We will explain why this happens, and how we manged to solve it in Computer graphics are a tricky issue (we should know!). Raster or pixel-wise means that in order to represent a line, we save the colour of all pixels (or squares) where the line passes through.<\/p>\n The latter means that we only save the starting point, the end point and the colour, which allows us to derive the pixel-wise data.<\/p>\n Clearly vector form graphics are more accurate and require less storage, but in order to represent graphics on a screen, or on paper (even digital like PDF), we sometimes need to rasterise or convert data to pixels.<\/p>\n This is the case with transparencies, which are not fully supported in PDF files or by printers, and certainly not in all cases where AutoCAD software can use them.<\/p>\n The way transparencies are handled traditionally is to assign each element a colour and a level of opacity. That means things have to be done pixel-wise, and with texts things get tricky again.<\/p>\n Text is easy, right? Well… Sadly no. Not for computers.<\/p>\n The main issue here are ligatures<\/a>, in languages that use the Roman alphabet, this isn’t that much of an issue, but we do use them a lot. E.g. aff<\/strong>inity uses a ligature to have a nicer typographical representation of In Roman alphabet-based languages, this is not much of an issue, since a lack of ligatures keeps text readable. For example: words like \u0627\u0644\u062d\u0643\u0648\u0645\u064a or \ufe8d\ufedf\ufe98\ufecc\ufe8d\ufeed\ufee7\ufef0 turn into \u0644 \u062d \u0643 \u0648 \u0645 \u064a or \u0644 \u062a \u0639 \u0627 \u0648 \u0646 \u0649 without ligatures; which is unreadable for speakers of Arabic.<\/p>\n Sadly, dealing with these ligatures in a pixel-wise fashion is pretty difficult and the lovely people at Autodesk<\/a> haven’t yet managed to make it work.<\/p>\n Which means that printing from AutoCAD<\/a> with transparencies enabled removes ligatures always, and is fairly visible in languages like Arabic.<\/p>\n Knowing what not<\/em> to do is sometimes as important as knowing what<\/em> to do.<\/p>\n Ideas we discarded:<\/p>\n Unicode<\/a> is an attempt to standardise text encoding and representation. For Arabic we are aware of two main Unicode<\/a> blocks: The latter is deprecated because it has limitations in how text is represented (it has no concept of ligatures). Since it has no ligatures, it means that the visual representation is going to be the same in AutoCAD software Before converting each DWG file to PDF, we convert seamlessly and without user interaction any Arabic text from its standard representation to the Arabic Presentations Form-B representation.<\/p>\n And after producing the PDF, we rollback any changes to the DWG file, so that users can benefit from the simpler input in the standard representation.<\/p>\n This setting is enabled automatically whenever transparencies are enabled and Arabic text is detected and it affects any loaded external references, so there is no need for any user action.<\/p>\n As you can see, even in very niche cases we are able to help our customers in simple, yet effective ways. And if you find any hard-to-solve issues, get in touch<\/a> because maybe we can help out.<\/p>\n","protected":false},"excerpt":{"rendered":" It is not widely known, that using transparencies This can have unexpected results. A notable example being Arabic texts.<\/p>\n
\none of our apps<\/a>: PlotMan<\/a> for all of our customers who can now
\njust use PlotMan<\/a> normally to create their PDF files and not worry about this at all.<\/p>\n\n
\n
\n
What is happening? (and why?!)<\/h2>\n
Transparencies and computers<\/h3>\n
\nTraditionally there are two ways of representing things: raster or pixel-wise and in vector form.<\/p>\n
\nThen draw the elements “bottom to top** and apply the percentage of the level of opacity as a weighted average.<\/p>\nTexts and computers<\/h3>\n
ff<\/code>.<\/p>\n
\nLanguages like Arabic on the other hand don’t have this luxury.<\/p>\nFinding a solution<\/h2>\n
What not<\/strong> to do<\/h3>\n
\n
Dive into Unicode<\/a><\/h3>\n
\nBasically, it sets the rules to how computers save and interpret text.<\/p>\n
\nArabic<\/a> and Arabic Presentations Form-B<\/a>.<\/p>\n
\nBut this case is precisely where it is supposed to be used.<\/p>\n
\nas in the resulting symbol-wise representation in the final PDF files.<\/p>\nThe solution<\/h3>\n
![\"plotman_arabic.png\"](\"https:\/\/camilion.eu\/wp-content\/uploads\/2024\/02\/plotman_arabic.png\" "\\"\\"")
<\/p>\nConclusion<\/h2>\n
\nGive PlotMan<\/a> a go and let us know how it works (or doesn’t) for you.<\/p>\n
\nin Autodesk\u00ae<\/a> AutoCAD\u00ae<\/a> software
\nmakes the resulting PDF files be rasterised.<\/p>\n