽度和高度。

func (*Context) MoveTo 

func (dc *Context) MoveTo(x, y float64)

MoveTo starts a new subpath within the current path starting at the specified point.

在当前路径中从指定点开始新的子路径。

func (*Context) NewSubPath 

func (dc *Context) NewSubPath()

NewSubPath starts a new subpath within the current path. There is no current point after this operation.

在当前路径中开始一个新的子路径。 此操作后没有当前点。

func (*Context) ParseFontFace added in v1.1.0 

func (dc *Context) ParseFontFace(data []byte, points float64) error

Load the font from bytes

加载 data 中的字体

func (*Context) Pop 

func (dc *Context) Pop()

Pop restores the last saved context state from the stack.

从堆栈中恢复上次保存的上下文状态。

func (*Context) Push 

func (dc *Context) Push()

Push saves the current state of the context for later retrieval. These can be nested.

保存上下文的当前状态以供以后检索。 这些可以嵌套。

func (*Context) QuadraticTo 

func (dc *Context) QuadraticTo(x1, y1, x2, y2 float64)

QuadraticTo adds a quadratic bezier curve to the current path starting at the current point. If there is no current point, it first performs MoveTo(x1, y1)

将二次贝塞尔曲线添加到从当前点开始的当前路径。 如果没有当前点，则首先执行 MoveTo(x1, y1)

func (*Context) ResetClip 

func (dc *Context) ResetClip()

ResetClip clears the clipping region.

清除剪裁区域。

func (*Context) Rotate 

func (dc *Context) Rotate(angle float64)

Rotate updates the current matrix with a anticlockwise rotation. Rotation occurs about the origin. Angle is specified in radians.

逆时针旋转更新当前矩阵。围绕原点发生旋转。 角度以弧度指定。

func (*Context) RotateAbout 

func (dc *Context) RotateAbout(angle, x, y float64)

RotateAbout updates the current matrix with a anticlockwise rotation. Rotation occurs about the specified point. Angle is specified in radians.

逆时针旋转更新当前矩阵。围绕指定点进行旋转。 角度以弧度指定。

func (*Context) SaveJPG 

func (dc *Context) SaveJPG(path string, quality int) error

SaveJPG encodes the image as a JPG and writes it to disk.

将图像编码为 JPG 并将其写入磁盘。

func (*Context) SavePNG 

func (dc *Context) SavePNG(path string) error

SavePNG encodes the image as a PNG and writes it to disk.

将图像编码为 PNG 并将其写入磁盘。

func (*Context) Scale 

func (dc *Context) Scale(x, y float64)

Scale updates the current matrix with a scaling factor. Scaling occurs about the origin.

使用缩放因子更新当前矩阵。缩放发生在原点附近。

func (*Context) ScaleAbout 

func (dc *Context) ScaleAbout(sx, sy, x, y float64)

ScaleAbout updates the current matrix with a scaling factor. Scaling occurs about the specified point.

使用缩放因子更新当前矩阵。在指定点附近发生缩放。

func (*Context) SetColor 

func (dc *Context) SetColor(c color.Color)

SetColor sets the current color(for both fill and stroke).

设置当前颜色（用于填充和笔划）

func (*Context) SetDash 

func (dc *Context) SetDash(dashes ...float64)

SetDash sets the current dash pattern to use. Call with zero arguments to disable dashes. The values specify the lengths of each dash, with alternating on and off lengths.

设置要使用的当前破折号图案。使用零参数调用 禁用破折号。这些值指定每个破折号的长度，包括： 交替开启和关闭长度。

func (*Context) SetDashOffset 

func (dc *Context) SetDashOffset(offset float64)

SetDashOffset sets the initial offset into the dash pattern to use when stroking dashed paths.

将初始偏移量设置为虚线模式，以在描边虚线路径时使用。

func (*Context) SetFillRule 

func (dc *Context) SetFillRule(fillRule FillRule)

设置填充规则

func (*Context) SetFillRuleEvenOdd 

func (dc *Context) SetFillRuleEvenOdd()

设置填充规则偶数奇数

func (*Context) SetFillRuleWinding 

func (dc *Context) SetFillRuleWinding()

设置填充规则绕组

func (*Context) SetFillStyle 

func (dc *Context) SetFillStyle(pattern Pattern)

SetFillStyle sets current fill style

设置当前填充样式

func (*Context) SetFontFace 

func (dc *Context) SetFontFace(fontFace font.Face)

设置字体面

func (*Context) SetHexColor 

func (dc *Context) SetHexColor(x string)

SetHexColor sets the current color using a hex string. The leading pound sign (#) is optional. Both 3- and 6-digit variations are supported. 8 digits may be provided to set the alpha value as well.

使用十六进制字符串设置当前颜色。前置的 符号（#）是可选的。支持3位数和6位数的变体。8位数字 也可以提供设置 alpha 值。

func (*Context) SetLineCap 

func (dc *Context) SetLineCap(lineCap LineCap)

设置线帽

func (*Context) SetLineCapButt 

func (dc *Context) SetLineCapButt()

设置线帽对齐

func (*Context) SetLineCapRound 

func (dc *Context) SetLineCapRound()

设置线帽圆

func (*Context) SetLineCapSquare 

func (dc *Context) SetLineCapSquare()

设置线帽正方形

func (*Context) SetLineJoin 

func (dc *Context) SetLineJoin(lineJoin LineJoin)

设置线帽连接

func (*Context) SetLineJoinBevel 

func (dc *Context) SetLineJoinBevel()

/ 设置线帽连接斜面

func (*Context) SetLineJoinRound 

func (dc *Context) SetLineJoinRound()

设置线帽连接圆

func (*Context) SetLineWidth 

func (dc *Context) SetLineWidth(lineWidth float64)

设置线宽

func (*Context) SetMask 

func (dc *Context) SetMask(mask *image.Alpha) error

SetMask allows you to directly set the *image.Alpha to be used as a clipping mask. It must be the same size as the context, else an error is returned and the mask is unchanged.

允许您直接设置 *image.Alpha 用作剪贴蒙版。 它必须与上下文大小相同，否则返回错误并且掩码不变。

func (*Context) SetPixel 

func (dc *Context) SetPixel(x, y int)

SetPixel sets the color of the specified pixel using the current color.

使用当前颜色设置指定像素的颜色。

func (*Context) SetRGB 

func (dc *Context) SetRGB(r, g, b float64)

SetRGB sets the current color. r, g, b values should be between 0 and 1, inclusive. Alpha will be set to 1 (fully opaque).

设置当前颜色。 r、g、b 值应介于 0 和 1 之间， 包括。 Alpha 将设置为 1（完全不透明）。

func (*Context) SetRGB255 

func (dc *Context) SetRGB255(r, g, b int)

SetRGB255 sets the current color. r, g, b values should be between 0 and 255, inclusive. Alpha will be set to 255 (fully opaque).

设置当前颜色。 r、g、b 值应介于 0 和 255 之间，包括。 Alpha 将设置为 255（完全不透明）。

func (*Context) SetRGBA 

func (dc *Context) SetRGBA(r, g, b, a float64)

SetRGBA sets the current color. r, g, b, a values should be between 0 and 1, inclusive.

SetRGBA 设置当前颜色。 r、g、b、a 值应介于 0 和 1 之间， 包括。

func (*Context) SetRGBA255 

func (dc *Context) SetRGBA255(r, g, b, a int)

SetRGBA255 sets the current color. r, g, b, a values should be between 0 and 255, inclusive.

设置当前颜色。r、g、b、a 值应介于 0 和 255，包括在内。

func (*Context) SetScaleApproxBiLinear 

func (dc *Context) SetScaleApproxBiLinear()

设置比例近似双线性

func (*Context) SetScaleBiLinear 

func (dc *Context) SetScaleBiLinear()

设置比例双线性

func (*Context) SetScaleCatmullRom 

func (dc *Context) SetScaleCatmullRom()

设置比例为 CatmullRom

func (*Context) SetScaleNearestNeighbor 

func (dc *Context) SetScaleNearestNeighbor()

设置最近邻的比例

func (*Context) SetScaleStyle 

func (dc *Context) SetScaleStyle(s ScaleStyle)

设置比例样式

func (*Context) SetStrokeStyle 

func (dc *Context) SetStrokeStyle(pattern Pattern)

SetStrokeStyle sets current stroke style

设置当前笔划样式

func (*Context) Shear 

func (dc *Context) Shear(x, y float64)

Shear updates the current matrix with a shearing angle. Shearing occurs about the origin.

用剪切角更新当前矩阵。剪切发生在原点附近。

func (*Context) ShearAbout 

func (dc *Context) ShearAbout(sx, sy, x, y float64)

ShearAbout updates the current matrix with a shearing angle. Shearing occurs about the specified point.

用剪切角更新当前矩阵。剪切发生在指定点附近。

func (*Context) String added in v1.1.0 

func (dc *Context) String() string

String 以哈希形式打印已绘制图片的 md5, 形如 <gg.Context [md5]>

func (*Context) Stroke 

func (dc *Context) Stroke()

Stroke strokes the current path with the current color, line width, line cap, line join and dash settings. The path is cleared after this operation.

使用当前颜色、线宽、线帽、线连接和虚线设置描边当前路径。 此操作后路径被清除。

func (*Context) StrokePreserve 

func (dc *Context) StrokePreserve()

StrokePreserve strokes the current path with the current color, line width, line cap, line join and dash settings. The path is preserved after this operation.

使用当前颜色、线宽、线帽、线连接和虚线设置描边当前路径。 此操作后将保留路径。

func (*Context) TakeColor added in v1.1.3 

func (dc *Context) TakeColor(k int) []color.RGBA

Takecolor 实现基于k-means算法的图像取色算法

func (*Context) TransformPoint 

func (dc *Context) TransformPoint(x, y float64) (tx, ty float64)

TransformPoint multiplies the specified point by the current matrix, returning a transformed position.

将指定点乘以当前矩阵，返回转换后的位置。

func (*Context) Translate 

func (dc *Context) Translate(x, y float64)

Translate updates the current matrix with a translation.

使用平移更新当前矩阵。

func (*Context) W 

func (dc *Context) W() int

W 返回图像的宽度 (以像素为单位)

func (*Context) Width 

func (dc *Context) Width() int

Width returns the width of the image in pixels.

返回图像的宽度（以像素为单位）

func (*Context) WordWrap 

func (dc *Context) WordWrap(s string, w float64) []string

WordWrap wraps the specified string to the given max width and current font face.

将指定的字符串换行到给定的最大宽度和当前字体。

type FillRule 

type FillRule int
const (
	FillRuleWinding FillRule = iota
	FillRuleEvenOdd
)

type Gradient 

type Gradient interface {
	Pattern
	AddColorStop(offset float64, color color.Color)
}

func NewConicGradient 

func NewConicGradient(cx, cy, deg float64) Gradient

func NewLinearGradient 

func NewLinearGradient(x0, y0, x1, y1 float64) Gradient

func NewRadialGradient 

func NewRadialGradient(x0, y0, r0, x1, y1, r1 float64) Gradient

type LineCap 

type LineCap int
const (
	LineCapRound LineCap = iota
	LineCapButt
	LineCapSquare
)

type LineJoin 

type LineJoin int
const (
	LineJoinRound LineJoin = iota
	LineJoinBevel
)

type Matrix 

type Matrix struct {
	XX, YX, XY, YY, X0, Y0 float64
}

func Identity 

func Identity() Matrix

func Rotate 

func Rotate(angle float64) Matrix

func Scale 

func Scale(x, y float64) Matrix

func Shear 

func Shear(x, y float64) Matrix

func Translate 

func Translate(x, y float64) Matrix

func (Matrix) Multiply 

func (a Matrix) Multiply(b Matrix) Matrix

func (Matrix) Rotate 

func (a Matrix) Rotate(angle float64) Matrix

func (Matrix) Scale 

func (a Matrix) Scale(x, y float64) Matrix

func (Matrix) Shear 

func (a Matrix) Shear(x, y float64) Matrix

func (Matrix) TransformPoint 

func (a Matrix) TransformPoint(x, y float64) (tx, ty float64)

func (Matrix) TransformVector 

func (a Matrix) TransformVector(x, y float64) (tx, ty float64)

func (Matrix) Translate 

func (a Matrix) Translate(x, y float64) Matrix

type Pattern 

type Pattern interface {
	ColorAt(x, y int) color.Color
}

func NewSolidPattern 

func NewSolidPattern(color color.Color) Pattern

func NewSurfacePattern 

func NewSurfacePattern(im image.Image, op RepeatOp) Pattern

type Point 

type Point struct {
	X, Y float64
}

func CubicBezier 

func CubicBezier(x0, y0, x1, y1, x2, y2, x3, y3 float64) []Point

func QuadraticBezier 

func QuadraticBezier(x0, y0, x1, y1, x2, y2 float64) []Point

func (Point) Distance 

func (a Point) Distance(b Point) float64

func (Point) Fixed 

func (a Point) Fixed() fixed.Point26_6

func (Point) Interpolate 

func (a Point) Interpolate(b Point, t float64) Point

type RepeatOp 

type RepeatOp int
const (
	RepeatBoth RepeatOp = iota
	RepeatX
	RepeatY
	RepeatNone
)

type ScaleStyle 

type ScaleStyle int

ScaleStyle determines the way image pixels are interpolated when scaled. See 

https://pkg.go.dev/golang.org/x/image/draw

for the corresponding interpolators.

确定缩放时图像像素的插值方式。 请看 https://pkg.go.dev/golang.org/x/image/draw 对应的插值器。 

const (
	// BiLinear is the tent kernel. It is slow, but usually gives high quality
	// results.
	//
	// BiLinear 是帐篷内核。 它很慢，但通常会产生高质量的结果。
	BiLinear ScaleStyle = iota

	// ApproxBiLinear is a mixture of the nearest neighbor and bi-linear
	// interpolators. It is fast, but usually gives medium quality results.
	//
	// It implements bi-linear interpolation when upscaling and a bi-linear
	// blend of the 4 nearest neighbor pixels when downscaling. This yields
	// nicer quality than nearest neighbor interpolation when upscaling, but
	// the time taken is independent of the number of source pixels, unlike the
	// bi-linear interpolator. When downscaling a large image, the performance
	// difference can be significant.
	//
	// ApproxBiLinear 是最近邻和双线性插值器的混合。 它速度很快，但通常会给出中等质量的结果。
	// 它在放大时实现双线性插值，在缩小时实现 4 个最近邻像素的双线性混合。
	// 这在放大时产生比最近邻插值更好的质量，但与双线性插值器不同，所花费的时间与源像素的数量无关。
	// 缩小大图像时，性能差异可能很大。
	ApproxBiLinear

	// NearestNeighbor is the nearest neighbor interpolator. It is very fast,
	// but usually gives very low quality results. When scaling up, the result
	// will look 'blocky'.
	//
	// NearestNeighbor 是最近邻插值器。 它非常快，但通常会给出非常低质量的结果。
	// 放大时，结果将看起来“块状”。
	NearestNeighbor

	// CatmullRom is the Catmull-Rom kernel. It is very slow, but usually gives
	// very high quality results.
	//
	// It is an instance of the more general cubic BC-spline kernel with parameters
	// B=0 and C=0.5. See Mitchell and Netravali, "Reconstruction Filters in
	// Computer Graphics", Computer Graphics, Vol. 22, No. 4, pp. 221-228.
	//
	// CatmullRom 是 Catmull-Rom 内核。 它很慢，但通常会给出非常高质量的结果。
	// 它是参数 B=0 和 C=0.5 的更一般的三次 BC 样条核的实例。
	// 参见 Mitchell 和 Netravali，“计算机图形学中的重构过滤器”，
	// 计算机图形学，卷.22，第 4 期，第 221-228 页。
	CatmullRom
)

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