Feature: typeahead in menu matches text anywhere

This commit implements a tweak to the typeahead feature already existent in
fluxbox: If the user opens up a menu and starts typing, fluxbox tries to
detect matching menu items and makes them available for quick selection.
The typed pattern is now search also in the middle of the text.

I opted to strip down the code quite a bit and remove complexity by throwing
out FbTk::TypeAhead and FbTk::SearchResult because I do not see the need for a
general solution when the only use case for such a feature is in fluxbox'
menus. FbTk::ITypeAheadable shrunk down to 2 functions; the whole file might
be combined with the code that implements FbTk::Menu::TypeSearch.
FbTk::Menu::setIndex() and related code is also gone: the position of each
menu item is defined by it's position in the items container. This reduces the
mount of book keeping fluxbox has to do. Fewer moving parts is a good thing.

It's possible that users start to complaint because they expect their
typed pattern to match only at the beginning of the text OR that some
demand other tweaks. We will see.

This commit also fixes a regression introduced by 8387742c. The bug made
the menu vanish.

1 files changed, 32 insertions, 20 deletions

diff --git a/src/FbTk/MenuItem.cc b/src/FbTk/MenuItem.cc
index c128c57..3918a96 100644
--- a/src/FbTk/MenuItem.cc
+++ b/src/FbTk/MenuItem.cc
@@ -28,10 +28,13 @@
 #include "App.hh"
 #include "StringUtil.hh"
 #include "Menu.hh"
+
 #include <X11/keysym.h>
 
 namespace FbTk {
 
+MenuItem::~MenuItem() { }
+
 void MenuItem::click(int button, int time, unsigned int mods) {
     if (m_command.get() != 0) {
         if (m_menu && m_close_on_click && (mods & ControlMask) == 0)
@@ -43,41 +46,50 @@ void MenuItem::click(int button, int time, unsigned int mods) {
 }
 
 void MenuItem::drawLine(FbDrawable &draw,
-                        const FbTk::ThemeProxy<MenuTheme> &theme, size_t size,
-                        int text_x, int text_y, unsigned int width) const {
-
-    unsigned int height = theme->itemHeight();
-    int bevelW = theme->bevelWidth();
+                        const FbTk::ThemeProxy<MenuTheme> &theme, size_t n_chars,
+                        int text_x, int text_y, unsigned int width,
+                        size_t skip_chars) const {
 
-    int font_top = (height - theme->hiliteFont().height())/2;
-    int underline_height = font_top + theme->hiliteFont().ascent() + 2;
-    int bottom = height - bevelW - 1;
-
-    text_y += bottom > underline_height ? underline_height : bottom;
+    // avoid drawing an ugly dot
+    if (n_chars == 0) {
+        return;
+    }
 
-    int text_w = theme->hiliteFont().textWidth(label());
+    const FbString& text = m_label.visual();
+    const size_t n = std::min(n_chars, text.size());
+    const FbTk::Font& font = theme->hiliteFont();
+    int font_height = static_cast<int>(font.height());
+    int height = static_cast<int>(theme->itemHeight());
+    int font_top = (height - font_height)/2;
+    int bevel_width = static_cast<int>(theme->bevelWidth());
+    int underline_height = font_top + font.ascent() + 2;
+    int bottom = height - bevel_width - 1;
+    int text_w = font.textWidth(label());
+    int text_pixels = font.textWidth(text.c_str()+skip_chars, n);
+    int skip_pixels = 0;
+    if (skip_chars > 0) {
+        skip_pixels = font.textWidth(text.c_str(), skip_chars);
+    }
 
-    const FbString& visual = m_label.visual();
-    BiDiString search_string(FbString(visual, 0, size > visual.size() ? visual.size() : size));
-    int search_string_w = theme->hiliteFont().textWidth(search_string);
+    text_y += std::min(bottom, underline_height);
 
     // pay attention to the text justification
     switch(theme->hiliteFontJustify()) {
     case FbTk::LEFT:
-        text_x += bevelW + height + 1;
+        text_x += bevel_width + height + 1;
         break;
     case FbTk::RIGHT:
-        text_x += width - (height + bevelW + text_w);
+        text_x += width - (height + bevel_width + text_w);
         break;
     default: //center
         text_x += ((width + 1 - text_w) / 2);
         break;
     }
 
-    // avoid drawing an ugly dot
-    if (size != 0)
-        draw.drawLine(theme->hiliteUnderlineGC().gc(),
-                      text_x, text_y, text_x + search_string_w, text_y);
+    text_x += skip_pixels;
+
+    draw.drawLine(theme->hiliteUnderlineGC().gc(),
+                  text_x, text_y, text_x + text_pixels, text_y);
 
 }