Add command and submenu to switch between selection styles

Make it possible to set `pdf-view-selection-style` from Easy Menu.

Closes: vedang#190

lisp/pdf-misc.el

@@ -143,6 +143,19 @@
     ["Copy region" pdf-view-kill-ring-save
      :keys "\\[kill-ring-save]"
      :active (pdf-view-active-region-p)]
+    ("Selection style"
+     ["Glyph" (pdf-view-set-selection-style 'glyph)
+      :style radio
+      :selected (eq pdf-view-selection-style 'glyph)
+      :help "When dragging the mouse, select individual characters."]
+     ["Word" (pdf-view-set-selection-style 'word)
+      :style radio
+      :selected (eq pdf-view-selection-style 'word)
+      :help "When dragging the mouse, select entire words."]
+     ["Line" (pdf-view-set-selection-style 'line)
+      :style radio
+      :selected (eq pdf-view-selection-style 'line)
+      :help "When dragging the mouse, select entire lines."])
     "--"
     ["Isearch document" isearch-forward
      :visible (bound-and-true-p pdf-isearch-minor-mode)]

lisp/pdf-view.el

@@ -1624,6 +1624,20 @@ the `convert' program is used."
       (dolist (f (cons result images))
         (when (file-exists-p f)
           (delete-file f))))))
+
+(defun pdf-view-set-selection-style (&optional style)
+  "Set `pdf-view-selection-style' to STYLE in the current buffer.
+
+When called interactively or without an argument, cycle between
+the selection styles."
+  (interactive)
+  (unless style
+    (setq style (or (cadr (memq pdf-view-selection-style '(glyph word line)))
+                    'glyph))
+    (message "Setting selection style to `%s'." style))
+  (pdf-view-deactivate-region)
+  (setq-local pdf-view-selection-style style))
+
 
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