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https://github.com/michaelrsweet/pdfio.git
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Add some documentation on the code128 example.
Clean up the code128 code a bit and use the Helvetica font for the text. Add support for writing to a PDF file on the command-line vs. just doing redirection.
This commit is contained in:
Michael R Sweet
parent
f8639fbd64
commit
53967552df
174
doc/pdfio.md
174
doc/pdfio.md
@ -33,7 +33,7 @@ PDFio requires the following to build the software:
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IDE files for Xcode (macOS/iOS) and Visual Studio (Windows) are also provided.
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Installing pdfio
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Installing PDFio
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----------------
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PDFio comes with a configure script that creates a portable makefile that will
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@ -315,8 +315,9 @@ Reading PDF Files
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You open an existing PDF file using the [`pdfioFileOpen`](@@) function:
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```c
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pdfio_file_t *pdf = pdfioFileOpen("myinputfile.pdf", password_cb, password_data,
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error_cb, error_data);
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pdfio_file_t *pdf =
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pdfioFileOpen("myinputfile.pdf", password_cb, password_data,
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error_cb, error_data);
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```
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@ -865,6 +866,7 @@ escaping, as needed:
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Examples
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========
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Read PDF Metadata
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-----------------
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@ -995,3 +997,169 @@ create_pdf_image_file(const char *pdfname, const char *imagename,
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pdfioFileClose(pdf);
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}
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```
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Generate a Code 128 Barcode
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---------------------------
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One-dimensional barcodes are often rendered using special fonts that map ASCII
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characters to sequences of bars that can be read. The "examples" directory
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contains such a font to create "Code 128" barcodes, with an accompanying bit of
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example code.
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The first thing you need to do is prepare the barcode string to use with the
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font. Each barcode begins with a start pattern followed by the characters or
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digits you want to encode, a weighted sum digit, and a stop pattern. The
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`make_code128` function creates this string:
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```c
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static char * // O - Output string
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make_code128(char *dst, // I - Destination buffer
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const char *src, // I - Source string
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size_t dstsize) // I - Size of destination buffer
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{
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char *dstptr, // Pointer into destination buffer
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*dstend; // End of destination buffer
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int sum; // Weighted sum
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static const char *code128_chars = // Code 128 characters
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" !\"#$%&'()*+,-./0123456789:;<=>?"
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"@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_"
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"`abcdefghijklmnopqrstuvwxyz{|}~\303"
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"\304\305\306\307\310\311\312";
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static const char code128_start_code_b = '\314';
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// Start code B
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static const char code128_stop = '\316';
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// Stop pattern
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// Start a Code B barcode...
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dstptr = dst;
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dstend = dst + dstsize - 3;
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*dstptr++ = code128_start_code_b;
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sum = code128_start_code_b - 100;
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while (*src && dstptr < dstend)
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{
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if (*src >= ' ' && *src < 0x7f)
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{
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sum += (dstptr - dst) * (*src - ' ');
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*dstptr++ = *src;
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}
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src ++;
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}
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// Add the weighted sum modulo 103
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*dstptr++ = code128_chars[sum % 103];
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// Add the stop pattern and return...
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*dstptr++ = code128_stop;
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*dstptr = '\0';
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return (dst);
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}
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```
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The `main` function does the rest of the work. The barcode font is imported
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using the [`pdfioFileCreateFontObjFromFile`](@@) function. We pass `false`
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for the "unicode" argument since we just want the (default) ASCII encoding:
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```c
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barcode_font = pdfioFileCreateFontObjFromFile(pdf, "code128.ttf",
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/*unicode*/false);
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```
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Since barcodes usually have the number or text represented by the barcode
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printed underneath it, we also need a regular text font, for which we can choose
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one of the standard 14 PostScript base fonts using the
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[`pdfioFIleCreateFontObjFromBase`](@@) function:
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```c
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text_font = pdfioFileCreateFontObjFromBase(pdf, "Helvetica");
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```
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Once we have these fonts we can measure the barcode and regular text labels
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using the [`pdfioContentTextMeasure`](@@) function to determine how large the
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PDF page needs to be to hold the barcode and text:
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```c
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// Compute sizes of the text...
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const char *barcode = argv[1];
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char barcode_temp[256];
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if (!(barcode[0] & 0x80))
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barcode = make_code128(barcode_temp, barcode, sizeof(barcode_temp));
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double barcode_height = 36.0;
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double barcode_width =
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pdfioContentTextMeasure(barcode_font, barcode, barcode_height);
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const char *text = argv[2];
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double text_height = 0.0;
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double text_width = 0.0;
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if (text && text_font)
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{
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text_height = 9.0;
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text_width = pdfioContentTextMeasure(text_font, text,
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text_height);
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}
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// Compute the size of the PDF page...
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pdfio_rect_t media_box;
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media_box.x1 = 0.0;
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media_box.y1 = 0.0;
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media_box.x2 = (barcode_width > text_width ?
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barcode_width : text_width) + 18.0;
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media_box.y2 = barcode_height + text_height + 18.0;
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```
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Finally, we just need to create a page of the specified size that references the
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two fonts:
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```c
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// Start a page for the barcode...
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page_dict = pdfioDictCreate(pdf);
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pdfioDictSetRect(page_dict, "MediaBox", &media_box);
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pdfioDictSetRect(page_dict, "CropBox", &media_box);
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pdfioPageDictAddFont(page_dict, "B128", barcode_font);
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if (text_font)
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pdfioPageDictAddFont(page_dict, "TEXT", text_font);
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page_st = pdfioFileCreatePage(pdf, page_dict);
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```
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With the barcode font called "B128" and the text font called "TEXT", we can
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use them to draw two strings:
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```c
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// Draw the page...
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pdfioContentSetFillColorGray(page_st, 0.0);
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pdfioContentSetTextFont(page_st, "B128", barcode_height);
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pdfioContentTextBegin(page_st);
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pdfioContentTextMoveTo(page_st, 0.5 * (media_box.x2 - barcode_width),
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9.0 + text_height);
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pdfioContentTextShow(page_st, /*unicode*/false, barcode);
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pdfioContentTextEnd(page_st);
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if (text && text_font)
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{
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pdfioContentSetTextFont(page_st, "TEXT", text_height);
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pdfioContentTextBegin(page_st);
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pdfioContentTextMoveTo(page_st, 0.5 * (media_box.x2 - text_width), 9.0);
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pdfioContentTextShow(page_st, /*unicode*/false, text);
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pdfioContentTextEnd(page_st);
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}
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pdfioStreamClose(page_st);
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```
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Convert Markdown to PDF
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-----------------------
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@ -23,7 +23,6 @@
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// extended characters are ignored in the source string.
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//
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static char * // O - Output string
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make_code128(char *dst, // I - Destination buffer
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const char *src, // I - Source string
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@ -54,9 +53,9 @@ make_code128(char *dst, // I - Destination buffer
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static const char code128_start_code_a = '\313';
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// Start code A
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static const char code128_start_code_b = '\314';
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// Start code A
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// Start code B
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static const char code128_start_code_c = '\315';
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// Start code A
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// Start code C
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static const char code128_stop = '\316';
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// Stop pattern
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@ -149,7 +148,7 @@ main(int argc, // I - Number of command-line arguments
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// Load fonts...
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barcode_font = pdfioFileCreateFontObjFromFile(pdf, "code128.ttf", /*unicode*/false);
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if (text)
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text_font = pdfioFileCreateFontObjFromFile(pdf, "../testfiles/OpenSans-Regular.ttf", /*unicode*/true);
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text_font = pdfioFileCreateFontObjFromBase(pdf, "Helvetica");
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// Generate Code128 characters for the desired barcode...
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if (!(barcode[0] & 0x80))
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@ -182,7 +181,7 @@ main(int argc, // I - Number of command-line arguments
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page_st = pdfioFileCreatePage(pdf, page_dict);
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// Draw the page...
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pdfioContentSetStrokeColorGray(page_st, 0.0);
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pdfioContentSetFillColorGray(page_st, 0.0);
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pdfioContentSetTextFont(page_st, "B128", barcode_height);
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pdfioContentTextBegin(page_st);
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@ -195,7 +194,7 @@ main(int argc, // I - Number of command-line arguments
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pdfioContentSetTextFont(page_st, "TEXT", text_height);
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pdfioContentTextBegin(page_st);
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pdfioContentTextMoveTo(page_st, 0.5 * (media_box.x2 - text_width), 9.0);
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pdfioContentTextShow(page_st, /*unicode*/true, text);
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pdfioContentTextShow(page_st, /*unicode*/false, text);
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pdfioContentTextEnd(page_st);
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}
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@ -8,6 +8,7 @@
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//
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// Usage:
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//
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// ./md2pdf FILENAME.md FILENAME.pdf
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// ./md2pdf FILENAME.md >FILENAME.pdf
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//
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// The generated PDF file is formatted for a "universal" paper size (8.27x11",
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@ -262,9 +263,10 @@ main(int argc, // I - Number of command-line arguments
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setbuf(stderr, NULL);
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// Get the markdown file from the command-line...
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if (argc != 2)
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if (argc < 2 || argc > 3)
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{
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fputs("Usage: md2pdf FILENANE.md >FILENAME.pdf\n", stderr);
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fputs("Usage: md2pdf FILENANE.md [FILENAME.pdf]\n", stderr);
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fputs(" md2pdf FILENANE.md >FILENAME.pdf\n", stderr);
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return (1);
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}
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@ -289,13 +291,20 @@ main(int argc, // I - Number of command-line arguments
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dd.title = mmdGetMetadata(doc, "title");
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// Output a PDF file to the standard output...
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if (argc == 2)
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{
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// Output a PDF file to the standard output...
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#ifdef _WIN32
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setmode(1, O_BINARY); // Force binary output on Windows
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setmode(1, O_BINARY); // Force binary output on Windows
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#endif // _WIN32
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if ((dd.pdf = pdfioFileCreateOutput(output_cb, /*output_cbdata*/NULL, /*version*/NULL, /*media_box*/NULL, /*crop_box*/NULL, /*error_cb*/NULL, /*error_data*/NULL)) == NULL)
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if ((dd.pdf = pdfioFileCreateOutput(output_cb, /*output_cbdata*/NULL, /*version*/NULL, /*media_box*/NULL, /*crop_box*/NULL, /*error_cb*/NULL, /*error_data*/NULL)) == NULL)
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return (1);
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}
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else if ((dd.pdf = pdfioFileCreate(argv[2], /*version*/NULL, /*media_box*/NULL, /*crop_box*/NULL, /*error_cb*/NULL, /*error_data*/NULL)) == NULL)
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{
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return (1);
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}
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if ((value = mmdGetMetadata(doc, "author")) != NULL)
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pdfioFileSetAuthor(dd.pdf, value);
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