// Copyright (c) 2005-2021 Jay Berkenbilt

// Copyright (c) 2022-2025 Jay Berkenbilt and Manfred Holger

//

// This file is part of qpdf.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License. You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied. See the License for the specific language governing permissions and limitations under

// the License.

//

// Versions of qpdf prior to version 7 were released under the terms of version 2.0 of the Artistic

// License. At your option, you may continue to consider qpdf to be licensed under those terms.

// Please see the manual for additional information.

#ifndef QPDFPAGEOBJECTHELPER_HH

#define QPDFPAGEOBJECTHELPER_HH

#include <qpdf/QPDFAnnotationObjectHelper.hh>

#include <qpdf/QPDFMatrix.hh>

#include <qpdf/QPDFObjectHelper.hh>

#include <qpdf/DLL.h>

#include <qpdf/QPDFObjectHandle.hh>

#include <functional>

class QPDFAcroFormDocumentHelper;

// This is a helper class for page objects, but as of qpdf 10.1, many of the methods also work

// for form XObjects. When this is the case, it is noted in the comment.

class QPDFPageObjectHelper: public QPDFObjectHelper

{

  public:

    QPDF_DLL

    QPDFPageObjectHelper(QPDFObjectHandle);

    ~QPDFPageObjectHelper() override = default;

    // PAGE ATTRIBUTES

    // The getAttribute method works with pages and form XObjects. It returns the value of the

    // requested attribute from the page/form XObject's dictionary, taking inheritance from the

    // pages tree into consideration. For pages, the attributes /MediaBox, /CropBox, /Resources, and

    // /Rotate are inheritable, meaning that if they are not present directly on the page node, they

    // may be inherited from ancestor nodes in the pages tree.

    //

    // There are two ways that an attribute can be "shared":

    //

    // * For inheritable attributes on pages, it may appear in a higher level node of the pages tree

    //

    // * For any attribute, the attribute may be an indirect object which may be referenced by more

    // than one page/form XObject.

    //

    // If copy_if_shared is true, then this method will replace the attribute with a shallow copy if

    // it is indirect or inherited and return the copy. You should do this if you are going to

    // modify the returned object and want the modifications to apply to the current page/form

    // XObject only.

    QPDF_DLL

    QPDFObjectHandle getAttribute(std::string const& name, bool copy_if_shared);

    // PAGE BOXES

    //

    // Pages have various types of boundary boxes. These are described in detail in the PDF

    // specification (section 14.11.2 Page boundaries). They are, by key in the page dictionary:

    //

    // * /MediaBox -- boundaries of physical page

    // * /CropBox -- clipping region of what is displayed

    // * /BleedBox -- clipping region for production environments

    // * /TrimBox -- dimensions of final printed page after trimming

    // * /ArtBox -- extent of meaningful content including margins

    //

    // Of these, only /MediaBox is required. If any are absent, the

    // fallback value for /CropBox is /MediaBox, and the fallback

    // values for the other boxes are /CropBox.

    //

    // As noted above (PAGE ATTRIBUTES), /MediaBox and /CropBox can be inherited from parent nodes

    // in the pages tree. The other boxes can't be inherited.

    //

    // When the comments below refer to the "effective value" of a box, this takes into

    // consideration both inheritance through the pages tree (in the case of /MediaBox and /CropBox)

    // and fallback values for missing attributes (for all except /MediaBox).

    //

    // For the methods below, copy_if_shared is passed to getAttribute and therefore refers only to

    // indirect objects and values that are inherited through the pages tree.

    //

    // If copy_if_fallback is true, a copy is made if the object's value was obtained by falling

    // back to a different box.

    //

    // The copy_if_shared and copy_if_fallback parameters carry across multiple layers. This is

    // explained below.

    //

    // You should set copy_if_shared to true if you want to modify a bounding box for the current

    // page without affecting other pages but you don't want to change the fallback behavior. For

    // example, if you want to modify the /TrimBox for the current page only but have it continue to

    // fall back to the value of /CropBox or /MediaBox if they are not defined, you could set

    // copy_if_shared to true.

    //

    // You should set copy_if_fallback to true if you want to modify a specific box as distinct from

    // any other box. For example, if you want to make /TrimBox differ from /CropBox, then you

    // should set copy_if_fallback to true.

    //

    // The copy_if_fallback flags were added in qpdf 11.

    //

    // For example, suppose that neither /CropBox nor /TrimBox is present on a page but /CropBox is

    // present in the page's parent node in the page tree.

    //

    // * getTrimBox(false, false) would return the /CropBox from the parent node.

    //

    // * getTrimBox(true, false) would make a shallow copy of the /CropBox from the parent node into

    //   the current node and return it.

    //

    // * getTrimBox(false, true) would make a shallow copy of the /CropBox from the parent node into

    //   /TrimBox of the current node and return it.

    //

    // * getTrimBox(true, true) would make a shallow copy of the /CropBox from the parent node into

    //   the current node, then make a shallow copy of the resulting copy to /TrimBox of the current

    //   node, and then return that.

    //

    // To illustrate how these parameters carry across multiple layers, suppose that neither

    // /MediaBox, /CropBox, nor /TrimBox is present on a page but /MediaBox is present on the

    // parent. In this case:

    //

    // * getTrimBox(false, false) would return the value of /MediaBox from the parent node.

    //

    // * getTrimBox(true, false) would copy /MediaBox to the current node and return it.

    //

    // * getTrimBox(false, true) would first copy /MediaBox from the parent to /CropBox, then copy

    //   /CropBox to /TrimBox, and then return the result.

    //

    // * getTrimBox(true, true) would first copy /MediaBox from the parent to the current page, then

    //   copy it to /CropBox, then copy /CropBox to /TrimBox, and then return the result.

    //

    // If you need different behavior, call getAttribute directly and take care of your own copying.

    // Return the effective MediaBox

    QPDF_DLL

    QPDFObjectHandle getMediaBox(bool copy_if_shared = false);

    // Return the effective CropBox. If not defined, fall back to MediaBox

    QPDF_DLL

    QPDFObjectHandle getCropBox(bool copy_if_shared = false, bool copy_if_fallback = false);

    // Return the effective BleedBox. If not defined, fall back to CropBox.

    QPDF_DLL

    QPDFObjectHandle getBleedBox(bool copy_if_shared = false, bool copy_if_fallback = false);

    // Return the effective TrimBox. If not defined, fall back to CropBox.

    QPDF_DLL

    QPDFObjectHandle getTrimBox(bool copy_if_shared = false, bool copy_if_fallback = false);

    // Return the effective ArtBox. If not defined, fall back to CropBox.

    QPDF_DLL

    QPDFObjectHandle getArtBox(bool copy_if_shared = false, bool copy_if_fallback = false);

    // Iterate through XObjects, possibly recursing into form XObjects. This works with pages or

    // form XObjects. Call action on each XObject for which selector, if specified, returns true.

    // With no selector, calls action for every object. In addition to the object being passed to

    // action, the containing XObject dictionary and key are passed in. Remember that the XObject

    // dictionary may be shared, and the object may appear in multiple XObject dictionaries.

    QPDF_DLL

    void forEachXObject(

        bool recursive,

        std::function<void(

            QPDFObjectHandle& obj, QPDFObjectHandle& xobj_dict, std::string const& key)> action,

        std::function<bool(QPDFObjectHandle)> selector = nullptr);

    // Only call action for images

    QPDF_DLL

    void forEachImage(

        bool recursive,

        std::function<void(

            QPDFObjectHandle& obj, QPDFObjectHandle& xobj_dict, std::string const& key)> action);

    // Only call action for form XObjects

    QPDF_DLL

    void forEachFormXObject(

        bool recursive,

        std::function<void(

            QPDFObjectHandle& obj, QPDFObjectHandle& xobj_dict, std::string const& key)> action);

    // Returns an empty map if there are no images or no resources. Prior to qpdf 8.4.0, this

    // function did not support inherited resources, but it does now. Return value is a map from

    // XObject name to the image object, which is always a stream. Works with form XObjects as well

    // as pages. This method does not recurse into nested form XObjects. For that, use forEachImage.

    QPDF_DLL

    std::map<std::string, QPDFObjectHandle> getImages();

    // Old name -- calls getImages()

    QPDF_DLL

    std::map<std::string, QPDFObjectHandle> getPageImages();

    // Returns an empty map if there are no form XObjects or no resources. Otherwise, returns a map

    // of keys to form XObjects directly referenced from this page or form XObjects. This does not

    // recurse into nested form XObjects. For that, use forEachFormXObject.

    QPDF_DLL

    std::map<std::string, QPDFObjectHandle> getFormXObjects();

    // Converts each inline image to an external (normal) image if the size is at least the

    // specified number of bytes. This method works with pages or form XObjects. By default, it

    // recursively processes nested form XObjects. Pass true as shallow to avoid this behavior.

    // Prior to qpdf 10.1, form XObjects were ignored, but this was considered a bug.

    QPDF_DLL

    void externalizeInlineImages(size_t min_size = 0, bool shallow = false);

    // Return the annotations in the page's "/Annots" list, if any. If only_subtype is non-empty,

    // only include annotations of the given subtype.

    QPDF_DLL

    std::vector<QPDFAnnotationObjectHelper> getAnnotations(std::string const& only_subtype = "");

    // Returns a vector of stream objects representing the content streams for the given page.  This

    // routine allows the caller to not care whether there are one or more than one content streams

    // for a page.

    QPDF_DLL

    std::vector<QPDFObjectHandle> getPageContents();

    // Add the given object as a new content stream for this page. If parameter 'first' is true, add

    // to the beginning. Otherwise, add to the end. This routine automatically converts the page

    // contents to an array if it is a scalar, allowing the caller not to care what the initial

    // structure is. You can call coalesceContentStreams() afterwards if you want to force it to be

    // a single stream.

    QPDF_DLL

    void addPageContents(QPDFObjectHandle contents, bool first);

    // Rotate a page. If relative is false, set the rotation of the page to angle. Otherwise, add

    // angle to the rotation of the page. Angle must be a multiple of 90. Adding 90 to the rotation

    // rotates clockwise by 90 degrees.

    QPDF_DLL

    void rotatePage(int angle, bool relative);

    // Coalesce a page's content streams. A page's content may be a stream or an array of streams.

    // If this page's content is an array, concatenate the streams into a single stream. This can be

    // useful when working with files that split content streams in arbitrary spots, such as in the

    // middle of a token, as that can confuse some software. You could also call this after calling

    // addPageContents.

    QPDF_DLL

    void coalesceContentStreams();

    //

    // Content stream handling

    //

    // Parse a page's contents through ParserCallbacks, described above. This method works whether

    // the contents are a single stream or an array of streams. Call on a page object. Also works

    // for form XObjects.

    QPDF_DLL

    void parseContents(QPDFObjectHandle::ParserCallbacks* callbacks);

    // Old name

    QPDF_DLL

    void parsePageContents(QPDFObjectHandle::ParserCallbacks* callbacks);

    // Pass a page's or form XObject's contents through the given TokenFilter. If a pipeline is also

    // provided, it will be the target of the write methods from the token filter. If a pipeline is

    // not specified, any output generated by the token filter will be discarded. Use this interface

    // if you need to pass a page's contents through filter for work purposes without having that

    // filter automatically applied to the page's contents, as happens with addContentTokenFilter.

    // See examples/pdf-count-strings.cc for an example.

    QPDF_DLL

    void filterContents(QPDFObjectHandle::TokenFilter* filter, Pipeline* next = nullptr);

    // Old name -- calls filterContents()

    QPDF_DLL

    void filterPageContents(QPDFObjectHandle::TokenFilter* filter, Pipeline* next = nullptr);

    // Pipe a page's contents through the given pipeline. This method works whether the contents are

    // a single stream or an array of streams. Also works on form XObjects.

    QPDF_DLL

    void pipeContents(Pipeline* p);

    // Old name

    QPDF_DLL

    void pipePageContents(Pipeline* p);

    // Attach a token filter to a page's contents. If the page's contents is an array of streams, it

    // is automatically coalesced. The token filter is applied to the page's contents as a single

    // stream. Also works on form XObjects.

    QPDF_DLL

    void addContentTokenFilter(std::shared_ptr<QPDFObjectHandle::TokenFilter> token_filter);

    // A page's resources dictionary maps names to objects elsewhere in the file. This method walks

    // through a page's contents and keeps tracks of which resources are referenced somewhere in the

    // contents. Then it removes from the resources dictionary any object that is not referenced in

    // the contents. This operation is most useful after calling

    // QPDFPageDocumentHelper::pushInheritedAttributesToPage(). This method is used by page

    // splitting code to avoid copying unused objects in files that used shared resource

    // dictionaries across multiple pages. This method recurses into form XObjects and can be called

    // with a form XObject as well as a page.

    QPDF_DLL

    void removeUnreferencedResources();

    // Return a new QPDFPageObjectHelper that is a duplicate of the page. The returned object is an

    // indirect object that is ready to be inserted into the same or a different QPDF object using

    // any of the addPage methods in QPDFPageDocumentHelper or QPDF. Without calling one of those

    // methods, the page will not be added anywhere. The new page object shares all content streams

    // and indirect object resources with the original page, so if you are going to modify the

    // contents or other aspects of the page, you will need to handling copying of the component

    // parts separately.

    QPDF_DLL

    QPDFPageObjectHelper shallowCopyPage();

    // Return a transformation matrix whose effect is the same as the page's /Rotate and /UserUnit

    // parameters. If invert is true, return a matrix whose effect is the opposite. The regular

    // matrix is suitable for taking something from this page to put elsewhere, and the second one

    // is suitable for putting something else onto this page. The page's TrimBox is used as the

    // bounding box for purposes of computing the matrix.

    QPDF_DLL

    QPDFObjectHandle::Matrix getMatrixForTransformations(bool invert = false);

    // Return a form XObject that draws this page. This is useful for n-up operations, underlay,

    // overlay, thumbnail generation, or any other case in which it is useful to replicate the

    // contents of a page in some other context. The dictionaries are shallow copies of the original

    // page dictionary, and the contents are coalesced from the page's contents. The resulting

    // object handle is not referenced anywhere. If handle_transformations is true, the resulting

    // form XObject's /Matrix will be set to replicate rotation (/Rotate) and scaling (/UserUnit) in

    // the page's dictionary. In this way, the page's transformations will be preserved when placing

    // this object on another page.

    QPDF_DLL

    QPDFObjectHandle getFormXObjectForPage(bool handle_transformations = true);

    // Return content stream text that will place the given form XObject (fo) using the resource

    // name "name" on this page centered within the given rectangle. If invert_transformations is

    // true, the effect of any rotation (/Rotate) and scaling (/UserUnit) applied to the current

    // page will be inverted in the form XObject placement. This will cause the form XObject's

    // absolute orientation to be preserved. You could overlay one page on another by calling

    // getFormXObjectForPage on the original page, QPDFObjectHandle::getUniqueResourceName on the

    // destination page's Resources dictionary to generate a name for the resulting object, and

    // calling placeFormXObject on the destination page. Then insert the new fo (or, if it comes

    // from a different file, the result of calling copyForeignObject on it) into the resources

    // dictionary using name, and append or prepend the content to the page's content streams. See

    // the overlay/underlay code in qpdf.cc or examples/pdf-overlay-page.cc for an example. From

    // qpdf 10.0.0, the allow_shrink and allow_expand parameters control whether the form XObject is

    // allowed to be shrunk or expanded to stay within or maximally fill the destination rectangle.

    // The default values are for backward compatibility with the pre-10.0.0 behavior.

    QPDF_DLL

    std::string placeFormXObject(

        QPDFObjectHandle fo,

        std::string const& name,

        QPDFObjectHandle::Rectangle rect,

        bool invert_transformations = true,

        bool allow_shrink = true,

        bool allow_expand = false);

    // Alternative version that also fills in the transformation matrix that was used.

    QPDF_DLL

    std::string placeFormXObject(

        QPDFObjectHandle fo,

        std::string const& name,

        QPDFObjectHandle::Rectangle rect,

        QPDFMatrix& cm,

        bool invert_transformations = true,

        bool allow_shrink = true,

        bool allow_expand = false);

    // Return the transformation matrix that translates from the given form XObject's coordinate

    // system into the given rectangular region on the page. The parameters have the same meaning as

    // for placeFormXObject.

    QPDF_DLL

    QPDFMatrix getMatrixForFormXObjectPlacement(

        QPDFObjectHandle fo,

        QPDFObjectHandle::Rectangle rect,

        bool invert_transformations = true,

        bool allow_shrink = true,

        bool allow_expand = false);

    // If a page is rotated using /Rotate in the page's dictionary, instead rotate the page by the

    // same amount by altering the contents and removing the /Rotate key. This method adjusts the

    // various page bounding boxes (/MediaBox, etc.) so that the page will have the same semantics.

    // This can be useful to work around problems with PDF applications that can't properly handle

    // rotated pages. If a QPDFAcroFormDocumentHelper is provided, it will be used for resolving any

    // form fields that have to be rotated. If not, one will be created inside the function, which

    // is less efficient.

    QPDF_DLL

    void flattenRotation(QPDFAcroFormDocumentHelper* afdh = nullptr);

    // Copy annotations from another page into this page. The other page may be from the same QPDF

    // or from a different QPDF. Each annotation's rectangle is transformed by the given matrix. If

    // the annotation is a widget annotation that is associated with a form field, the form field is

    // copied into this document's AcroForm dictionary as well. You can use this to copy annotations

    // from a page that was converted to a form XObject and added to another page. For example of

    // this, see examples/pdf-overlay-page.cc. This method calls

    // QPDFAcroFormDocumentHelper::transformAnnotations, which will copy annotations and form fields

    // so that you can copy annotations from a source page to any number of other pages, even with

    // different matrices, and maintain independence from the original annotations. See also

    // QPDFAcroFormDocumentHelper::fixCopiedAnnotations, which can be used if you copy a page and

    // want to repair the annotations on the destination page to make them independent from the

    // original page's annotations.

    //

    // If you pass in a QPDFAcroFormDocumentHelper*, the method will use that instead of creating

    // one in the function. Creating QPDFAcroFormDocumentHelper objects is expensive, so if you're

    // doing a lot of copying, it can be more efficient to create these outside and pass them in.

    QPDF_DLL

    void copyAnnotations(

        QPDFPageObjectHelper from_page,

        QPDFMatrix const& cm = QPDFMatrix(),

        QPDFAcroFormDocumentHelper* afdh = nullptr,

        QPDFAcroFormDocumentHelper* from_afdh = nullptr);

  private:

    QPDFObjectHandle getAttribute(

        std::string const& name,

        bool copy_if_shared,

        std::function<QPDFObjectHandle()> get_fallback,

        bool copy_if_fallback);

    static bool

    removeUnreferencedResourcesHelper(QPDFPageObjectHelper ph, std::set<std::string>& unresolved);

    class Members

    {

        friend class QPDFPageObjectHelper;

      public:

        ~Members() = default;

      private:

        Members() = default;

        Members(Members const&) = delete;

    };

    std::shared_ptr<Members> m;

};

#endif // QPDFPAGEOBJECTHELPER_HH