FontEditor: Support flipping and rotating

This is especially useful for highly symmetric scripts like this:
https://www.unicode.org/charts/PDF/U1400.pdf

Userland/Applications/FontEditor/FontEditor.cpp

@@ -113,6 +113,9 @@ FontEditorWidget::FontEditorWidget(const String& path, RefPtr<Gfx::BitmapFont>&&
     auto& toolbar = *find_descendant_of_type_named<GUI::Toolbar>("toolbar");
     auto& glyph_map_container = *find_descendant_of_type_named<GUI::Widget>("glyph_map_container");
     auto& move_glyph_button = *find_descendant_of_type_named<GUI::Button>("move_glyph_button");
+    auto& rotate_90_button = *find_descendant_of_type_named<GUI::Button>("rotate_90");
+    auto& flip_vertical_button = *find_descendant_of_type_named<GUI::Button>("flip_vertical");
+    auto& flip_horizontal_button = *find_descendant_of_type_named<GUI::Button>("flip_horizontal");
     m_statusbar = *find_descendant_of_type_named<GUI::Statusbar>("statusbar");
     m_glyph_editor_container = *find_descendant_of_type_named<GUI::Widget>("glyph_editor_container");
     m_left_column_container = *find_descendant_of_type_named<GUI::Widget>("left_column_container");
@@ -329,6 +332,21 @@ FontEditorWidget::FontEditorWidget(const String& path, RefPtr<Gfx::BitmapFont>&&
     };
     move_glyph_button.set_icon(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/selection-move.png").release_value_but_fixme_should_propagate_errors());
 
+    rotate_90_button.on_click = [&](auto) {
+        m_glyph_editor_widget->rotate_90();
+    };
+    rotate_90_button.set_icon(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/edit-rotate-cw.png").release_value_but_fixme_should_propagate_errors());
+
+    flip_vertical_button.on_click = [&](auto) {
+        m_glyph_editor_widget->flip_vertically();
+    };
+    flip_vertical_button.set_icon(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/edit-flip-vertical.png").release_value_but_fixme_should_propagate_errors());
+
+    flip_horizontal_button.on_click = [&](auto) {
+        m_glyph_editor_widget->flip_horizontally();
+    };
+    flip_horizontal_button.set_icon(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/edit-flip-horizontal.png").release_value_but_fixme_should_propagate_errors());
+
     GUI::Clipboard::the().on_change = [&](const String& data_type) {
         m_paste_action->set_enabled(data_type == "glyph/x-fonteditor");
     };

Userland/Applications/FontEditor/FontEditorWindow.gml

@@ -58,9 +58,37 @@
                         checkable: true
                     }
                 }
-            }
 
-            @GUI::Widget {
+                @GUI::Widget {
+                    shrink_to_fit: true
+
+                    layout: @GUI::HorizontalBoxLayout {
+                    }
+
+                    @GUI::Button {
+                        name: "flip_vertical"
+                        fixed_width: 22
+                        tooltip: "Flip vertically (top to bottom)"
+                        button_style: "Coolbar"
+                        focus_policy: "TabFocus"
+                    }
+
+                    @GUI::Button {
+                        name: "flip_horizontal"
+                        fixed_width: 22
+                        tooltip: "Flip horizontally (left to right)"
+                        button_style: "Coolbar"
+                        focus_policy: "TabFocus"
+                    }
+
+                    @GUI::Button {
+                        name: "rotate_90"
+                        fixed_width: 22
+                        tooltip: "Rotate 90° clockwise"
+                        button_style: "Coolbar"
+                        focus_policy: "TabFocus"
+                    }
+                }
             }
         }
 

Userland/Applications/FontEditor/GlyphEditorWidget.cpp

@@ -250,6 +250,92 @@ void GlyphEditorWidget::move_at_mouse(const GUI::MouseEvent& event)
     update();
 }
 
+static Vector<Vector<u8>> glyph_as_matrix(Gfx::GlyphBitmap const& bitmap)
+{
+    Vector<Vector<u8>> result;
+    result.ensure_capacity(bitmap.height());
+
+    for (int y = 0; y < bitmap.height(); y++) {
+        result.empend();
+        auto& row = result.last();
+        row.ensure_capacity(bitmap.width());
+        for (int x = 0; x < bitmap.width(); x++) {
+            row.append(bitmap.bit_at(x, y));
+        }
+    }
+
+    return result;
+}
+
+void GlyphEditorWidget::rotate_90()
+{
+    if (on_undo_event)
+        on_undo_event();
+
+    auto bitmap = font().raw_glyph(m_glyph).glyph_bitmap();
+    auto matrix = glyph_as_matrix(bitmap);
+
+    for (int y = 0; y < bitmap.height(); y++) {
+        for (int x = 0; x < bitmap.width(); x++) {
+            int source_x = y;
+            int source_y = bitmap.width() - 1 - x;
+            bool value = false;
+            if (source_x < bitmap.width() && source_y < bitmap.height()) {
+                value = matrix[source_y][source_x];
+            }
+            bitmap.set_bit_at(x, y, value);
+        }
+    }
+
+    if (on_glyph_altered)
+        on_glyph_altered(m_glyph);
+    update();
+}
+
+void GlyphEditorWidget::flip_vertically()
+{
+    if (on_undo_event)
+        on_undo_event();
+
+    auto bitmap = font().raw_glyph(m_glyph).glyph_bitmap();
+    auto matrix = glyph_as_matrix(bitmap);
+
+    for (int y = 0; y < bitmap.height(); y++) {
+        for (int x = 0; x < bitmap.width(); x++) {
+            int source_x = x;
+            int source_y = bitmap.height() - 1 - y;
+            bool value = matrix[source_y][source_x];
+            bitmap.set_bit_at(x, y, value);
+        }
+    }
+
+    if (on_glyph_altered)
+        on_glyph_altered(m_glyph);
+    update();
+}
+
+void GlyphEditorWidget::flip_horizontally()
+{
+    if (on_undo_event)
+        on_undo_event();
+
+    auto bitmap = font().raw_glyph(m_glyph).glyph_bitmap();
+    auto matrix = glyph_as_matrix(bitmap);
+
+    for (int y = 0; y < bitmap.height(); y++) {
+        for (int x = 0; x < bitmap.width(); x++) {
+            int source_x = bitmap.width() - 1 - x;
+            int source_y = y;
+            bool value = matrix[source_y][source_x];
+            bitmap.set_bit_at(x, y, value);
+        }
+    }
+
+    if (on_glyph_altered)
+        on_glyph_altered(m_glyph);
+    update();
+}
+
 int GlyphEditorWidget::preferred_width() const
 {
     return frame_thickness() * 2 + font().max_glyph_width() * m_scale - 1;

Userland/Applications/FontEditor/GlyphEditorWidget.h

@@ -34,6 +34,10 @@ public:
     void delete_glyph();
     bool is_glyph_empty();
 
+    void rotate_90();
+    void flip_vertically();
+    void flip_horizontally();
+
     int preferred_width() const;
     int preferred_height() const;