121 lines
2.9 KiB
Go

// Package epubimage Image helpers to transform image.
package epubimage
import (
"fmt"
"image"
"strings"
)
type Image struct {
Id int
Part int
Raw image.Image
Width int
Height int
IsBlank bool
DoublePage bool
Path string
Name string
Position string
Format string
OriginalAspectRatio float64
Error error
}
// SpaceKey key name of the blank page after the image
func (i Image) SpaceKey() string {
return fmt.Sprintf("space_%d", i.Id)
}
// SpacePath path of the blank page
func (i Image) SpacePath() string {
return fmt.Sprintf("Text/%s.xhtml", i.SpaceKey())
}
// EPUBSpacePath path of the blank page into the EPUB
func (i Image) EPUBSpacePath() string {
return fmt.Sprintf("OEBPS/%s", i.SpacePath())
}
// PageKey key for page
func (i Image) PageKey() string {
return fmt.Sprintf("page_%d_p%d", i.Id, i.Part)
}
// PagePath page path linked to the image
func (i Image) PagePath() string {
return fmt.Sprintf("Text/%s.xhtml", i.PageKey())
}
// EPUBPagePath page path into the EPUB
func (i Image) EPUBPagePath() string {
return fmt.Sprintf("OEBPS/%s", i.PagePath())
}
// ImgKey key for image
func (i Image) ImgKey() string {
return fmt.Sprintf("img_%d_p%d", i.Id, i.Part)
}
// ImgPath image path
func (i Image) ImgPath() string {
return fmt.Sprintf("Images/%s.%s", i.ImgKey(), i.Format)
}
// EPUBImgPath image path into the EPUB
func (i Image) EPUBImgPath() string {
return fmt.Sprintf("OEBPS/%s", i.ImgPath())
}
// ImgStyle style to apply to the image.
//
// center by default.
// align to left or right if it's part of the split double page.
func (i Image) ImgStyle(viewWidth, viewHeight int, align string) string {
relWidth, relHeight := i.RelSize(viewWidth, viewHeight)
marginW, marginH := float64(viewWidth-relWidth)/2, float64(viewHeight-relHeight)/2
var style []string
style = append(style, fmt.Sprintf("width:%dpx", relWidth))
style = append(style, fmt.Sprintf("height:%dpx", relHeight))
style = append(style, fmt.Sprintf("top:%.2f%%", marginH*100/float64(viewHeight)))
if align == "" {
switch i.Position {
case "rendition:page-spread-left":
style = append(style, "right:0")
case "rendition:page-spread-right":
style = append(style, "left:0")
default:
style = append(style, fmt.Sprintf("left:%.2f%%", marginW*100/float64(viewWidth)))
}
} else {
style = append(style, align)
}
return strings.Join(style, "; ")
}
func (i Image) RelSize(viewWidth, viewHeight int) (relWidth, relHeight int) {
w, h := viewWidth, viewHeight
srcw, srch := i.Width, i.Height
if w <= 0 || h <= 0 || srcw <= 0 || srch <= 0 {
return
}
wratio := float64(srcw) / float64(w)
hratio := float64(srch) / float64(h)
if wratio > hratio {
relWidth = w
relHeight = int(float64(srch)/wratio + 0.5)
} else {
relHeight = h
relWidth = int(float64(srcw)/hratio + 0.5)
}
return
}