Refactoring pass

This commit bundles a few general C++ code quality improvements.

- Replaced almost all use of ``const std::string &`` as string passing
  convention by the more general ``std::string_view``.

- Complete removal of ``unordered_map`` from header files. Maps
  are replaced either by vectors (when few elements are expected)
  or ``tsl::map`` using the pIMPL design pattern to keep those internals
  out of header files. This should not impact outside users of the API.

- Bumped macOS version requirement to 10.11 (Big Sur, EOL Sep 2023)

- Common header files are included once in ``common.h``

Author: wjakob

CMakeLists.txt

@@ -1,5 +1,6 @@
 cmake_minimum_required (VERSION 3.13..3.18)
-set(CMAKE_OSX_DEPLOYMENT_TARGET 10.14)
+
+set(CMAKE_OSX_DEPLOYMENT_TARGET 11.0) # macOS Big Sur (released Nov 2020, EOL Sep 2023)
 
 # Extract project version from source
 file(STRINGS "${CMAKE_CURRENT_SOURCE_DIR}/include/nanogui/common.h"
@@ -453,6 +454,11 @@ if (NOT NANOGUI_SKIP_STB_IMAGE_IMPLEMENTATION)
     PRIVATE -DNVG_STB_IMAGE_IMPLEMENTATION)
 endif()
 
+target_include_directories(nanogui
+  PRIVATE
+  ${CMAKE_CURRENT_SOURCE_DIR}/ext/nanobind/ext/robin_map/include
+)
+
 target_include_directories(nanogui
   PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
@@ -510,6 +516,11 @@ else()
   target_link_libraries(nanogui PUBLIC ${NANOGUI_LIBS})
 endif()
 
+if (MSVC)
+  # warning C4324: "...": structure was padded due to alignment specifier
+  target_compile_options(nanogui PRIVATE /wd4324)
+endif()
+
 target_link_libraries(nanogui PRIVATE nfd)
 
 # Auto-detect GLES include directory on Raspberry PI

include/nanogui/button.h

@@ -53,13 +53,13 @@ class NANOGUI_EXPORT Button : public Widget {
      * \param icon
      *     The icon to display with this Button.  See \ref nanogui::Button::mIcon.
      */
-    Button(Widget *parent, const std::string &caption = "Untitled", int icon = 0);
+    Button(Widget *parent, std::string_view caption = "Untitled", int icon = 0);
 
     /// Returns the caption of this Button.
-    const std::string &caption() const { return m_caption; }
+    std::string_view caption() const { return m_caption; }
 
     /// Sets the caption of this Button.
-    void set_caption(const std::string &caption) { m_caption = caption; }
+    void set_caption(std::string_view caption) { m_caption = caption; }
 
     /// Returns the background color of this Button.
     const Color &background_color() const { return m_background_color; }

include/nanogui/checkbox.h

@@ -45,22 +45,22 @@ class NANOGUI_EXPORT CheckBox : public Widget {
      *     \ref nanogui::CheckBox::mPushed for the difference between "pushed"
      *     and "checked".
      */
-    CheckBox(Widget *parent, const std::string &caption = "Untitled",
+    CheckBox(Widget *parent, std::string_view caption = "Untitled",
              const std::function<void(bool)> &callback = std::function<void(bool)>());
 
-    /// The caption of this CheckBox.
-   const std::string &caption() const { return m_caption; }
+    /// The caption of this check box.
+    std::string_view caption() const { return m_caption; }
 
-    /// Sets the caption of this CheckBox.
-    void set_caption(const std::string &caption) { m_caption = caption; }
+    /// Sets the caption of this check box
+    void set_caption(std::string_view caption) { m_caption = caption; }
 
-    /// Whether or not this CheckBox is currently checked.
+    /// Return whether or not this widget is currently checked.
     const bool &checked() const { return m_checked; }
 
-    /// Sets whether or not this CheckBox is currently checked.
+    /// Sets whether or not this widget is currently checked
     void set_checked(const bool &checked) { m_checked = checked; }
 
-    /// Whether or not this CheckBox is currently pushed.  See \ref nanogui::CheckBox::m_pushed.
+    /// Whether or not this widget is currently pushed.  See \ref nanogui::CheckBox::m_pushed.
     const bool &pushed() const { return m_pushed; }
     void set_pushed(const bool &pushed) { m_pushed = pushed; }
 
@@ -81,6 +81,7 @@ class NANOGUI_EXPORT CheckBox : public Widget {
 protected:
     /// The caption text of this CheckBox.
     std::string m_caption;
+
     /**
      * Internal tracking variable to distinguish between mouse click and release.
      * \ref nanogui::CheckBox::m_callback is only called upon release.  See

include/nanogui/colorpicker.h

@@ -67,16 +67,16 @@ class NANOGUI_EXPORT ColorPicker : public PopupButton {
     void set_color(const Color& color);
 
     /// The current caption of the \ref nanogui::ColorPicker::m_pick_button.
-    const std::string &pick_button_caption() { return m_pick_button->caption(); }
+    std::string_view pick_button_caption() { return m_pick_button->caption(); }
 
     /// Sets the current caption of the \ref nanogui::ColorPicker::m_pick_button.
-    void set_pick_button_caption(const std::string &caption) { m_pick_button->set_caption(caption); }
+    void set_pick_button_caption(std::string_view caption) { m_pick_button->set_caption(caption); }
 
     /// The current caption of the \ref nanogui::ColorPicker::m_reset_button.
-    const std::string &reset_button_caption() { return m_reset_button->caption(); }
+    std::string_view reset_button_caption() { return m_reset_button->caption(); }
 
     /// Sets the current caption of the \ref nanogui::ColorPicker::m_reset_button.
-    void set_reset_button_caption(const std::string &caption) { m_reset_button->set_caption(caption); }
+    void set_reset_button_caption(std::string_view caption) { m_reset_button->set_caption(caption); }
 protected:
     /// The "fast" callback executed when the ColorWheel has changed.
     std::function<void(const Color &)> m_callback;

include/nanogui/common.h

@@ -15,13 +15,15 @@
 
 #pragma once
 
-#include <stdint.h>
-
-#include <algorithm>
+#include <cstdint>
 #include <array>
+#include <utility>
 #include <functional>
 #include <string>
+#include <string_view>
 #include <vector>
+#include <stdexcept>
+#include <cassert>
 
 #define NANOGUI_VERSION_MAJOR 0
 #define NANOGUI_VERSION_MINOR 2
@@ -349,7 +351,7 @@ extern NANOGUI_EXPORT std::vector<std::pair<int, std::string>>
 /// Convenience function for instanting a PNG icon from the application's data segment (via bin2c)
 #define nvgImageIcon(ctx, name) nanogui::__nanogui_get_image(ctx, #name, name##_png, name##_png_size)
 /// Helper function used by nvg_image_icon
-extern NANOGUI_EXPORT int __nanogui_get_image(NVGcontext *ctx, const std::string &name,
+extern NANOGUI_EXPORT int __nanogui_get_image(NVGcontext *ctx, std::string_view name,
                                               uint8_t *data, uint32_t size);
 
 static const size_t DITHER_MATRIX_SIZE = 8;

include/nanogui/formhelper.h

@@ -128,7 +128,7 @@ class FormHelper {
 
     /// Add a new top-level window
     Window *add_window(const Vector2i &pos,
-                         const std::string &title = "Untitled") {
+                       std::string_view title = "Untitled") {
         assert(m_screen);
         m_window = new Window(m_screen, title);
         m_layout = new AdvancedGridLayout({10, 0, 10, 0}, {});
@@ -141,7 +141,7 @@ class FormHelper {
     }
 
     /// Add a new group that may contain several sub-widgets
-    Label *add_group(const std::string &caption) {
+    Label *add_group(std::string_view caption) {
         Label* label = new Label(m_window, caption, m_group_font_name, m_group_font_size);
         if (m_layout->row_count() > 0)
             m_layout->append_row(m_pre_group_spacing); /* Spacing */
@@ -153,7 +153,7 @@ class FormHelper {
 
     /// Add a new data widget controlled using custom getter/setter functions
     template <typename Type> detail::FormWidget<Type> *
-    add_variable(const std::string &label, const std::function<void(const Type &)> &setter,
+    add_variable(std::string_view label, const std::function<void(const Type &)> &setter,
                 const std::function<Type()> &getter, bool editable = true) {
         Label *label_w = new Label(m_window, label, m_label_font_name, m_label_font_size);
         auto widget = new detail::FormWidget<Type>(m_window);
@@ -180,7 +180,7 @@ class FormHelper {
 
     /// Add a new data widget that exposes a raw variable in memory
     template <typename Type> detail::FormWidget<Type> *
-    add_variable(const std::string &label, Type &value, bool editable = true) {
+    add_variable(std::string_view label, Type &value, bool editable = true) {
         return add_variable<Type>(label,
             [&](const Type & v) { value = v; },
             [&]() -> Type { return value; },
@@ -189,7 +189,7 @@ class FormHelper {
     }
 
     /// Add a button with a custom callback
-    Button *add_button(const std::string &label, const std::function<void()> &cb) {
+    Button *add_button(std::string_view label, const std::function<void()> &cb) {
         Button *button = new Button(m_window, label);
         button->set_callback(cb);
         button->set_fixed_height(25);
@@ -201,7 +201,7 @@ class FormHelper {
     }
 
     /// Add an arbitrary (optionally labeled) widget to the layout
-    void add_widget(const std::string &label, Widget *widget) {
+    void add_widget(std::string_view label, Widget *widget) {
         m_layout->append_row(0);
         if (label == "") {
             m_layout->set_anchor(widget, AdvancedGridLayout::Anchor(1, m_layout->row_count()-1, 3, 1));
@@ -237,16 +237,16 @@ class FormHelper {
     Vector2i fixed_size() { return m_fixed_size; }
 
     /// The font name being used for group headers.
-    const std::string &group_font_name() const { return m_group_font_name; }
+    std::string_view group_font_name() const { return m_group_font_name; }
 
     /// Sets the font name to be used for group headers.
-    void set_group_font_name(const std::string &name) { m_group_font_name = name; }
+    void set_group_font_name(std::string_view name) { m_group_font_name = name; }
 
     /// The font name being used for labels.
-    const std::string &label_font_name() const { return m_label_font_name; }
+    std::string_view label_font_name() const { return m_label_font_name; }
 
     /// Sets the font name being used for labels.
-    void set_label_font_name(const std::string &name) { m_label_font_name = name; }
+    void set_label_font_name(std::string_view name) { m_label_font_name = name; }
 
     /// The size of the font being used for group headers.
     int group_font_size() const { return m_group_font_size; }

include/nanogui/graph.h

@@ -23,16 +23,16 @@ NAMESPACE_BEGIN(nanogui)
  */
 class NANOGUI_EXPORT Graph : public Widget {
 public:
-    Graph(Widget *parent, const std::string &caption = "Untitled");
+    Graph(Widget *parent, std::string_view caption = "Untitled");
 
-    const std::string &caption() const { return m_caption; }
-    void set_caption(const std::string &caption) { m_caption = caption; }
+    std::string_view caption() const { return m_caption; }
+    void set_caption(std::string_view caption) { m_caption = caption; }
 
-    const std::string &header() const { return m_header; }
-    void set_header(const std::string &header) { m_header = header; }
+    std::string_view header() const { return m_header; }
+    void set_header(std::string_view header) { m_header = header; }
 
-    const std::string &footer() const { return m_footer; }
-    void set_footer(const std::string &footer) { m_footer = footer; }
+    std::string_view footer() const { return m_footer; }
+    void set_footer(std::string_view footer) { m_footer = footer; }
 
     const Color &background_color() const { return m_background_color; }
     void set_background_color(const Color &background_color) { m_background_color = background_color; }

include/nanogui/label.h

@@ -26,18 +26,18 @@ NAMESPACE_BEGIN(nanogui)
  */
 class NANOGUI_EXPORT Label : public Widget {
 public:
-    Label(Widget *parent, const std::string &caption,
-          const std::string &font = "sans", int font_size = -1);
+    Label(Widget *parent, std::string_view caption,
+          std::string_view font = "sans", int font_size = -1);
 
     /// Get the label's text caption
-    const std::string &caption() const { return m_caption; }
+    std::string_view caption() const { return m_caption; }
     /// Set the label's text caption
-    void set_caption(const std::string &caption) { m_caption = caption; }
+    void set_caption(std::string_view caption) { m_caption = caption; }
 
     /// Set the currently active font (2 are available by default: 'sans' and 'sans-bold')
-    void set_font(const std::string &font) { m_font = font; }
+    void set_font(std::string_view font) { m_font = font; }
     /// Get the currently active font
-    const std::string &font() const { return m_font; }
+    std::string_view font() const { return m_font; }
 
     /// Get the label color
     Color color() const { return m_color; }

include/nanogui/layout.h

@@ -17,10 +17,6 @@
 
 #include <nanogui/object.h>
 #include <nanogui/vector.h>
-#include <unordered_map>
-
-#include <stdexcept>
-#include <vector>
 
 NAMESPACE_BEGIN(nanogui)
 
@@ -419,39 +415,37 @@ class NANOGUI_EXPORT AdvancedGridLayout : public Layout {
     /// Creates an AdvancedGridLayout with specified columns, rows, and margin.
     AdvancedGridLayout(const std::vector<int> &cols = {}, const std::vector<int> &rows = {}, int margin = 0);
 
+    /// Destructor
+    virtual ~AdvancedGridLayout();
+
     /// The margin of this AdvancedGridLayout.
-    int margin() const { return m_margin; }
+    int margin() const;
     /// Sets the margin of this AdvancedGridLayout.
-    void set_margin(int margin) { m_margin = margin; }
+    void set_margin(int margin);
 
     /// Return the number of cols
-    int col_count() const { return (int) m_cols.size(); }
+    int col_count() const;
 
     /// Return the number of rows
-    int row_count() const { return (int) m_rows.size(); }
+    int row_count() const;
 
     /// Append a row of the given size (and stretch factor)
-    void append_row(int size, float stretch = 0.f) { m_rows.push_back(size); m_row_stretch.push_back(stretch); }
+    void append_row(int size, float stretch = 0.f);
 
     /// Append a column of the given size (and stretch factor)
-    void append_col(int size, float stretch = 0.f) { m_cols.push_back(size); m_col_stretch.push_back(stretch); }
+    void append_col(int size, float stretch = 0.f);
 
     /// Set the stretch factor of a given row
-    void set_row_stretch(int index, float stretch) { m_row_stretch.at(index) = stretch; }
+    void set_row_stretch(int index, float stretch);
 
     /// Set the stretch factor of a given column
-    void set_col_stretch(int index, float stretch) { m_col_stretch.at(index) = stretch; }
+    void set_col_stretch(int index, float stretch);
 
     /// Specify the anchor data structure for a given widget
-    void set_anchor(const Widget *widget, const Anchor &anchor) { m_anchor[widget] = anchor; }
+    void set_anchor(const Widget *widget, const Anchor &anchor);
 
     /// Retrieve the anchor data structure for a given widget
-    Anchor anchor(const Widget *widget) const {
-        auto it = m_anchor.find(widget);
-        if (it == m_anchor.end())
-            throw std::runtime_error("Widget was not registered with the grid layout!");
-        return it->second;
-    }
+    Anchor anchor(const Widget *widget) const;
 
     /* Implementation of the layout interface */
 
@@ -466,24 +460,9 @@ class NANOGUI_EXPORT AdvancedGridLayout : public Layout {
     void compute_layout(NVGcontext *ctx, const Widget *widget,
                         std::vector<int> *grid) const;
 
-protected:
-    /// The columns of this AdvancedGridLayout.
-    std::vector<int> m_cols;
-
-    /// The rows of this AdvancedGridLayout.
-    std::vector<int> m_rows;
-
-    /// The stretch for each column of this AdvancedGridLayout.
-    std::vector<float> m_col_stretch;
-
-    /// The stretch for each row of this AdvancedGridLayout.
-    std::vector<float> m_row_stretch;
-
-    /// The mapping of widgets to their specified anchor points.
-    std::unordered_map<const Widget *, Anchor> m_anchor;
-
-    /// The margin around this AdvancedGridLayout.
-    int m_margin;
+private:
+    struct Impl;
+    Impl *p;
 };
 
 NAMESPACE_END(nanogui)

include/nanogui/messagedialog.h

@@ -30,10 +30,10 @@ class NANOGUI_EXPORT MessageDialog : public Window {
         Warning
     };
 
-    MessageDialog(Widget *parent, Type type, const std::string &title = "Untitled",
-                  const std::string &message = "Message",
-                  const std::string &button_text = "OK",
-                  const std::string &alt_button_text = "Cancel", bool alt_button = false);
+    MessageDialog(Widget *parent, Type type, std::string_view title = "Untitled",
+                  std::string_view message = "Message",
+                  std::string_view button_text = "OK",
+                  std::string_view alt_button_text = "Cancel", bool alt_button = false);
 
     Label *message_label() { return m_message_label; }
     const Label *message_label() const { return m_message_label; }