Generate previews Leave feedback
GroupDocs.Parser provides the functionality to generate document page previews by generatePreview(PreviewOptions) method:
void generatePreview(PreviewOptions previewOptions)
PreviewOptions class is used to set requirements and stream delegates for preview generation.
Here are the steps to generate document page previews:
- Prepare PreviewOptions object;
- Instantiate Parser object;
- Call generatePreview(PreviewOptions) method.
The following example shows how to generate document page previews:
// Create an instance of Parser class to generate document page previews
try (Parser parser = new Parser(Constants.SamplePdfWithToc)) {
// Create preview options
PreviewOptions previewOptions = new PreviewOptions(
new ICreatePageStream() {
@Override
public OutputStream createPageStream(int pageNumber) {
try {
return new FileOutputStream(getOutputPath(String.format("preview_%d.png", pageNumber)));
} catch (IOException ex) {
throw new RuntimeException(ex.getMessage());
}
}
});
// Set PNG as an output image format
previewOptions.setPreviewFormat(PreviewFormats.Png);
// Set DPI for the output image
previewOptions.setDpi(72);
// Generate previews
parser.generatePreview(previewOptions);
}
private static String getOutputPath(String fileName) throws java.io.IOException {
return Constants.getOutputFilePath(fileName);
}
NoteSpreadsheets are rendered by tiles. See the example bellow.
Here are the steps to generate spreadsheets page previews:
- Prepare PreviewOptions object;
- Instantiate Parser object;
- Call generatePreview(PreviewOptions) method.
The following example shows how to generate spreadsheet page previews:
// Create an instance of Parser class to generate spreadsheet page previews
try (Parser parser = new Parser(Constants.SampleXlsx)) {
final PageRenderInfo[] renderInfo = {null};
// Create preview options
PreviewOptions previewOptions = new PreviewOptions(
new ICreatePageStream() {
@Override
public OutputStream createPageStream(int pageNumber) {
try {
return new FileOutputStream(getOutputPath(renderInfo[0], pageNumber));
} catch (IOException ex) {
throw new RuntimeException(ex.getMessage());
}
}
});
// Set delegate to obtain the render info
previewOptions.setPreviewPageRender(
new IPreviewPageRender() {
@Override
public void previewPageRender(PageRenderInfo pageRenderInfo) {
renderInfo[0] = pageRenderInfo;
}
});
// Set PNG as an output image format
previewOptions.setPreviewFormat(PreviewFormats.Png);
// Set DPI for the output image
previewOptions.setDpi(72);
// Generate previews
parser.generatePreview(previewOptions);
}
private static String getOutputPath(PageRenderInfo renderInfo, int pageNumber) throws java.io.IOException {
// Set the file name. If the render info is set, then tile name is {Row}x{Column}.png
String fileName = renderInfo == null
? String.format("preview_%d.png", pageNumber)
: String.format("%d\\%dx%d.png", renderInfo.getPageNumber(), renderInfo.getRow(pageNumber), renderInfo.getColumn(pageNumber));
return Constants.getOutputFilePath(fileName);
}
You may easily run the code above and see the feature in action in our GitHub examples:
Along with full featured .NET library we provide simple, but powerful free Apps.
You are welcome to parse documents and extract data from PDF, DOC, DOCX, PPT, PPTX, XLS, XLSX, Emails and more with our free online Free Online Document Parser App.
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