Write Text to an XPS OM

This topic describes how to write text to an XPS OM.

Text is placed in an XPS OM by creating and formatting an IXpsOMGlyphs interface and then adding the IXpsOMGlyphs interface to the page's or canvas' list of visual objects. Each IXpsOMGlyphs interface represents a glyph run, which is a continuous run of characters that share a common format. When a character format element (such as font type or size) changes or when a line breaks, a new IXpsOMGlyphs interface must be created and added to the list of visual objects.

Some of the properties of a glyph run can be set by using the methods of the IXpsOMGlyphs interface. Some properties, however, interact with others and must be set by using an IXpsOMGlyphsEditor interface.

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

Code Example

Create a glyph run from a string

A glyph run is commonly created in several steps that include loading the font resources that are used by the glyph run, setting a fill brush, specifying the font size and starting location, and setting the Unicode string.

The following section of the code example contains a routine that accepts some variables, including the font size, color and location, and the characters to be written. The code then creates a glyph run and then adds it to a page. The code example assumes that the initialization described in Initialize an XPS OM has occurred and that the document has at least one page. For more information about creating a blank XPS OM, refer to Create a Blank XPS OM.


// Write Text to an XPS OM
HRESULT
WriteText_AddTextToPage(
            // A pre-created object factory
    __in    IXpsOMObjectFactory   *xpsFactory,
            // The font resource to use for this run
    __in    IXpsOMFontResource    *xpsFont,
            // The font size
    __in    float                 fontEmSize,
            // The solid color brush to use for the font
    __in    IXpsOMSolidColorBrush *xpsBrush,
            // The starting location of this glyph run
    __in    XPS_POINT             *origin,
            // The text to use for this run
    __in    LPCWSTR               unicodeString,
            // The page on which to write this glyph run
    __inout IXpsOMPage            *xpsPage        
)
{
    // The data type definitions are included in this function
    // for the convenience of this code example. In an actual
    // implementation they would probably belong in a header file.
    HRESULT                       hr = S_OK;
    XPS_POINT                     glyphsOrigin = {origin->x, origin->y};
    IXpsOMGlyphsEditor            *glyphsEditor = NULL;
    IXpsOMGlyphs                  *xpsGlyphs = NULL;
    IXpsOMVisualCollection        *pageVisuals = NULL;

    // Create a new Glyphs object and set its properties.
    hr = xpsFactory->CreateGlyphs(xpsFont, &xpsGlyphs);
    hr = xpsGlyphs->SetOrigin(&glyphsOrigin);
    hr = xpsGlyphs->SetFontRenderingEmSize(fontEmSize);
    hr = xpsGlyphs->SetFillBrushLocal(xpsBrush);

    // Some properties are inter-dependent so they
    //    must be changed by using a GlyphsEditor.
    hr = xpsGlyphs->GetGlyphsEditor(&glyphsEditor);
    hr = glyphsEditor->SetUnicodeString(unicodeString);
    hr = glyphsEditor->ApplyEdits();

    // Add the new Glyphs object to the page
    hr = xpsPage->GetVisuals(&pageVisuals);
    hr = pageVisuals->Append(xpsGlyphs);

    // Release interface pointers.
    if (NULL != xpsGlyphs) xpsGlyphs->Release();
    if (NULL != glyphsEditor) glyphsEditor->Release();
    if (NULL != pageVisuals) pageVisuals->Release();

    return hr;
}


Load and create resources

Creation of an IXpsOMGlyphs interface requires a font resource. In many cases, a block of text uses the same font and color. Hence, this section of the code example will create the font resource interfaces that will be used in the calls that place the text on the page.


    // fontFileName is the name of the font file and it 
    //  is defined outside of this example.

    HRESULT                       hr = S_OK;

    GUID                          fontNameGuid;
    WCHAR                         guidString[128] = {0};
    WCHAR                         uriString[256] = {0};

    IStream                       *fontStream  = NULL;
    IOpcPartUri                   *fontUri = NULL;
    IXpsOMFontResource            *fontResource = NULL;
    IXpsOMVisualCollection        *pageVisuals = NULL;
    IXpsOMPage                    *page = NULL;
    IXpsOMVisual                  *canvasVisual = NULL;
    IXpsOMSolidColorBrush         *xpsTextColor = NULL;
    XPS_COLOR                     xpsColorBodyText;
 
    // Create font stream.
    hr = xpsFactory->CreateReadOnlyStreamOnFile ( 
        fontFileName, &fontStream );
    
    // Create new obfuscated part name for this resource using a GUID.
    hr = CoCreateGuid( &fontNameGuid );
    hr = StringFromGUID2( 
            fontNameGuid, 
            guidString, 
            ARRAYSIZE(guidString));

    // Create a URI string for this font resource that will place 
    //  the font part in the /Resources/Fonts folder of the package.
    wcscpy_s(uriString, ARRAYSIZE(uriString), L"/Resources/Fonts/");

    // Create the part name using the GUID string as the name and 
    //  ".odttf" as the extension GUID string start and ends with 
    //  curly braces so they are removed.
    wcsncat_s(uriString, ARRAYSIZE(uriString), 
        guidString + 1, wcslen(guidString) - 2); 
    wcscat_s(uriString, ARRAYSIZE(uriString), L".odttf");

    // Create the font URI interface.
    hr = xpsFactory->CreatePartUri(
        uriString,
        &fontUri);
    // Create the font resource.
    hr = xpsFactory->CreateFontResource(
        fontStream,
        XPS_FONT_EMBEDDING_OBFUSCATED,
        fontUri,
        FALSE,     // isObfSourceStream
        &fontResource);
    if (NULL != fontUri) fontUri->Release();

    // Create the brush to use for the font.
    xpsColorBodyText.colorType = XPS_COLOR_TYPE_SRGB;
    xpsColorBodyText.value.sRGB.alpha = 0xFF;
    xpsColorBodyText.value.sRGB.red = 0x00;
    xpsColorBodyText.value.sRGB.green = 0x00;
    xpsColorBodyText.value.sRGB.blue = 0x00;

    hr = xpsFactory->CreateSolidColorBrush( 
        &xpsColorBodyText,
        NULL, // This color type does not use a color profile resource.             
        &xpsTextColor);

    // xpsTextColor is released after it has been used.


Draw text in a page

The final section of the code example creates the glyph runs for each run of similarly formatted text. To execute the code in this final section, the xpsFactory interface as well as the font resource and a text color brush are necessary and must have been instantiated and initialized. In this example, the function described in the first section is used to create the glyph runs and to add them to the page.


    // The following interfaces are created outside of this example.

    // The page on which to place the text.
    IXpsOMPage                *page = NULL;

    // The object factory used by this program.
    IXpsOMObjectFactory       *xpsFactory = NULL;

    // The font resource created in the previous snippet.
    IXpsOMFontResource        *fontResource = NULL;

    // The color brush created in the previous snippet.
    IXpsOMSolidColorBrush     *xpsTextColor = NULL;

    // The following variables are defined outside of this example.

    // An array of pointers to the Unicode strings to write.
    LPCWSTR                   *textRuns = NULL;

    // An array of start points that correspond to the 
    //    strings in textRuns.
    XPS_POINT                 *startPoints = NULL;

    // The number of text runs to add to the page.
    UINT32                    numRuns = 0;            

    HRESULT                   hr = S_OK;

    FLOAT                     fontSize = 7.56f;
    UINT32                    thisRun;

    // Add all the text runs to the page.
    thisRun = 0;
    while (thisRun < numRuns) {  
        hr = WriteText_AddTextToPage(
            xpsFactory, 
            fontResource,
            fontSize,
            xpsTextColor,
            &startPoints[thisRun],
            textRuns[thisRun],
            page);
        thisRun++;
    }


Related topics

Next Steps
Navigate the XPS OM
Draw Graphics in an XPS OM
Place Images in an XPS OM
Write an XPS OM to an XPS Document
Print an XPS OM
Used in This Section
IOpcPartUri
IXpsOMFontResource
IXpsOMGlyphs
IXpsOMGlyphsEditor
IXpsOMObjectFactory
IXpsOMPage
IXpsOMSolidColorBrush
IXpsOMVisual
IXpsOMVisualCollection
For More Information
Initialize an XPS OM
XPS Document API Reference
XML Paper Specification

 

 

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