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--- contrib:externalviewers [2015/05/02 09:45] – clarify brucemutton
+++ contrib:externalviewers [2019/07/13 09:41] (current) – typo What it means "transparency knockout" sluka
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-====== (External) Viewers for Therion Outputs ======
+====== Viewers for Therion Outputs (not part of Therion package) ======
 How many ways to view the fruits of your labour?
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 If a file is open while Therion updates the file, it automatically reloads the file. Zoom and rendering of all details works very well too. The rendered PDF looks the same as Foxit Reader (See example screenshots in the next section below).
-As a Windows user I find non-file locking readers very useful for drawing new scraps, because if you set up a map to just render the few scraps you are working on so that the overall survey is not too large then you can keep the PDF open in Evince and recompile your project to immediately see the changes. The problems with clipping area fills in Evince means you cannot preview these, but walls, lines and point symbols are fine. SumatraPDF does a good job of both rendering and automatically displaying changes when the PDF is regenerated. This workflow is great for refining scrap joins as you can adjust the positions of line ends and immediately see the effect with the Evince viewer open alongside your Therion editor window, and for checking that area fills are working as planned. - Footleg
+As a Windows user I find non-file locking readers very useful for drawing new scraps, because if you set up a map to just render the few scraps you are working on so that the overall survey is not too large then you can keep the PDF open in Evince/SumatraPDF and recompile your project to immediately see the changes. The problems with clipping area fills in Evince means you cannot preview these, but walls, lines and point symbols are fine. SumatraPDF does a good job of both rendering and automatically displaying changes when the PDF is regenerated. This workflow is great for refining scrap joins as you can adjust the positions of line ends and immediately see the effect with the Evince viewer open alongside your Therion editor window, and for checking that area fills are working as planned. - Footleg
-Seems best for viewing small file sizes and small 'paper' sizes.  No 'zoom to Window' so slow to navigate (even with 'mouse-roll').  Very slow to render medium sized files (10MB, 1.5m x 2.0m)- it renders non-visible areas before the area within the viewport!!  It does not recognise layers in pdfs, so you are stuck with all layers 'on'.  It does allow you to open the file in any other readers you have installed which is nice. Therion produced Atlas files work OK.  So great for monitoring drawing editing on small snippet maps, but no good as a general viewer.  - Bruce
+Works well and is fairly fast to render large maps with Windows 10. Great for monitoring drawings while editing, but you don't want this as your only viewer. Is not always good at printing. - Bruce
 **MacOSX: Quick Look**
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 **MacOSX: Skim (free)**
 It looks very promising (only short test). It is possible to set it to automatic refresh. It preserves zoom and position. [[http://sourceforge.net/projects/skim-app/ |Skim]]. The rendering is the same as Foxit.
+**Xpdf** https://www.xpdfreader.com/
 **List of Free Software PDF readers** http://pdfreaders.org/ \\
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 **A comment...**
-The transparency of areas with filled backgrounds in pdfs is quite different when viewed with Adobe and Foxit Readers. The reason is the library used to render PDFs (up to early 2013 on ongoing...) //If viewer is based on PDF Kit from Apple the rendering is incorrect. There is the bug in PDF Kit evidently - it ignores command "transparency knockout group".//
+The transparency of areas with filled backgrounds in pdfs is quite different when viewed with Adobe and Foxit Readers. The reason is the library used to render PDFs (up to early 2013 on ongoing...) //If viewer is based on PDFKit from Apple the rendering is incorrect. There is the bug in PDF Kit evidently - it ignores command "transparency knockout group".//
-Adobe renders them opaque, and Foxit renders them translucent (except for area u:) and except for objects that explicitly have //–place bottom// set and except for my custom area water and area sump.  This difference in behaviour persists through to the printed documents as well.
+Adobe uses PDFToolkit and renders them opaque, and Foxit renders them translucent (except for area u:) and except for objects that explicitly have //–place bottom// set and except for my custom area water and area sump.  This difference in behaviour persists through to the printed documents as well.
 Objects with //–place bottom// are always completely obscured by areas with default placement regardless of the viewer.
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 Objects with //–place top// render the same as objects with default placement over areas with default placement in both viewers.
-The Foxit behaviour is preferable I think, although, with some symbol sets, you can never get a rock that looks like it is definitively ‘high and dry above the water’, unless you say, draw two rocks, one directly above the other.
+The Foxit behaviour is preferable I think, although, with some symbol sets, you can never get a rock that looks like it is definitively ‘high and dry above the water’, unless you say, draw two rocks, one directly above the other.\\ (Note: Anyway, Foxit ignores [[https://www.pdfa.org/what-does-%C2%93support-pdf%C2%94-really-mean/?highlight=knockout|official definition of PDF]], Sluka)
 Some further information here [[:tips#drawing_order_how_to_draw_symbols_over_or_under_an_area]]
+**What it means "transparency knockout"**\\
+Transparency knockout is part of PDF definition which Adobe applications as Illustrator, InDesign, Photoshop, etc. use. It means, that there is possibility to switch off transparency for a particular group of objects (sublayer) when transparency of superior layer is on. The explanation you may find [[https://helpx.adobe.com/illustrator/using/transparency-blending-modes.html|here]].\\
+In case of Therion it means that you didn't want rocks to be transparent, but rocks in position above another passage should be partially transparent to show details from underlaying passage.
+See attached examples of preview in program using PDFToolkit (transparency knockout rendered) and PDFKit (transparency knockout ignored).\\
+{{:contrib:pdftoolkit.png|300px|}}{{:contrib:pdfkit.png|300px|}}
 =====Examples of Rendering Differences Between PDF Viewers=====
 Each of the PDF readers renders Therion generated PDFs differently. Here are some examples from Windows versions of the PDF readers.
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 {{:contrib:adobereader-inkscape.png|}}
-All the above PDF screenshots are using Footleg's custom symbols for UK styles. But the default Therion symbols render with the same differences. You can generate these examples with these {{:examples:overlappingareas.zip|source project files}}
+**MacOSX Quick Look and Preview** \\
+Rendering looks like Foxit Reader, Quick Look (press spacebar when file highlighted) is quite fast way how to see file. Preview has some editing capabilities. In last MacOSX version (Mojave) Quick Look has editing possibility too.
+{{:contrib:preview_macosx.png|}}
+**xpdf** \\
+Correct rendering of overlap objects. On MacOSX it is possible to install it by homebrew installer. xpdf should antialias vectors, but not in this case, so rendering is quite coarse. The reason is when transparency knockout is used, the antialiasing in layers is not rendered. It should be corrected in next version of xpdf - current version is 4.
+{{:contrib:xpdf.png|}}
+All the above PDF screenshots are using Footleg's custom symbols for UK styles. But the default Therion symbols render with the same differences. You can generate these examples with these {{:examples:overlappingareas.zip|source project files}}
 =====For SVG files=====
 [[http://inkscape.org|Inkscape]]\\