Vocabulary builder: support extracting context from pdfs (#9622)

Move getSelectedWordContext(), now document specific,
from ReaderHighlight into each document module.

frontend/apps/reader/modules/readerhighlight.lua

@@ -1282,26 +1282,12 @@ dbg:guard(ReaderHighlight, "lookup",
     end)
 
 function ReaderHighlight:getSelectedWordContext(nb_words)
-    if not self.ui.rolling or not self.selected_text then return nil end
-    local pos_start = self.selected_text.pos0
-    local pos_end = self.selected_text.pos1
-
-    for i=0, nb_words do
-        local ok, start = pcall(self.ui.document.getPrevVisibleWordStart, self.ui.document, pos_start)
-        if ok then pos_start = start
-        else break end
-    end
-
-    for i=0, nb_words do
-        local ok, ending = pcall(self.ui.document.getNextVisibleWordEnd, self.ui.document, pos_end)
-        if ok then pos_end = ending
-        else break end
+    if not self.selected_text then return end
+    local ok, prev_context, next_context = pcall(self.ui.document.getSelectedWordContext, self.ui.document,
+                                                 self.selected_text.text, nb_words, self.selected_text.pos0, self.selected_text.pos1)
+    if ok then
+        return prev_context, next_context
     end
-
-    local ok_prev, prev = pcall(self.ui.document.getTextFromXPointers, self.ui.document, pos_start, self.selected_text.pos0)
-    local ok_next, next = pcall(self.ui.document.getTextFromXPointers, self.ui.document, self.selected_text.pos1, pos_end)
-
-    return ok_prev and prev, ok_next and next
 end
 
 function ReaderHighlight:viewSelectionHTML(debug_view, no_css_files_buttons)

frontend/document/credocument.lua

@@ -716,6 +716,28 @@ function CreDocument:getNextVisibleChar(xp)
     return self._document:getNextVisibleChar(xp)
 end
 
+function CreDocument:getSelectedWordContext(word, nb_words, pos0, pos1)
+    local pos_start = pos0
+    local pos_end = pos1
+
+    for i=0, nb_words do
+        local start = self:getPrevVisibleWordStart(pos_start)
+        if start then pos_start = start
+        else break end
+    end
+
+    for i=0, nb_words do
+        local ending = self:getNextVisibleWordEnd(pos_end)
+        if ending then pos_end = ending
+        else break end
+    end
+
+    local prev = self:getTextFromXPointers(pos_start, pos0)
+    local next = self:getTextFromXPointers(pos1, pos_end)
+
+    return prev, next
+end
+
 function CreDocument:drawCurrentView(target, x, y, rect, pos)
     if self.buffer and (self.buffer.w ~= rect.w or self.buffer.h ~= rect.h) then
         self.buffer:free()

frontend/document/djvudocument.lua

@@ -96,6 +96,10 @@ function DjvuDocument:nativeToPageRectTransform(pageno, rect)
     return self.koptinterface:nativeToPageRectTransform(self, pageno, rect)
 end
 
+function DjvuDocument:getSelectedWordContext(word, nb_words, pos)
+    return self.koptinterface:getSelectedWordContext(word, nb_words, pos)
+end
+
 function DjvuDocument:getOCRWord(pageno, wbox)
     return self.koptinterface:getOCRWord(self, pageno, wbox)
 end

frontend/document/koptinterface.lua

@@ -1037,6 +1037,7 @@ Get word and word box from `doc` position.
 function KoptInterface:getWordFromPosition(doc, pos)
     local text_boxes = self:getTextBoxes(doc, pos.page)
     if text_boxes then
+        self.last_text_boxes = text_boxes
         if doc.configurable.text_wrap == 1 then
             return self:getWordFromReflowPosition(doc, text_boxes, pos)
         else
@@ -1094,6 +1095,51 @@ function KoptInterface:getWordFromNativePosition(doc, boxes, pos)
     return word_box
 end
 
+function KoptInterface:getSelectedWordContext(word, nb_words, pos)
+    local boxes = self.last_text_boxes
+    if not pos or not boxes or #boxes == 0 then return end
+    local i, j = getWordBoxIndices(boxes, pos)
+    if boxes[i][j].word ~= word then return end
+
+    local li, wi = i, j
+    local prev_count, next_count = 0, 0
+    local prev_text, next_text = {}, {}
+    while prev_count < nb_words do
+        if li == 1 and wi == 1 then
+            break
+        elseif wi == 1 then
+            li = li - 1
+            wi = #boxes[li]
+        else
+            wi = wi - 1
+        end
+        local current_word = boxes[li][wi].word
+        if #current_word > 0 then
+            table.insert(prev_text, 1, current_word)
+            prev_count = prev_count + 1
+        end
+    end
+
+    li, wi = i, j
+    while next_count < nb_words do
+        if li == #boxes and wi == #boxes[li] then
+            break
+        elseif wi == #boxes[li] then
+            li = li + 1
+            wi = 1
+        else
+            wi = wi + 1
+        end
+        local current_word = boxes[li][wi].word
+        if #current_word > 0 then
+            table.insert(next_text, current_word)
+            next_count = next_count + 1
+        end
+    end
+    if #prev_text == 0 and #next_text == 0 then return end
+    return table.concat(prev_text, " "), table.concat(next_text, " ")
+end
+
 --[[--
 Get link from position in screen page.
 ]]--

frontend/document/pdfdocument.lua

@@ -129,6 +129,10 @@ function PdfDocument:nativeToPageRectTransform(pageno, rect)
     return self.koptinterface:nativeToPageRectTransform(self, pageno, rect)
 end
 
+function PdfDocument:getSelectedWordContext(word, nb_words, pos)
+    return self.koptinterface:getSelectedWordContext(word, nb_words, pos)
+end
+
 function PdfDocument:getOCRWord(pageno, wbox)
     return self.koptinterface:getOCRWord(self, pageno, wbox)
 end

plugins/vocabbuilder.koplugin/main.lua

@@ -517,7 +517,7 @@ function WordInfoDialog:init()
                             VerticalSpan:new{width= Size.padding.default},
                             has_context and
                             TextBoxWidget:new{
-                                text = "..." .. self.prev_context:gsub("\n", " ") .. "【" ..self.title.."】" .. self.next_context:gsub("\n", " ") .. "...",
+                                text = "..." .. (self.prev_context or ""):gsub("\n", " ") .. "【" ..self.title.."】" .. (self.next_context or ""):gsub("\n", " ") .. "...",
                                 width = width,
                                 face = Font:getFace("smallffont"),
                                 alignment = self.title_align or "left",