Align Search Suggestion with Line Edit

resources/css/style.css

@@ -32,8 +32,8 @@ QToolButton {
 
 SearchBar {
     background-color: white;
-    margin: 2px;
+    margin: 2px; /* XXX: duplicated in css_constants.h */
-    border: 1px solid #ccc;
+    border: 1px solid #ccc; /* XXX: duplicated in css_constants.h */
     border-radius: 3px;
 
     max-height: 40px;

src/css_constants.h

@@ -23,6 +23,11 @@ namespace tab {
 }
 }
 
+namespace SearchBar{
+    const int margin = 2;
+    const int border = 1;
+}
+
 namespace TopWidget {
 namespace QToolButton {
 namespace backButton {

src/searchbar.cpp

@@ -6,6 +6,7 @@
 
 #include "kiwixapp.h"
 #include "suggestionlistworker.h"
+#include "css_constants.h"
 
 BookmarkButton::BookmarkButton(QWidget *parent) :
     QToolButton(parent)
@@ -285,7 +286,7 @@ void SearchBarLineEdit::onInitialSuggestions(int)
     if (m_returnPressed) {
         openCompletion(getDefaulSuggestionIndex());
     } else {
-        m_completer.complete();
+        m_completer.complete(getCompleterRect());
 
         /* Make row 0 appear but do not highlight it */
         const auto completerFirstIdx = m_suggestionView->model()->index(0, 0);
@@ -339,6 +340,50 @@ QModelIndex SearchBarLineEdit::getDefaulSuggestionIndex() const
     return QModelIndex();
 }
 
+/* Line edit does not span the entire searchBar. Completer is displayed
+   based on line edit, and thus shifting and resizing is needed.
+*/
+QRect SearchBarLineEdit::getCompleterRect() const
+{
+    auto& searchBar = KiwixApp::instance()->getSearchBar();
+    const auto& searchGeo = searchBar.geometry();
+    const auto& searchLineEditGeo = searchBar.getLineEdit().geometry();
+
+    const int margin = CSS::SearchBar::margin;
+    const int border = CSS::SearchBar::border;
+    const int spaceAround = margin + border;
+
+    /* Border and margin are not accounted in height and width. */
+    const int top = searchGeo.height() - 2 * spaceAround;
+    const int width = searchGeo.width() - 2 * spaceAround;
+
+    /* Direction in Qt6 and Qt5 are determined differently. */
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+    const bool lineEditFlipped = KiwixApp::isRightToLeft();
+#else
+    const bool lineEditFlipped = m_searchbarInput.isRightToLeft();
+#endif
+
+    /* Shift completer to one of the two laterals of search bar, where which 
+       one it shifted to dependes on whether the line edit is flipped.
+    */
+    int left = -searchLineEditGeo.left();
+
+    /* When not flipped, left() is relative to within the search bar border, 
+       thus, we shift by spaceAround to match the side of search bar.
+
+       When flipped, the completer starts at the right end of the search bar 
+       We shift it by width to make the completer start at left lateral of 
+       search bar. Since in a flipped state, left() also considered the opposite
+       side's border, which means we need to shift by a border width in 
+       addition to spaceAround.
+    */
+    left += lineEditFlipped ? -width + spaceAround + border : spaceAround;
+
+    /* Can't set height to 0. Will cause rectangle to be ignored. */
+    return QRect(QPoint(left, top), QSize(width, 1));
+}
+
 SearchBar::SearchBar(QWidget *parent) :
     QToolBar(parent),
     m_searchBarLineEdit(this),

src/searchbar.h

@@ -68,6 +68,7 @@ private slots:
     void fetchSuggestions(NewSuggestionHandlerFuncPtr callback);
 
     QModelIndex getDefaulSuggestionIndex() const;
+    QRect getCompleterRect() const;
 };