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Fix image caching mechanism. Check for nils.

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This commit is contained in:
Gunnsteinn Hall 2019-01-28 22:40:40 +00:00
parent b0cbbf2dfb
commit 4078900f07
1 changed files with 40 additions and 18 deletions
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58
pdf/extractor/image.go
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@ -58,8 +58,13 @@ type imageExtractContext struct {
xObjectImages int
xObjectForms int
// Cache to avoid processing same objects many times.
processedXObjects map[string]bool
// Cache to avoid processing same image many times.
cacheXObjectImages map[*core.PdfObjectStream]*cachedImage
}
type cachedImage struct {
image *model.Image
cs model.PdfColorspace
}
func (ctx *imageExtractContext) extractImagesInContentStream(contents string, resources *model.PdfPageResources) error {
@ -69,7 +74,9 @@ func (ctx *imageExtractContext) extractImagesInContentStream(contents string, re
return err
}
ctx.processedXObjects = map[string]bool{}
if ctx.cacheXObjectImages == nil {
ctx.cacheXObjectImages = map[*core.PdfObjectStream]*cachedImage{}
}
processor := contentstream.NewContentStreamProcessor(*operations)
processor.AddHandler(contentstream.HandlerConditionEnumAllOperands, "",
@ -136,27 +143,39 @@ func (ctx *imageExtractContext) processOperand(op *contentstream.ContentStreamOp
return errTypeCheck
}
// Only process each one once.
_, has := ctx.processedXObjects[string(*name)]
if has {
// Already processed.
return nil
}
ctx.processedXObjects[string(*name)] = true
_, xtype := resources.GetXObjectByName(*name)
if xtype == model.XObjectTypeImage {
common.Log.Debug(" XObject Image: %s", *name)
ximg, err := resources.GetXObjectImageByName(*name)
if err != nil {
return err
stream, _ := resources.GetXObjectByName(*name)
if stream == nil {
return nil
}
img, err := ximg.ToImage()
if err != nil {
return err
// Cache on stream pointer so can ensure that it is the same object (better than using name).
cimg, cached := ctx.cacheXObjectImages[stream]
if !cached {
ximg, err := resources.GetXObjectImageByName(*name)
if err != nil {
return err
}
if ximg == nil {
return nil
}
img, err := ximg.ToImage()
if err != nil {
return err
}
cimg = &cachedImage{
image: img,
cs: ximg.ColorSpace,
}
ctx.cacheXObjectImages[stream] = cimg
}
img := cimg.image
cs := cimg.cs
common.Log.Debug("@Do CTM: %s", gs.CTM.String())
xDim := gs.CTM.ScalingFactorX()
@ -164,7 +183,7 @@ func (ctx *imageExtractContext) processOperand(op *contentstream.ContentStreamOp
xPos, yPos := gs.CTM.Translation()
angle := gs.CTM.Angle()
rgbImg, err := ximg.ColorSpace.ImageToRGB(*img)
rgbImg, err := cs.ImageToRGB(*img)
if err != nil {
return err
}
@ -185,6 +204,9 @@ func (ctx *imageExtractContext) processOperand(op *contentstream.ContentStreamOp
if err != nil {
return err
}
if xform == nil {
return nil
}
formContent, err := xform.GetContentStream()
if err != nil {