Unicode rectangles

Question

Given

• a matrix a of characters from u=" ╶╺╵└┕╹┖┗╴─╼┘┴┶┚┸┺╸╾━┙┵┷┛┹┻╷┌┍│├┝╿┞┡┐┬┮┤┼┾┦╀╄┑┭┯┥┽┿┩╃╇╻┎┏╽┟┢┃┠┣┒┰┲┧╁╆┨╂╊┓┱┳┪╅╈┫╉╋"
• the coordinates of a submatrix as x,y,w,h (left, top, width>1, height>1)
• a thickness t of 1 (as in ┌) or 2 (as in ┏)

render an inner border for the submatrix with the specified thickness, taking into account existing lines.

x=4;y=1;w=2;h=3;t=2;
a=[' ┌───┐',
   '┌┼┐  │',
   '│└┼──┘',
   '└─┘   ']

// output
r=[' ┌───┐',
   '┌┼┐ ┏┪',
   '│└┼─╂┨',
   '└─┘ ┗┛']

When overwriting a line fragment, the new thickness should be the greater of the old thickness and t.

This isn't about input parsing or finding the Kolmogorov complexity of Unicode, so you may assume a,u,x,y,w,h,t are available to you as variables. Also, you may put the result in a variable r instead of returning or outputting it, as long as r is of the same type as a.

If your language forces you to put code in functions (C, Java, Haskell, etc) and your solution consists of a single function, you can omit the function header and footer.

Larger test:

x=4;y=1;w=24;h=4;t=1;
a=['┏┱─────┐         ┌┐     ┎──┲━┓',
   '┠╂─────┘         ││     ┃  ┗━┛',
   '┃┃               ││     ┃     ',
   '┠╂──┲━━┓  ┏━━━━┓ ││    ┌╂┰┐   ',
   '┃┃  ┗━━┩  ┃    ┃ └╆━┓  └╂┸┘   ',
   '┃┃     │  ┃    ┃  ┃ ┃   ┃     ',
   '┗┹─────┘  ┗━━━━┛  ┗━┛   ╹     ']

// output
r=['┏┱─────┐         ┌┐     ┎──┲━┓',
   '┠╂──┬──┴─────────┼┼─────╂──╄━┛',
   '┃┃  │            ││     ┃  │  ',
   '┠╂──╆━━┓  ┏━━━━┓ ││    ┌╂┰┐│  ',
   '┃┃  ┗━━╃──╂────╂─┴╆━┱──┴╂┸┴┘  ',
   '┃┃     │  ┃    ┃  ┃ ┃   ┃     ',
   '┗┹─────┘  ┗━━━━┛  ┗━┛   ╹     ']

Answer 1

JavaScript, 218 bytes

(a,x,y,w,h,t,u)=>a.map((l,j)=>l.map((c,i)=>u[(g=(a,b)=>a?g(a/3|0,b/3|0)*3+Math.max(a%3,b%3):b)(u.indexOf(c),t*((j==y||j==y+h-1)*((i>x&&i<x+w)*9+(i>=x&&i<x+w-1))+(i==x||i==x+w-1)*((j>y&&j<y+h)*3+(j>=y&&j<y+h-1)*27)))]))

a should be taken as array of array of char.

f =

(a,x,y,w,h,t,u)=>a.map((l,j)=>l.map((c,i)=>u[(g=(a,b)=>a?g(a/3|0,b/3|0)*3+Math.max(a%3,b%3):b)(u.indexOf(c),t*((j==y||j==y+h-1)*((i>x&&i<x+w)*9+(i>=x&&i<x+w-1))+(i==x||i==x+w-1)*((j>y&&j<y+h)*3+(j>=y&&j<y+h-1)*27)))]))

x=4;y=1;w=24;h=4;t=1;
a=['┏┱─────┐         ┌┐     ┎──┲━┓',
   '┠╂─────┘         ││     ┃  ┗━┛',
   '┃┃               ││     ┃     ',
   '┠╂──┲━━┓  ┏━━━━┓ ││    ┌╂┰┐   ',
   '┃┃  ┗━━┩  ┃    ┃ └╆━┓  └╂┸┘   ',
   '┃┃     │  ┃    ┃  ┃ ┃   ┃     ',
   '┗┹─────┘  ┗━━━━┛  ┗━┛   ╹     '].map(x => [...x])
u=" ╶╺╵└┕╹┖┗╴─╼┘┴┶┚┸┺╸╾━┙┵┷┛┹┻╷┌┍│├┝╿┞┡┐┬┮┤┼┾┦╀╄┑┭┯┥┽┿┩╃╇╻┎┏╽┟┢┃┠┣┒┰┲┧╁╆┨╂╊┓┱┳┪╅╈┫╉╋";

output = f(a,x,y,w,h,t,u).map(x => x.join('')).join('\n');
document.write(`<pre lang="en" style="font-family: Consolas,Menlo,Monaco,Lucida Console,Liberation Mono,DejaVu Sans Mono,Bitstream Vera Sans Mono,Courier New,monospace,sans-serif;">${output}</pre>`)

Answer 2

Python 3, 226 201 197 bytes

n,m=x+w-1,y+h-1
r=[*map(list,a)]
R=range
for i in R(x,x+w):
 for j in R(y,y+h):A,B=j in(y,m),i in(x,n);r[j][i]=u[sum(3**o*max((i<n*A,y<j*B,x<i*A,j<m*B)[o]*t,u.index(a[j][i])//3**o%3)for o in R(4))]

Try it online!

Ungolfed:

n,m=x+w-1,y+h-1
r=[*map(list,a)]
for i in range(x,x+w):
 for j in range(y,y+h):
  p=u.index(a[j][i])
  c=(p%3,p%9//3,p%27//9,p//27)
  A,B=j in(y,m),i in(x,n)
  P=(i<n*A,y<j*B,x<i*A,j<m*B)
  l=sum(max(P[o]*t,c[o])*3**o for o in range(4))
  r[j][i]=u[l]

Answer 3

JavaScript (ES6), 174 bytes

r=a.map((l,j)=>l.map((c,i)=>u[c=u.indexOf(c),g=n=>c/n%3<t&&g(n,c+=n),j==y|j==h&&(i>=x&i<w&&g(1),i>x&i<=w&&g(9)),i==x|i==w&&(j>=y&j<h&&g(27),j>y&j<=h&&g(3)),c]),w+=x-1,h+=y-1)

a=`
┏┱─────┐         ┌┐     ┎──┲━┓
┠╂─────┘         ││     ┃  ┗━┛
┃┃               ││     ┃     
┠╂──┲━━┓  ┏━━━━┓ ││    ┌╂┰┐   
┃┃  ┗━━┩  ┃    ┃ └╆━┓  └╂┸┘   
┃┃     │  ┃    ┃  ┃ ┃   ┃     
┗┹─────┘  ┗━━━━┛  ┗━┛   ╹     
`.match(/.+/g).map(s=>[...s]);
x=4;
y=1;
w=24;
h=4;
t=1;
u=" ╶╺╵└┕╹┖┗╴─╼┘┴┶┚┸┺╸╾━┙┵┷┛┹┻╷┌┍│├┝╿┞┡┐┬┮┤┼┾┦╀╄┑┭┯┥┽┿┩╃╇╻┎┏╽┟┢┃┠┣┒┰┲┧╁╆┨╂╊┓┱┳┪╅╈┫╉╋";
r=a.map((l,j)=>l.map((c,i)=>u[c=u.indexOf(c),g=n=>c/n%3<t&&g(n,c+=n),j==y|j==h&&(i>=x&i<w&&g(1),i>x&i<=w&&g(9)),i==x|i==w&&(j>=y&j<h&&g(27),j>y&j<=h&&g(3)),c]),w+=x-1,h+=y-1)
;document.write(`<pre style="font-family:Consolas,Menlo,Monaco,Lucida Console,Liberation Mono,DejaVu Sans Mono,Bitstream Vera Sans Mono,Courier New,monospace,sans-serif">${r.map(s=>s.join``).join`\n`}</pre>`);