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Implement a single getInheritableProperty utility function

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This function combines the logic of two separate methods into one.
The loop limit is also a good thing to have for the calls in
`src/core/annotation.js`.

Moreover, since this is important functionality, a set of unit tests and
documentation is added.
This commit is contained in:
Tim van der Meij 2018-02-18 21:42:33 +01:00
parent 4e5eb59a33
commit f308d73d40
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GPG Key ID: 8C3FD2925A5F2762
4 changed files with 189 additions and 57 deletions
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26
src/core/annotation.js
View File

@ -15,7 +15,8 @@
import {
AnnotationBorderStyleType, AnnotationFieldFlag, AnnotationFlag,
AnnotationType, OPS, stringToBytes, stringToPDFString, Util, warn
AnnotationType, getInheritableProperty, OPS, stringToBytes, stringToPDFString,
Util, warn
} from '../shared/util';
import { Catalog, FileSpec, ObjectLoader } from './obj';
import { Dict, isDict, isName, isRef, isStream } from './primitives';
@ -60,7 +61,7 @@ class AnnotationFactory {
return new TextAnnotation(parameters);
case 'Widget':
let fieldType = Util.getInheritableProperty(dict, 'FT');
let fieldType = getInheritableProperty({ dict, key: 'FT', });
fieldType = isName(fieldType) ? fieldType.name : null;
switch (fieldType) {
@ -580,15 +581,16 @@ class WidgetAnnotation extends Annotation {
data.annotationType = AnnotationType.WIDGET;
data.fieldName = this._constructFieldName(dict);
data.fieldValue = Util.getInheritableProperty(dict, 'V',
/* getArray = */ true);
data.fieldValue = getInheritableProperty({ dict, key: 'V',
getArray: true, });
data.alternativeText = stringToPDFString(dict.get('TU') || '');
data.defaultAppearance = Util.getInheritableProperty(dict, 'DA') || '';
let fieldType = Util.getInheritableProperty(dict, 'FT');
data.defaultAppearance = getInheritableProperty({ dict, key: 'DA', }) || '';
let fieldType = getInheritableProperty({ dict, key: 'FT', });
data.fieldType = isName(fieldType) ? fieldType.name : null;
this.fieldResources = Util.getInheritableProperty(dict, 'DR') || Dict.empty;
this.fieldResources = getInheritableProperty({ dict, key: 'DR', }) ||
Dict.empty;
data.fieldFlags = Util.getInheritableProperty(dict, 'Ff');
data.fieldFlags = getInheritableProperty({ dict, key: 'Ff', });
if (!Number.isInteger(data.fieldFlags) || data.fieldFlags < 0) {
data.fieldFlags = 0;
}
@ -675,18 +677,20 @@ class TextWidgetAnnotation extends WidgetAnnotation {
constructor(params) {
super(params);
const dict = params.dict;
// The field value is always a string.
this.data.fieldValue = stringToPDFString(this.data.fieldValue || '');
// Determine the alignment of text in the field.
let alignment = Util.getInheritableProperty(params.dict, 'Q');
let alignment = getInheritableProperty({ dict, key: 'Q', });
if (!Number.isInteger(alignment) || alignment < 0 || alignment > 2) {
alignment = null;
}
this.data.textAlignment = alignment;
// Determine the maximum length of text in the field.
let maximumLength = Util.getInheritableProperty(params.dict, 'MaxLen');
let maximumLength = getInheritableProperty({ dict, key: 'MaxLen', });
if (!Number.isInteger(maximumLength) || maximumLength < 0) {
maximumLength = null;
}
@ -814,7 +818,7 @@ class ChoiceWidgetAnnotation extends WidgetAnnotation {
// inherit the options from a parent annotation (issue 8094).
this.data.options = [];
let options = Util.getInheritableProperty(params.dict, 'Opt');
let options = getInheritableProperty({ dict: params.dict, key: 'Opt', });
if (Array.isArray(options)) {
let xref = params.xref;
for (let i = 0, ii = options.length; i < ii; i++) {

54
src/core/document.js
View File

@ -16,8 +16,8 @@
import { Catalog, ObjectLoader, XRef } from './obj';
import { Dict, isDict, isName, isStream } from './primitives';
import {
info, isArrayBuffer, isNum, isSpace, isString, MissingDataException, OPS,
shadow, stringToBytes, stringToPDFString, Util, warn
getInheritableProperty, info, isArrayBuffer, isNum, isSpace, isString,
MissingDataException, OPS, shadow, stringToBytes, stringToPDFString, Util
} from '../shared/util';
import { NullStream, Stream, StreamsSequenceStream } from './stream';
import { AnnotationFactory } from './annotation';
@ -62,33 +62,19 @@ var Page = (function PageClosure() {
}
Page.prototype = {
getInheritedPageProp: function Page_getInheritedPageProp(key, getArray) {
var dict = this.pageDict, valueArray = null, loopCount = 0;
var MAX_LOOP_COUNT = 100;
getArray = getArray || false;
// Always walk up the entire parent chain, to be able to find
// e.g. \Resources placed on multiple levels of the tree.
while (dict) {
var value = getArray ? dict.getArray(key) : dict.get(key);
if (value !== undefined) {
if (!valueArray) {
valueArray = [];
}
valueArray.push(value);
}
if (++loopCount > MAX_LOOP_COUNT) {
warn('getInheritedPageProp: maximum loop count exceeded for ' + key);
return valueArray ? valueArray[0] : undefined;
}
dict = dict.get('Parent');
/**
* @private
*/
_getInheritableProperty(key, getArray = false) {
let value = getInheritableProperty({ dict: this.pageDict, key, getArray,
stopWhenFound: false, });
if (!Array.isArray(value)) {
return value;
}
if (!valueArray) {
return undefined;
if (value.length === 1 || !isDict(value[0])) {
return value[0];
}
if (valueArray.length === 1 || !isDict(valueArray[0])) {
return valueArray[0];
}
return Dict.merge(this.xref, valueArray);
return Dict.merge(this.xref, value);
},
get content() {
@ -100,11 +86,12 @@ var Page = (function PageClosure() {
// present, but can be empty. Some document omit it still, in this case
// we return an empty dictionary.
return shadow(this, 'resources',
this.getInheritedPageProp('Resources') || Dict.empty);
this._getInheritableProperty('Resources') || Dict.empty);
},
get mediaBox() {
var mediaBox = this.getInheritedPageProp('MediaBox', true);
var mediaBox = this._getInheritableProperty('MediaBox',
/* getArray = */ true);
// Reset invalid media box to letter size.
if (!Array.isArray(mediaBox) || mediaBox.length !== 4) {
return shadow(this, 'mediaBox', LETTER_SIZE_MEDIABOX);
@ -113,7 +100,8 @@ var Page = (function PageClosure() {
},
get cropBox() {
var cropBox = this.getInheritedPageProp('CropBox', true);
var cropBox = this._getInheritableProperty('CropBox',
/* getArray = */ true);
// Reset invalid crop box to media box.
if (!Array.isArray(cropBox) || cropBox.length !== 4) {
return shadow(this, 'cropBox', this.mediaBox);
@ -143,7 +131,7 @@ var Page = (function PageClosure() {
},
get rotate() {
var rotate = this.getInheritedPageProp('Rotate') || 0;
var rotate = this._getInheritableProperty('Rotate') || 0;
// Normalize rotation so it's a multiple of 90 and between 0 and 270
if (rotate % 90 !== 0) {
rotate = 0;
@ -180,7 +168,7 @@ var Page = (function PageClosure() {
loadResources: function Page_loadResources(keys) {
if (!this.resourcesPromise) {
// TODO: add async getInheritedPageProp and remove this.
// TODO: add async `_getInheritableProperty` and remove this.
this.resourcesPromise = this.pdfManager.ensure(this, 'resources');
}
return this.resourcesPromise.then(() => {
@ -316,7 +304,7 @@ var Page = (function PageClosure() {
get annotations() {
var annotations = [];
var annotationRefs = this.getInheritedPageProp('Annots') || [];
var annotationRefs = this._getInheritableProperty('Annots') || [];
for (var i = 0, n = annotationRefs.length; i < n; ++i) {
var annotationRef = annotationRefs[i];
var annotation = AnnotationFactory.create(this.xref, annotationRef,

59
src/shared/util.js
View File

@ -644,6 +644,53 @@ function isEvalSupported() {
}
}
/**
* Get the value of an inheritable property.
*
* If the PDF specification explicitly lists a property in a dictionary as
* inheritable, then the value of the property may be present in the dictionary
* itself or in one or more parents of the dictionary.
*
* If the key is not found in the tree, `undefined` is returned. Otherwise,
* the value for the key is returned or, if `stopWhenFound` is `false`, a list
* of values is returned. To avoid infinite loops, the traversal is stopped when
* the loop limit is reached.
*
* @param {Dict} dict - Dictionary from where to start the traversal.
* @param {string} key - The key of the property to find the value for.
* @param {boolean} getArray - Whether or not the value should be fetched as an
* array. The default value is `false`.
* @param {boolean} stopWhenFound - Whether or not to stop the traversal when
* the key is found. If set to `false`, we always walk up the entire parent
* chain, for example to be able to find `\Resources` placed on multiple
* levels of the tree. The default value is `true`.
*/
function getInheritableProperty({ dict, key, getArray = false,
stopWhenFound = true, }) {
const LOOP_LIMIT = 100;
let loopCount = 0;
let values;
while (dict) {
const value = getArray ? dict.getArray(key) : dict.get(key);
if (value !== undefined) {
if (stopWhenFound) {
return value;
}
if (!values) {
values = [];
}
values.push(value);
}
if (++loopCount > LOOP_LIMIT) {
warn(`getInheritableProperty: maximum loop count exceeded for "${key}"`);
break;
}
dict = dict.get('Parent');
}
return values;
}
var IDENTITY_MATRIX = [1, 0, 0, 1, 0, 0];
var Util = (function UtilClosure() {
@ -853,17 +900,6 @@ var Util = (function UtilClosure() {
}
};
Util.getInheritableProperty =
function Util_getInheritableProperty(dict, name, getArray) {
while (dict && !dict.has(name)) {
dict = dict.get('Parent');
}
if (!dict) {
return null;
}
return getArray ? dict.getArray(name) : dict.get(name);
};
Util.inherit = function Util_inherit(sub, base, prototype) {
sub.prototype = Object.create(base.prototype);
sub.prototype.constructor = sub;
@ -1609,6 +1645,7 @@ export {
createPromiseCapability,
createObjectURL,
deprecated,
getInheritableProperty,
getLookupTableFactory,
getVerbosityLevel,
info,

107
test/unit/util_spec.js
View File

@ -14,9 +14,12 @@
*/
import {
bytesToString, isArrayBuffer, isBool, isEmptyObj, isNum, isSpace, isString,
log2, ReadableStream, removeNullCharacters, stringToBytes, stringToPDFString
bytesToString, getInheritableProperty, isArrayBuffer, isBool, isEmptyObj,
isNum, isSpace, isString, log2, ReadableStream, removeNullCharacters,
stringToBytes, stringToPDFString
} from '../../src/shared/util';
import { Dict, Ref } from '../../src/core/primitives';
import { XRefMock } from './test_utils';
describe('util', function() {
describe('bytesToString', function() {
@ -50,6 +53,106 @@ describe('util', function() {
});
});
describe('getInheritableProperty', function() {
it('handles non-dictionary arguments', function() {
expect(getInheritableProperty({ dict: null, key: 'foo', }))
.toEqual(undefined);
expect(getInheritableProperty({ dict: undefined, key: 'foo', }))
.toEqual(undefined);
});
it('handles dictionaries that do not contain the property', function() {
// Empty dictionary.
const emptyDict = new Dict();
expect(getInheritableProperty({ dict: emptyDict, key: 'foo', }))
.toEqual(undefined);
// Filled dictionary with a different property.
const filledDict = new Dict();
filledDict.set('bar', 'baz');
expect(getInheritableProperty({ dict: filledDict, key: 'foo', }))
.toEqual(undefined);
});
it('fetches the property if it is not inherited', function() {
const ref = new Ref(10, 0);
const xref = new XRefMock([{ ref, data: 'quux', }]);
const dict = new Dict(xref);
// Regular values should be fetched.
dict.set('foo', 'bar');
expect(getInheritableProperty({ dict, key: 'foo', })).toEqual('bar');
// Array value should be fetched (with references resolved).
dict.set('baz', ['qux', ref]);
expect(getInheritableProperty({ dict, key: 'baz', getArray: true, }))
.toEqual(['qux', 'quux']);
});
it('fetches the property if it is inherited and present on one level',
function() {
const ref = new Ref(10, 0);
const xref = new XRefMock([{ ref, data: 'quux', }]);
const firstDict = new Dict(xref);
const secondDict = new Dict(xref);
firstDict.set('Parent', secondDict);
// Regular values should be fetched.
secondDict.set('foo', 'bar');
expect(getInheritableProperty({ dict: firstDict, key: 'foo', }))
.toEqual('bar');
// Array value should be fetched (with references resolved).
secondDict.set('baz', ['qux', ref]);
expect(getInheritableProperty({ dict: firstDict, key: 'baz',
getArray: true, }))
.toEqual(['qux', 'quux']);
});
it('fetches the property if it is inherited and present on multiple levels',
function() {
const ref = new Ref(10, 0);
const xref = new XRefMock([{ ref, data: 'quux', }]);
const firstDict = new Dict(xref);
const secondDict = new Dict(xref);
firstDict.set('Parent', secondDict);
// Regular values should be fetched.
firstDict.set('foo', 'bar1');
secondDict.set('foo', 'bar2');
expect(getInheritableProperty({ dict: firstDict, key: 'foo', }))
.toEqual('bar1');
expect(getInheritableProperty({ dict: firstDict, key: 'foo',
getArray: false, stopWhenFound: false, }))
.toEqual(['bar1', 'bar2']);
// Array value should be fetched (with references resolved).
firstDict.set('baz', ['qux1', ref]);
secondDict.set('baz', ['qux2', ref]);
expect(getInheritableProperty({ dict: firstDict, key: 'baz',
getArray: true, stopWhenFound: false, }))
.toEqual([['qux1', 'quux'], ['qux2', 'quux']]);
});
it('stops searching when the loop limit is reached', function() {
const dict = new Dict();
let currentDict = dict;
let parentDict = null;
for (let i = 0; i < 150; i++) { // Exceeds the loop limit of 100.
parentDict = new Dict();
currentDict.set('Parent', parentDict);
currentDict = parentDict;
}
parentDict.set('foo', 'bar'); // Never found because of loop limit.
expect(getInheritableProperty({ dict, key: 'foo', })).toEqual(undefined);
dict.set('foo', 'baz');
expect(getInheritableProperty({ dict, key: 'foo', getArray: false,
stopWhenFound: false, }))
.toEqual(['baz']);
});
});
describe('isArrayBuffer', function() {
it('handles array buffer values', function() {
expect(isArrayBuffer(new ArrayBuffer(0))).toEqual(true);