CSS/Text selection: adds a few "-cr-hint:" tweaks

One can use "-cr-hint: text-selection-inline",
"text-selection-block" and "text-selection-skip" to
target some elements and tweak how their text will
appear (or not) in user text selection.
Might be useful to exclude the content of ruby
annotations (<ruby><rt>) from text selection when
providing it to dict lookup or translation.

crengine/include/cssdef.h

@@ -350,7 +350,10 @@ enum css_cr_hint_t {
     css_cr_hint_toc_level5,
     css_cr_hint_toc_level6,
     css_cr_hint_toc_ignore,
-    css_cr_hint_strut_confined
+    css_cr_hint_strut_confined,
+    css_cr_hint_text_selection_inline,
+    css_cr_hint_text_selection_block,
+    css_cr_hint_text_selection_skip
 };
 
 /// css length value

crengine/src/lvstsheet.cpp

@@ -1620,6 +1620,11 @@ static const char * css_cr_hint_names[]={
                             // baseline and height (it could have been a non-standard named
                             // value for line-height:, but we want to be able to not override
                             // existing line-height: values)
+
+        // Tweak text selection when traversing a node with these hints
+        "text-selection-inline", // don't add a '\n' before inner text, even if the node happens to be block
+        "text-selection-block",  // add a '\n' before inner text even if the node happens to be inline
+        "text-selection-skip",   // don't include inner text in text selection
         NULL
 };
 

crengine/src/lvtinydom.cpp

@@ -11702,8 +11702,21 @@ class ldomTextCollector : public ldomNodeCallback
     {
 #if BUILD_LITE!=1
         ldomNode * elem = (ldomNode *)ptr->getNode();
-        if ( elem->getRendMethod()==erm_invisible )
+        if ( elem->getRendMethod() == erm_invisible )
+            return false;
+        // Allow tweaking that with hints
+        css_cr_hint_t hint = elem->getStyle()->cr_hint;
+        if ( hint == css_cr_hint_text_selection_skip ) {
             return false;
+        }
+        else if ( hint == css_cr_hint_text_selection_inline ) {
+            newBlock = false;
+            return true;
+        }
+        else if ( hint == css_cr_hint_text_selection_block ) {
+            newBlock = true;
+            return true;
+        }
         switch ( elem->getStyle()->display ) {
         /*
         case css_d_inherit: