Add annotations to images in Flutter

Nutrient Flutter SDK offers a few methods to programmatically get, add, and remove annotations. All of these methods use the Instant JSON format to represent annotations.

Method	Description
`getAnnotations(int pageIndex, String type)`	Gets all annotations on the given page index of the given type. List of all supported annotation types.
`getAllUnsavedAnnotations()`	Gets all the unsaved annotations from the entire document.
`addAnnotation(dynamic jsonAnnotation)`	Adds the given annotation to the document.
`removeAnnotation(dynamic jsonAnnotation)`	Removes the given annotation from the document. If the given annotation doesn’t exist, this method does nothing.

Getting all annotations

The example below shows how to get all annotations on the first page of the document:

dynamic allAnnotations = await pdfDocument.getAnnotations(0, 'all');
print(allAnnotations);

Removing all annotations

The example below shows how to remove an array of annotations from the document:

dynamic allAnnotations = await pdfDocument.getAnnotations(0, 'all');
print(allAnnotations);

// Make sure that at least one annotation exists in the document.
// Remove the first annotation.
await pdfDocument.removeAnnotation(allAnnotations[0]);
print(allAnnotations);

Adding annotations

The example below shows how to programmatically add an ink annotation:

// Create an annotation in the Instant JSON format.
dynamic annotationJSON = '''{
  "bbox": [18.4609375, 582.3333740234375, 431.6640625, 426.00003051757812],
  "blendMode": "normal",
  "createdAt": "2019-11-15T15:36:25Z",
  "creatorName": "PSPDFKit",
  "isDrawnNaturally": false,
  "lineWidth": 10,
  "lines": {
    "intensities": [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]],
    "points": [[[271.6171875, 598], [266.93331909179688, 595.16668701171875], [259.71206665039062, 591.5833740234375], [255.27398681640625, 590.16668701171875], [248.65992736816406, 588.75], [244.59376525878906, 588.0030517578125], [239.75138854980469, 587.3333740234375], [234.60507202148438, 587.3333740234375], [229.98934936523438, 587.3333740234375], [225.3984375, 588.5908203125], [218.64601135253906, 588.75], [212.66595458984375, 588.75], [206.78047180175781, 590.16668701171875], [190.50941467285156, 591.5833740234375], [179.1796875, 593.75], [167.80718994140625, 595.16668701171875], [158.66848754882812, 596.5833740234375], [150.61857604980469, 598], [144.00840759277344, 600.125], [139.43266296386719, 600.125], [135.82032775878906, 601.54168701171875], [130.93865966796875, 604.41668701171875], [125.97789764404297, 607.9583740234375], [120.16405487060547, 609.6793212890625], [114.53083038330078, 612.2083740234375], [109.08804321289062, 614.375], [104.01295471191406, 616.29022216796875], [98.109375, 619.43707275390625], [92.337196350097656, 622.16668701171875], [87.625740051269531, 625.04168701171875], [82.543983459472656, 628.5833740234375], [77.507820129394531, 631.41668701171875], [71.68023681640625, 636.41668701171875], [68.25, 641.36651611328125], [63.281246185302734, 644.66424560546875], [58.289066314697266, 650.6976318359375], [54.0234375, 658.99774169921875], [49.0546875, 669.7379150390625], [42.656242370605469, 681.2083740234375], [37.6875, 694.83612060546875], [32.695316314697266, 707.46807861328125], [29.859375, 717.4583740234375], [28.429689407348633, 730.241943359375], [24.867185592651367, 742.06866455078125], [24.867185592651367, 753.7083740234375], [23.4609375, 768.94134521484375], [23.4609375, 782.875], [23.4609375, 799.98004150390625], [23.4609375, 814.16668701171875], [24.867185592651367, 828.375], [27, 841.2083740234375], [29.859375, 854], [32.695316314697266, 867.92138671875], [36.257816314697266, 880.78863525390625], [41.226566314697266, 893.8333740234375], [42.656242370605469, 904.97161865234375], [44.085941314697266, 913.21966552734375], [45.185382843017578, 919.41668701171875], [48.017143249511719, 928.0272216796875], [51.890621185302734, 937.18316650390625], [56.882816314697266, 946.41668701171875], [61.938720703125, 952.8333740234375], [64.687507629394531, 957.05609130859375], [70.581169128417969, 962.0833740234375], [78.143966674804688, 968.4583740234375], [86.742179870605469, 973.4583740234375], [96.703125, 979.875], [109.5, 984.125], [124.87102508544922, 989.0833740234375], [137.95753479003906, 992.66668701171875], [149.32032775878906, 995.5], [163.54685974121094, 999.04168701171875], [184.17189025878906, 1000.4583740234375], [209.76560974121094, 1001.9166870117188], [231.79685974121094, 1003.3333740234375], [250.99217224121094, 1003.3333740234375], [265.053955078125, 1003.3333740234375], [276.60940551757812, 1003.3333740234375], [287.2734375, 1001.9166870117188], [301.83041381835938, 1000.2388916015625], [317.83590698242188, 995.5], [333.4921875, 992.66668701171875], [345.98687744140625, 984.57415771484375], [355.52838134765625, 976.28839111328125], [366.91409301757812, 965.625], [384.67971801757812, 952.8333740234375], [401.74224853515625, 941.4583740234375], [414.5625, 932.2083740234375], [425.454345703125, 924.84600830078125], [432.32809448242188, 915.875], [436.59375, 901.6387939453125], [441.58590698242188, 881], [442.99221801757812, 854], [445.125, 830.54168701171875], [445.125, 807.79168701171875], [442.99221801757812, 788.7923583984375], [440.15625, 771.5], [435.16409301757812, 752.2916259765625], [430.19534301757812, 736.66668701171875], [427.35934448242188, 724.387451171875], [424.5, 715.0751953125], [420.96090698242188, 708.2083740234375], [415.96810913085938, 698.25], [410.59469604492188, 690.4583740234375], [406.734375, 682.9306640625], [403.17190551757812, 677.268798828125], [400.33590698242188, 671.87744140625], [395.66424560546875, 668.41668701171875], [389.95599365234375, 662.67138671875], [381.23092651367188, 657], [373.3125, 650.625], [366.91409301757812, 645.625], [360.19537353515625, 641.375], [354.17913818359375, 637.8333740234375], [349.00265502929688, 634.9583740234375], [345.44509887695312, 631.41668701171875], [339.6290283203125, 628.5833740234375], [334.68048095703125, 625.04168701171875], [330.84097290039062, 623.5833740234375], [325.87319946289062, 622.16668701171875], [319.62060546875, 620.75], [315.2069091796875, 618.625], [309.99786376953125, 618.6029052734375], [304.51095581054688, 617.2083740234375], [300.08163452148438, 617.2083740234375], [297.23440551757812, 616.544189453125], [292.9212646484375, 615.7916259765625], [287.88607788085938, 615.7916259765625], [283.19888305664062, 615.7916259765625], [277.85714721679688, 615.7916259765625], [273.72171020507812, 615.043701171875], [268.078125, 614.58349609375], [264.75930786132812, 615.7916259765625], [260.88003540039062, 615.7916259765625], [256.7109375, 615.7916259765625], [252.39967346191406, 617.2083740234375], [247.453125, 622.875], [243.87890625, 623.5833740234375], [239.98826599121094, 625.04168701171875]]]
  },
  "name": "ed9b4f2f-8178-4b69-9c50-bb59f820e10e",
  "opacity": 1,
  "pageIndex": 0,
  "strokeColor": "#2196F3",
  "type": "pspdfkit/ink",
  "updatedAt": "2019-11-15T15:36:25Z",
  "v": 1
}''';

// Add the annotation to the document.
await pdfDocument.addAnnotation(annotationJSON);

// Get the annotations on the first page.
dynamic allAnnotations = await pdfDocument.getAnnotations(0, 'all');

// Print the annotations. This should contain the annotation added above.
print(allAnnotations);