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Fix memory leak in pdf-invert-images

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A class can't have a PointerHolder to itself since PointerHolder
doesn't have the concept of weak references.
This commit is contained in:
Jay Berkenbilt 2020-04-08 19:46:10 -04:00
parent 93de6eaf96
commit b89b1d772d
1 changed files with 13 additions and 16 deletions
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29
examples/pdf-invert-images.cc
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@ -40,12 +40,12 @@ class ImageInverter: public QPDFObjectHandle::StreamDataProvider
virtual void provideStreamData(int objid, int generation,
Pipeline* pipeline) override;
void setSelfPh(PointerHolder<QPDFObjectHandle::StreamDataProvider>);
void registerImage(QPDFObjectHandle image);
void registerImage(
QPDFObjectHandle image,
PointerHolder<QPDFObjectHandle::StreamDataProvider> self);
private:
QPDF other;
PointerHolder<QPDFObjectHandle::StreamDataProvider> self_ph;
// Map og in original to copied image
std::map<QPDFObjGen, QPDFObjectHandle> copied_images;
};
@ -56,18 +56,18 @@ ImageInverter::ImageInverter()
}
void
ImageInverter::setSelfPh(PointerHolder<QPDFObjectHandle::StreamDataProvider> p)
ImageInverter::registerImage(
QPDFObjectHandle image,
PointerHolder<QPDFObjectHandle::StreamDataProvider> self)
{
// replaceStreamData requires a pointer holder to the stream data
// provider, but there's no way for us to generate one ourselves,
// so we have to have it handed to us.
this->self_ph = p;
}
// so we have to have it handed to us. Don't be tempted to have
// the class contain a PointerHolder to itself as a member. Doing
// this will prevent the class from ever being deleted since the
// reference count will never drop to zero (and PointerHolder
// doesn't have weak references).
void
ImageInverter::registerImage(QPDFObjectHandle image)
{
QPDFObjGen og(image.getObjGen());
// Store information about the images based on the object and
// generation number. Recall that a single image object may be
@ -88,7 +88,7 @@ ImageInverter::registerImage(QPDFObjectHandle image)
// filterable in the input QPDF object, so we don't have to deal
// with it explicitly here. We could explicitly use /DCTDecode and
// write through a DCT filter if we wanted.
image.replaceStreamData(this->self_ph,
image.replaceStreamData(self,
QPDFObjectHandle::newNull(),
QPDFObjectHandle::newNull());
}
@ -149,9 +149,6 @@ int main(int argc, char* argv[])
ImageInverter* inv = new ImageInverter;
PointerHolder<QPDFObjectHandle::StreamDataProvider> p = inv;
// We need to give ImageInverter the pointer holder that it
// needs to pass to replaceStreamData.
inv->setSelfPh(p);
// For each page...
std::vector<QPDFPageObjectHelper> pages =
@ -186,7 +183,7 @@ int main(int argc, char* argv[])
(color_space.getName() == "/DeviceGray") &&
(bits_per_component.getIntValue() == 8))
{
inv->registerImage(image);
inv->registerImage(image, p);
}
}
}