Navigate the XPS OM

Статья
06/01/2017

This topic describes how to navigate an XPS OM and to access different parts of the in-memory document.

The organization of the XPS Document API mirrors the organization of an XPS document. The following table illustrates how the interfaces of the XPS Document API relate to the components of an XPS document.

XPS document component	XPS Document API interface	Method to call for the next level down in the hierarchy
XPS document file (contains OPC package)	IXpsOMPackage	GetDocumentSequence
FixedDocumentSequence part	IXpsOMDocumentSequence	GetDocuments
FixedDocument part	IXpsOMDocument	GetPageReferences
PageContent element in the FixedDocument markup	IXpsOMPageReference	GetPage CollectPartResources
FixedPage part	IXpsOMPage	GetVisuals
Canvas element in the FixedPage markup	IXpsOMCanvas	GetVisuals
Path element in the FixedPage markup	IXpsOMPath	End of document hierarchy.
Glyphs element in the FixedPage markup	IXpsOMGlyphs	End of document hierarchy.
Font part	IXpsOMFontResource	End of document hierarchy.
Image part	IXpsOMImageResource	End of document hierarchy.

Before using the following code examples in your program, read the disclaimer in Common XPS Document Programming Tasks.

Code Example

The following code example assumes the existence of an initialized XPS OM, and package points to an IXpsOMPackage interface that represents that XPS OM. For information about creating an XPS OM, see Read an XPS Document into an XPS OM or Create a Blank XPS OM.

    HRESULT                        hr = S_OK;

    IXpsOMDocumentSequence         *docSeq = NULL;
    IXpsOMDocumentCollection       *docs = NULL;
    IXpsOMDocument                 *doc = NULL;
    IXpsOMPageReferenceCollection  *pages = NULL;
    IXpsOMPageReference            *pageRef = NULL;
    IXpsOMPage                     *page = NULL;
    IXpsOMCanvas                   *canvas = NULL;
    IXpsOMPath                     *path = NULL;
    IXpsOMPartResources            *pageParts = NULL;
    IXpsOMGlyphs                   *glyphs = NULL;
    IXpsOMFontResourceCollection   *fonts = NULL; 
    IXpsOMFontResource             *font = NULL;
    IXpsOMImageResourceCollection  *images = NULL;
    IXpsOMImageResource            *image = NULL;
    IXpsOMVisualCollection         *visuals = NULL;
    IXpsOMVisual                   *visual = NULL;

    UINT32  numDocs = 0;
    UINT32  thisDoc = 0;

    UINT32  numPageRefs = 0;
    UINT32  thisPageRef = 0;

    UINT32  numVisuals = 0;
    UINT32  thisVisual = 0;

    UINT32  numFonts = 0;
    UINT32  thisFont = 0;

    UINT32  numImages = 0;
    UINT32  thisImage = 0;

    XPS_OBJECT_TYPE  visualType;
 
    // package points to the IXpsOMPackage interface to walk.

    // Get the fixed document sequence of the package.
    hr = package->GetDocumentSequence(&docSeq);

    // Get the fixed documents in the fixed document sequence.
    hr = docSeq->GetDocuments(&docs);

    // Walk the collection of documents.
    hr = docs->GetCount(&numDocs);
    thisDoc = 0;
    while (thisDoc < numDocs) {
        hr = docs->GetAt(thisDoc, &doc);
        
        // Get the doc contents.
        hr = doc->GetPageReferences(&pages);
        
        // Walk the collection of page references
        hr = pages->GetCount(&numPageRefs);
        thisPageRef = 0;
        while (thisPageRef < numPageRefs) {
            // Get this page reference.
            hr = pages->GetAt(thisPageRef, &pageRef);

            // Get the page content of this page reference.
            {
                hr = pageRef->GetPage (&page);

                // Get the visual tree of this page.
                hr = page->GetVisuals (&visuals);
                
                // Walk the visuals.
                hr = visuals->GetCount (&numVisuals);
                thisVisual = 0;
                while (thisVisual < numVisuals) {
                    hr = visuals->GetAt (thisVisual, &visual);
                    // Get visual type.
                    hr = visual->GetType( &visualType );
                    
                    // Do other stuff with the visual.

                    // Release the visual.
                    if (NULL != visual) {visual->Release(); visual = NULL;}
                    thisVisual++; // Get next visual in collection.
                }
                if (NULL != visuals) {visuals->Release(); visuals = NULL;}
                if (NULL != page) {page->Release(); page = NULL;}
            }
            // Get the part resources used by this page.
            hr = pageRef->CollectPartResources (&pageParts);

            // Get the font resources.
            {
                hr = pageParts->GetFontResources (&fonts);
                
                // Walk the fonts.
                hr = fonts->GetCount (&numFonts);
                thisFont = 0;
                while (thisFont < numFonts) {
                    hr = fonts->GetAt(thisFont, &font);
                    if (NULL != font) {font->Release(); font = NULL;}

                    thisFont++; // Get the next font in collection.
                }
                if (NULL != fonts) {fonts->Release(); fonts = NULL;}
            }

            // Get the image resources.
            {
                hr = pageParts->GetImageResources (&images);

                // walk the images
                hr = images->GetCount (&numImages);
                thisImage = 0;
                while (thisImage < numImages) {
                    hr = images->GetAt(thisImage, &image);
                    thisImage++;
                    if (NULL != image) {image->Release(); image = NULL;}
                }
                if (NULL != images) {images->Release(); images = NULL;}
            }
            if (NULL != pageRef) {pageRef->Release(); pageRef = NULL;}
            thisPageRef++; // Get next page in doc.
        }
        if (NULL != pages) {pages->Release(); pages = NULL;}
        if (NULL != doc) {doc->Release(); doc = NULL;}
        thisDoc++; // Get next doc in collection.
    }

    // Release interface pointers.
    if (NULL != docs) docs->Release();
    if (NULL != docSeq) docSeq->Release();

Next Steps

Write Text to an XPS OM

Draw Graphics in an XPS OM

Place Images in an XPS OM

Used in This Page

IXpsOMDocument

IXpsOMDocumentCollection

IXpsOMDocumentSequence

IXpsOMFontResource

IXpsOMFontResourceCollection

IXpsOMImageResource

IXpsOMImageResourceCollection