Use WebP for CVD simulation demo in docs instead of indexed PNG

docs/make.jl

@@ -1,3 +1,21 @@
+using Pkg
+dependents = ["ImageCore"] # direct
+idependents = ["WebP"] # indirect
+devdir = get(ENV, "JULIA_PKG_DEVDIR", nothing) # backup
+workdir = joinpath(@__DIR__, "work")
+ENV["JULIA_PKG_DEVDIR"] = workdir
+Pkg.activate(workdir)
+Pkg.develop(dependents, preserve=PRESERVE_DIRECT)
+ENV["JULIA_PKG_DEVDIR"] = devdir # restore
+for dep in dependents
+    Pkg.activate(joinpath(workdir, dep))
+    Pkg.compat("Colors", "< 1")
+end
+Pkg.activate(@__DIR__) # this project
+pkgspecs = [PackageSpec(path=joinpath(workdir, dep)) for dep in dependents]
+Pkg.develop(pkgspecs, preserve=PRESERVE_DIRECT)
+Pkg.add(idependents)
+
 using Documenter, Colors
 
 abstract type SVG end
@@ -39,3 +57,6 @@ makedocs(
 deploydocs(
     repo = "github.com/JuliaGraphics/Colors.jl.git",
     target = "build")
+
+
+Pkg.rm([idependents; dependents], io=IOBuffer())

docs/sampleimages.jl

@@ -3,91 +3,42 @@ module SampleImages
 
 using Colors
 using Base64
+using WebP
 
 struct BeadsImageSVG <: Main.SVG
     buf::IOBuffer
 end
 
+const beads = WebP.read_webp(joinpath(@__DIR__, "src", "assets", "figures", "beads.webp"))
 
 # The following code is ad-hoc and highly depends on "beads.svg".
 # Be careful when modifying the svg file or its code.
 function BeadsImageSVG(caption::String; filter=nothing, width="64mm", height="36mm")
     io = IOBuffer()
-    id = string(hash(caption), base=16)
 
-    open(joinpath("assets", "figures", "beads.svg"), "r") do file
-        for line in eachline(file, keep=true)
-            occursin("<?xml", line) && continue
-            if occursin("<svg", line)
-                line = replace(line, ">"=>
-                    """ width="$width" height="$height" style="display:inline; margin-left:1em; margin-bottom:1em">""")
-            elseif occursin("filter_beads_g", line)
-                line = replace(line, "filter_beads_g"=>"filter_"*id)
-            elseif occursin("</svg>", line)
-                text = """
-                       <text x="16" y="1000" style="fill:black;opacity:0.9;font-size:80px;">$caption</text>
-                       </svg>"""
-                line = replace(line, "</svg>"=>text)
-            end
+    write(io, """<svg version="1.1" viewBox="0 0 1920 1080" """)
+    write(io, """xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" """)
+    write(io, """width="$width" height="$height" image-rendering="optimizeQuality" """)
+    write(io, """style="display:inline; margin-left:1em; margin-bottom:1em">\n""")
 
-            m = match(r"data:image/png;base64,([^\"]+)", line)
-            if filter === nothing || m === nothing
-                write(io, line)
-                continue
-            end
+    img = filter === nothing ? beads : filter.(beads)
+    webp = WebP.encode(img, lossy=true, quality=85)
 
-            head = m.offsets[1]
-            write(io, SubString(line, 1, head - 1))
-            src = IOBuffer(m.captures[1])
-            b64dec = Base64DecodePipe(src) # decode all for simplicity
-            b64enc = Base64EncodePipe(io)
-            write(b64enc, read(b64dec, 33)) # before the length of "PLTE"
-            replace_palette(b64enc, b64dec, filter)
-            n = write(b64enc, read(b64dec))
-            close(b64enc)
-            close(b64dec)
-            write(io, SubString(line, head + length(m.captures[1]), length(line)))
-        end
-    end
-    BeadsImageSVG(io)
-end
+    write(io, """<image width="1920" height="1080" xlink:href="data:image/webp;base64,""")
 
+    b64enc = Base64EncodePipe(io)
+    write(b64enc, webp)
+    close(b64enc)
 
-function replace_palette(dest::IO, src::IO, filter)
-    buf = IOBuffer() # to calculate chunk CRCs
+    write(io, """" />\n""")
 
-    u8(x) = write(buf, UInt8(x & 0xFF))
-    u16(x) = (u8((x & 0xFFFF)>>8); u8(x))
-    u32(x) = (u16((x & 0xFFFFFFFF)>>16); u16(x))
-    function read_palette()
-        uint32 = (UInt32(read(src, UInt8)) << 16) |
-                 (UInt32(read(src, UInt8)) <<  8) | read(src, UInt8)
-        reinterpret(RGB24, uint32)
-    end
-    function write_palette(c::Color)
-        rgb24 = convert(RGB24,c)
-        u8(rgb24.color>>16); u8(rgb24.color>>8); u8(rgb24.color)
-    end
-    crct(x) = (for i = 1:8; x = x & 1==1 ? 0xEDB88320 ⊻ (x>>1) : x>>1 end; x)
-    table = UInt32[crct(i) for i = 0x00:0xFF]
-    function crc32()
-        seekstart(buf)
-        crc = 0xFFFFFFFF
-        while !eof(buf)
-            crc = (crc>>8) ⊻ table[(crc&0xFF) ⊻ read(buf, UInt8) + 1]
-        end
-        u32(crc ⊻ 0xFFFFFFFF)
+    for style in ("fill:white;stroke:white;stroke-width:20;opacity:0.2", "fill:black;opacity:0.9")
+        write(io,"""<text x="16" y="1000" style="$style;font-size:80px;">$caption</text>\n""")
     end
-    lenbytes = read(src, 4)
-    len = (UInt32(lenbytes[3]) << 8) | lenbytes[4]
-    write(dest, lenbytes)
-    write(buf, read(src, 4)) # "PLTE"
-    for i = 1:(len÷3)
-        write_palette(filter(read_palette()))
-    end
-    read(src, 4) # CRC
-    crc32()
-    write(dest, take!(seekstart(buf)))
+
+    write(io, """</svg>\n""")
+
+    BeadsImageSVG(io)
 end
 
 end