Aspose::Words::IWarningCallback interface

IWarningCallback interface

Implement this interface if you want to have your own custom method called to capture loss of fidelity warnings that can occur during document loading or saving.

class IWarningCallback : public virtual System::Object

Methods

Method	Description
GetType() const override
Is(const System::TypeInfo&) const override
static Type()
virtual Warning(System::SharedPtr<Aspose::Words::WarningInfo>)	Aspose.Words invokes this method when it encounters some issue during document loading or saving that might result in loss of formatting or data fidelity.

Examples

Shows how to use the IWarningCallback interface to monitor font substitution warnings.

void SubstitutionWarning()
{
    auto doc = MakeObject<Document>();
    auto builder = MakeObject<DocumentBuilder>(doc);

    builder->get_Font()->set_Name(u"Times New Roman");
    builder->Writeln(u"Hello world!");

    auto callback = MakeObject<ExFontSettings::FontSubstitutionWarningCollector>();
    doc->set_WarningCallback(callback);

    // Store the current collection of font sources, which will be the default font source for every document
    // for which we do not specify a different font source.
    ArrayPtr<SharedPtr<FontSourceBase>> originalFontSources = FontSettings::get_DefaultInstance()->GetFontsSources();

    // For testing purposes, we will set Aspose.Words to look for fonts only in a folder that does not exist.
    FontSettings::get_DefaultInstance()->SetFontsFolder(String::Empty, false);

    // When rendering the document, there will be no place to find the "Times New Roman" font.
    // This will cause a font substitution warning, which our callback will detect.
    doc->Save(ArtifactsDir + u"FontSettings.SubstitutionWarning.pdf");

    FontSettings::get_DefaultInstance()->SetFontsSources(originalFontSources);

    ASSERT_TRUE(callback->FontSubstitutionWarnings->idx_get(0)->get_WarningType() == WarningType::FontSubstitution);
    ASSERT_TRUE(System::ObjectExt::Equals(callback->FontSubstitutionWarnings->idx_get(0)->get_Description(),
                                          u"Font 'Times New Roman' has not been found. Using 'Fanwood' font instead. Reason: first available font."));
}

class FontSubstitutionWarningCollector : public IWarningCallback
{
public:
    SharedPtr<WarningInfoCollection> FontSubstitutionWarnings;

    void Warning(SharedPtr<WarningInfo> info) override
    {
        if (info->get_WarningType() == WarningType::FontSubstitution)
        {
            FontSubstitutionWarnings->Warning(info);
        }
    }

    FontSubstitutionWarningCollector() : FontSubstitutionWarnings(MakeObject<WarningInfoCollection>())
    {
    }
};

Shows how to set the property for finding the closest match for a missing font from the available font sources.

void EnableFontSubstitution()
{
    // Open a document that contains text formatted with a font that does not exist in any of our font sources.
    auto doc = MakeObject<Document>(MyDir + u"Missing font.docx");

    // Assign a callback for handling font substitution warnings.
    auto substitutionWarningHandler = MakeObject<ExFontSettings::HandleDocumentSubstitutionWarnings>();
    doc->set_WarningCallback(substitutionWarningHandler);

    // Set a default font name and enable font substitution.
    auto fontSettings = MakeObject<FontSettings>();
    fontSettings->get_SubstitutionSettings()->get_DefaultFontSubstitution()->set_DefaultFontName(u"Arial");
    ;
    fontSettings->get_SubstitutionSettings()->get_FontInfoSubstitution()->set_Enabled(true);

    // We will get a font substitution warning if we save a document with a missing font.
    doc->set_FontSettings(fontSettings);
    doc->Save(ArtifactsDir + u"FontSettings.EnableFontSubstitution.pdf");

    {
        SharedPtr<System::Collections::Generic::IEnumerator<SharedPtr<WarningInfo>>> warnings = substitutionWarningHandler->FontWarnings->GetEnumerator();
        while (warnings->MoveNext())
        {
            std::cout << warnings->get_Current()->get_Description() << std::endl;
        }
    }

    // We can also verify warnings in the collection and clear them.
    ASSERT_EQ(WarningSource::Layout, substitutionWarningHandler->FontWarnings->idx_get(0)->get_Source());
    ASSERT_EQ(u"Font '28 Days Later' has not been found. Using 'Calibri' font instead. Reason: alternative name from document.",
              substitutionWarningHandler->FontWarnings->idx_get(0)->get_Description());

    substitutionWarningHandler->FontWarnings->Clear();

    ASSERT_EQ(0, substitutionWarningHandler->FontWarnings->get_Count());
}

class HandleDocumentSubstitutionWarnings : public IWarningCallback
{
public:
    SharedPtr<WarningInfoCollection> FontWarnings;

    void Warning(SharedPtr<WarningInfo> info) override
    {
        if (info->get_WarningType() == WarningType::FontSubstitution)
        {
            FontWarnings->Warning(info);
        }
    }

    HandleDocumentSubstitutionWarnings() : FontWarnings(MakeObject<WarningInfoCollection>())
    {
    }
};

Shows added a fallback to bitmap rendering and changing type of warnings about unsupported metafile records.

void HandleBinaryRasterWarnings()
{
    auto doc = MakeObject<Document>(MyDir + u"WMF with image.docx");

    auto metafileRenderingOptions = MakeObject<MetafileRenderingOptions>();

    // Set the "EmulateRasterOperations" property to "false" to fall back to bitmap when
    // it encounters a metafile, which will require raster operations to render in the output PDF.
    metafileRenderingOptions->set_EmulateRasterOperations(false);

    // Set the "RenderingMode" property to "VectorWithFallback" to try to render every metafile using vector graphics.
    metafileRenderingOptions->set_RenderingMode(MetafileRenderingMode::VectorWithFallback);

    // Create a "PdfSaveOptions" object that we can pass to the document's "Save" method
    // to modify how that method converts the document to .PDF and applies the configuration
    // in our MetafileRenderingOptions object to the saving operation.
    auto saveOptions = MakeObject<PdfSaveOptions>();
    saveOptions->set_MetafileRenderingOptions(metafileRenderingOptions);

    auto callback = MakeObject<ExPdfSaveOptions::HandleDocumentWarnings>();
    doc->set_WarningCallback(callback);

    doc->Save(ArtifactsDir + u"PdfSaveOptions.HandleBinaryRasterWarnings.pdf", saveOptions);

    ASSERT_EQ(1, callback->Warnings->get_Count());
    ASSERT_EQ(u"'R2_XORPEN' binary raster operation is not supported.", callback->Warnings->idx_get(0)->get_Description());
}

class HandleDocumentWarnings : public IWarningCallback
{
public:
    SharedPtr<WarningInfoCollection> Warnings;

    void Warning(SharedPtr<WarningInfo> info) override
    {
        if (info->get_WarningType() == WarningType::MinorFormattingLoss)
        {
            std::cout << (String(u"Unsupported operation: ") + info->get_Description()) << std::endl;
            Warnings->Warning(info);
        }
    }

    HandleDocumentWarnings() : Warnings(MakeObject<WarningInfoCollection>())
    {
    }
};

Aspose::Words::IWarningCallback interface

IWarningCallback interface

Methods

Examples

See Also