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go-exif
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Partial commit. Incomplete and untested.

pull/21/head
Dustin Oprea 2019-05-27 13:51:31 -04:00
parent 17eaca4233
commit 7a8bf6e109
1 changed files with 39 additions and 5 deletions
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42
ifd_builder.go
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@ -24,6 +24,18 @@ var (
ErrChildIbNotFound = errors.New("child IB not found")
)
// IfdPathAndTag very specfically describes any one tag within a given IFD tree.
type IfdPathAndTag struct {
// IfdPath is either a normal or fully-qualified (with indices) IFD path.
IfdPath string
// TagName is the name of a tag. This must be populated if `TagId` is not.
TagName string
// TagId is the ID of a tag. This must be populated if `TagName` is not.
TagId uint16
}
type IfdBuilderTagValue struct {
valueBytes []byte
ib *IfdBuilder
@ -288,11 +300,15 @@ func NewIfdBuilderWithExistingIfd(ifd *Ifd) (ib *IfdBuilder) {
// NewIfdBuilderFromExistingChain creates a chain of IB instances from an
// IFD chain generated from real data.
func NewIfdBuilderFromExistingChain(rootIfd *Ifd, itevr *IfdTagEntryValueResolver) (firstIb *IfdBuilder) {
func NewIfdBuilderFromExistingChain(rootIfd *Ifd, itevr *IfdTagEntryValueResolver) (ib *IfdBuilder) {
ib = NewIfdBuilderFromExistingChainWithFilter(rootIfd, itevr, nil)
return ib
}
func NewIfdBuilderFromExistingChainWithFilter(rootIfd *Ifd, itevr *IfdTagEntryValueResolver, includeFilter []IfdPathAndTag, excludeFilter []IfdPathAndTag) (firstIb *IfdBuilder) {
// TODO(dustin): !! When we actually write the code to flatten the IB to bytes, make sure to skip the tags that have a nil value (which will happen when we add-from-exsting without a resolver instance).
var lastIb *IfdBuilder
i := 0
for thisExistingIfd := rootIfd; thisExistingIfd != nil; thisExistingIfd = thisExistingIfd.NextIfd {
newIb := NewIfdBuilder(rootIfd.ifdMapping, rootIfd.tagIndex, rootIfd.FqIfdPath, thisExistingIfd.ByteOrder)
if firstIb == nil {
@ -301,11 +317,12 @@ func NewIfdBuilderFromExistingChain(rootIfd *Ifd, itevr *IfdTagEntryValueResolve
lastIb.SetNextIb(newIb)
}
err := newIb.AddTagsFromExisting(thisExistingIfd, itevr, nil, nil)
err := newIb.AddTagsFromExistingWithFilter(thisExistingIfd, itevr, includeFilter, excludeFilter)
log.PanicIf(err)
if len(newIb.Tags()) > 0 {
lastIb = newIb
i++
}
}
return firstIb
@ -983,6 +1000,23 @@ func (ib *IfdBuilder) NewBuilderTagFromBuilder(childIb *IfdBuilder) (bt *Builder
return bt
}
func (ib *IfdBuilder) AddTagsFromExistingWithFilter(ifd *Ifd, itevr *IfdTagEntryValueResolver, includeFilter []IfdPathAndTag, excludeFilter []IfdPathAndTag) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
// TODO(dustin): !! We'd like to implement our IfdPathAndTag-based filter, but:
//
// - we might not be able to avoid duplicating AddTagsFromExisting since:
// 1) the existing filtering, which is insufficient, is so pervasive.
// 2) we really don't want to add support for both types of filtering to the signature of the existing AddTagsFromExisting.
// - we'll need to curry the given filters back to the NewIfdBuilderFromExistingChain method above.
return nil
}
// AddTagsFromExisting does a verbatim copy of the entries in `ifd` to this
// builder. It excludes child IFDs. These must be added explicitly via
// `AddChildIb()`.