Getting Exact Text Height

[arunsrinivaasrs]

gs.GetFontSize() gives me the font size. How can i get exactly font height of Ascent.

font.getAscent() gives height in glph coordinate . How to convert that to world co-ordinate (or) font-size.

Bounding Box of font also gives size in glyph coordinates.

Bounding Box of text element cannot be used for height because the box is not optimal one.

[Support]

It sounds like you would like to use TextExtractor methods to get bbox for line/word/character:

https://www.pdftron.com/pdfnet/mobile/docs/Android/pdftron/PDF/TextExtractor.Line.html#getBBox()
https://www.pdftron.com/pdfnet/mobile/docs/Android/pdftron/PDF/TextExtractor.Word.html#getQuad()
https://www.pdftron.com/pdfnet/mobile/docs/Android/pdftron/PDF/TextExtractor.Word.html#getGlyphQuad(int)

Alternatively if you are working with ElementReader you could use element.GetBBox() 

... or for more low lever control see 

https://groups.google.com/d/msg/pdfnet-sdk/B82iGlKnVUQ/zU7ATQE0bm4J

FYI, section 9.4.4. Text Space Details ( http://xodo.com/view/#/c0c11968-ee14-478e-9b09-6dc5635c0915 ) provides info on how to map all gstate and font parameters to a bbox in user coordinate system.

[arunsrinivaasrs]

Thanks. for you reply. element.getBBox is not accurate. Anyways i dont need entire height, i need the split of ascent and descent. 

 Below is the code that i used from 9.4.4 pdf spec. My Idea is to just derive a perfect Font Ascent value.

          1.)   pdftron::Common::Matrix2D Trm;

                double Tfs = gs.GetFontSize();

                double Th = gs.GetHorizontalScale() / 100;

                double Trise = gs.GetTextRise();

                Trm.m_a = Tfs * Th;

                Trm.m_b = 0;

                Trm.m_c = 0;

                Trm.m_d = Tfs;

                Trm.m_h = 0;

                Trm.m_v = Trise;

                pdftron::Common::Matrix2D Trm_mtx = element.GetCTM() * element.GetTextMatrix() * Trm;

                pdftron::PDF::Rect outBBox outBBoxText = font.GetBBox();

                tX1 = outBBoxText.GetX1() / 1000;

                tY1 = outBBoxText.GetY1() / 1000;

                tX2 = outBBoxText.GetX2() / 1000;

                tY2 = outBBoxText.GetY2() / 1000;

                Trm_mtx.Mult(tX1,tY1);

                Trm_mtx.Mult(tX2,tY2);

                tY2-tY1 should be the height of the ascent. But this value is inaccurate and is quite high. 

             2.)  Other method that i used to derive Ascent is

                

 double PdfRenderer::getFontHeight(double fontsize, const pdftron::Common::Matrix2D& mtx) { 

    double x = mtx.m_c * fontsize; 

    double y = mtx.m_d * fontsize; 

    return sqrt(x*x + y*y); 

}

                fontSize = getFontHeight(gs.GetFontSize() , element.GetCTM() * element.GetTextMatrix());

                outBBoxText = font.GetBBox();

                double bBoxAscent = (outBBoxText.y2 /(outBBoxText.y2 - outBBoxText.y1)) * fontSize;

                double bBoxDescent = (abs(outBBoxText.y1) /(outBBoxText.y2 + abs(outBBoxText.y1))) * fontSize;

               In the above logic, i multiply fontsize with a factor derived from Ascent:Descent ratio. Even this ascent value is slightly inaccurate.

 I saw your post regarding taking each character Bounding Box. we render e_text_begin to e_text_end as one single text flow, so even when we take character by character ascent, we would still endup taking the tallest BBox height .  

Kindly share if there is any other way to get optimal value of Ascent of Text.

On Thursday, January 15, 2015 at 12:09:29 PM UTC+8, Support wrote:

It sounds like you would like to use TextExtractor methods to get bbox for line/word/character:

https://www.pdftron.com/pdfnet/mobile/docs/Android/pdftron/PDF/TextExtractor.Line.html#getBBox()
https://www.pdftron.com/pdfnet/mobile/docs/Android/pdftron/PDF/TextExtractor.Word.html#getQuad()
https://www.pdftron.com/pdfnet/mobile/docs/Android/pdftron/PDF/TextExtractor.Word.html#getGlyphQuad(int)

Alternatively if you are working with ElementReader you could use element.GetBBox() 

... or for more low lever control see 

https://groups.google.com/d/msg/pdfnet-sdk/B82iGlKnVUQ/zU7ATQE0bm4J

FYI, section 9.4.4. Text Space Details ( http://xodo.com/view/#/c0c11968-ee14-478e-9b09-6dc5635c0915 ) provides info on how to map all gstate and font parameters to a bbox in user coordinate system.

On Wednesday, January 14, 2015 at 6:55:38 PM UTC-8, arunsrinivaasrs wrote: