Sample code for 30+ languages & platforms
Delphi DLL

Google Cloud Vision Text Detection

See more HTTP Misc Examples

Demonstrates calling the Google Cloud Vision for text detection (performs Optical Character Recognition). "Detects and extracts text within an image with support for a broad range of languages. It also features automatic language identification." See https://cloud.google.com/vision/docs/detecting-text

Chilkat Delphi DLL Downloads

Delphi DLL
uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, BinData, StringBuilder, HttpResponse, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
imageData: HCkBinData;
json: HCkJsonObject;
http: HCkHttp;
sb: HCkStringBuilder;
url: PWideChar;
resp: HCkHttpResponse;
sbResponseBody: HCkStringBuilder;
i: Integer;
count_i: Integer;
fullTextAnnotationText: PWideChar;
j: Integer;
count_j: Integer;
locale: PWideChar;
description: PWideChar;
k: Integer;
count_k: Integer;
x: Integer;
y: Integer;
width: Integer;
height: Integer;
languageCode: PWideChar;
blockType: PWideChar;
i1: Integer;
count_i1: Integer;
j1: Integer;
count_j1: Integer;
k1: Integer;
count_k1: Integer;
text: PWideChar;
propertyDetectedBreakType: PWideChar;
i2: Integer;
count_i2: Integer;
json1: HCkJsonObject;
json2: HCkJsonObject;

begin
success := False;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Build the following request:

// {
//   "requests": [
//     {
//       "image": {
//         "content": "/9j/7QBEUGhvdG9zaG9...base64-encoded-image-content...fXNWzvDEeYxxxzj/Coa6Bax//Z"
//       },
//       "features": [
//         {
//           "type": "TEXT_DETECTION"
//         }
//       ]
//     }
//   ]
// }

// Use this online tool to generate the code from sample JSON: 
// Generate Code to Create JSON

// Load an image file.
imageData := CkBinData_Create();
// This image file contains some text...
success := CkBinData_LoadFile(imageData,'qa_data/jpg/text.jpg');
if (success <> True) then
  begin
    Memo1.Lines.Add('Failed to load image file.');
    Exit;
  end;

// Create the above JSON.
json := CkJsonObject_Create();
CkJsonObject_UpdateBd(json,'requests[0].image.content','base64',imageData);
CkJsonObject_UpdateString(json,'requests[0].features[0].type','TEXT_DETECTION');

// Send the following POST with the HTTP request body containing the above JSON.
// POST https://vision.googleapis.com/v1/images:annotate?key=YOUR_API_KEY

http := CkHttp_Create();
CkHttp_putSessionLogFilename(http,'c:/aaworkarea/sessionLog.txt');

sb := CkStringBuilder_Create();
url := 'https://vision.googleapis.com/v1/images:annotate?key=YOUR_API_KEY';
resp := CkHttpResponse_Create();
success := CkHttp_HttpJson(http,'POST',url,json,'application/json',resp);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

Memo1.Lines.Add('status = ' + IntToStr(CkHttpResponse_getStatusCode(resp)));

// A 200 response status indicate success.
if (CkHttpResponse_getStatusCode(resp) <> 200) then
  begin
    Memo1.Lines.Add(CkHttpResponse__bodyStr(resp));
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

sbResponseBody := CkStringBuilder_Create();
CkHttpResponse_GetBodySb(resp,sbResponseBody);
CkStringBuilder_WriteFile(sbResponseBody,'qa_output/textDetectResponse.json','utf-8',False);
CkJsonObject_LoadSb(json,sbResponseBody);

// The response is a JSON document like this:

// Use this online tool to generate parsing code from sample JSON: 
// Generate Parsing Code from JSON

// {
//   "responses": [
//     {
//       "textAnnotations": [
//         {
//           "locale": "en",
//           "description": "Chilkat is a cross-language, cross-platform\nAPl providing 90+ classes for many Internet\nprotocols, formats, and algorithms.\n",
//           "boundingPoly": {
//             "vertices": [
//               {
//                 "x": 17,
//                 "y": 14
//               },
// 	...
//             ]
//           }
//         ],
//         "text": "Chilkat is a cross-language, cross-platform\nAPl providing 90+ classes for many Internet\nprotocols, formats, and algorithms.\n"
//       }
//     }
//   ]
// }

// The parsing code generated from the online tool:

json1 := CkJsonObject_Create();
json2 := CkJsonObject_Create();

i := 0;
count_i := CkJsonObject_SizeOfArray(json,'responses');
while i < count_i do
  begin
    CkJsonObject_putI(json,i);
    fullTextAnnotationText := CkJsonObject__stringOf(json,'responses[i].fullTextAnnotation.text');
    j := 0;
    count_j := CkJsonObject_SizeOfArray(json,'responses[i].textAnnotations');
    while j < count_j do
      begin
        CkJsonObject_putJ(json,j);
        locale := CkJsonObject__stringOf(json,'responses[i].textAnnotations[j].locale');
        description := CkJsonObject__stringOf(json,'responses[i].textAnnotations[j].description');
        k := 0;
        count_k := CkJsonObject_SizeOfArray(json,'responses[i].textAnnotations[j].boundingPoly.vertices');
        while k < count_k do
          begin
            CkJsonObject_putK(json,k);
            x := CkJsonObject_IntOf(json,'responses[i].textAnnotations[j].boundingPoly.vertices[k].x');
            y := CkJsonObject_IntOf(json,'responses[i].textAnnotations[j].boundingPoly.vertices[k].y');
            k := k + 1;
          end;

        j := j + 1;
      end;

    j := 0;
    count_j := CkJsonObject_SizeOfArray(json,'responses[i].fullTextAnnotation.pages');
    while j < count_j do
      begin
        CkJsonObject_putJ(json,j);
        width := CkJsonObject_IntOf(json,'responses[i].fullTextAnnotation.pages[j].width');
        height := CkJsonObject_IntOf(json,'responses[i].fullTextAnnotation.pages[j].height');
        k := 0;
        count_k := CkJsonObject_SizeOfArray(json,'responses[i].fullTextAnnotation.pages[j].property.detectedLanguages');
        while k < count_k do
          begin
            CkJsonObject_putK(json,k);
            languageCode := CkJsonObject__stringOf(json,'responses[i].fullTextAnnotation.pages[j].property.detectedLanguages[k].languageCode');
            k := k + 1;
          end;

        k := 0;
        count_k := CkJsonObject_SizeOfArray(json,'responses[i].fullTextAnnotation.pages[j].blocks');
        while k < count_k do
          begin
            CkJsonObject_putK(json,k);
            blockType := CkJsonObject__stringOf(json,'responses[i].fullTextAnnotation.pages[j].blocks[k].blockType');
            CkJsonObject_ObjectOf2(json,'responses[i].fullTextAnnotation.pages[j].blocks[k]',json1);

            i1 := 0;
            count_i1 := CkJsonObject_SizeOfArray(json1,'property.detectedLanguages');
            while i1 < count_i1 do
              begin
                CkJsonObject_putI(json1,i1);
                languageCode := CkJsonObject__stringOf(json1,'property.detectedLanguages[i].languageCode');
                i1 := i1 + 1;
              end;

            CkJsonObject_ObjectOf2(json,'responses[i].fullTextAnnotation.pages[j].blocks[k]',json1);

            i1 := 0;
            count_i1 := CkJsonObject_SizeOfArray(json1,'boundingBox.vertices');
            while i1 < count_i1 do
              begin
                CkJsonObject_putI(json1,i1);
                x := CkJsonObject_IntOf(json1,'boundingBox.vertices[i].x');
                y := CkJsonObject_IntOf(json1,'boundingBox.vertices[i].y');
                i1 := i1 + 1;
              end;

            CkJsonObject_ObjectOf2(json,'responses[i].fullTextAnnotation.pages[j].blocks[k]',json1);

            i1 := 0;
            count_i1 := CkJsonObject_SizeOfArray(json1,'paragraphs');
            while i1 < count_i1 do
              begin
                CkJsonObject_putI(json1,i1);
                j1 := 0;
                count_j1 := CkJsonObject_SizeOfArray(json1,'paragraphs[i].property.detectedLanguages');
                while j1 < count_j1 do
                  begin
                    CkJsonObject_putJ(json1,j1);
                    languageCode := CkJsonObject__stringOf(json1,'paragraphs[i].property.detectedLanguages[j].languageCode');
                    j1 := j1 + 1;
                  end;

                j1 := 0;
                count_j1 := CkJsonObject_SizeOfArray(json1,'paragraphs[i].boundingBox.vertices');
                while j1 < count_j1 do
                  begin
                    CkJsonObject_putJ(json1,j1);
                    x := CkJsonObject_IntOf(json1,'paragraphs[i].boundingBox.vertices[j].x');
                    y := CkJsonObject_IntOf(json1,'paragraphs[i].boundingBox.vertices[j].y');
                    j1 := j1 + 1;
                  end;

                j1 := 0;
                count_j1 := CkJsonObject_SizeOfArray(json1,'paragraphs[i].words');
                while j1 < count_j1 do
                  begin
                    CkJsonObject_putJ(json1,j1);
                    k1 := 0;
                    count_k1 := CkJsonObject_SizeOfArray(json1,'paragraphs[i].words[j].property.detectedLanguages');
                    while k1 < count_k1 do
                      begin
                        CkJsonObject_putK(json1,k1);
                        languageCode := CkJsonObject__stringOf(json1,'paragraphs[i].words[j].property.detectedLanguages[k].languageCode');
                        k1 := k1 + 1;
                      end;

                    k1 := 0;
                    count_k1 := CkJsonObject_SizeOfArray(json1,'paragraphs[i].words[j].boundingBox.vertices');
                    while k1 < count_k1 do
                      begin
                        CkJsonObject_putK(json1,k1);
                        x := CkJsonObject_IntOf(json1,'paragraphs[i].words[j].boundingBox.vertices[k].x');
                        y := CkJsonObject_IntOf(json1,'paragraphs[i].words[j].boundingBox.vertices[k].y');
                        k1 := k1 + 1;
                      end;

                    k1 := 0;
                    count_k1 := CkJsonObject_SizeOfArray(json1,'paragraphs[i].words[j].symbols');
                    while k1 < count_k1 do
                      begin
                        CkJsonObject_putK(json1,k1);
                        text := CkJsonObject__stringOf(json1,'paragraphs[i].words[j].symbols[k].text');
                        propertyDetectedBreakType := CkJsonObject__stringOf(json1,'paragraphs[i].words[j].symbols[k].property.detectedBreak.type');
                        CkJsonObject_ObjectOf2(json1,'paragraphs[i].words[j].symbols[k]',json2);

                        i2 := 0;
                        count_i2 := CkJsonObject_SizeOfArray(json2,'property.detectedLanguages');
                        while i2 < count_i2 do
                          begin
                            CkJsonObject_putI(json2,i2);
                            languageCode := CkJsonObject__stringOf(json2,'property.detectedLanguages[i].languageCode');
                            i2 := i2 + 1;
                          end;

                        CkJsonObject_ObjectOf2(json1,'paragraphs[i].words[j].symbols[k]',json2);

                        i2 := 0;
                        count_i2 := CkJsonObject_SizeOfArray(json2,'boundingBox.vertices');
                        while i2 < count_i2 do
                          begin
                            CkJsonObject_putI(json2,i2);
                            x := CkJsonObject_IntOf(json2,'boundingBox.vertices[i].x');
                            y := CkJsonObject_IntOf(json2,'boundingBox.vertices[i].y');
                            i2 := i2 + 1;
                          end;

                        k1 := k1 + 1;
                      end;

                    j1 := j1 + 1;
                  end;

                i1 := i1 + 1;
              end;

            k := k + 1;
          end;

        j := j + 1;
      end;

    i := i + 1;
  end;

Memo1.Lines.Add('Success.');

CkBinData_Dispose(imageData);
CkJsonObject_Dispose(json);
CkHttp_Dispose(http);
CkStringBuilder_Dispose(sb);
CkHttpResponse_Dispose(resp);
CkStringBuilder_Dispose(sbResponseBody);
CkJsonObject_Dispose(json1);
CkJsonObject_Dispose(json2);

end;