Add rectangle capabilities

docs/examples.md

@@ -124,7 +124,7 @@ worker
   });
 ```
 
-### with pdf output (^2.0.0-alpha.7)
+### with pdf output (^2.0.0-alpha.12)
 
 In this example, pdf file will be downloaded in browser and write to file system in Node.js
 
@@ -139,7 +139,7 @@ worker
     'https://tesseract.projectnaptha.com/img/eng_bw.png',
     'eng',
     {
-      'tessedit_create_pdf': '1',
+      'tessjs_create_pdf': '1',
     }
   )
   .progress((p) => {
@@ -164,9 +164,9 @@ worker
     'https://tesseract.projectnaptha.com/img/eng_bw.png',
     'eng',
     {
-      'tessedit_create_pdf': '1',
-      'pdf_auto_download': false, // disable auto download
-      'pdf_bin': true,            // add pdf file bin array in result
+      'tessjs_create_pdf': '1',
+      'tessjs_pdf_auto_download': false, // disable auto download
+      'tessjs_pdf_bin': true,            // add pdf file bin array in result
     }
   )
   .progress((p) => {
@@ -198,3 +198,31 @@ loadLang({ langs: 'eng', langPath: worker.options.langPath })
   });
 
 ```
+
+### with only part of the image (^2.0.0-alpha.12)
+
+```javascript
+import Tesseract from 'tesseract.js';
+
+const { TesseractWorker } = Tesseract;
+const worker = new TesseractWorker();
+
+worker
+  .recognize(
+    'https://tesseract.projectnaptha.com/img/eng_bw.png',
+    'eng',
+    {
+      tessjs_image_rectangle_left: 0,
+      tessjs_image_rectangle_top: 0,
+      tessjs_image_rectangle_width: 500,
+      tessjs_image_rectangle_height: 250,
+    }
+  )
+  .progress((p) => {
+    console.log('progress', p);
+  })
+  .then(({ text }) => {
+    console.log(text);
+    worker.terminate();
+  });
+```

docs/tesseract_parameters.md

@@ -24,14 +24,17 @@ worker
 | tessedit\_ocr\_engine\_mode | enum | OEM.LSTM\_ONLY | Check [HERE](https://github.com/tesseract-ocr/tesseract/blob/4.0.0/src/ccstruct/publictypes.h#L268) for definition of each mode | 
 | tessedit\_pageseg\_mode | enum | PSM.SINGLE\_BLOCK | Check [HERE](https://github.com/tesseract-ocr/tesseract/blob/4.0.0/src/ccstruct/publictypes.h#L163) for definition of each mode |
 | tessedit\_char\_whitelist | string | '' | setting white list characters makes the result only contains these characters, useful the content in image is limited |
-| tessedit\_create\_pdf | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js generates a pdf output |
-| tessedit\_create\_hocr | string | '1' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes hocr in the result |
-| tessedit\_create\_tsv | string | '1' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes tsv in the result |
-| tessedit\_create\_box | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes box in the result |
-| tessedit\_create\_unlv | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes unlv in the result |
-| tessedit\_create\_osd | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes osd in the result |
-| pdf\_name | string | 'tesseract.js-ocr-result' | the name of the generated pdf file |
-| pdf\_title | string | 'Tesseract.js OCR Result' | the title of the generated pdf file |
-| pdf\_auto\_download | boolean | true | If the value is true, tesseract.js will automatic download/writeFile pdf file |
-| pdf\_bin | boolean | false | whether to include pdf binary array in the result object (result.files.pdf) |
-
+| tessjs\_create\_pdf | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js generates a pdf output |
+| tessjs\_create\_hocr | string | '1' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes hocr in the result |
+| tessjs\_create\_tsv | string | '1' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes tsv in the result |
+| tessjs\_create\_box | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes box in the result |
+| tessjs\_create\_unlv | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes unlv in the result |
+| tessjs\_create\_osd | string | '0' | only 2 values, '0' or '1', when the value is '1', tesseract.js includes osd in the result |
+| tessjs\_pdf\_name | string | 'tesseract.js-ocr-result' | the name of the generated pdf file |
+| tessjs\_pdf\_title | string | 'Tesseract.js OCR Result' | the title of the generated pdf file |
+| tessjs\_pdf\_auto\_download | boolean | true | If the value is true, tesseract.js will automatic download/writeFile pdf file |
+| tessjs\_pdf\_bin | boolean | false | whether to include pdf binary array in the result object (result.files.pdf) |
+| tessjs\_image\_rectangle\_left | number | 0 | The left of the sub-rectangle of the image. |
+| tessjs\_image\_rectangle\_top | number | 0 | The top of the sub-rectangle of the image. |
+| tessjs\_image\_rectangle\_width | number | -1 | The width of the sub-rectangle of the image, -1 means auto width detection |
+| tessjs\_image\_rectangle\_height | number | -1 | The height of the sub-rectangle of the image, -1 means auto height detection |

src/common/dump.js

@@ -43,11 +43,11 @@ const deindent = (html) => {
  * @returns {object} dumpped JSON object
  */
 module.exports = (TessModule, api, {
-  tessedit_create_hocr,
-  tessedit_create_tsv,
-  tessedit_create_box,
-  tessedit_create_unlv,
-  tessedit_create_osd,
+  tessjs_create_hocr,
+  tessjs_create_tsv,
+  tessjs_create_box,
+  tessjs_create_unlv,
+  tessjs_create_osd,
 }) => {
   const ri = api.GetIterator();
   const blocks = [];
@@ -183,11 +183,11 @@ module.exports = (TessModule, api, {
 
   return {
     text: api.GetUTF8Text(),
-    hocr: tessedit_create_hocr === '1' ? deindent(api.GetHOCRText()) : null,
-    tsv: tessedit_create_tsv === '1' ? api.GetTSVText() : null,
-    box: tessedit_create_box === '1' ? api.GetBoxText() : null,
-    unlv: tessedit_create_unlv === '1' ? api.GetUNLVText() : null,
-    osd: tessedit_create_osd === '1' ? api.GetOsdText() : null,
+    hocr: tessjs_create_hocr === '1' ? deindent(api.GetHOCRText()) : null,
+    tsv: tessjs_create_tsv === '1' ? api.GetTSVText() : null,
+    box: tessjs_create_box === '1' ? api.GetBoxText() : null,
+    unlv: tessjs_create_unlv === '1' ? api.GetUNLVText() : null,
+    osd: tessjs_create_osd === '1' ? api.GetOsdText() : null,
     confidence: api.MeanTextConf(),
     blocks,
     psm: enumToString(api.GetPageSegMode(), 'PSM'),

src/common/options.js

@@ -16,16 +16,20 @@ module.exports = {
     tessedit_ocr_engine_mode: OEM.LSTM_ONLY,
     tessedit_pageseg_mode: PSM.SINGLE_BLOCK,
     tessedit_char_whiltelist: '',
-    tessedit_create_pdf: '0',
-    tessedit_create_hocr: '1',
-    tessedit_create_tsv: '1',
-    tessedit_create_box: '0',
-    tessedit_create_unlv: '0',
-    tessedit_create_osd: '0',
-    textonly_pdf: '0',
-    pdf_name: 'tesseract.js-ocr-result',
-    pdf_title: 'Tesseract.js OCR Result',
-    pdf_auto_download: true,
-    pdf_bin: false,
+    tessjs_create_pdf: '0',
+    tessjs_create_hocr: '1',
+    tessjs_create_tsv: '1',
+    tessjs_create_box: '0',
+    tessjs_create_unlv: '0',
+    tessjs_create_osd: '0',
+    tessjs_textonly_pdf: '0',
+    tessjs_pdf_name: 'tesseract.js-ocr-result',
+    tessjs_pdf_title: 'Tesseract.js OCR Result',
+    tessjs_pdf_auto_download: true,
+    tessjs_pdf_bin: false,
+    tessjs_image_rectangle_left: 0,
+    tessjs_image_rectangle_top: 0,
+    tessjs_image_rectangle_width: -1,
+    tessjs_image_rectangle_height: -1,
   },
 };

src/common/workerUtils.js

@@ -32,7 +32,13 @@ let adapter = {};
  * @param {array} image - binary array in array format
  * @returns {number} - an emscripten pointer of the image
  */
-const setImage = (image) => {
+const setImage = (image, params) => {
+  const {
+    tessjs_image_rectangle_left: left,
+    tessjs_image_rectangle_top: top,
+    tessjs_image_rectangle_width: width,
+    tessjs_image_rectangle_height: height,
+  } = params;
   const {
     w, h, bytesPerPixel, data, pix,
   } = readImage(TessModule, Array.from(image));
@@ -48,7 +54,12 @@ const setImage = (image) => {
   } else {
     api.SetImage(data, w, h, bytesPerPixel, w * bytesPerPixel);
   }
-  api.SetRectangle(0, 0, w, h);
+  api.SetRectangle(
+    (left < 0) ? 0 : left,
+    (top < 0) ? 0 : top,
+    (width < 0) ? w : width,
+    (height < 0) ? h : height,
+  );
   return data === null ? pix : data;
 };
 
@@ -74,7 +85,9 @@ const handleParams = (langs, iParams) => {
   } = iParams;
   api.Init(null, getLangsStr(langs), tessedit_ocr_engine_mode);
   Object.keys(params).forEach((key) => {
-    api.SetVariable(key, params[key]);
+    if (!key.startsWith('tessjs')) {
+      api.SetVariable(key, params[key]);
+    }
   });
 };
 
@@ -89,32 +102,32 @@ const handleParams = (langs, iParams) => {
 const handleOutput = (customParams) => {
   let files = {};
   const {
-    tessedit_create_pdf,
-    textonly_pdf,
-    pdf_name,
-    pdf_title,
-    pdf_auto_download,
-    pdf_bin,
+    tessjs_create_pdf,
+    tessjs_textonly_pdf,
+    tessjs_pdf_name,
+    tessjs_pdf_title,
+    tessjs_pdf_auto_download,
+    tessjs_pdf_bin,
   } = {
     ...defaultParams,
     ...customParams,
   };
 
-  if (tessedit_create_pdf === '1') {
-    const pdfRenderer = new TessModule.TessPDFRenderer(pdf_name, '/', textonly_pdf === '1');
-    pdfRenderer.BeginDocument(pdf_title);
+  if (tessjs_create_pdf === '1') {
+    const pdfRenderer = new TessModule.TessPDFRenderer(tessjs_pdf_name, '/', tessjs_textonly_pdf === '1');
+    pdfRenderer.BeginDocument(tessjs_pdf_title);
     pdfRenderer.AddImage(api);
     pdfRenderer.EndDocument();
     TessModule._free(pdfRenderer);
 
-    const data = TessModule.FS.readFile(`/${pdf_name}.pdf`);
+    const data = TessModule.FS.readFile(`/${tessjs_pdf_name}.pdf`);
 
-    if (pdf_bin) {
+    if (tessjs_pdf_bin) {
       files = { pdf: data, ...files };
     }
 
-    if (pdf_auto_download) {
-      adapter.writeFile(`${pdf_name}.pdf`, data, 'application/pdf');
+    if (tessjs_pdf_auto_download) {
+      adapter.writeFile(`${tessjs_pdf_name}.pdf`, data, 'application/pdf');
     }
   }
 
@@ -216,7 +229,7 @@ const handleRecognize = ({
             progressUpdate(0);
             handleParams(langs, params);
             progressUpdate(0.5);
-            const ptr = setImage(image);
+            const ptr = setImage(image, params);
             progressUpdate(1);
             api.Recognize(null);
             const files = handleOutput(params);
@@ -244,7 +257,7 @@ const handleRecognize = ({
  * @param {object} res - job instance
  */
 const handleDetect = ({
-  image, langs, options,
+  image, langs, options, params: customParams,
 }, res) => (
   handleInit(options, res)
     .then(() => (
@@ -252,8 +265,12 @@ const handleDetect = ({
         .then(() => {
           api.Init(null, getLangsStr(langs));
           api.SetPageSegMode(TessModule.PSM_OSD_ONLY);
+          const params = {
+            ...defaultParams,
+            ...customParams,
+          };
 
-          const ptr = setImage(image);
+          const ptr = setImage(image, params);
           const results = new TessModule.OSResults();
 
           if (!api.DetectOS(results)) {