LibCards: Support highlighting cards of interest

For example, in Solitaire, when dragging a card around, it's common for
other implementations to highlight the card underneath the dragged card
if that other card is a valid drop target. This implementation will draw
a rounded rectangle within the edges of the highlighted card, using a
rudimentary complementary color of the board background color.

1 files changed, 39 insertions, 0 deletions

diff --git a/Userland/Libraries/LibCards/CardPainter.cpp b/Userland/Libraries/LibCards/CardPainter.cpp
index c2c869617a..e073f9feae 100644
--- a/Userland/Libraries/LibCards/CardPainter.cpp
+++ b/Userland/Libraries/LibCards/CardPainter.cpp
@@ -102,6 +102,21 @@ NonnullRefPtr<Gfx::Bitmap> CardPainter::card_back()
     return *m_card_back;
 }
 
+NonnullRefPtr<Gfx::Bitmap> CardPainter::card_front_highlighted(Suit suit, Rank rank)
+{
+    auto suit_id = to_underlying(suit);
+    auto rank_id = to_underlying(rank);
+
+    auto& existing_bitmap = m_cards_highlighted[suit_id][rank_id];
+    if (!existing_bitmap.is_null())
+        return *existing_bitmap;
+
+    m_cards_highlighted[suit_id][rank_id] = create_card_bitmap();
+    paint_highlighted_card(*m_cards_highlighted[suit_id][rank_id], card_front(suit, rank));
+
+    return *m_cards_highlighted[suit_id][rank_id];
+}
+
 NonnullRefPtr<Gfx::Bitmap> CardPainter::card_front_inverted(Suit suit, Rank rank)
 {
     auto suit_id = to_underlying(suit);
@@ -140,6 +155,17 @@ void CardPainter::set_background_image_path(DeprecatedString path)
         paint_inverted_card(*m_card_back_inverted, *m_card_back);
 }
 
+void CardPainter::set_background_color(Color background_color)
+{
+    m_background_color = background_color;
+
+    // Clear any cached card bitmaps that depend on the background color.
+    for (auto& suit_array : m_cards_highlighted) {
+        for (auto& rank_array : suit_array)
+            rank_array = nullptr;
+    }
+}
+
 NonnullRefPtr<Gfx::Bitmap> CardPainter::create_card_bitmap()
 {
     return Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, { Card::width, Card::height }).release_value_but_fixme_should_propagate_errors();
@@ -212,4 +238,17 @@ void CardPainter::paint_inverted_card(Gfx::Bitmap& bitmap, Gfx::Bitmap const& so
     });
 }
 
+void CardPainter::paint_highlighted_card(Gfx::Bitmap& bitmap, Gfx::Bitmap const& source_to_highlight)
+{
+    Gfx::Painter painter { bitmap };
+    auto paint_rect = source_to_highlight.rect();
+    auto background_complement = m_background_color.xored(Color::White);
+
+    painter.fill_rect_with_rounded_corners(paint_rect, Color::Black, Card::card_radius);
+    paint_rect.shrink(2, 2);
+    painter.fill_rect_with_rounded_corners(paint_rect, background_complement, Card::card_radius - 1);
+    paint_rect.shrink(2, 2);
+    painter.blit({ 4, 4 }, source_to_highlight, source_to_highlight.rect().shrunken(8, 8));
+}
+
 }