mupdf - MuPDF PDF reader and library

Age	Commit message (Collapse)	Author
2017-10-24	Make sure shades use proper "default" color space.	Michael Vrhel
	Fixes some issues in Altona test file.
2017-10-24	Only do proof conversion in final pop.	Michael Vrhel
	The proof conversion should only be done after we have done all our drawing in the separations group. Fixes issue in page 7 of Altona test.
2017-10-24	Fix overprint with shadings.	Robin Watts

2017-08-09	Add common fz_write_image_as_data_uri function for HTML and SVG output.	Tor Andersson
	Also ensure we don't write CMYK JPEG images.
2017-07-27	Add fz_write_base64 function.	Tor Andersson

2017-07-19	Add spots to fz_pixmaps.	Robin Watts
	Update separations interface further to cope with whether spots should be rendered separately, or as composite colors.
2017-07-17	Add colorspace handling to transparency groups	Michael Vrhel
	Also force softmasks to be isolated groups.
2017-06-22	Add Color Management interface to MuPDF, with LCMS implementation.	Michael Vrhel
	This commit adds an interface for a color management engine to MuPDF, together with the internal changes required to use it. We also add an implementation of this interface using the LCMS2 library. This commit is the "lcms" development branch squashed to a single commit. The individual commits that make it up are as follows: ------ Add LCMS2 submodule. Add required source files to MSVC libthirdparty project. Plus changes to the Makefile. ------ Change name of libfont to libresources The library can hold things other than fonts including ICC profiles and eventually halftone screens etc. ------ Generate and include icc profiles on windows solution Makefile for linux needs to be updated ------ Initial cut at interface to little cms Methods for getting profile handles, link handles and transform buffers as well as individual colors. ------ Install ICC profiles from source When the source color space is an ICC profile install the ICC space. Use alternative color space if ICC is invalid. ------ Rename ICC resources The way that fontdump generates the names was causing some redundant prefix/suffix combinations. ------ Make resource ICC profiles usable This brings in the resource profiles for use with the target device. When mudraw is invoked with the icc color type, it will set up the target pixmap to have an icc based color space. ------ Make Default ICC color spaces not storable The ICC color spaces in the color context should not be put into the store. ICC color spaces that are contained in the source document are however storable. ------ Add in support for single color conversion This adds in the selection of the icc single color converter. Note that we may want to look at using the float conversion in lcms here since we are going from and to float. The down side is that the creation of such converters may be expensive. ------ Pixmap ICC conversion Also clean up and further simplify some of the code. Use common dst, src in function parameters instead of src, dst. ------ Add md5 calculation for profiles Compare md5 of source and destination. If they are the same set link as identity and do not bother creating link from cmm. ------ Initial attempt at adding links to store Next need to make sure I have all the dropping set up correctly and that the links are getting freed when we are all done with them. ------ Add drop for link Make sure that we drop the links when we are done with them. ------ Fix icc link store ref. counting + rendering intent The key allocations, rc and removal was wrong for the icc links. Also added in support on the graphic state for rendering intent. ------ Add ICC profiles to Makefile. ------ Move ICC profile loading to colorspace.c ------ Fix build on linux. ------ Use hexdump in creating icc profiles ------ First cut at CalRGB CalGray handling These color spaces are converted to equivalent ICC profiles when the drawing operation occurs. ToDo still is avoid creating brand new CalGray, CalRGB or ICC color spaces when we encounter the same object in the source file. Instead we should make use of the store. ------ Adding fz_color_params into device API Stroke and fill of paths and text which will have color rendering related settings including overprint, overprint mode, rendering intent and black point settings. Images have a fz_color_params member added to them. ------ Rendering intent support for graphic and text Graphic fills and strokes as well as text fill and strokes handle the rendering intent settings. This works through the display list. The parameters related to color rendering, ri, bp, op, opm are packed in the flags bits through the display list. To do: Add support for images and shadings. ------ Add support for rendering intent with images Required change to fill_image api, hence the large number of files touched. ------ Add support for shadings rendering intent and DeviceN This adds support for the rendering intent in shading fills. Also, adds in support for color management of DeviceN and Separation color spaces where the base space is defined to be ICC. ------ Add clamping proc to colorspace-imp.h In the head of mupdf, the index color values were not being clamped properly. I moved the clamping operation to be performed by a procedure in of the color space. The a, b values in LAB will need to include a range value for proper clamping as well as the ICC color space at some point. ------ Fix assert test with index images ------ Support for DeviceN images color managed The base space for DeviceN and separation images is now color managed when the ICC work flow is used. ------ Add DefaultGray etc to names.txt The DefaultGray, DefaultRGB, and DefaultCMYK settings in the pdf page resource dictionary need to be parsed and handled if present. ------ Remove methods for setting color space in context The methods that existed for setting the color spaces in the color space context were broken and we will not be changing them from their initial setting at startup. ------ Add front end support for default color spaces PDF can specify in the resource dictionary color spaces that should be used for DeviceGray, DeviceRGB and DeviceCMYK. This commit handles the extraction of these color spaces and passes them through the display list and gets them into a structure on a draw device (if one is used). Next step is to have the draw device make use of them. ------ Backend of default color spaces This handles the use of page level definitions for DefaultGray, DefaultRGB, DefaultCMYK in the draw device. The interface for the pixmap color conversion had to be expanded a bit to pass the default_cs object. This was needed due to the fact that the image could be DeviceN or Separation and have a base space that needs to be replaced by a page level Default color space. Tested this with a file that had two pages each with an common reference image object but different DefaultCMYK definitions in the page resource dictionary. Proper rendering was obtained. ------ Add icc support to band-writer and png output For image viewers that support icc profiles, it is important that we include the icc profile into those formats that support. Currently the only output format we have that supports it is PNG. But if we decide to do tiff, jpeg or psd those also support the embedding of icc profiles. ------ Work toward multithreading Each cloned context creates a new cmm context to reduce contention. This may not be optimal though as it may create conflicts in any shared store. ------ Add missing files. Failed to check in icc-imp.h and icc34.h ------ Fix default device color calls copy and paste errors. ------ Fixes ------ Fix clamping of lab colors The lab colors when used with the lab resource profile need to be properly clamped and scaled. ------ Turn off ICC create debug define ------ Fix memory leak issues ------ Set clamp proc in color context color spaces When NO_ICC is enabled there was an issue as the default spaces did not have the clamp proc (which was added in the lcms branch). ------ Fix several issues after rebase During rebase of the branch there were several issues that came up. In addition there was a fix related to the use of the lcms2 context branch that did not make it in for some reason. ------ Fix for fz_store_type structure changes ------ Fixes for multithreaded This fixes a few issues. One issue is that we can not be changing the input and output formatter for the links if they are being shared among threads. This adds the format as part of the link definition. Next step is to create a link clone operation in lcms so that we can readily create a different one with everything the same except the formatter. Also, this shares the profiles that exist in the color context among the threads. When a context is cloned, it will use the profiles in the current context but it will create a new cmm context.c ------ Fix NO_ICC issues There were a few issues that occurred when we compiled and ran with the NO_ICC setting. ------ Change CMM to use lower resolution tables in links The table resolution greatly affects the performance for some files. I don't see any significant color rendering issues going with a lower resolution. Selecting cmsFLAGS_LOWRESPRECALC uses a MLUT resolution of 17. This is going to be sufficient color wise and gives a large improvement performance wise especially for files where the color link creation is significant compared to the rendering. ------ Fix link key creation to populate alpha and bit depth. The store key for icc links needs to include the bit depth and if the transform has to handle an alpha value. This is needed due to the fact that we can't change the formatter when we are sharing links among different threads. ------ Pull in some MSVC 2005 fixes for lcms2 ------ Fix non-prototype prototype. ------ Miscellaneous typos, whitespace fixes. ------ Tidy colorspace creation API. Rather than pass a magic implementation reference count value (-1 for static, 1 for normal), pass a boolean "is_static" flag. This gives a nicer API (IMAO etc). ------ Make all colorspaces use an fz_buffer. ------ Fix internal naming of MSVC project file. ------ Fix some error handling. ------ Add some consts. ------ Tweak fz_color_params and fz_store_hash. Use uint8_t for fz_color_param entries - no need to use larger. Same change in fz_store_hash. This limits the size required for the hash table too. ------ Throw on errors, rather than returning NULL. fz_cmm_transform_pixmap should throw if it's fed pixmaps incompatible with its transforms. fz_cmm_new_ctx should throw if the cmm fails to initialise. ------ Ensure LCMS2_OBJs are built/linked using Makefile. Also ensure that ICC_OBJs are included. ------ Fix some unused variable warnings. ------ cs_params fixes. Use the ones that are passed. ------ fz_color_params tweaks. Make them const in many places. Cope with cs_params == NULL meaning default (i.e. fz_cs_param(ctx)). Minimise the places we call fz_cs_params(ctx). Consistently use cs_params rather than a mix of cs_param and cs_params. ------ Improve PDF color params handling. PDF allows different OP settings for strokes and fills. This means that either we need to keep separate entries in each fz_color_param structure for the stroke one or the fill one, OR we need to duplicate the fz_color_param structure. It seems neatest to do the latter (not least because this means we don't pass more information to each device function than it actually needs). Accordingly, we put an fz_color_param in each pdf_material. We update the code that reads ExtGStates to set the values appropriately. We take the opportunity to add support for the PDF 2.0 UseBlackPtComp option too. ------ Fix colorspace ref count problems. 1) Don't drop colorspace until we've finished using it. 2) Don't drop it twice. ------ Convert NULL deref into a thrown error. Seen with: mutool draw -D -o out.png ../tests_private/comparefiles/Bug689760.pdf We seem to have a pdf-cal space with no profile. Talk to Michael about this. ------ Avoid using colorspace names to distinguish colorspaces. Using strcmp is slow. ------ Cope with failure to parse default colorspaces during PDF page load. ------ Avoid SEGV due to to pdf_cal space with no profile. As seen in: tests_private/pdf/PDFIA1.7_SUBSET/CATX4879.pdf ------ Handle cases where base space of sep is pdf-cal We handled this for images, but not for solid fills. ------ Accelerate ICC color conversion. ------ Cope with indexed images in the color management. Some images (JPX images) come to the cm code still in the indexed color space. Their base space could be DevN so we need to cope with multiple base decodes. This continues the decode until we get to a space for which we can create an ICC link. ------ Ignore alpha presence in component count check ------ Eliminate recursion in fz_source_colorspace_cm. ------ Cope with bare ICCBased colorspace defs. Bug692137.pdf has ICCBased colorspaced definitions given directly as a stream, rather than as [ /ICCBased <stream reference> ] Acrobat copes with these, as does gs. We therefore update our code to cope too. Also, the PDF spec says that any problems found when reading the Default spaces should be ignored (or at least not to abort rendering). Update our code to do that too. ------ Tweak color converter logic for speed. When we are using an icc profile based conversion, avoid ever having to lookup the color converter for each conversion call; do it at the lookup stage. ------ Harden us against failures during ICC link creation. Seen with corrupted profiles. ------ Fix for handling alpha with lcms. Note that this currently maintains an alpha when it is present. We may need to do some work for the gray scale conversion to alpha mask. ------ Delay pdf-cal profile creation Put the creation of the pdf cal profile into the link creation function (rather than have it scattered). Also be robust in the condition of failure to create the profile. ------ Proper clamping with embedded CIELAB ICC profile If the ICC profiles alternate color space is LAB then use the LAB clamping proc. ------ Use the color space clamp when converting to base color spaces In many of the Ghent test files, we have a DeviceN image whose alternate color space is CIELAB. We need to make sure to use the CIELAB clamping operation in this case. ------ Make ICC runtime configurable. Add fz_icc_flowflow, fz_set_icc_workflow functions to read ICC workflow state, and set the ICC workflow state. The latter will throw an error if trying to enable ICC workflow in a NO_ICC build. Add -N flag to mutool to disable ICC. Incorporates build fixes from Michael. ------ Ensure fz_draw_fill_image uses the pixmap colorspace It appears that the image colorspace historically has been able to differ from the pixmap colorspace. While we've fixed the cases that we know about for this (see the previous commits), tweak fz_draw_fill_image to work the way it always has in the past. ------ Add support for output intent PDF documents can have an ICC profile defined in their Catalog which defines the output color space and the color space to use for one of the Device color spaces (e.g. DeviceGray, DeviceRGB or DeviceCMYK). ------ Catch errors in default color spaces Before setting the default color space contained in the file, make sure it is the correct type. Bug692213.pdf ------ Clamp to base space during sep color conversion This was the source of a problem when the base space was CIELAB. ------ Rename some functions to be more MuPDFy drop rather than free etc. ------ Fix "casting away const" warning. srcv is a const *. Do the clamping operation on src_map (the same value) before it is assigned into the const variable. ------ Rejig top level color management interface slightly. Same code, just change the encapsulation. ------ Remove pre-multiplied alpha prior to color management The pixmaps in mupdf use a premultiplied alpha format. Prior to doing any color management we need to undo the alpha and then reapply after color management. ------ Remove global output intent as unused. ------ Move fz_color_params to be the final arg in dev calls. Frequently this will be NULL, and it doesn't form part of the colorspace/color/alpha triple. ------ Rename fz_default_xxx static variables. Remove fz prefix, to prepare for a later renaming that would conflict. ------ Rename cs_params to color_params. ------ Rename lcms branch identifiers. ------ Return device colorspaces if the default colorspace is NULL. ------ Clean up device call function for set_default_colorspaces. ------ Add missing rethrow. ------ Load page default colorspaces lazily. ------ murun: Add color params device argument. Stubbed to always be NULL at the moment. ------ Rename extgstate processor ops. ------ Fix a few minor issues from Tor Removes icc-imp.h Rename color-icccreate.c Add context to some methods ------ Fix javalib with recent lcms dev changes. ------ Update lcms2 with sub project fixes. ------ Fix build failure. ------ Add icc profile into other PNG output methods ------ Fix some ints that should be size_t's. ------ Tweak fz_new_icc_data_from_icc_colorspace. Ensure that the colorspace is const, and that we set size to 0 if we don't find any data. ------ Combine band writer methods for header and ICC writing For many formats (like PSD), we need to delay writing some of the header until we know whether we are getting an ICC profile to write or not. Makes more sense to just write them at the same time. ------ Miscellaneous tweaks in colorspace.c Mainly to avoid pointer aliasing, "nicer" whitespace, and a leak on error. ------ Avoid rightward drift in get_base_icc. ------ Ensure that pdf_load_output_intent copes with exceptions. If load_icc_based throws and exception, warn and continue. Don't not render a file just because the inbuilt default profiles are broken. ------ Revert change in pdf-page.c The page resources load had been moved so we could get the default colorspaces, but this has been moved into run_contents, so putting stuff back as it was before. ------ Revert changes in mudraw. We had added some colorspages in mudraw, and then later removed them. Revert the changes to accomodate this to make the overall branch diffs smaller. ------ Use fz_buffer in color-icc-create.c ------ Force mapping through proof icc profile always. ------ Fix behaviour on fz_cmm_new_profile failure. If the profile fails to be made, return an error code, and have the callers take sane steps. ------ Tweak load_icc_based Cope better with errors in reading the ICC space not stopping us loading the alternate. ------ Remove unused variable. ------ Get page resource for DefaultCS look-up res = pdf_dict_get(ctx, PDF_NAME_Resources, page->obj); was not returning resource. Replaced with res = pdf_page_resources(ctx, page); ------ Move default color space set up to pdf_run_page_contents_with_usage ------ Review fixes for lcms branch. ------ Fixes for calibrated colorspace loading. ------ Add fz_document_output_intent wrapper. Lazy load intent for PDF. ------ Copy DefaultCS logic into pdf_run_annot_with_usage. Same code as from pdf_run_page_contents_with_usage. ------ More review fixes. ------ Avoid rightward drift in pdf_load_cal_common ------ Rename color_converter functions to be find/drop. Better than than lookup/discard. lookup suggests something that doesn't need dropping, and we use drop rather than discard by convention. ------ Move cmm from context into colorspace context. ------ Review fixes: Remove recursion and rename functions. ------ Don't access doc->oi directly in pdf_load_default_colorspaces. ------ Rename fz_colorspace_is_pdf_cal to fz_colorspace_is_cal and make it public. ------ Tweak function naming to be more consistent. ------ fz_md5_icc can be implemented using fz_md5_buffer. ------ Print full md5 checksums in link key debug prints. ------ Make fz_md5_buffer NULL safe. ------ Simplify debug saving of ICC profiles. ------ Rename fz_cmm_new/drop_profile to init/fin. ------ Indentation cleanups. ------ Move CMM static inline functions from private header to C file. ------ Tweak fz_icc_data_from_icc_colorspace to return a buffer. Also, remove the _new_ from the name to reflect the fact that we are passed a borrowed handle, not given a new reference. ------ java: Add ColorParams.pack() function. ------ Generate one C file for the embedded ICC profiles. ------ Return const pointer from fz_default_color_params. ------ Change misleading argument names to fz_new_colorspace. ------ Rename fz_cmm_new/drop_link to fz_cmm_init/fin_link. ------ Change definition of fz_cmm_instance. Rather than void, use an undefined struct in keeping with the rest of the code. ------ Add support for color managed bgr color space ------ Return unsigned char array from fz_lookup_icc. ------ Make default_color_params immutable. Changing the defaults used by the draw device should happen via a device call, should we need the functionality in the future. ------ Clean up error handling in color-lcms.c ------ Fix signed/unsigned warning.
2017-05-31	Avoid double literals causing casts to float.	Sebastian Rasmussen

2017-04-27	Include required system headers.	Tor Andersson

2017-03-28	Rejig fz_new_device to be fz_new_derived_device.	Robin Watts
	In keeping with the rest of the code.
2017-03-22	Rename fz_putc/puts/printf to fz_write_*.	Tor Andersson
	Rename fz_write to fz_write_data. Rename fz_write_buffer_* and fz_buffer_printf to fz_append_. Be consistent in naming: fz_write_ calls write to fz_output. fz_append_* calls append to fz_buffer. Update documentation.
2017-03-15	svgwrite: Use width of glyph to position characters in cluster maps.	Tor Andersson
	This evenly spaces the sub-parts of a ligature.
2017-03-15	svgwrite: Use #RRGGBB color syntax.	Tor Andersson

2017-03-15	svgwrite: Fix pen advance for ligatures.	Tor Andersson
	harfbuzz puts all ligature component characters at the same coordinate as the glyph.
2017-03-15	Optimize svg text output.	Tor Andersson
	Emit one <tspan> per line, so we only need to emit one 'y' coordinate for the whole line, instead of repeating it for each character.
2017-03-02	Improve SVG text output.	Tor Andersson
	Use xml:space="preserve" to remove the whitespace workaround. Fix output of glyph clusters.
2017-02-20	Add no-reuse-images option to SVG device.	Tor Andersson
	Also add explicit viewBox and width/height to image symbol and use elements, to work around a strange clipping/image scaling issue with firefox.
2017-02-20	Fix svg text output when text span is all whitespace or empty.	Tor Andersson
	We were emitting unbalanced quotes for the x and y attributes.
2017-02-20	Add fz_font_is_bold and italic functions. Use them for svg output.	Tor Andersson

2017-02-20	Emit more newlines in svg output.	Tor Andersson
	The aim is to put each tag on a line of its own.
2017-02-14	Make svg text output format a runtime option.	Tor Andersson

2017-02-08	Add SVG_TEXT_AS_TEXT define.	Robin Watts
	Build with this defined, and we no longer send text as reusable symbols, but instead send it as genuine text, with all the potential problems (mismatching fonts etc) that this entails. Requested by a customer.
2016-12-27	Strip extraneous blank lines.	Tor Andersson

2016-12-19	SVG output: Fix dropped group alpha.	Robin Watts

2016-11-14	More API tweaks.	Robin Watts
	Move internal functions from public to private headers.
2016-11-14	Make fz_buffer structure private to fitz.	Robin Watts
	Move the definition of the structure contents into new fitz-imp.h file. Make all code outside of fitz access the buffer through the defined API. Add a convenience API for people that want to get buffers as null terminated C strings.
2016-11-14	Workaround 0 line-width strokes in svg output.	Robin Watts
	A line width of 0 has special meaning in PDF files. SVGs don't understand it, so modify our SVG output device to send all line widths smaller than 1 as being 1.
2016-10-07	Add ctx to fz_font functions.	Robin Watts

2016-10-05	Move fz_font definition to be private.	Robin Watts
	Move the definition of fz_font to be in a private header file rather than in the public API. Add accessors for specific parts of the structure and use them as appropriate. The font flags, and the harfbuzz records remain public. This means that only 3 files now need access to the font implementation (font.c, pdf-font.c and pdf-type3.c). This may be able to be improved further in future.
2016-09-16	Bug 695988: Avoid sending image data multiple times.	Robin Watts
	If the same image is used repeatedly, then we currently send the data again and again. Instead, send each image as a reusable symbol and reuse it as required. This reduces the size of the output by over 50% for the example file, but unfortunately results in the example file killing both Firefox and Edge when we attempt to load it. The file seems entirely valid though, and this is a saving on sane files. There is a #define that can be made to revert to the old behaviour (SVG_SEND_REPEATED_IMAGES).
2016-09-06	Devices now handle colorspace being NULL as alpha-only.	Sebastian Rasmussen

2016-09-01	Use fz_convert_color().	Sebastian Rasmussen
	In preference to colorspace internal to_rgb() function pointer.
2016-07-20	Add char encoding to produced SVG files.	Robin Watts
	Stops a warning with the validator.
2016-07-13	Fix memory leaks in SVG device.	Robin Watts

2016-07-13	Bug 696846: Fix badly formed SVG output.	Robin Watts
	This has been broken since fz_text was changed to be multiple fz_text_spans.
2016-07-08	Separate close and drop functionality for devices and writers.	Tor Andersson
	Closing a device or writer may throw exceptions, but much of the foreign language bindings (JNI and JS) depend on drop to never throw an exception (exceptions in finalizers are bad).
2016-06-20	Bug 696847: Fix SEGV in svg device.	Robin Watts
	Silly typo.
2016-06-17	Use 'size_t' instead of int as appropriate.	Robin Watts
	This silences the many warnings we get when building for x64 in windows. This does not address any of the warnings we get in thirdparty libraries - in particular harfbuzz. These look (at a quick glance) harmless though.
2016-05-24	fz_pixmap revamp: add stride and make alpha optional	Robin Watts
	fz_pixmaps now have an explicit stride value. By default no change from before, but code all copes with extra gaps at the end of the line. The alpha data in fz_pixmaps is no longer compulsory. mudraw: use rgb not rgba (ppmraw), cmyk not cmyka (pkmraw). Update halftone code to not expect alpha plane. Update PNG writing to cope with alpha less input. Also hide repeated params within the png output context. ARM code needs updating.
2016-04-28	Refactor fz_image code cases.	Robin Watts
	Split compressed images (images based on a compressed buffer) and pixmap images (images based on a pixmap) out into separate subclasses.
2016-04-28	Partial image decode.	Robin Watts
	Update the core fz_get_pixmap_from_image code to allow fetching a subarea of a pixmap. We pass in the required subarea, together with the transformation matrix for the whole image. On return, we have a pixmap at least as big as was requested, and the transformation matrix is updated to map the supplied area to the correct place on the screen. The draw device is updated to use this as required. Everywhere else passes NULLs in, and so gets unchanged behaviour. The standard 'get_pixmap' function has been updated to decode just the required areas of the bitmaps. This means that banded rendering of pages will decode just the image subareas that are required for each band, limiting the memory use. The downside to this is that each band will redecode the image again to extract just the section we want. The image subareas are put into the fz_store in the same way as full images. Currently image areas in the store are only matched when they match exactly; subareas are not identified as being able to use existing images.
2016-04-27	Add fz_close_device function.	Tor Andersson
	Garbage collected languages need a way to signal that they are done with a device other than freeing it. Call it implicitly on fz_drop_device; so take care not to call it again in case it has been explicitly called already.
2016-02-24	Add optional scissor hint argument to text clipping functions.	Tor Andersson

2016-02-24	Clarify scissor argument to clip device functions.	Tor Andersson
	The scissor argument is an optional (potentially NULL) rectangle that can give hints to devices about the area that can be scissored. This is used by the draw device and display list device to minimize the size of temporary clip mask buffers. The scissor rectangle, if used, must have been transformed by the current transform matrix.
2016-02-22	Rename fz_path_processor to fz_path_walker.	Tor Andersson

2016-02-22	Drop const from fz_image.	Tor Andersson
	Image objects are immutable and opaque once constructed. Therefore there is no need for the const keyword.
2016-02-22	Drop const from fz_shade.	Tor Andersson
	Shading objects are immutable and opaque once constructed. Therefore there is no need for the const keyword.
2016-01-21	Drop const from fz_colorspace.	Tor Andersson
	It's an opaque immutable structure, that we don't expect to ever want to change after creation. Therefore the const keyword is not useful, and is only line noise.
2016-01-13	Add lots of consts.	Robin Watts
	In general, we should use 'const fz_blah' in device calls whenever the callee should not alter the fz_blah. Push this through. This shows up various places where we fz_keep and fz_drop these const things. I've updated the fz_keep and fz_drops with appropriate casts to remove the consts. We may need to do the union dance to avoid the consts for some compilers, but will only do that if required. I think this is nicer overall, even allowing for the const<->no const problems.