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Merge pull request #249 from oheil/svg-issue-150
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Svg issue 150
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@cormullion
cormullion authored Dec 19, 2022
2 parents a04b373 + d9faff1 commit 2105b3d
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169 changes: 167 additions & 2 deletions src/drawings.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ mutable struct Drawing
elseif stype == :image
the_surface = Cairo.CairoImageSurface(w, h, Cairo.FORMAT_ARGB32)
else
error("Unknown Luxor surface type \"$stype\"")
error("Unknown Luxor surface type" \"$stype\"")
end
the_cr = Cairo.CairoContext(the_surface)
# @info("drawing '$f' ($w w x $h h) created in $(pwd())")
Expand Down Expand Up @@ -614,6 +614,153 @@ function Drawing(paper_size::AbstractString, f="luxor-drawing.png"; strokescale=
Drawing(w, h, f, strokescale=strokescale)
end


@doc raw"""
_adjust_background_rects(buffer::UInt8[])
See issue https://github.com/JuliaGraphics/Luxor.jl/issues/150 for discussion details.\
Setting backgrounds in a recording surface (:rec) and creating a svg from it result in elements as
```
<rect x="0" y="0" width="16777215" height="16777215" .../>
```
independent of an existing transformation matrix (e.g. set with origin(...) or snapshot with a crop bounding box).\
An existing transformation matrix manifests in the svg file as
```
<use xlink:href="#surface199" transform="matrix(3 1 -1 3 30 40)"/>
```
which is applied to every element including the background rects.\
This transformation needs to be inversed for the background rects which is added in this function.
"""
function _adjust_background_rects(buffer)
adjusted_buffer=String(buffer)
# get SVG viewbox coordinates to replace the generic 16777215 values
# expected example:
# <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="300pt" height="300pt" viewBox="0 0 300 300" version="1.1">
m=match(r"<svg\s+?[^>]*?viewBox=\"(.+?)\s+(.+?)\s+(.+?)\s+(.+?)\".*?>"is,adjusted_buffer)
adjust_vb=false
if !isnothing(m) && length(m.captures) == 4
(vbx,vby,vbw,vbh)=string.([ parse(Float64,m[i]) for i in 1:4 ])
adjust_vb=true
end
# do adjustment for all <use ...> elements (after <defs>) which have a transform attribute as matrix
# expected example:
# </defs>...<use xlink:href="#surface5" transform="matrix(1,0,0,1,150,150)"/>...</svg>
# xlink:href is deprecated and can be replaced by just href
# a group block with id "surface5" must exist: <g id="surface5" clip-path="url(#clip1)">
# in this group block adjust all background rects with the inverse transform matrix like:
# from:
# <rect x="0" y="0" width="16777215" height="16777215" style="..."/>
# to:
# <rect class="luxor_adjusted" x="0" y="0" width="300" height="300" style="..." transform="matrix(1,0,0,1,-150,-150)"/>
# adding class as verification that tweak was applied.
m=findall(r"<defs\s*?>"is,adjusted_buffer)
# check if there is exactly 1 <defs> element
if length(m) == 1
# get SVG part after </defs> to search for <use ...>
# could be done in a single RegEx but can produce ERROR: PCRE.exec error: match limit exceeded
m=match(r"</defs\s*?>(.*)$"is,adjusted_buffer)
if length(m.captures) == 1
adjusted_buffer_part=m[1]
for m in eachmatch(r"<use[^>]*?(xlink:)*?href=\"#(.*?)\"[^>]*?transform=\"matrix\((.+?),(.+?),(.+?),(.+?),(.+?),(.+?)\)\"/>"is,adjusted_buffer_part)
if length(m.captures) == 8
# id of group block
id=m[2]
# transform matrix applied to all elements in group block
transform=vcat(reshape([ parse(Float64,m[i]) for i in 3:8 ],2,3),[0.0 0.0 1.0])
# inverse transform matrix must be applied to background rect to neutralize transform matrix
it=inv(transform)
# get the group block with id into mid::String
(head,mid,tail,split_ok)=_split_string_into_head_mid_tail(adjusted_buffer,id)
if split_ok
# add inverse transform matrix to every background rect
# background rects look like:
# <rect x="0" y="0" width="16777215" height="16777215" style="fill:rgb(0%,69.803922%,93.333333%);fill-opacity:1;stroke:none;"/>
# add class="luxor_adjusted" too, for future reference that element has been tweaked
invtransformstring="transform=\"matrix("*join(string.(it[1:2,1:3][:]),",")*")\""
mid=replace(mid,r"(<rect) (x=\"0\" y=\"0\" width=\"16777215\" height=\"16777215\".*?)/>"is => SubstitutionString("\\1 class=\"luxor_adjusted\" \\2 $(invtransformstring)/>") )
if adjust_vb
# some SVG tools don't like this huge rects (e.g. inkscape)
# => replace 0,0,16777215,16777215 with viewBox coordinates
mid=replace(mid,r"(?<a><rect\s+?.*?\s+?x=\")0(?<b>\" y=\")0(?<c>\" width=\")16777215(?<d>\" height=\")16777215(?<e>\".*?/>)"is => SubstitutionString("\\g<a>$(vbx)\\g<b>$(vby)\\g<c>$(vbw)\\g<d>$(vbh)\\g<e>"))
end
adjusted_buffer=head*mid*tail
end
end
end
end
end
adjusted_buffer=UInt8.(collect(adjusted_buffer))
return adjusted_buffer
end

@doc raw"""
_split_string_into_head_mid_tail(s::String,id::String)
splits s into head, mid and tail string.\
Example:\
```
s="head...<g id="\$id">...</g>...tail"
```
results in\
```
head="head..."
mid="<g id="\$id">...</g>"
tail="...tail"
```
"""
function _split_string_into_head_mid_tail(s,id)
head=""
mid=s
tail=""
split_ok=false
# find all group start elements <g ...>
startgroups=findall(r"<g(?:>|\s+?.*?>)"is,s)
# find all group end elements </g...>
endgroups=findall(r"</g\s*>"is,s)
# there must be as many start elements as end elements
if length(startgroups) == length(endgroups)
#if length(startgroups) != length(endgroups)
# @warn "number of group starting tags <g ...> do not match number of closing tags </g> in SVG"
#else
# find the group start element with the proper id
first_group=findfirst(Regex("<g\\s+?[^>]*?id=\"$(id)\".*?>","is"),s)
group_start_index=findfirst(e->e==first_group,startgroups)
if !isnothing(group_start_index) && !isempty(group_start_index)
mid_start=first_group[1]
group_end_index=0
# starting with group start element with the proper id traverse the end group elements
# and the start group elements until the number traversed are equal the first time
while group_start_index-group_end_index !== 0 && group_start_index < length(startgroups) && group_end_index <= length(endgroups)
group_end_index+=1
while group_end_index <= length(endgroups) && endgroups[group_end_index][1] < startgroups[group_start_index][1]
group_end_index+=1
end
while group_start_index < length(startgroups) && startgroups[group_start_index+1][1] < endgroups[group_end_index][1]
group_start_index+=1
end
end
if group_start_index-group_end_index == 0
mid_end=endgroups[group_end_index][end]
# start and end character of mid is found, construct the substrings
if prevind(s,mid_start) > 0
head=s[1:prevind(s,mid_start)]
end
if nextind(s,mid_end)>0
tail=s[nextind(s,mid_end):end]
end
mid=s[mid_start:mid_end]
split_ok=true
end
end
end
return (head,mid,tail,split_ok)
end

"""
finish()
Expand Down Expand Up @@ -642,7 +789,25 @@ function finish()
Cairo.destroy(current_surface())

if current_filename() != ""
write(current_filename(), current_bufferdata())
if current_surface_type() != :svg
write(current_filename(), current_bufferdata())
else
# next function call adresses the issue in
# https://github.com/JuliaGraphics/Luxor.jl/issues/150
# short: setting a background in svg results in
# <rect x="0" y="0" width="16777215" height="16777215" .../>
# independent of an existing transform matrix (e.g. set with origin(...)
# or snapshot with a negative crop bounding box).
# An existing transform matrix manifests in the svg file as
# <use xlink:href="#surface199" transform="matrix(3 1 -1 3 30 40)"/>
# which is applied to every element including the background rects.
# This transformation needs to be inversed for the background rects
# which is added in this function.
buffer=_adjust_background_rects(copy(current_bufferdata()))
# hopefully safe as we are at the end of finish:
_current_drawing()[_current_drawing_index()].bufferdata=buffer
write(current_filename(), buffer)
end
end

return true
Expand Down
85 changes: 85 additions & 0 deletions test/place-svg.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -41,5 +41,90 @@ function place_svgtest(fnamein, fnameout)
println("...finished test: output in $(fnameout)")
end

function svg_rec_format()
# Checking for specific expectations when using recordings (:rec) and svg snapshots.
# These tests are especially intended to help in case cairo changes the svg elements
# which are used to tweak the result by function _adjust_background_rects(buffer) in drawings.jl
Drawing(NaN, NaN, :rec)
background("deepskyblue2")
setcolor("grey")
rect(-140,-140,280,280, :fill)
setcolor("black")
circle(O, 100, :stroke)
circle(O, 100, :clip)
background("magenta")
# now doing what
# snapshot(;fname="test.svg",cb=BoundingBox(Point(-150,-150),Point(150,150)))
# does without the _adjust_background_rects(buffer) tweak
fname="test.svg"
cb=BoundingBox(Point(-150,-150),Point(150,150))
scalefactor = 1.0
rd = currentdrawing()
rs = Luxor.current_surface()
Luxor.Cairo.flush(rs)
rma = getmatrix()
rmai = juliatocairomatrix(cairotojuliamatrix(rma)^-1)
rtlxu, rtlyu = boxtopleft(cb)
rtlxd, rtlyd, _ = cairotojuliamatrix(rma) * [rtlxu, rtlyu, 1]
x, y = -rtlxd, -rtlyd
nw = Float64(round(scalefactor * boxwidth(cb)))
nh = Float64(round(scalefactor * boxheight(cb)))
nm = scalefactor.* [rmai[1], rmai[2], rmai[3], rmai[4], 0.0, 0.0]
nd = Drawing(round(nw), round(nh), fname)
setmatrix(nm)
Luxor.set_source(nd.cr, rs, x, y)
paint()
# now doing what
# finish()
# does without the _adjust_background_rects(buffer) tweak
Luxor.Cairo.finish(Luxor.current_surface())
Luxor.Cairo.destroy(Luxor.current_surface())
buffer=copy(Luxor.current_bufferdata())
Luxor._current_drawing()[Luxor._current_drawing_index()] = rd
finish()

testsvg=String(buffer)
# check if the SVG contains lines like
# <use xlink:href="#surface31" transform="matrix(1,0,0,1,150,150)"/>
# or
# <use href="#surface31" transform="matrix(1,0,0,1,150,150)"/>
# after </defs>
m=match(r"</defs\s*?>(.*)$"is,testsvg)
@test length(m.captures) == 1
if length(m.captures) == 1
testsvg_part=m[1]
m=match(r"<use[^>]*?(xlink:)*?href=\"#(.*?)\"[^>]*?transform=\"matrix\((.+?),(.+?),(.+?),(.+?),(.+?),(.+?)\)\"/>"is,testsvg_part)
@test !isnothing(m) && length(m.captures) == 8
id=m[2]
# check if the SVG contains line like
# <g id="surface31" clip-path="url(#clip1)">
m=match(Regex("<g\\s+?[^>]*?id=\"($(id))\".*?>","is"),testsvg)
@test !isnothing(m) && m[1] == id
# check if <g id="$id">...</g> is extracted correct
group="<g id=\"other\"></g><g id=\""*id*"\"><g><g></g></g><g></g></g><g id=\"other\"></g>"
(head,mid,tail,split_ok)=Luxor._split_string_into_head_mid_tail(group,id)
@test split_ok == true
@test head == "<g id=\"other\"></g>"
@test mid == "<g id=\""*id*"\"><g><g></g></g><g></g></g>"
@test tail == "<g id=\"other\"></g>"
# _split_string_into_head_mid_tail(group,id) needs to be robust
# do nothing if split fails
group="</g><g id=\"other\"></g><g id=\""*id*"\"><g><g></g></g>"
(head,mid,tail,split_ok)=Luxor._split_string_into_head_mid_tail(group,id)
@test split_ok == false
group="</g></g><g><g id=\""*id*"\">"
(head,mid,tail,split_ok)=Luxor._split_string_into_head_mid_tail(group,id)
@test split_ok == false
group="<g><g id=\"other\"></g></g>"
(head,mid,tail,split_ok)=Luxor._split_string_into_head_mid_tail(group,id)
@test split_ok == false
group="<g><g><g id=\""*id*"\"></g></g>"
(head,mid,tail,split_ok)=Luxor._split_string_into_head_mid_tail(group,id)
@test split_ok == false
end
return
end

svgstring_test()
place_svgtest("polysample.svg", "place-svg.svg")
svg_rec_format()

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