nanovgo

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 Go to latest Published: May 21, 2020 License: Zlib Imports: 14 Imported by: 0

README 

NanoVGo
=============

Pure golang implementation of `NanoVG <https://github.com/memononen/nanovg>`_. NanoVG is a vector graphics engine inspired by HTML5 Canvas API.

`DEMO <https://vizicist.github.io/nanovgo/>`_

API Reference
---------------

See `GoDoc <https://godoc.org/github.com/vizicist/nanovgo>`_

Porting Memo
--------------

* Root folder ``.go`` files

  Ported from NanoVG.

* ``fontstashmini/fontstash_mini.go``

  Ported from `fontstash <https://github.com/memononen/fontstash>`_. It includes only needed functions.

* ``fontstashmini/truetype``

  Copy from ``https://github.com/TheOnly92/fontstash.go`` (Public Domain)

License
----------

zlib license

Original (NanoVG) Author
---------------------------

* `Mikko Mononen <https://github.com/memononen>`_

Author
---------------

* `Yoshiki Shibukawa <https://github.com/vizicist>`_

Contribution
----------------

* Moriyoshi Koizumi
* @hnakamur2
* @mattn_jp
* @hagat
* @h_doxas
* FSX

Documentation

Index

Constants

View Source 
const (
	// Kappa90 is length proportional to radius of a cubic bezier handle for 90deg arcs.)
	Kappa90 float32 = 0.5522847493
	// PI of float32
	PI float32 = 3.14159265358979323846264338327
)

Variables

This section is empty.

Functions

func DegToRad 

func DegToRad(deg float32) float32

DegToRad converts degree to radian.

func RadToDeg 

func RadToDeg(rad float32) float32

RadToDeg converts radian to degree.

Types

type Align 

type Align int

Align is used for text location 

const (
	// AlignLeft (default) is used for horizontal align. Align text horizontally to left.
	AlignLeft Align = 1 << 0
	// AlignCenter is used for horizontal align. Align text horizontally to center.
	AlignCenter Align = 1 << 1
	// AlignRight is used for horizontal align. Align text horizontally to right.
	AlignRight Align = 1 << 2
	// AlignTop is used for vertical align. Align text vertically to top.
	AlignTop Align = 1 << 3
	// AlignMiddle is used for vertical align. Align text vertically to middle.
	AlignMiddle Align = 1 << 4
	// AlignBottom is used for vertical align. Align text vertically to bottom.
	AlignBottom Align = 1 << 5
	// AlignBaseline (default) is used for vertical align. Align text vertically to baseline.
	AlignBaseline Align = 1 << 6
)

type Color 

type Color struct {
	R, G, B, A float32
}

Color utils

Colors in NanoVGo are stored as unsigned ints in ABGR format.

func HSL 

func HSL(h, s, l float32) Color

HSL returns color value specified by hue, saturation and lightness. HSL values are all in range [0..1], alpha will be set to 255.

func HSLA 

func HSLA(h, s, l float32, a uint8) Color

HSLA returns color value specified by hue, saturation and lightness and alpha. HSL values are all in range [0..1], alpha in range [0..255]

func LerpRGBA 

func LerpRGBA(c0, c1 Color, u float32) Color

LerpRGBA linearly interpolates from color c0 to c1, and returns resulting color value.

func MONO 

func MONO(i, alpha uint8) Color

MONO returns color value specified by intensity value.

func MONOf 

func MONOf(i, alpha float32) Color

MONOf returns color value specified by intensity value.

func RGB 

func RGB(r, g, b uint8) Color

RGB returns a color value from red, green, blue values. Alpha will be set to 255 (1.0f).

func RGBA 

func RGBA(r, g, b, a uint8) Color

RGBA returns a color value from red, green, blue and alpha values.

func RGBAf 

func RGBAf(r, g, b, a float32) Color

RGBAf returns a color value from red, green, blue and alpha values.

func RGBf 

func RGBf(r, g, b float32) Color

RGBf returns a color value from red, green, blue values. Alpha will be set to 1.0f.

func (Color) ContrastingColor 

func (c Color) ContrastingColor() Color

ContrastingColor color

func (Color) HSLA 

func (c Color) HSLA() (h, s, l, a float32)

HSLA converter

func (Color) List 

func (c Color) List() []float32

List returns color value as array.

func (Color) Luminance 

func (c Color) Luminance() float32

Luminance value calculation

func (Color) PreMultiply 

func (c Color) PreMultiply() Color

PreMultiply preset alpha to each color.

func (Color) TransRGBA 

func (c Color) TransRGBA(a uint8) Color

TransRGBA sets transparency of a color value.

func (Color) TransRGBAf 

func (c Color) TransRGBAf(a float32) Color

TransRGBAf sets transparency of a color value.

type Context 

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

Context is an entry point object to use NanoVGo API and created by NewContext() function.

State Handling

NanoVG contains state which represents how paths will be rendered. The state contains transform, fill and stroke styles, text and font styles, and scissor clipping.

Render styles

Fill and stroke render style can be either a solid color or a paint which is a gradient or a pattern. Solid color is simply defined as a color value, different kinds of paints can be created using LinearGradient(), BoxGradient(), RadialGradient() and ImagePattern().

Current render style can be saved and restored using Save() and Restore().

Transforms

The paths, gradients, patterns and scissor region are transformed by an transformation matrix at the time when they are passed to the API. The current transformation matrix is a affine matrix: 

[sx kx tx]
[ky sy ty]
[ 0  0  1]

Where: sx,sy define scaling, kx,ky skewing, and tx,ty translation. The last row is assumed to be 0,0,1 and is not stored.

Apart from ResetTransform(), each transformation function first creates specific transformation matrix and pre-multiplies the current transformation by it.

Current coordinate system (transformation) can be saved and restored using Save() and Restore().

Images

NanoVG allows you to load jpg, png, psd, tga, pic and gif files to be used for rendering. In addition you can upload your own image. The image loading is provided by stb_image. The parameter imageFlags is combination of flags defined in ImageFlags.

Paints

NanoVG supports four types of paints: linear gradient, box gradient, radial gradient and image pattern. These can be used as paints for strokes and fills.

Scissoring

Scissoring allows you to clip the rendering into a rectangle. This is useful for various user interface cases like rendering a text edit or a timeline.

Paths

Drawing a new shape starts with BeginPath(), it clears all the currently defined paths. Then you define one or more paths and sub-paths which describe the shape. The are functions to draw common shapes like rectangles and circles, and lower level step-by-step functions, which allow to define a path curve by curve.

NanoVG uses even-odd fill rule to draw the shapes. Solid shapes should have counter clockwise winding and holes should have counter clockwise order. To specify winding of a path you can call PathWinding(). This is useful especially for the common shapes, which are drawn CCW.

Finally you can fill the path using current fill style by calling Fill(), and stroke it with current stroke style by calling Stroke().

The curve segments and sub-paths are transformed by the current transform.

Text

NanoVG allows you to load .ttf files and use the font to render text.

The appearance of the text can be defined by setting the current text style and by specifying the fill color. Common text and font settings such as font size, letter spacing and text align are supported. Font blur allows you to create simple text effects such as drop shadows.

At render time the font face can be set based on the font handles or name.

Font measure functions return values in local space, the calculations are carried in the same resolution as the final rendering. This is done because the text glyph positions are snapped to the nearest pixels sharp rendering.

The local space means that values are not rotated or scale as per the current transformation. For example if you set font size to 12, which would mean that line height is 16, then regardless of the current scaling and rotation, the returned line height is always 16. Some measures may vary because of the scaling since aforementioned pixel snapping.

While this may sound a little odd, the setup allows you to always render the same way regardless of scaling. I.e. following works regardless of scaling: 

vg.TextBounds(x, y, "Text me up.", bounds)
vg.BeginPath()
vg.RoundedRect(bounds[0],bounds[1], bounds[2]-bounds[0], bounds[3]-bounds[1])
vg.Fill()

Note: currently only solid color fill is supported for text.

func NewContext 

func NewContext(flags CreateFlags) (*Context, error)

NewContext makes new NanoVGo context that is entry point of this API

func (*Context) Arc 

func (c *Context) Arc(cx, cy, r, a0, a1 float32, dir Direction)

Arc creates new circle arc shaped sub-path. The arc center is at cx,cy, the arc radius is r, and the arc is drawn from angle a0 to a1, and swept in direction dir (CounterClockwise, or Clockwise). Angles are specified in radians.

func (*Context) ArcTo 

func (c *Context) ArcTo(x1, y1, x2, y2, radius float32)

ArcTo adds an arc segment at the corner defined by the last path point, and two specified points.

func (*Context) BeginFrame 

func (c *Context) BeginFrame(windowWidth, windowHeight int, devicePixelRatio float32)

BeginFrame begins drawing a new frame Calls to NanoVGo drawing API should be wrapped in Context.BeginFrame() & Context.EndFrame() Context.BeginFrame() defines the size of the window to render to in relation currently set viewport (i.e. glViewport on GL backends). Device pixel ration allows to control the rendering on Hi-DPI devices. For example, GLFW returns two dimension for an opened window: window size and frame buffer size. In that case you would set windowWidth/Height to the window size devicePixelRatio to: frameBufferWidth / windowWidth.

func (*Context) BeginPath 

func (c *Context) BeginPath()

BeginPath clears the current path and sub-paths.

func (*Context) BezierTo 

func (c *Context) BezierTo(c1x, c1y, c2x, c2y, x, y float32)

BezierTo adds cubic bezier segment from last point in the path via two control points to the specified point.

func (*Context) Block 

func (c *Context) Block(block func())

Block makes Save/Restore block.

func (*Context) CancelFrame 

func (c *Context) CancelFrame()

CancelFrame cancels drawing the current frame.

func (*Context) Circle 

func (c *Context) Circle(cx, cy, r float32)

Circle creates new circle shaped sub-path.

func (*Context) ClosePath 

func (c *Context) ClosePath()

ClosePath closes current sub-path with a line segment.

func (*Context) CreateFont 

func (c *Context) CreateFont(name, filePath string) int

CreateFont creates font by loading it from the disk from specified file name. Returns handle to the font.

func (*Context) CreateFontFromMemory 

func (c *Context) CreateFontFromMemory(name string, data []byte, freeData uint8) int

CreateFontFromMemory creates image by loading it from the specified memory chunk. Returns handle to the font.

func (*Context) CreateImage 

func (c *Context) CreateImage(filePath string, flags ImageFlags) int

CreateImage creates image by loading it from the disk from specified file name. Returns handle to the image.

func (*Context) CreateImageFromGoImage 

func (c *Context) CreateImageFromGoImage(imageFlag ImageFlags, img image.Image) int

CreateImageFromGoImage creates image by loading it from the specified image.Image object. Returns handle to the image.

func (*Context) CreateImageFromMemory 

func (c *Context) CreateImageFromMemory(flags ImageFlags, data []byte) int

CreateImageFromMemory creates image by loading it from the specified chunk of memory. Returns handle to the image.

func (*Context) CreateImageRGBA 

func (c *Context) CreateImageRGBA(w, h int, imageFlags ImageFlags, data []byte) int

CreateImageRGBA creates image from specified image data. Returns handle to the image.

func (*Context) CurrentTransform 

func (c *Context) CurrentTransform() TransformMatrix

CurrentTransform returns the top part (a-f) of the current transformation matrix. 

[a c e]
[b d f]
[0 0 1]

There should be space for 6 floats in the return buffer for the values a-f.

func (*Context) DebugDumpPathCache 

func (c *Context) DebugDumpPathCache()

DebugDumpPathCache prints cached path information to console

func (*Context) Delete 

func (c *Context) Delete()

Delete is called when tearing down NanoVGo context

func (*Context) DeleteImage 

func (c *Context) DeleteImage(img int)

DeleteImage deletes created image.

func (*Context) Ellipse 

func (c *Context) Ellipse(cx, cy, rx, ry float32)

Ellipse creates new ellipse shaped sub-path.

func (*Context) EndFrame 

func (c *Context) EndFrame()

EndFrame ends drawing flushing remaining render state.

func (*Context) Fill 

func (c *Context) Fill()

Fill fills the current path with current fill style.

func (*Context) FindFont 

func (c *Context) FindFont(name string) int

FindFont finds a loaded font of specified name, and returns handle to it, or -1 if the font is not found.

func (*Context) FontBlur 

func (c *Context) FontBlur() float32

FontBlur gets the font blur of current text style.

func (*Context) FontFace 

func (c *Context) FontFace() string

FontFace gets the font face name of current text style.

func (*Context) FontFaceID 

func (c *Context) FontFaceID() int

FontFaceID gets the font face id of current text style.

func (*Context) FontSize 

func (c *Context) FontSize() float32

FontSize gets the font size of current text style.

func (*Context) GlobalAlpha 

func (c *Context) GlobalAlpha() float32

GlobalAlpha gets the transparency applied to all rendered shapes.

func (*Context) ImageSize 

func (c *Context) ImageSize(img int) (int, int, error)

ImageSize returns the dimensions of a created image.

func (*Context) IntersectScissor 

func (c *Context) IntersectScissor(x, y, w, h float32)

IntersectScissor calculates intersects current scissor rectangle with the specified rectangle. The scissor rectangle is transformed by the current transform. Note: in case the rotation of previous scissor rect differs from the current one, the intersection will be done between the specified rectangle and the previous scissor rectangle transformed in the current transform space. The resulting shape is always rectangle.

func (*Context) LineCap 

func (c *Context) LineCap() LineCap

LineCap gets how the end of the line (cap) is drawn,

func (*Context) LineJoin 

func (c *Context) LineJoin() LineCap

LineJoin gets how sharp path corners are drawn.

func (*Context) LineTo 

func (c *Context) LineTo(x, y float32)

LineTo adds line segment from the last point in the path to the specified point.

func (*Context) MiterLimit 

func (c *Context) MiterLimit() float32

MiterLimit gets the miter limit of the stroke style.

func (*Context) MoveTo 

func (c *Context) MoveTo(x, y float32)

MoveTo starts new sub-path with specified point as first point.

func (*Context) PathWinding 

func (c *Context) PathWinding(winding Winding)

PathWinding sets the current sub-path winding, see Winding.

func (*Context) QuadTo 

func (c *Context) QuadTo(cx, cy, x, y float32)

QuadTo adds quadratic bezier segment from last point in the path via a control point to the specified point.

func (*Context) Rect 

func (c *Context) Rect(x, y, w, h float32)

Rect creates new rectangle shaped sub-path.

func (*Context) Reset 

func (c *Context) Reset()

Reset resets current render state to default values. Does not affect the render state stack.

func (*Context) ResetScissor 

func (c *Context) ResetScissor()

ResetScissor resets and disables scissoring.

func (*Context) ResetTransform 

func (c *Context) ResetTransform()

ResetTransform resets current transform to a identity matrix.

func (*Context) Restore 

func (c *Context) Restore()

Restore pops and restores current render state.

func (*Context) Rotate 

func (c *Context) Rotate(angle float32)

Rotate rotates current coordinate system. Angle is specified in radians.

func (*Context) RoundedRect 

func (c *Context) RoundedRect(x, y, w, h, r float32)

RoundedRect creates new rounded rectangle shaped sub-path.

func (*Context) Save 

func (c *Context) Save()

Save pushes and saves the current render state into a state stack. A matching Restore() must be used to restore the state.

func (*Context) Scale 

func (c *Context) Scale(x, y float32)

Scale scales the current coordinate system.

func (*Context) Scissor 

func (c *Context) Scissor(x, y, w, h float32)

Scissor sets the current scissor rectangle. The scissor rectangle is transformed by the current transform.

func (*Context) SetFillColor 

func (c *Context) SetFillColor(color Color)

SetFillColor sets current fill style to a solid color.

func (*Context) SetFillPaint 

func (c *Context) SetFillPaint(paint Paint)

SetFillPaint sets current fill style to a paint, which can be a one of the gradients or a pattern.

func (*Context) SetFontBlur 

func (c *Context) SetFontBlur(blur float32)

SetFontBlur sets the font blur of current text style.

func (*Context) SetFontFace 

func (c *Context) SetFontFace(font string)

SetFontFace sets the font face based on specified name of current text style.

func (*Context) SetFontFaceID 

func (c *Context) SetFontFaceID(font int)

SetFontFaceID sets the font face based on specified id of current text style.

func (*Context) SetFontSize 

func (c *Context) SetFontSize(size float32)

SetFontSize sets the font size of current text style.

func (*Context) SetGlobalAlpha 

func (c *Context) SetGlobalAlpha(alpha float32)

SetGlobalAlpha sets the transparency applied to all rendered shapes. Already transparent paths will get proportionally more transparent as well.

func (*Context) SetLineCap 

func (c *Context) SetLineCap(cap LineCap)

SetLineCap sets how the end of the line (cap) is drawn, Can be one of: Butt (default), Round, Squre.

func (*Context) SetLineJoin 

func (c *Context) SetLineJoin(joint LineCap)

SetLineJoin sets how sharp path corners are drawn. Can be one of Miter (default), Round, Bevel.

func (*Context) SetMiterLimit 

func (c *Context) SetMiterLimit(limit float32)

SetMiterLimit sets the miter limit of the stroke style. Miter limit controls when a sharp corner is beveled.

func (*Context) SetStrokeColor 

func (c *Context) SetStrokeColor(color Color)

SetStrokeColor sets current stroke style to a solid color.

func (*Context) SetStrokePaint 

func (c *Context) SetStrokePaint(paint Paint)

SetStrokePaint sets current stroke style to a paint, which can be a one of the gradients or a pattern.

func (*Context) SetStrokeWidth 

func (c *Context) SetStrokeWidth(width float32)

SetStrokeWidth sets the stroke width of the stroke style.

func (*Context) SetTextAlign 

func (c *Context) SetTextAlign(align Align)

SetTextAlign sets the text align of current text style.

func (*Context) SetTextLetterSpacing 

func (c *Context) SetTextLetterSpacing(spacing float32)

SetTextLetterSpacing sets the letter spacing of current text style.

func (*Context) SetTextLineHeight 

func (c *Context) SetTextLineHeight(lineHeight float32)

SetTextLineHeight sets the line height of current text style.

func (*Context) SetTransform 

func (c *Context) SetTransform(t TransformMatrix)

SetTransform premultiplies current coordinate system by specified matrix.

func (*Context) SetTransformByValue 

func (c *Context) SetTransformByValue(a, b, cc, d, e, f float32)

SetTransformByValue premultiplies current coordinate system by specified matrix. The parameters are interpreted as matrix as follows: 

[a c e]
[b d f]
[0 0 1]

func (*Context) SkewX 

func (c *Context) SkewX(angle float32)

SkewX skews the current coordinate system along X axis. Angle is specified in radians.

func (*Context) SkewY 

func (c *Context) SkewY(angle float32)

SkewY skews the current coordinate system along Y axis. Angle is specified in radians.

func (*Context) Stroke 

func (c *Context) Stroke()

Stroke draws the current path with current stroke style.

func (*Context) StrokeWidth 

func (c *Context) StrokeWidth() float32

StrokeWidth gets the stroke width of the stroke style.

func (*Context) Text 

func (c *Context) Text(x, y float32, str string) float32

Text draws text string at specified location. If end is specified only the sub-string up to the end is drawn.

func (*Context) TextAlign 

func (c *Context) TextAlign() Align

TextAlign gets the text align of current text style.

func (*Context) TextBounds 

func (c *Context) TextBounds(x, y float32, str string) (float32, []float32)

TextBounds measures the specified text string. Parameter bounds should be a pointer to float[4], if the bounding box of the text should be returned. The bounds value are [xmin,ymin, xmax,ymax] Returns the horizontal advance of the measured text (i.e. where the next character should drawn). Measured values are returned in local coordinate space.

func (*Context) TextBox 

func (c *Context) TextBox(x, y, breakRowWidth float32, str string)

TextBox draws multi-line text string at specified location wrapped at the specified width. If end is specified only the sub-string up to the end is drawn. White space is stripped at the beginning of the rows, the text is split at word boundaries or when new-line characters are encountered. Words longer than the max width are slit at nearest character (i.e. no hyphenation). Draws text string at specified location. If end is specified only the sub-string up to the end is drawn.

func (*Context) TextBoxBounds 

func (c *Context) TextBoxBounds(x, y, breakRowWidth float32, str string) [4]float32

TextBoxBounds measures the specified multi-text string. Parameter bounds should be a pointer to float[4], if the bounding box of the text should be returned. The bounds value are [xmin,ymin, xmax,ymax] Measured values are returned in local coordinate space.

func (*Context) TextBreakLines 

func (c *Context) TextBreakLines(str string, breakRowWidth float32) []TextRow

TextBreakLines breaks the specified text into lines. If end is specified only the sub-string will be used. White space is stripped at the beginning of the rows, the text is split at word boundaries or when new-line characters are encountered. Words longer than the max width are slit at nearest character (i.e. no hyphenation).

func (*Context) TextBreakLinesRune 

func (c *Context) TextBreakLinesRune(runes []rune, breakRowWidth float32) []TextRow

TextBreakLinesRune is an alternate version of TextBreakLines that accepts rune slice

func (*Context) TextGlyphPositions 

func (c *Context) TextGlyphPositions(x, y float32, str string) []GlyphPosition

TextGlyphPositions calculates the glyph x positions of the specified text. If end is specified only the sub-string will be used. Measured values are returned in local coordinate space.

func (*Context) TextGlyphPositionsRune 

func (c *Context) TextGlyphPositionsRune(x, y float32, runes []rune) []GlyphPosition

TextGlyphPositionsRune is an alternate version of TextGlyphPositions that accepts rune slice

func (*Context) TextLetterSpacing 

func (c *Context) TextLetterSpacing() float32

TextLetterSpacing gets the letter spacing of current text style.

func (*Context) TextLineHeight 

func (c *Context) TextLineHeight() float32

TextLineHeight gets the line height of current text style.

func (*Context) TextMetrics 

func (c *Context) TextMetrics() (float32, float32, float32)

TextMetrics returns the vertical metrics based on the current text style. Measured values are returned in local coordinate space.

func (*Context) TextRune 

func (c *Context) TextRune(x, y float32, runes []rune) float32

TextRune is an alternate version of Text that accepts rune slice.

func (*Context) Translate 

func (c *Context) Translate(x, y float32)

Translate translates current coordinate system.

func (*Context) UpdateImage 

func (c *Context) UpdateImage(img int, data []byte) error

UpdateImage updates image data specified by image handle.

type CreateFlags 

type CreateFlags int

CreateFlags is used when NewContext() to create NanoVGo context. 

const (
	// AntiAlias sets NanoVGo to use AA
	AntiAlias CreateFlags = 1 << 0
	// StencilStrokes sets NanoVGo to use stencil buffer to draw strokes
	StencilStrokes CreateFlags = 1 << 1
	// Debug shows OpenGL errors to console
	Debug CreateFlags = 1 << 2
)

type Direction 

type Direction int

Direction is used with Context.Arc 

const (
	// CounterClockwise specify Arc curve direction
	CounterClockwise Direction = 1
	// Clockwise specify Arc curve direction
	Clockwise Direction = 2
)

type Float 

type Float float32

Float is

type GlyphPosition 

type GlyphPosition struct {
	Index      int // Position of the glyph in the input string.
	Runes      []rune
	X          float32 // The x-coordinate of the logical glyph position.
	MinX, MaxX float32 // The bounds of the glyph shape.
}

GlyphPosition keeps glyph location information

type ImageFlags 

type ImageFlags int

ImageFlags is used for setting image object 

const (
	// ImageGenerateMipmaps generates mipmaps during creation of the image.
	ImageGenerateMipmaps ImageFlags = 1 << 0
	// ImageRepeatX repeats image in X direction.
	ImageRepeatX ImageFlags = 1 << 1
	// ImageRepeatY repeats image in X direction.
	ImageRepeatY ImageFlags = 1 << 2
	// ImageFlippy flips (inverses) image in Y direction when rendered.
	ImageFlippy ImageFlags = 1 << 3
	// ImagePreMultiplied specifies image data has premultiplied alpha.
	ImagePreMultiplied ImageFlags = 1 << 4
)
const (
	// ImageNoDelete don't delete from memory when removing image
	ImageNoDelete ImageFlags = 1 << 16
)

type LineCap 

type LineCap int

LineCap is used for line cap and joint 

const (
	// Butt is used for line cap (default value)
	Butt LineCap = iota
	// Round is used for line cap and joint
	Round
	// Square is used for line cap
	Square
	// Bevel is used for joint
	Bevel
	// Miter is used for joint (default value)
	Miter
)

type Paint 

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

Paint structure represent paint information including gradient and image painting. Context.SetFillPaint() and Context.SetStrokePaint() accept this instance.

func BoxGradient 

func BoxGradient(x, y, w, h, r, f float32, iColor, oColor Color) Paint

BoxGradient creates and returns a box gradient. Box gradient is a feathered rounded rectangle, it is useful for rendering drop shadows or highlights for boxes. Parameters (x,y) define the top-left corner of the rectangle, (w,h) define the size of the rectangle, r defines the corner radius, and f feather. Feather defines how blurry the border of the rectangle is. Parameter icol specifies the inner color and ocol the outer color of the gradient. The gradient is transformed by the current transform when it is passed to Context.FillPaint() or Context.StrokePaint().

func ImagePattern 

func ImagePattern(cx, cy, w, h, angle float32, img int, alpha float32) Paint

ImagePattern creates and returns an image patter. Parameters (ox,oy) specify the left-top location of the image pattern, (ex,ey) the size of one image, angle rotation around the top-left corner, image is handle to the image to render. The gradient is transformed by the current transform when it is passed to Context.FillPaint() or Context.StrokePaint().

func LinearGradient 

func LinearGradient(sx, sy, ex, ey float32, iColor, oColor Color) Paint

LinearGradient creates and returns a linear gradient. Parameters (sx,sy)-(ex,ey) specify the start and end coordinates of the linear gradient, icol specifies the start color and ocol the end color. The gradient is transformed by the current transform when it is passed to Context.FillPaint() or Context.StrokePaint().

func RadialGradient 

func RadialGradient(cx, cy, inR, outR float32, iColor, oColor Color) Paint

RadialGradient creates and returns a radial gradient. Parameters (cx,cy) specify the center, inr and outr specify the inner and outer radius of the gradient, icol specifies the start color and ocol the end color. The gradient is transformed by the current transform when it is passed to Context.FillPaint() or Context.StrokePaint().

type TextRow 

type TextRow struct {
	Runes      []rune  // The input string.
	StartIndex int     // Index to the input text where the row starts.
	EndIndex   int     // Index to the input text where the row ends (one past the last character).
	NextIndex  int     // Index to the beginning of the next row.
	Width      float32 // Logical width of the row.
	MinX, MaxX float32 // Actual bounds of the row. Logical with and bounds can differ because of kerning and some parts over extending.
}

TextRow keeps row geometry information

type TransformMatrix 

type TransformMatrix [6]float32

TransformMatrix is a 2x3 matrix is represented as float[6].

func IdentityMatrix 

func IdentityMatrix() TransformMatrix

IdentityMatrix makes the transform to identity matrix.

func RotateMatrix 

func RotateMatrix(a float32) TransformMatrix

RotateMatrix makes the transform to rotate matrix. Angle is specified in radians.

func ScaleMatrix 

func ScaleMatrix(sx, sy float32) TransformMatrix

ScaleMatrix makes the transform to scale matrix.

func SkewXMatrix 

func SkewXMatrix(a float32) TransformMatrix

SkewXMatrix makes the transform to skew-x matrix. Angle is specified in radians.

func SkewYMatrix 

func SkewYMatrix(a float32) TransformMatrix

SkewYMatrix makes the transform to skew-y matrix. Angle is specified in radians.

func TranslateMatrix 

func TranslateMatrix(tx, ty float32) TransformMatrix

TranslateMatrix makes the transform to translation matrix matrix.

func (TransformMatrix) Inverse 

func (t TransformMatrix) Inverse() TransformMatrix

Inverse makes the destination to inverse of specified transform. Returns 1 if the inverse could be calculated, else 0.

func (TransformMatrix) Multiply 

func (t TransformMatrix) Multiply(s TransformMatrix) TransformMatrix

Multiply makes the transform to the result of multiplication of two transforms, of A = A*B.

func (TransformMatrix) PreMultiply 

func (t TransformMatrix) PreMultiply(s TransformMatrix) TransformMatrix

PreMultiply makes the transform to the result of multiplication of two transforms, of A = B*A.

func (TransformMatrix) ToMat3x4 

func (t TransformMatrix) ToMat3x4() []float32

ToMat3x4 makes 3x4 matrix.

func (TransformMatrix) TransformPoint 

func (t TransformMatrix) TransformPoint(sx, sy float32) (dx, dy float32)

TransformPoint transforms a point by given TransformMatrix.

type Winding 

type Winding int

Winding is used for changing filling strategy 

const (
	// Solid fills internal hole
	Solid Winding = 1
	// Hole keeps internal hole
	Hole Winding = 2
)

Source Files

View all Source files

Directories

Path Synopsis
truetype
This library processes TrueType files: - parse files - extract glyph metrics - extract glyph shapes - render glyphs to one-channel bitmaps with antialiasing (box filter)
 This library processes TrueType files: - parse files - extract glyph metrics - extract glyph shapes - render glyphs to one-channel bitmaps with antialiasing (box filter)
demo
tjt1

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