Method drawCoordinateSystem

src/ImageCanvas.cpp:218–364

}

void ImageCanvas::drawCoordinateSystem(NVGcontext* ctx) {
    TEV_ASSERT(mImage, "Can only draw coordinate system if there exists an image.");

    const auto displayWindowToNano = displayWindowToNanogui(mImage.get());

    enum DrawFlags {
        Label = 1,
        Region = 2,
    };

    const auto drawWindow = [&](Box2f window, Color color, bool top, bool right, string_view name, DrawFlags flags) {
        float fontSize = 20;
        float strokeWidth = 3.0f;

        Vector2i topLeft = m_pos +
            Vector2i{
                displayWindowToNano * Vector2f{window.min.x(), window.min.y()}
        };
        Vector2i topRight = m_pos +
            Vector2i{
                displayWindowToNano * Vector2f{window.max.x(), window.min.y()}
        };
        Vector2i bottomLeft = m_pos +
            Vector2i{
                displayWindowToNano * Vector2f{window.min.x(), window.max.y()}
        };
        Vector2i bottomRight = m_pos +
            Vector2i{
                displayWindowToNano * Vector2f{window.max.x(), window.max.y()}
        };

        nvgSave(ctx);

        nvgFontFace(ctx, "sans-bold");
        nvgFontSize(ctx, fontSize);
        nvgTextAlign(ctx, (right ? NVG_ALIGN_RIGHT : NVG_ALIGN_LEFT) | (top ? NVG_ALIGN_BOTTOM : NVG_ALIGN_TOP));
        float textWidth = nvgTextBounds(ctx, 0, 0, name.data(), name.data() + name.size(), nullptr);
        float textAlpha = std::max(std::min(1.0f, (((topRight.x() - topLeft.x() - textWidth - 5) / 30))), 0.0f);
        float regionAlpha = std::max(std::min(1.0f, (((topRight.x() - topLeft.x() - textWidth - 5) / 30))), 0.0f);

        Color textColor = Color(190, 255);
        textColor.a() = textAlpha;

        if (flags & Region) {
            color.a() = regionAlpha;

            nvgBeginPath(ctx);
            nvgMoveTo(ctx, bottomLeft.x(), bottomLeft.y());
            nvgLineTo(ctx, topLeft.x(), topLeft.y());
            nvgLineTo(ctx, topRight.x(), topRight.y());
            nvgLineTo(ctx, bottomRight.x(), bottomRight.y());
            nvgLineTo(ctx, bottomLeft.x(), bottomLeft.y());
            nvgStrokeWidth(ctx, strokeWidth);
            nvgStrokeColor(ctx, color);
            nvgStroke(ctx);
        }

        if (!name.empty() && (flags & Label)) {