Read a PDF file in Obj-C (parse & extract text)

//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2023 by Apryse Software Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

#import <OBJC/PDFNetOBJC.h>
#import <Foundation/Foundation.h>

// This sample illustrates the basic text extraction capabilities of PDFNet.

// A utility method used to dump all text content in the console window.
void DumpAllText(PTElementReader *reader) 
{
    PTElement *element; 
    while ((element = [reader Next]) != NULL)
    {
        switch ([element GetType]) 
        {
        case e_pttext_begin: 
            NSLog(@"--> Text Block Begin");
            break;
        case e_pttext_end:
            NSLog(@"--> Text Block End");
            break;
        case e_pttext:
            {
                PTPDFRect * bbox = [element GetBBox];
                NSLog(@"--> BBox: %f, %f, %f, %f", [bbox GetX1], [bbox GetY1], [bbox GetX2], [bbox GetY2]);

                NSLog(@"%@", [element GetTextString]);
            }
            break;
        case e_pttext_new_line:
            NSLog(@"--> New Line");
            break;
        case e_ptform:                // Process form XObjects
            [reader FormBegin]; 
            DumpAllText(reader);
            [reader End]; 
            break;
        default:
            break;
        }
    }
}

// A helper method for ReadTextFromRect
void RectTextSearch(PTElementReader *reader, PTPDFRect * pos, NSString **srch_str)
{            
    PTElement *element; 
    while ((element = [reader Next]) != NULL)
    {
        switch ([element GetType]) 
        {
        case e_pttext:
            {
                PTPDFRect * bbox = [element GetBBox];
                if([bbox IntersectRect: bbox rect2: pos]) 
                {
                    NSString *arr = [element GetTextString];
                    *srch_str = [*srch_str stringByAppendingString: arr];
                    *srch_str = [*srch_str stringByAppendingString: @"\n"]; // add a new line?
                }
                break;
            }
        case e_pttext_new_line:
            {
                break;
            }
        case e_ptform: // Process form XObjects
            {
                [reader FormBegin]; 
                RectTextSearch(reader, pos, &(*srch_str));
                [reader End]; 
                break; 
            }
        default:
            break;
        }
    }
}

// A utility method used to extract all text content from
// a given selection rectangle. The rectangle coordinates are
// expressed in PDF user/page coordinate system.
NSString* ReadTextFromRect(PTPage *page, PTPDFRect * pos, PTElementReader *reader)
{
    NSString *srch_str = @"";
    [reader Begin: page];
    RectTextSearch(reader, pos, &srch_str);
    [reader End];
    return srch_str;
}


void PrintStyle(PTTextExtractorStyle *s)
{
    NSArray *rgb = [s GetColor];
    NSString * name = [s GetFontName ];
    const char* font_family = [name UTF8String];
    double font_size = [s GetFontSize];
    const char * san_serif = ([s IsSerif]) ? " sans-serif;" : "";
    int R = [rgb[0] intValue];
    int G = [rgb[1] intValue];
    int B = [rgb[2] intValue];
    printf(" style=\"font-family:%s; font-size:%g;%s color:#%02X%02X%02X;\"", font_family, font_size, san_serif, [rgb[0] intValue], [rgb[1] intValue], [rgb[2] intValue]);
}

int main(int argc, char *argv[])
{
    @autoreleasepool {
        int ret = 0;
        [PTPDFNet Initialize: 0];

        bool example1_basic     = false;
        bool example2_xml       = false;
        bool example3_wordlist  = false;
        bool example4_advanced  = true;
        bool example5_low_level = false;

        // Sample code showing how to use high-level text extraction APIs.
        @try
        {
            PTPDFDoc *doc = [[PTPDFDoc alloc] initWithFilepath: @"../../TestFiles/newsletter.pdf"];
            [doc InitSecurityHandler];

            PTPage *page = [doc GetPage: 1];
            if (![page IsValid]){
                NSLog(@"Page not found.");
                return 1;
            }

            PTTextExtractor *txt = [[PTTextExtractor alloc] init];
            [txt Begin: page clip_ptr: 0 flags: 0]; // Read the page.
            // Other options you may want to consider...
            // txt.Begin(*itr, 0, TextExtractor::e_no_dup_remove);
            // txt.Begin(*itr, 0, TextExtractor::e_remove_hidden_text);


            // Example 1. Get all text on the page in a single string.
            // Words will be separated with space or new line characters.
            if (example1_basic) 
            {
                // Get the word count.
                NSLog(@"Word Count: %d", [txt GetWordCount]);

                NSString *text = [txt GetAsText: YES];
                NSLog(@"\n\n- GetAsText --------------------------\n%@", text);
                NSLog(@"-----------------------------------------------------------");
            }

            // Example 2. Get XML logical structure for the page.
            if (example2_xml) 
            {
                NSString *text = [txt GetAsXML: e_ptwords_as_elements | e_ptoutput_bbox | e_ptoutput_style_info];
                NSLog(@"\n\n- GetAsXML  --------------------------\n %@", text);
                NSLog(@"-----------------------------------------------------------");
            }

            // Example 3. Extract words one by one.
            if (example3_wordlist) 
            {
                PTTextExtractorLine *line = [txt GetFirstLine];
                PTWord *word;
                for (; [line IsValid]; line=[line GetNextLine])    {
                    for (word=[line GetFirstWord]; [word IsValid]; word=[word GetNextWord]) {
                        NSLog(@"%@", [word GetString]);
                    }
                }
                NSLog(@"-----------------------------------------------------------");
            }

            // Example 4. A more advanced text extraction example. 
            // The output is XML structure containing paragraphs, lines, words, 
            // as well as style and positioning information.
            if (example4_advanced) 
            {
                PTPDFRect * b, *q;
                int cur_flow_id=-1, cur_para_id=-1;

                NSString *uni_str;
                PTTextExtractorLine *line;
                PTWord *word;
                PTTextExtractorStyle *s, *line_style;

                printf("<PDFText>\n");
                // For each line on the page...
                for (line=[txt GetFirstLine]; [line IsValid]; line=[line GetNextLine])
                {
                    if ( [line GetNumWords] == 0 )
                    {
                        continue;
                    }
                    
                    if (cur_flow_id != [line GetFlowID]) {
                        if (cur_flow_id != -1) {
                            if (cur_para_id != -1) {
                                cur_para_id = -1;
                                printf("</Para>\n");
                            }
                            printf("</Flow>\n");
                        }
                        cur_flow_id = [line GetFlowID];
                        printf("<Flow id=\"%d\">\n", cur_flow_id);
                    }

                    if (cur_para_id != [line GetParagraphID]) {
                        if (cur_para_id != -1)
                            printf("</Para>\n");
                        cur_para_id = [line GetParagraphID];
                        printf("<Para id=\"%d\">\n", cur_para_id);
                    }    

                    b = [line GetBBox];
                    line_style = [line GetStyle];
                    printf("<Line box=\"%.2f, %.2f, %.2f, %.2f\"", [b GetX1], [b GetY1], [b GetX2], [b GetY2]);
                    PrintStyle(line_style);
                    printf(" cur_num=\"%d\"", [line GetCurrentNum]);
                    printf(">\n");

                    // For each word in the line...
                    for (word=[line GetFirstWord]; [word IsValid]; word=[word GetNextWord])
                    {
                        // Output the bounding box for the word.
                        q = [word GetBBox];
                        printf("<Word box=\"%.2f, %.2f, %.2f, %.2f\"", [q GetX1], [q GetY1], [q GetX2], [q GetY2]);
                        printf(" cur_num=\"%d\"", [word GetCurrentNum]);
                        
                        int sz = [word GetStringLen];
                        if (sz == 0) continue;

                        // If the word style is different from the parent style, output the new style.
                    
                        s = [word GetStyle];    
                        if(![s isEqualTo:line_style]){
                            PrintStyle(s);
                        }

                        uni_str = [word GetString];
                        printf(">%s", [uni_str UTF8String]);
                        printf("</Word>\n");
                    }
                    printf("</Line>\n");
                }

                if (cur_flow_id != -1) {
                    if (cur_para_id != -1) {
                        cur_para_id = -1;
                        printf("</Para>\n");
                    }
                    printf("</Flow>\n");
                }
                printf("</PDFText>\n");
            }
        }
        @catch(NSException *e)
        {
            NSLog(@"%@", e.reason);
            ret = 1;
        }

        if(example5_low_level)
        {
            @try
            {
                PTPDFDoc *doc = [[PTPDFDoc alloc] initWithFilepath: @"../../TestFiles/newsletter.pdf"];
                [doc InitSecurityHandler];

                // Example 1. Extract all text content from the document

                PTElementReader *reader = [[PTElementReader alloc] init];
                //  Read every page
                PTPageIterator *itr;
                for (itr=[doc GetPageIterator: 1]; [itr HasNext]; [itr Next]) 
                {                
                    [reader Begin: [itr Current]];
                    DumpAllText(reader);
                    [reader End];
                }

                // Example 2. Extract text content based on the 
                // selection rectangle.
                NSLog(@"\n----------------------------------------------------");
                NSLog(@"\nExtract text based on the selection rectangle.");
                NSLog(@"\n----------------------------------------------------\n");

                PTPage *first_page = [doc GetPage: 1];
                PTPDFRect * rect1 = [[PTPDFRect alloc] initWithX1: 27 y1: 392 x2: 563 y2: 534];
                NSString *s1 = ReadTextFromRect(first_page, rect1, reader);
                NSLog(@"\nField 1: %@", s1);

                PTPDFRect * rect2 = [[PTPDFRect alloc] initWithX1: 28 y1: 551 x2: 106 y2: 623];
                s1 = ReadTextFromRect(first_page, rect2, reader);
                NSLog(@"\nField 2: %@", s1);

                PTPDFRect * rect3 = [[PTPDFRect alloc] initWithX1: 208 y1: 550 x2: 387 y2: 621];
                s1 = ReadTextFromRect(first_page, rect3, reader);
                NSLog(@"\nField 3: %@", s1);

                // ... 
                NSLog(@"Done.");
            }
            @catch(NSException *e)
            {
                NSLog(@"%@", e.reason);
                ret = 1;
            }
        }
        [PTPDFNet Terminate: 0];
        return ret;
    }
}