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drawing.go
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drawing.go
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package drawing
import (
"image/color"
"github.com/golang/freetype/truetype"
)
// FillRule defines the type for fill rules
type FillRule int
const (
// FillRuleEvenOdd determines the "insideness" of a point in the shape
// by drawing a ray from that point to infinity in any direction
// and counting the number of path segments from the given shape that the ray crosses.
// If this number is odd, the point is inside; if even, the point is outside.
FillRuleEvenOdd FillRule = iota
// FillRuleWinding determines the "insideness" of a point in the shape
// by drawing a ray from that point to infinity in any direction
// and then examining the places where a segment of the shape crosses the ray.
// Starting with a count of zero, add one each time a path segment crosses
// the ray from left to right and subtract one each time
// a path segment crosses the ray from right to left. After counting the crossings,
// if the result is zero then the point is outside the path. Otherwise, it is inside.
FillRuleWinding
)
// LineCap is the style of line extremities
type LineCap int
const (
// RoundCap defines a rounded shape at the end of the line
RoundCap LineCap = iota
// ButtCap defines a squared shape exactly at the end of the line
ButtCap
// SquareCap defines a squared shape at the end of the line
SquareCap
)
// LineJoin is the style of segments joint
type LineJoin int
const (
// BevelJoin represents cut segments joint
BevelJoin LineJoin = iota
// RoundJoin represents rounded segments joint
RoundJoin
// MiterJoin represents peaker segments joint
MiterJoin
)
// StrokeStyle keeps stroke style attributes
// that is used by the Stroke method of a Drawer
type StrokeStyle struct {
// Color defines the color of stroke
Color color.Color
// Line width
Width float64
// Line cap style rounded, butt or square
LineCap LineCap
// Line join style bevel, round or miter
LineJoin LineJoin
// offset of the first dash
DashOffset float64
// array represented dash length pair values are plain dash and impair are space between dash
// if empty display plain line
Dash []float64
}
// SolidFillStyle define style attributes for a solid fill style
type SolidFillStyle struct {
// Color defines the line color
Color color.Color
// FillRule defines the file rule to used
FillRule FillRule
}
// Valign Vertical Alignment of the text
type Valign int
const (
// ValignTop top align text
ValignTop Valign = iota
// ValignCenter centered text
ValignCenter
// ValignBottom bottom aligned text
ValignBottom
// ValignBaseline align text with the baseline of the font
ValignBaseline
)
// Halign Horizontal Alignment of the text
type Halign int
const (
// HalignLeft Horizontally align to left
HalignLeft = iota
// HalignCenter Horizontally align to center
HalignCenter
// HalignRight Horizontally align to right
HalignRight
)
// TextStyle describe text property
type TextStyle struct {
// Color defines the color of text
Color color.Color
// Size font size
Size float64
// The font to use
Font *truetype.Font
// Horizontal Alignment of the text
Halign Halign
// Vertical Alignment of the text
Valign Valign
}
// ScalingPolicy is a constant to define how to scale an image
type ScalingPolicy int
const (
// ScalingNone no scaling applied
ScalingNone ScalingPolicy = iota
// ScalingStretch the image is stretched so that its width and height are exactly the given width and height
ScalingStretch
// ScalingWidth the image is scaled so that its width is exactly the given width
ScalingWidth
// ScalingHeight the image is scaled so that its height is exactly the given height
ScalingHeight
// ScalingFit the image is scaled to the largest scale that allow the image to fit within a rectangle width x height
ScalingFit
// ScalingSameArea the image is scaled so that its area is exactly the area of the given rectangle width x height
ScalingSameArea
// ScalingFill the image is scaled to the smallest scale that allow the image to fully cover a rectangle width x height
ScalingFill
)
// ImageScaling style attributes used to display the image
type ImageScaling struct {
// Horizontal Alignment of the image
Halign Halign
// Vertical Alignment of the image
Valign Valign
// Width Height used by scaling policy
Width, Height float64
// ScalingPolicy defines the scaling policy to applied to the image
ScalingPolicy ScalingPolicy
}