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Attempt to improve the detection of (metric) page names, by fuzzy matching the dimensions

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The following is an example of a PDF file (the specification to be exact) where the page size (compare the size displayed in Adobe Reader), and the page name, isn't correctly displayed without the patch: https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf
This commit is contained in:
Jonas Jenwald 2018-03-21 13:39:07 +01:00
parent d86b816c2b
commit b004308f88
1 changed files with 35 additions and 4 deletions
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39
web/pdf_document_properties.js
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@ -287,19 +287,50 @@ class PDFDocumentProperties {
}
const isPortrait = isPortraitOrientation(pageSizeInches);
const sizeInches = {
let sizeInches = {
width: Math.round(pageSizeInches.width * 100) / 100,
height: Math.round(pageSizeInches.height * 100) / 100,
};
// 1in == 25.4mm; no need to round to 2 decimals for millimeters.
const sizeMillimeters = {
let sizeMillimeters = {
width: Math.round(pageSizeInches.width * 25.4 * 10) / 10,
height: Math.round(pageSizeInches.height * 25.4 * 10) / 10,
};
let pageName = null;
const name = getPageName(sizeInches, isPortrait, US_PAGE_NAMES) ||
getPageName(sizeMillimeters, isPortrait, METRIC_PAGE_NAMES);
let name = getPageName(sizeInches, isPortrait, US_PAGE_NAMES) ||
getPageName(sizeMillimeters, isPortrait, METRIC_PAGE_NAMES);
if (!name && !(Number.isInteger(sizeMillimeters.width) &&
Number.isInteger(sizeMillimeters.height))) {
// Attempt to improve the page name detection by falling back to fuzzy
// matching of the metric dimensions, to account for e.g. rounding errors
// and/or PDF files that define the page sizes in an imprecise manner.
const exactMillimeters = {
width: pageSizeInches.width * 25.4,
height: pageSizeInches.height * 25.4,
};
const intMillimeters = {
width: Math.round(sizeMillimeters.width),
height: Math.round(sizeMillimeters.height),
};
// Try to avoid false positives, by only considering "small" differences.
if (Math.abs(exactMillimeters.width - intMillimeters.width) < 0.1 &&
Math.abs(exactMillimeters.height - intMillimeters.height) < 0.1) {
name = getPageName(intMillimeters, isPortrait, METRIC_PAGE_NAMES);
if (name) {
// Update *both* sizes, computed above, to ensure that the displayed
// dimensions always correspond to the detected page name.
sizeInches = {
width: Math.round(intMillimeters.width / 25.4 * 100) / 100,
height: Math.round(intMillimeters.height / 25.4 * 100) / 100,
};
sizeMillimeters = intMillimeters;
}
}
}
if (name) {
pageName = this.l10n.get('document_properties_page_size_name_' +
name.toLowerCase(), null, name);