UI/AppKit: Implement an autocomplete view for the location bar

Author: https://github.com/trflynn89
Commit: https://github.com/LadybirdBrowser/ladybird/commit/c1fe912bf9d
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4156

UI/AppKit/Interface/Autocomplete.mm

@@ -0,0 +1,203 @@
+/*
+ * Copyright (c) 2025, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#import <Interface/Autocomplete.h>
+#import <Utilities/Conversions.h>
+
+static NSString* const AUTOCOMPLETE_IDENTIFIER = @"Autocomplete";
+static constexpr auto MAX_NUMBER_OF_ROWS = 8uz;
+static constexpr auto POPOVER_PADDING = 6uz;
+
+@interface Autocomplete () <NSTableViewDataSource, NSTableViewDelegate>
+{
+    Vector<String> m_suggestions;
+}
+
+@property (nonatomic, weak) id<AutocompleteObserver> observer;
+@property (nonatomic, weak) NSToolbarItem* toolbar_item;
+
+@property (nonatomic, strong) NSTableView* table_view;
+
+@end
+
+@implementation Autocomplete
+
+- (instancetype)init:(id<AutocompleteObserver>)observer
+     withToolbarItem:(NSToolbarItem*)toolbar_item
+{
+    if (self = [super init]) {
+        self.observer = observer;
+        self.toolbar_item = toolbar_item;
+
+        auto* column = [[NSTableColumn alloc] init];
+        [column setEditable:NO];
+
+        self.table_view = [[NSTableView alloc] init];
+        [self.table_view setAction:@selector(selectSuggestion:)];
+        [self.table_view setBackgroundColor:[NSColor clearColor]];
+        [self.table_view setIntercellSpacing:NSMakeSize(0, 5)];
+        [self.table_view setHeaderView:nil];
+        [self.table_view setRefusesFirstResponder:YES];
+        [self.table_view setRowSizeStyle:NSTableViewRowSizeStyleDefault];
+        [self.table_view addTableColumn:column];
+        [self.table_view setDataSource:self];
+        [self.table_view setDelegate:self];
+        [self.table_view setTarget:self];
+
+        auto* scroll_view = [[NSScrollView alloc] init];
+        [scroll_view setHasVerticalScroller:YES];
+        [scroll_view setDocumentView:self.table_view];
+        [scroll_view setDrawsBackground:NO];
+
+        auto* content_view = [[NSView alloc] init];
+        [content_view addSubview:scroll_view];
+
+        auto* controller = [[NSViewController alloc] init];
+        [controller setView:content_view];
+
+        [self setAnimates:NO];
+        [self setBehavior:NSPopoverBehaviorTransient];
+        [self setContentViewController:controller];
+        [self setValue:[NSNumber numberWithBool:YES] forKeyPath:@"shouldHideAnchor"];
+    }
+
+    return self;
+}
+
+#pragma mark - Public methods
+
+- (void)showWithSuggestions:(Vector<String>)suggestions
+{
+    m_suggestions = move(suggestions);
+    [self.table_view reloadData];
+
+    if (m_suggestions.is_empty()) {
+        [self close];
+    } else {
+        [self show];
+    }
+}
+
+- (BOOL)close
+{
+    if (!self.isShown)
+        return NO;
+
+    [super close];
+    return YES;
+}
+
+- (Optional<String>)selectedSuggestion
+{
+    if (!self.isShown || self.table_view.numberOfRows == 0)
+        return {};
+
+    auto row = [self.table_view selectedRow];
+    if (row < 0)
+        return {};
+
+    return m_suggestions[row];
+}
+
+- (BOOL)selectNextSuggestion
+{
+    if (self.table_view.numberOfRows == 0)
+        return NO;
+
+    if (!self.isShown) {
+        [self show];
+        return YES;
+    }
+
+    [self selectRow:[self.table_view selectedRow] + 1];
+    return YES;
+}
+
+- (BOOL)selectPreviousSuggestion
+{
+    if (self.table_view.numberOfRows == 0)
+        return NO;
+
+    if (!self.isShown) {
+        [self show];
+        return YES;
+    }
+
+    [self selectRow:[self.table_view selectedRow] - 1];
+    return YES;
+}
+
+- (void)selectSuggestion:(id)sender
+{
+    if (auto suggestion = [self selectedSuggestion]; suggestion.has_value())
+        [self.observer onSelectedSuggestion:suggestion.release_value()];
+}
+
+#pragma mark - Private methods
+
+- (void)show
+{
+    auto height = (self.table_view.rowHeight + self.table_view.intercellSpacing.height) * min(self.table_view.numberOfRows, MAX_NUMBER_OF_ROWS);
+    auto frame = NSMakeRect(0, 0, [[self.toolbar_item view] frame].size.width, height);
+
+    [self.table_view.enclosingScrollView setFrame:NSInsetRect(frame, 0, POPOVER_PADDING)];
+    [self setContentSize:frame.size];
+
+    [self.table_view deselectAll:nil];
+    [self.table_view scrollRowToVisible:0];
+
+    [self showRelativeToToolbarItem:self.toolbar_item];
+
+    [self showRelativeToRect:self.toolbar_item.view.frame
+                      ofView:self.toolbar_item.view
+               preferredEdge:NSRectEdgeMaxY];
+}
+
+- (void)selectRow:(NSInteger)row
+{
+    if (row < 0)
+        row = self.table_view.numberOfRows - 1;
+    else if (row >= self.table_view.numberOfRows)
+        row = 0;
+
+    [self.table_view selectRowIndexes:[NSIndexSet indexSetWithIndex:row] byExtendingSelection:NO];
+    [self.table_view scrollRowToVisible:[self.table_view selectedRow]];
+}
+
+#pragma mark - NSTableViewDataSource
+
+- (NSInteger)numberOfRowsInTableView:(NSTableView*)tableView
+{
+    return static_cast<NSInteger>(m_suggestions.size());
+}
+
+#pragma mark - NSTableViewDelegate
+
+- (NSView*)tableView:(NSTableView*)table_view
+    viewForTableColumn:(NSTableColumn*)table_column
+                   row:(NSInteger)row
+{
+    NSTableCellView* view = [table_view makeViewWithIdentifier:AUTOCOMPLETE_IDENTIFIER owner:self];
+
+    if (view == nil) {
+        view = [[NSTableCellView alloc] initWithFrame:NSZeroRect];
+
+        NSTextField* text_field = [[NSTextField alloc] initWithFrame:NSZeroRect];
+        [text_field setBezeled:NO];
+        [text_field setDrawsBackground:NO];
+        [text_field setEditable:NO];
+        [text_field setSelectable:NO];
+
+        [view addSubview:text_field];
+        [view setTextField:text_field];
+        [view setIdentifier:AUTOCOMPLETE_IDENTIFIER];
+    }
+
+    [view.textField setStringValue:Ladybird::string_to_ns_string(m_suggestions[row])];
+    return view;
+}
+
+@end