positioning image instead of creating view size image

internal/epub/epub.go

@@ -97,9 +97,10 @@ func (e *ePub) writeImage(wz *epubZip, img *Image) error {
 	err := wz.WriteFile(
 		fmt.Sprintf("OEBPS/%s", img.TextPath()),
 		e.render(textTmpl, map[string]any{
-			"Title":     fmt.Sprintf("Image %d Part %d", img.Id, img.Part),
-			"ViewPort":  fmt.Sprintf("width=%d,height=%d", e.ViewWidth, e.ViewHeight),
-			"ImagePath": img.ImgPath(),
+			"Title":      fmt.Sprintf("Image %d Part %d", img.Id, img.Part),
+			"ViewPort":   fmt.Sprintf("width=%d,height=%d", e.ViewWidth, e.ViewHeight),
+			"ImagePath":  img.ImgPath(),
+			"ImageStyle": img.ImgStyle(e.ViewWidth, e.ViewHeight, e.Manga),
 		}),
 	)
 

internal/epub/epub_image_filters.go

@@ -20,7 +20,6 @@ func NewGift(options *ImageOptions) *gift.GIFT {
 	}
 	g.Add(
 		filters.Resize(options.ViewWidth, options.ViewHeight, gift.LanczosResampling),
-		filters.Position(options.ViewWidth, options.ViewHeight, filters.PositionCenter),
 		filters.Pixel(),
 	)
 	return g
@@ -37,7 +36,7 @@ func NewGiftSplitDoublePage(options *ImageOptions) []*gift.GIFT {
 		filters.CropSplitDoublePage(!options.Manga),
 	)
 
-	for i, g := range gifts {
+	for _, g := range gifts {
 		if options.Contrast != 0 {
 			g.Add(gift.Contrast(float32(options.Contrast)))
 		}
@@ -45,14 +44,8 @@ func NewGiftSplitDoublePage(options *ImageOptions) []*gift.GIFT {
 			g.Add(gift.Brightness(float32(options.Brightness)))
 		}
 
-		position := filters.PositionLeft
-		if (i == 1) == options.Manga {
-			position = filters.PositionRight
-		}
-
 		g.Add(
 			filters.Resize(options.ViewWidth, options.ViewHeight, gift.LanczosResampling),
-			filters.Position(options.ViewWidth, options.ViewHeight, position),
 		)
 	}
 

internal/epub/epub_image_processing.go

@@ -53,6 +53,36 @@ func (i *Image) ImgPath() string {
 	return fmt.Sprintf("Images/%d_p%d.jpg", i.Id, i.Part)
 }
 
+func (i *Image) ImgStyle(viewWidth, viewHeight int, manga bool) 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 {
+			align = "right:0"
+		}
+	case 2:
+		if manga {
+			align = "right:0"
+		} else {
+			align = "left:0"
+		}
+	}
+
+	return fmt.Sprintf(
+		"width:%dpx; height:%dpx; top:%.2f%%; %s;",
+		i.Width,
+		i.Height,
+		top,
+		align,
+	)
+}
+
 func (i *Image) SpacePath() string {
 	return fmt.Sprintf("Text/%d_sp.xhtml", i.Id)
 }

internal/epub/filters/epub_filters_position.go

@@ -1,67 +0,0 @@
-package filters
-
-import (
-	"image"
-	"image/draw"
-
-	"github.com/disintegration/gift"
-)
-
-const (
-	PositionCenter = iota
-	PositionLeft
-	PositionRight
-)
-
-func Position(viewWidth, viewHeight int, align int) gift.Filter {
-	return &positionFilter{
-		viewWidth, viewHeight, align,
-	}
-}
-
-type positionFilter struct {
-	viewWidth, viewHeight, align int
-}
-
-func (p *positionFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
-	w, h := p.viewWidth, p.viewHeight
-	srcw, srch := srcBounds.Dx(), srcBounds.Dy()
-
-	if w <= 0 || h <= 0 || srcw <= 0 || srch <= 0 {
-		return image.Rect(0, 0, 0, 0)
-	}
-
-	return image.Rect(0, 0, w, h)
-}
-
-func (p *positionFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
-	if dst.Bounds().Dx() == 0 || dst.Bounds().Dy() == 0 {
-		return
-	}
-
-	draw.Draw(dst, dst.Bounds(), image.White, dst.Bounds().Min, draw.Over)
-
-	srcBounds := src.Bounds()
-	left, top := 0, (dst.Bounds().Dy()-srcBounds.Dy())/2
-
-	if p.align == PositionCenter {
-		left = (dst.Bounds().Dx() - srcBounds.Dx()) / 2
-	}
-
-	if p.align == PositionRight {
-		left = dst.Bounds().Dx() - srcBounds.Dx()
-	}
-
-	draw.Draw(
-		dst,
-		image.Rect(
-			left,
-			top,
-			dst.Bounds().Dx(),
-			dst.Bounds().Dy(),
-		),
-		src,
-		srcBounds.Min,
-		draw.Over,
-	)
-}

internal/epub/templates/epub_templates_style.css.tmpl

@@ -15,8 +15,4 @@ img {
   margin:0;
   padding:0;
   z-index:0;
-  top:0;
-  left:0;
-  width: {{ .PageWidth }}px;
-  height: {{ .PageHeight }}px;
 }

internal/epub/templates/epub_templates_text.xhtml.tmpl

@@ -9,7 +9,7 @@
   </head>
   <body>
     <div>
-      <img src="../{{ .ImagePath }}" alt="{{ .Title }}"/>
+      <img src="../{{ .ImagePath }}" alt="{{ .Title }}" style="{{ .ImageStyle }}"/>
     </div>
   </body>
 </html>