Initial image support

* png: add missing filters, various decoder fixes
* term: fix kitty response interpretation, add support for kitty image
  detection
* buffer, pager: initial image display support

Emphasis on "initial"; it only "works" with kitty output and PNG input.
Also, it's excruciatingly slow, and repaints images way too often.

Left undocumented intentionally it for now, until it actually becomes
useful.  In the meantime, adventurous users can find out themselves why:

[[siteconf]]
url = "https://.*"
images = true

1 files changed, 85 insertions, 12 deletions

diff --git a/src/local/term.nim b/src/local/term.nim
index eee53039..0da700f5 100644
--- a/src/local/term.nim
+++ b/src/local/term.nim
@@ -8,7 +8,9 @@ import std/unicode
 
 import bindings/termcap
 import config/config
+import img/bitmap
 import io/posixstream
+import js/base64
 import types/cell
 import types/color
 import types/opt
@@ -64,6 +66,7 @@ type
     attrs*: WindowAttributes
     colormode: ColorMode
     formatmode: FormatMode
+    imagemode: ImageMode
     smcup: bool
     tc: Termcap
     tname: string
@@ -128,6 +131,15 @@ const RMCUP = DECRST(1049)
 const SGRMOUSEBTNON = DECSET(1002, 1006)
 const SGRMOUSEBTNOFF = DECRST(1002, 1006)
 
+# application program command
+
+# This is only used in kitty images, and join()'ing kilobytes of base64
+# is rather inefficient so we don't use a template.
+const APC = "\e_"
+const ST = "\e\\"
+
+const KITTYQUERY = APC & "Gi=1,a=q;" & ST
+
 when not termcap_found:
   const CNORM = DECSET(25)
   const CIVIS = DECRST(25)
@@ -555,15 +567,13 @@ proc applyConfig(term: Terminal) =
   # colors, formatting
   if term.config.display.color_mode.isSome:
     term.colormode = term.config.display.color_mode.get
-  elif term.isatty():
-    let colorterm = getEnv("COLORTERM")
-    if colorterm in ["24bit", "truecolor"]:
-      term.colormode = cmTrueColor
   if term.config.display.format_mode.isSome:
     term.formatmode = term.config.display.format_mode.get
   for fm in FormatFlags:
     if fm in term.config.display.no_format_mode:
       term.formatmode.excl(fm)
+  if term.config.display.image_mode.isSome:
+    term.imagemode = term.config.display.image_mode.get
   if term.isatty():
     if term.config.display.alt_screen.isSome:
       term.smcup = term.config.display.alt_screen.get
@@ -603,6 +613,50 @@ proc outputGrid*(term: Terminal) =
   for i in 0 ..< term.canvas.cells.len:
     term.pcanvas[i] = term.canvas[i]
 
+proc clearImages*(term: Terminal) =
+  if term.imagemode == imKitty:
+    term.write(APC & "Ga=d" & ST)
+
+proc outputImage*(term: Terminal; bmp: Bitmap; x, y, maxw, maxh: int) =
+  case term.imagemode
+  of imNone: discard
+  of imSixel:
+    discard #TODO
+  of imKitty:
+    # max 4096 bytes, base encoded
+    const MaxPixels = ((4096 div 4) * 3) div 3
+    let offx = if x < 0: -(x * term.attrs.ppc) else: 0
+    let offy = if y < 0: -(y * term.attrs.ppl) else: 0
+    let w = int(bmp.width)
+    let h = int(bmp.height)
+    var dispw = w
+    if x + dispw div term.attrs.ppc > maxw:
+      dispw = (maxw - x) * term.attrs.ppc
+    var disph = h
+    if y + disph div term.attrs.ppl > maxh:
+      disph = (maxh - y) * term.attrs.ppl
+    var outs = term.cursorGoto(max(x, 0), max(y, 0))
+    outs &= APC & "Gf=24,m=1,a=T,C=1,s=" & $w & ",v=" & $h &
+      ",x=" & $offx & ",y=" & $offy & ",w=" & $dispw & ",h=" & $disph & ';'
+    var buf = newStringOfCap(MaxPixels * 4)
+    var i = 0
+    # transcode to RGB
+    while i < bmp.px.len: # max is 4096
+      if i > 0 and i mod MaxPixels == 0:
+        outs &= btoa(buf)
+        outs &= ST
+        term.write(outs)
+        buf.setLen(0)
+        outs = APC & "Gm=1;"
+      buf &= char(bmp.px[i].r)
+      buf &= char(bmp.px[i].g)
+      buf &= char(bmp.px[i].b)
+      inc i
+    outs = APC & "Gm=0;"
+    outs &= btoa(buf)
+    outs &= ST
+    term.write(outs)
+
 proc clearCanvas*(term: Terminal) =
   term.cleared = false
 
@@ -665,7 +719,7 @@ when termcap_found:
 
 type
   QueryAttrs = enum
-    qaAnsiColor, qaRGB, qaSixel
+    qaAnsiColor, qaRGB, qaSixel, qaKittyImage
 
   QueryResult = object
     success: bool
@@ -683,6 +737,7 @@ proc queryAttrs(term: Terminal; windowOnly: bool): QueryResult =
     const outs =
       XTGETFG &
       XTGETBG &
+      KITTYQUERY &
       GEOMPIXEL &
       GEOMCELL &
       XTGETTCAP("524742") &
@@ -764,12 +819,15 @@ proc queryAttrs(term: Terminal; windowOnly: bool): QueryResult =
       term.expect ';'
       if term.consume == 'r' and term.consume == 'g' and term.consume == 'b':
         term.expect ':'
-        template eat_color(tc: char): uint8 =
+        var was_esc = false
+        template eat_color(tc: set[char]): uint8 =
           var val = 0u8
           var i = 0
-          while (let c = term.consume; c != tc):
+          var c = char(0)
+          while (c = term.consume; c notin tc):
             let v0 = hexValue(c)
-            if i > 4 or v0 == -1: fail # wat
+            if i > 4 or v0 == -1:
+              fail # wat
             let v = uint8(v0)
             if i == 0: # 1st place
               val = (v shl 4) or v
@@ -777,10 +835,14 @@ proc queryAttrs(term: Terminal; windowOnly: bool): QueryResult =
               val = (val xor 0xF) or v
             # all other places are irrelevant
             inc i
+          was_esc = c == '\e'
           val
-        let r = eat_color '/'
-        let g = eat_color '/'
-        let b = eat_color '\a'
+        let r = eat_color {'/'}
+        let g = eat_color {'/'}
+        let b = eat_color {'\a', '\e'}
+        if was_esc:
+          # we got ST, not BEL; at least kitty does this
+          term.expect '\\'
         if c == '0':
           result.fgcolor = some(rgb(r, g, b))
         else:
@@ -805,7 +867,14 @@ proc queryAttrs(term: Terminal; windowOnly: bool): QueryResult =
         if id == tcapRGB:
           result.attrs.incl(qaRGB)
       else: # 0
-        term.expect '\e' # ST (1)
+        # pure insanity: kitty returns P0, but also +r524742 after. please
+        # make up your mind!
+        term.skip_until '\e' # ST (1)
+      term.expect '\\' # ST (2)
+    of '_': # APC
+      term.expect 'G'
+      result.attrs.incl(qaKittyImage)
+      term.skip_until '\e' # ST (1)
       term.expect '\\' # ST (2)
     else:
       fail
@@ -844,6 +913,10 @@ proc detectTermAttributes(term: Terminal; windowOnly: bool): TermStartResult =
         term.colormode = cmANSI
       if qaRGB in r.attrs:
         term.colormode = cmTrueColor
+      if qaSixel in r.attrs:
+        term.imagemode = imSixel
+      if qaKittyImage in r.attrs:
+        term.imagemode = imKitty
       # just assume the terminal doesn't choke on these.
       term.formatmode = {ffStrike, ffOverline}
       if r.bgcolor.isSome: