From bcad0389fa11589e490cb45f13095d7f5e59217d Mon Sep 17 00:00:00 2001
From: celogeek <65178+celogeek@users.noreply.github.com>
Date: Sun, 30 Apr 2023 16:25:02 +0200
Subject: [PATCH] improve alignment on spread images for landscape

---
 internal/epub/epub.go                         |  8 ++++--
 internal/epub/image/epub_image.go             | 26 +++++++------------
 .../epub/templates/epub_templates_content.go  |  4 ++-
 3 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/internal/epub/epub.go b/internal/epub/epub.go
index e3623f8..abf1b45 100644
--- a/internal/epub/epub.go
+++ b/internal/epub/epub.go
@@ -77,7 +77,7 @@ func (e *ePub) writeImage(wz *epubzip.EPUBZip, img *epubimage.Image, zipImg *zip
 			"Title":      fmt.Sprintf("Image %d Part %d", img.Id, img.Part),
 			"ViewPort":   fmt.Sprintf("width=%d,height=%d", e.Image.View.Width, e.Image.View.Height),
 			"ImagePath":  img.ImgPath(),
-			"ImageStyle": img.ImgStyle(e.Image.View.Width, e.Image.View.Height, e.Image.Manga),
+			"ImageStyle": img.ImgStyle(e.Image.View.Width, e.Image.View.Height, ""),
 		})),
 	)
 	if err == nil {
@@ -251,6 +251,10 @@ func (e *ePub) Write() error {
 		if totalParts > 1 {
 			title = fmt.Sprintf("%s [%d/%d]", title, i+1, totalParts)
 		}
+		titleAlign := "left:0"
+		if e.Image.Manga {
+			titleAlign = "right:0"
+		}
 
 		content := []zipContent{
 			{"META-INF/container.xml", epubtemplates.Container},
@@ -280,7 +284,7 @@ func (e *ePub) Write() error {
 				"Title":      title,
 				"ViewPort":   fmt.Sprintf("width=%d,height=%d", e.Image.View.Width, e.Image.View.Height),
 				"ImagePath":  "Images/title.jpg",
-				"ImageStyle": part.Cover.ImgStyle(e.Image.View.Width, e.Image.View.Height, e.Image.Manga),
+				"ImageStyle": part.Cover.ImgStyle(e.Image.View.Width, e.Image.View.Height, titleAlign),
 			})},
 		}
 
diff --git a/internal/epub/image/epub_image.go b/internal/epub/image/epub_image.go
index 0bcf180..e88a414 100644
--- a/internal/epub/image/epub_image.go
+++ b/internal/epub/image/epub_image.go
@@ -19,6 +19,7 @@ type Image struct {
 	DoublePage bool
 	Path       string
 	Name       string
+	Position   string
 }
 
 // key name of the blank plage after the image
@@ -70,24 +71,17 @@ func (i *Image) EPUBImgPath() string {
 //
 // center by default.
 // align to left or right if it's part of the splitted double page.
-func (i *Image) ImgStyle(viewWidth, viewHeight int, manga bool) string {
+func (i *Image) ImgStyle(viewWidth, viewHeight int, align string) string {
 	marginW, marginH := float64(viewWidth-i.Width)/2, float64(viewHeight-i.Height)/2
-	left, top := marginW*100/float64(viewWidth), marginH*100/float64(viewHeight)
-	var align string
-	switch i.Part {
-	case 0:
-		align = fmt.Sprintf("left:%.2f%%", left)
-	case 1:
-		if manga {
-			align = "left:0"
-		} else {
+
+	if align == "" {
+		switch i.Position {
+		case "rendition:page-spread-left":
 			align = "right:0"
-		}
-	case 2:
-		if manga {
-			align = "right:0"
-		} else {
+		case "rendition:page-spread-right":
 			align = "left:0"
+		default:
+			align = fmt.Sprintf("left:%.2f%%", marginW*100/float64(viewWidth))
 		}
 	}
 
@@ -95,7 +89,7 @@ func (i *Image) ImgStyle(viewWidth, viewHeight int, manga bool) string {
 		"width:%dpx; height:%dpx; top:%.2f%%; %s;",
 		i.Width,
 		i.Height,
-		top,
+		marginH*100/float64(viewHeight),
 		align,
 	)
 }
diff --git a/internal/epub/templates/epub_templates_content.go b/internal/epub/templates/epub_templates_content.go
index e3e9492..7271032 100644
--- a/internal/epub/templates/epub_templates_content.go
+++ b/internal/epub/templates/epub_templates_content.go
@@ -195,9 +195,11 @@ func getSpine(o *ContentOptions) []tag {
 				"",
 			})
 		}
+		// register position for style adjustment
+		img.Position = getSpread(img.DoublePage)
 		spine = append(spine, tag{
 			"itemref",
-			tagAttrs{"idref": img.PageKey(), "properties": getSpread(img.DoublePage)},
+			tagAttrs{"idref": img.PageKey(), "properties": img.Position},
 			"",
 		})
 	}