Merge pull request #199 from Guldoman/PR_svg_screenshot

Add `svg_screenshot`

2 files changed, 352 insertions, 0 deletions

diff --git a/manifest.json b/manifest.json
index e9a843d..88984a2 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1127,6 +1127,13 @@
       "mod_version": "3"
     },
     {
+      "description": "Takes an SVG screenshot. Only browsers seem to support the generated SVG properly.",
+      "version": "0.1",
+      "path": "plugins/svg_screenshot.lua",
+      "id": "svg_screenshot",
+      "mod_version": "3"
+    },
+    {
       "description": "Switch between open tabs by searching by name",
       "version": "0.1",
       "path": "plugins/tab_switcher.lua",
diff --git a/plugins/svg_screenshot.lua b/plugins/svg_screenshot.lua
new file mode 100644
index 0000000..87da77c
--- /dev/null
+++ b/plugins/svg_screenshot.lua
@@ -0,0 +1,345 @@
+-- mod-version:3
+
+--[[
+ base64 -- v1.5.3 public domain Lua base64 encoder/decoder
+ no warranty implied; use at your own risk
+ Needs bit32.extract function. If not present it's implemented using BitOp
+ or Lua 5.3 native bit operators. For Lua 5.1 fallbacks to pure Lua
+ implementation inspired by Rici Lake's post:
+   http://ricilake.blogspot.co.uk/2007/10/iterating-bits-in-lua.html
+ author: Ilya Kolbin (iskolbin@gmail.com)
+ url: github.com/iskolbin/lbase64
+ COMPATIBILITY
+ Lua 5.1+, LuaJIT
+ LICENSE
+ See end of file for license information.
+--]]
+
+-- This utility has been altered to remove unused functionality
+
+--[[
+------------------------------------------------------------------------------
+License for the base64 utility
+------------------------------------------------------------------------------
+MIT License
+Copyright (c) 2018 Ilya Kolbin
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+------------------------------------------------------------------------------
+--]]
+
+local base64 = {}
+
+local extract = function( v, from, width )
+  return ( v >> from ) & ((1 << width) - 1)
+end
+
+
+function base64.makeencoder( s62, s63, spad )
+  local encoder = {}
+  for b64code, char in pairs{[0]='A','B','C','D','E','F','G','H','I','J',
+    'K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y',
+    'Z','a','b','c','d','e','f','g','h','i','j','k','l','m','n',
+    'o','p','q','r','s','t','u','v','w','x','y','z','0','1','2',
+    '3','4','5','6','7','8','9',s62 or '+',s63 or'/',spad or'='} do
+    encoder[b64code] = char:byte()
+  end
+  return encoder
+end
+
+local DEFAULT_ENCODER = base64.makeencoder()
+
+local char, concat = string.char, table.concat
+
+function base64.encode( str, encoder, usecaching )
+  encoder = encoder or DEFAULT_ENCODER
+  local t, k, n = {}, 1, #str
+  local lastn = n % 3
+  local cache = {}
+  for i = 1, n-lastn, 3 do
+    local a, b, c = str:byte( i, i+2 )
+    local v = a*0x10000 + b*0x100 + c
+    local s
+    if usecaching then
+      s = cache[v]
+      if not s then
+        s = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[extract(v,0,6)])
+        cache[v] = s
+      end
+    else
+      s = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[extract(v,0,6)])
+    end
+    t[k] = s
+    k = k + 1
+  end
+  if lastn == 2 then
+    local a, b = str:byte( n-1, n )
+    local v = a*0x10000 + b*0x100
+    t[k] = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[64])
+  elseif lastn == 1 then
+    local v = str:byte( n )*0x10000
+    t[k] = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[64], encoder[64])
+  end
+  return concat( t )
+end
+
+--------------------------------------------------------------------------------
+
+local core = require "core"
+local common = require "core.common"
+local keymap = require "core.keymap"
+local command = require "core.command"
+local style = require "core.style"
+
+-- TODO: what about the vertical location of text? (svg uses the baseline)
+-- TODO: add the overrides only when screenshotting to avoid overhead
+-- TODO: complete the font table
+
+local start_screenshot = false
+local screenshotting = false
+local draw_data = {}
+local known_fonts = {}
+local known_colors = {}
+local current_clip = ""
+local known_clips = {}
+
+local function is_color(t)
+  if type(t) ~= "table" then return false end
+  if #t ~=4 then return false end
+  for i=1,4 do
+    if type(t[i]) ~= "number" then return false end
+  end
+  return true
+end
+
+local function get_color(color)
+  return "rgba(" .. table.concat(color, ",") .. ")"
+end
+
+local function get_fill_color(color)
+  if known_colors[color] then
+    return "var(--lxl_".. known_colors[color] .. ")"
+  end
+
+  local fill_color = get_color(color)
+  -- Try to find a known color with the same values
+  for k, v in pairs(known_colors) do
+    if get_color(k) == fill_color then
+      -- Save the color with the name of the found color
+      known_colors[color] = v
+      return get_fill_color(k)
+    end
+  end
+  -- Try to find the color with a different opacity
+  local opaque_color = {table.unpack(color)}
+  opaque_color[4] = 255
+  local opaque_fill_color = get_color(opaque_color)
+  for k, _ in pairs(known_colors) do
+    if get_color(k) == opaque_fill_color then
+      -- Hacky way to reuse the defined color with a custom opacity
+      return get_fill_color(k) .. '" opacity="' .. color[4]/255
+    end
+  end
+  -- Logging warning next frame to avoid drawing it in the screenshot
+  core.add_thread(function()
+    core.warn("Unknown color: %s", common.serialize(color))
+  end)
+  return fill_color
+end
+
+local old_begin_frame = renderer.begin_frame
+function renderer.begin_frame(...)
+  if start_screenshot then
+    start_screenshot = false
+    screenshotting = true
+    known_fonts = {}
+    current_clip = ""
+    known_clips = {}
+    -- `shape-rendering="crispEdges"` is needed to avoid antialisaing issues like
+    -- spaces between rects
+    -- `font-variant-ligatures: none;` is needed because we don't support ligatures,
+    -- so the svg shouldn't too
+    table.insert(draw_data, string.format([[
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg width="%d" height="%d" viewBox="0 0 %d %d" xmlns="http://www.w3.org/2000/svg" version="1.1" shape-rendering="crispEdges">
+<style>
+  * {
+    font-variant-ligatures: none;
+  }
+</style>]], core.root_view.size.x, core.root_view.size.y, core.root_view.size.x, core.root_view.size.y))
+    -- Extract known colors
+    known_colors = {}
+    local colors = {}
+    for k, v in pairs(style) do
+      if is_color(v) then
+        known_colors[v] = k
+        table.insert(colors, string.format([[
+--lxl_%s: %s;
+]], k, get_color(v)))
+      end
+    end
+    for k, v in pairs(style.syntax) do
+      if is_color(v) then
+        known_colors[v] = k
+        table.insert(colors, string.format([[
+--lxl_%s: %s;
+]], k, get_color(v)))
+      end
+    end
+    table.insert(draw_data, "<style>\n:root{" .. table.concat(colors) .. "}</style>")
+    -- Needed because we close it when we first set a clip
+    table.insert(draw_data, "<g>")
+  end
+  return old_begin_frame(...)
+end
+
+local old_end_frame = renderer.end_frame
+function renderer.end_frame(...)
+  local res = old_end_frame(...)
+  if screenshotting then
+    screenshotting = false
+    -- Needed to close the last clip
+    table.insert(draw_data, "</g>")
+    table.insert(draw_data, string.format("</svg>"))
+    core.command_view:enter("Choose a name", {
+      validate = function(text) return #text > 0 end,
+      submit = function(name)
+        -- Add extension if needed
+        name = string.gsub(name, "%.[sS][vV][gG]", "") .. ".svg"
+        local fp = assert( io.open(name, "wb") )
+        fp:write(table.concat(draw_data, "\n"))
+        fp:close()
+      end
+    })
+  end
+  return res
+end
+
+-- Used by our renderer to round coordinates
+local function rect_to_grid(x, y, w, h)
+  local x1, y1, x2, y2 = math.floor(x + .5), math.floor(y + .5),
+                        math.floor(x + w + .5), math.floor(y + h + .5)
+  return x1, y1, x2 - x1, y2 - y1
+end
+
+local old_draw_rect = renderer.draw_rect
+function renderer.draw_rect(x, y, width, height, color, ...)
+  if screenshotting then
+    local _x, _y, _w, _h = rect_to_grid(x, y, width, height)
+    local fill_color = get_fill_color(color)
+    table.insert(draw_data,
+                string.format([[<rect x="%d" y="%d" width="%d" height="%d" fill="%s" />]],
+                             _x, _y, _w, _h, fill_color))
+  end
+  return old_draw_rect(x, y, width, height, color, ...)
+end
+
+local function get_font_style(font)
+  local path = font:get_path()
+  -- Only consider the first font in a fontgroup
+  if type(path) == "table" then path = path[1] end
+  local fp = assert( io.open(path, "rb") )
+  local font_content = fp:read("a")
+  fp:close()
+  local name, extension = string.match(common.basename(path), "(.*)%.(.-)$")
+  local encoded_font = base64.encode(font_content)
+  -- TODO: We need a table of extensions -> mime-type
+  --       For now we just assume TrueType
+  return name, string.format([[
+<style>
+  @font-face{
+      font-family:"%s";
+      src:url(data:application/font-%s;charset=utf-8;base64,%s) format("%s");
+      font-weight:normal;font-style:normal;
+  }
+</style>]], name, extension, encoded_font, "truetype")
+end
+
+local old_draw_text = renderer.draw_text
+function renderer.draw_text(font, text, x, y, color, ...)
+  if screenshotting then
+    local font_path = font:get_path()
+  -- Only consider the first font in a fontgroup
+    if type(font_path) == "table" then font_path = font_path[1] end
+    if not known_fonts[font_path] then
+      local name, encoded_font = get_font_style(font)
+      known_fonts[font_path] = name
+      -- FIXME: We might want to keep all of those and add them all at the start,
+      --        before concatenating the draw_data
+      table.insert(draw_data, encoded_font)
+    end
+    local fill_color = get_fill_color(color)
+    -- Split at spaces, because multiple spaces get removed by svg renderers
+    for s, e in string.gmatch(text, "()%S+()") do
+      local partial_text = string.sub(text, s, e - 1)
+      partial_text = partial_text:gsub("%]%]>", "]]]]><![CDATA[>") -- escape eventual CDATA end token in the text
+      partial_text = partial_text:gsub("%]", "]]>]<![CDATA[") -- escape `]` because WebKit ends the CDATA with it <.<
+      local offset = font:get_width(string.sub(text, 1, s - 1))
+      table.insert(draw_data, string.format([=[
+<text x="%.2f" y="%d" font-family="%s" font-size="%.2fpx" fill="%s">
+  <![CDATA[%s]]>
+</text>]=], x + offset, math.floor(y + font:get_height() * 0.8), known_fonts[font_path],
+            math.floor(font:get_size()), fill_color, partial_text))
+    end
+  end
+  return old_draw_text(font, text, x, y, color, ...)
+end
+
+local old_set_clip_rect = renderer.set_clip_rect
+function renderer.set_clip_rect(x, y, width, height, ...)
+  if screenshotting then
+    local _x, _y, _w, _h = rect_to_grid(x, y, width, height)
+    current_clip = string.format("%d_%d_%d_%d", _x, _y, _w, _h)
+    -- Close last clip
+    table.insert(draw_data, "</g>")
+    -- Ideally we don't need this, but just use the `<g clip-path="path(...`
+    -- that is commented below, but it looks like each browser handles it
+    -- differently:
+    -- * Chromium considers the path as relative for some reason, and doesn't
+    --   seem to support `view-box` correctly.
+    -- * Epiphany (WebKit) has the same relative issue, but at least works with
+    --   `view-box`.
+    -- * Firefox seems to handle it correctly.
+    --
+    -- So for now let's just use the clipPaths with their id...
+    if not known_clips[current_clip] then
+      known_clips[current_clip] = true
+      table.insert(draw_data, string.format([[
+<clipPath id="clip-%s">
+  <rect x="%d" y="%d" width="%d" height="%d" />
+</clipPath>]], current_clip, _x, _y, _w, _h))
+    end
+
+--     table.insert(draw_data, string.format([[
+-- <g clip-path="path('M%d %d h%d v%d h%d Z') view-box">
+-- ]], _x, _y, _w, _h, -_w))
+
+    table.insert(draw_data, string.format([[
+<g clip-path="url(#clip-%s)">
+]], current_clip))
+  end
+  return old_set_clip_rect(x, y, width, height, ...)
+end
+
+command.add(nil, {
+  ["screenshot:svg-screenshot"] = function()
+    start_screenshot = true
+  end
+})
+
+keymap.add({
+  ["ctrl+f12"] = "screenshot:svg-screenshot"
+})