Widget.h

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// The MIT License (MIT)
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// Copyright (c) 2021 www.open3d.org
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#pragma once

#include <memory>
#include <vector>

#include "open3d/visualization/gui/Gui.h"

namespace open3d {

namespace visualization {
namespace rendering {
class Renderer;
}
}  // namespace visualization

namespace visualization {
namespace gui {

class Color;
struct MouseEvent;
struct KeyEvent;
struct TickEvent;
struct Theme;

struct LayoutContext {
    const Theme& theme;
    FontContext& fonts;
};

struct DrawContext {
    const Theme& theme;
    visualization::rendering::Renderer& renderer;
    FontContext& fonts;
    int uiOffsetX;
    int uiOffsetY;
    int screenWidth;
    int screenHeight;
    int emPx;
    float frameDelta;  // in seconds
};

class Widget {
    friend class Window;

public:
    Widget();
    explicit Widget(const std::vector<std::shared_ptr<Widget>>& children);
    virtual ~Widget();

    void AddChild(std::shared_ptr<Widget> child);
    const std::vector<std::shared_ptr<Widget>> GetChildren() const;

    const Rect& GetFrame() const;
    virtual void SetFrame(const Rect& f);

    const Color& GetBackgroundColor() const;
    bool IsDefaultBackgroundColor() const;
    void SetBackgroundColor(const Color& color);

    bool IsVisible() const;
    virtual void SetVisible(bool vis);

    bool IsEnabled() const;
    virtual void SetEnabled(bool enabled);

    void SetTooltip(const char* text);
    const char* GetTooltip() const;

    static constexpr int DIM_GROW = 10000;
    struct Constraints {
        int width = DIM_GROW;
        int height = DIM_GROW;
    };
    virtual Size CalcPreferredSize(const LayoutContext& context,
                                   const Constraints& constraints) const;

    virtual Size CalcMinimumSize(const LayoutContext& context) const;

    virtual void Layout(const LayoutContext& context);

    enum class DrawResult { NONE, REDRAW, RELAYOUT };
    virtual DrawResult Draw(const DrawContext& context);

    enum class EventResult { IGNORED, CONSUMED, DISCARD };

    virtual EventResult Mouse(const MouseEvent& e);

    virtual EventResult Key(const KeyEvent& e);

    virtual DrawResult Tick(const TickEvent& e);

protected:
    void DrawImGuiPushEnabledState();
    void DrawImGuiPopEnabledState();
    void DrawImGuiTooltip();

private:
    struct Impl;
    std::unique_ptr<Impl> impl_;
};

}  // namespace gui
}  // namespace visualization
}  // namespace open3d