perf(wordsoccupancy): implement caching to optimize performance

Author: guo-yong-zhi

src/strategy.jl

@@ -47,15 +47,15 @@ function feelingoccupancy(imgs, border=0, bgvalue=imgs[1][1])
     oc * 0.93
 end
 
-function wordsoccupancy!(wc)
+function wordsoccupancy!(wc, cache=(-ones(length(wc)), Vector(undef, length(wc))))
     words = wc.words
     fonts = getfonts(wc)
     angles = getangles(wc) ./ 180 .* π
     border = 1
     sizemax = size(wc.mask) .* √(getparameter(wc, :volume) / prod(size(wc.mask))) .* 0.9
     check = getparameter(wc, :maxfontsize0) == :auto
     check && setparameter!(wc, minimum(sizemax), :maxfontsize)
-    imgs = Vector(undef, length(words))
+    szcache, imgs = cache
     for i in 1:3
         fontsizes = getfontsizes(wc)
         success = true
@@ -64,6 +64,9 @@ function wordsoccupancy!(wc)
             for j in ichunk:nchunk:length(words) # it is a more balance split strategy since the words is sorted by size
                 success || break
                 c, sz, ft, θ = words[j], fontsizes[j], fonts[j], angles[j]
+                if szcache[j] == sz # only check the fontsize, assume the font won't change
+                    continue
+                end
                 img = Render.rendertext(string(c), sz, backgroundcolor=(0, 0, 0, 0), font=ft, border=border)
                 a, b = size(img)
                 imsz = max(a*abs(cos(θ)), b*abs(sin(θ))), max(a*abs(sin(θ)), b*abs(cos(θ)))
@@ -76,6 +79,7 @@ function wordsoccupancy!(wc)
                     end
                 end
                 imgs[j] = img
+                szcache[j] = sz
             end
             success || break
         end
@@ -145,6 +149,7 @@ function findscale!(wc::WC; initialscale=0, density=0.3, maxiter=5, tolerance=0.
     sc0 = 0.
     tg0 = 0.
     oneway_count = 1
+    occ_cache = (-ones(length(wc)), Vector(undef, length(wc)))
     while true
         step = step + 1
         if step > maxiter
@@ -153,7 +158,7 @@ function findscale!(wc::WC; initialscale=0, density=0.3, maxiter=5, tolerance=0.
         end
         # cal tg1
         setparameter!(wc, sc1, :scale)
-        tg1 = wordsoccupancy!(wc)
+        tg1 = wordsoccupancy!(wc, occ_cache)
         dens = tg1 / area
         @debug "⋯scale=$(getparameter(wc, :scale)), density=$dens\t" * (dens > density ? "↑" : "↓")
         if tg1 > target