implot.cpp

// MIT License

// Copyright (c) 2020 Evan Pezent

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

// ImPlot v0.2 WIP

/*

API BREAKING CHANGES
====================
Occasionally introducing changes that are breaking the API. We try to make the breakage minor and easy to fix.
Below is a change-log of API breaking changes only. If you are using one of the functions listed, expect to have to fix some code.
When you are not sure about a old symbol or function name, try using the Search/Find function of your IDE to look for comments or references in all implot files.
You can read releases logs https://github.com/epezent/implot/releases for more details.

- 2020/05/13 (0.2) - ImMarker was change to ImPlotMarker and ImAxisFlags was changed to ImPlotAxisFlags
- 2020/05/11 (0.2) - ImPlotFlags_Selection was changed to ImPlotFlags_BoxSelect
- 2020/05/11 (0.2) - The namespace ImGui:: was replaced with ImPlot::. As a result, the following additional changes were made:
                     - Functions that were prefixed or decorated with the word "Plot" have been truncated. E.g., `ImGui::PlotBar` is now just `ImPlot::Bar`.
                       It should be fairly obvious what was what.
                     - Some functions have been given names that would have otherwise collided with the ImGui namespace. This has been done to maintain a consistent
                       style with ImGui. E.g., 'ImGui::PushPlotStyleVar` is now 'ImPlot::PushStyleVar'.
- 2020/05/10 (0.2) - The following function/struct names were changes:
                    - ImPlotRange       -> ImPlotLimits
                    - GetPlotRange()    -> GetPlotLimits()
                    - SetNextPlotRange  -> SetNextPlotLimits
                    - SetNextPlotRangeX -> SetNextPlotLimitsX
                    - SetNextPlotRangeY -> SetNextPlotLimitsY
- 2020/05/10 (0.2) - Plot queries are pixel based by default. Query rects that maintain relative plot position have been removed. This was done to support multi-y-axis.

*/

#ifndef IMGUI_DEFINE_MATH_OPERATORS
#define IMGUI_DEFINE_MATH_OPERATORS
#endif

#include "implot.h"
#include "imgui_internal.h"

#ifdef _MSC_VER
#define sprintf sprintf_s
#endif

#define IM_NORMALIZE2F_OVER_ZERO(VX, VY)                                                           \
    {                                                                                              \
        float d2 = VX * VX + VY * VY;                                                              \
        if (d2 > 0.0f) {                                                                           \
            float inv_len = 1.0f / ImSqrt(d2);                                                     \
            VX *= inv_len;                                                                         \
            VY *= inv_len;                                                                         \
        }                                                                                          \
    }

// Special Color used to specific that a plot item color should set determined automatically.
#define IM_COL_AUTO ImVec4(0,0,0,-1)
// The maximum number of support y-axes
#define MAX_Y_AXES 3

ImPlotStyle::ImPlotStyle() {
    LineWeight = 1;
    Marker = ImPlotMarker_None;
    MarkerSize = 5;
    MarkerWeight = 1;
    ErrorBarSize = 5;
    ErrorBarWeight = 1.5;
    DigitalBitHeight = 8;

    Colors[ImPlotCol_Line]          = IM_COL_AUTO;
    Colors[ImPlotCol_Fill]          = IM_COL_AUTO;
    Colors[ImPlotCol_MarkerOutline] = IM_COL_AUTO;
    Colors[ImPlotCol_MarkerFill]    = IM_COL_AUTO;
    Colors[ImPlotCol_ErrorBar]      = IM_COL_AUTO;
    Colors[ImPlotCol_FrameBg]       = IM_COL_AUTO;
    Colors[ImPlotCol_PlotBg]        = IM_COL_AUTO;
    Colors[ImPlotCol_PlotBorder]    = IM_COL_AUTO;
    Colors[ImPlotCol_XAxis]         = IM_COL_AUTO;
    Colors[ImPlotCol_YAxis]         = IM_COL_AUTO;
    Colors[ImPlotCol_YAxis2]        = IM_COL_AUTO;
    Colors[ImPlotCol_YAxis3]        = IM_COL_AUTO;
    Colors[ImPlotCol_Selection]     = ImVec4(1,1,0,1);
    Colors[ImPlotCol_Query]         = ImVec4(0,1,0,1);
}

ImPlotRange::ImPlotRange() : Min(NAN), Max(NAN) {}

bool ImPlotRange::Contains(float v) const {
    return v >= Min && v <= Max;
}

float ImPlotRange::Size() const {
    return Max - Min;
}

ImPlotLimits::ImPlotLimits() {}

bool ImPlotLimits::Contains(const ImVec2& p) const {
    return X.Contains(p.x) && Y.Contains(p.y);
}

ImVec2 ImPlotLimits::Size() const {
    return ImVec2(X.Size(),Y.Size());
}

namespace ImPlot {

namespace {

//-----------------------------------------------------------------------------
// Private Utils
//-----------------------------------------------------------------------------

/// Returns true if a flag is set
template <typename TSet, typename TFlag>
inline bool HasFlag(TSet set, TFlag flag) {
    return (set & flag) == flag;
}

/// Flips a flag in a flagset
template <typename TSet, typename TFlag>
inline void FlipFlag(TSet& set, TFlag flag) {
    HasFlag(set, flag) ? set &= ~flag : set |= flag;
}

/// Linearly remaps float x from [x0 x1] to [y0 y1].
inline float Remap(float x, float x0, float x1, float y0, float y1) {
    return y0 + (x - x0) * (y1 - y0) / (x1 - x0);
}

/// Turns NANs to 0s
inline float ConstrainNan(float val) {
    return isnan(val) ? 0 : val;
}

/// Turns INFINITYs to FLT_MAXs
inline float ConstrainInf(float val) {
    return val == INFINITY ? FLT_MAX : val == -INFINITY ? -FLT_MAX : val;
}

/// Turns numbers less than or equal to 0 to 0.001 (sort of arbitrary, is there a better way?)
inline float ConstrainLog(float val) {
    return val <= 0 ? 0.001f : val;
}

/// Returns true if val is NAN or INFINITY
inline bool NanOrInf(float val) {
    return val == INFINITY || val == -INFINITY || isnan(val);
}

/// Utility function to that rounds x to powers of 2,5 and 10 for generating axis labels
/// Taken from Graphics Gems 1 Chapter 11.2, "Nice Numbers for Graph Labels"
inline double NiceNum(double x, bool round) {
    double f;  /* fractional part of x */
    double nf; /* nice, rounded fraction */
    int expv = (int)floor(log10(x));
    f = x / ImPow(10.0, (double)expv); /* between 1 and 10 */
    if (round)
        if (f < 1.5)
            nf = 1;
        else if (f < 3)
            nf = 2;
        else if (f < 7)
            nf = 5;
        else
            nf = 10;
    else if (f <= 1)
        nf = 1;
    else if (f <= 2)
        nf = 2;
    else if (f <= 5)
        nf = 5;
    else
        nf = 10;
    return nf * ImPow(10.0, expv);
}

/// Draws vertical text. The position is the bottom left of the text rect.
inline void AddTextVertical(ImDrawList *DrawList, const char *text, ImVec2 pos, ImU32 text_color) {
    pos.x                   = IM_ROUND(pos.x);
    pos.y                   = IM_ROUND(pos.y);
    ImFont *           font = GImGui->Font;
    const ImFontGlyph *glyph;
    for (char c = *text++; c; c = *text++) {
        glyph = font->FindGlyph(c);
        if (!glyph)
            continue;

        DrawList->PrimReserve(6, 4);
        DrawList->PrimQuadUV(
            pos + ImVec2(glyph->Y0, -glyph->X0), pos + ImVec2(glyph->Y0, -glyph->X1),
            pos + ImVec2(glyph->Y1, -glyph->X1), pos + ImVec2(glyph->Y1, -glyph->X0),

            ImVec2(glyph->U0, glyph->V0), ImVec2(glyph->U1, glyph->V0),
            ImVec2(glyph->U1, glyph->V1), ImVec2(glyph->U0, glyph->V1), text_color);
        pos.y -= glyph->AdvanceX;
    }
}

/// Calculates the size of vertical text
inline ImVec2 CalcTextSizeVertical(const char *text) {
    ImVec2 sz = ImGui::CalcTextSize(text);
    return ImVec2(sz.y, sz.x);
}

} // private namespace

//-----------------------------------------------------------------------------
// Forwards
//-----------------------------------------------------------------------------

ImVec4 NextColor();

//-----------------------------------------------------------------------------
// Structs
//-----------------------------------------------------------------------------

/// Tick mark info
struct ImTick {
    ImTick(double value, bool major, bool render_label = true) {
        PlotPos = value;
        Major = major;
        RenderLabel = render_label;
    }
    double PlotPos;
    float  PixelPos;
    ImVec2 Size;
    int    TextOffset;    
    bool   Major;
    bool   RenderLabel;    
};

struct ImPlotItem {
    ImPlotItem() {
        Show = true;
        Highlight = false;
        Color = NextColor();
        NameOffset = -1;
        ID = 0;
    }
    ~ImPlotItem() { ID = 0; }
    bool Show;
    bool Highlight;
    ImVec4 Color;
    int NameOffset;
    ImGuiID ID;
};

/// Plot axis structure. You shouldn't need to construct this!
struct ImPlotAxis {
    ImPlotAxis() {
        Dragging = false;
        Range.Min = 0;
        Range.Max = 1;
        Divisions = 3;
        Subdivisions = 10;
        Flags = PreviousFlags = ImPlotAxisFlags_Default;
    }
    bool Dragging;
    ImPlotRange Range;
    int Divisions;
    int Subdivisions;
    ImPlotAxisFlags Flags, PreviousFlags;
};

/// Holds Plot state information that must persist between frames
struct ImPlotState {
    ImPlotState() {
        Selecting = Querying = Queried = DraggingQuery = false;
        SelectStart =  QueryStart = ImVec2(0,0);
        Flags = PreviousFlags = ImPlotFlags_Default;
        ColorIdx = 0;
        CurrentYAxis = 0;
    }
    ImPool<ImPlotItem> Items;

    ImRect BB_Legend;
    ImVec2 SelectStart;
    bool Selecting;
    bool Querying;
    bool Queried;
    bool DraggingQuery;
    ImVec2 QueryStart;
    ImRect QueryRect; // relative to BB_grid!!

    ImPlotAxis XAxis;
    ImPlotAxis YAxis[MAX_Y_AXES];

    ImPlotFlags Flags, PreviousFlags;
    int ColorIdx;
    int CurrentYAxis;
};

struct ImNextPlotData {
    ImGuiCond XRangeCond;
    ImGuiCond YRangeCond[MAX_Y_AXES];
    bool HasXRange;
    bool HasYRange[MAX_Y_AXES];
    ImPlotRange X;
    ImPlotRange Y[MAX_Y_AXES];
};

/// Holds Plot state information that must persist only between calls to BeginPlot()/EndPlot()
struct ImPlotContext {
    ImPlotContext() : RenderX(), RenderY() {
        CurrentPlot = NULL;
        FitThisFrame = FitX = false;
        RestorePalette();
    }

    /// ALl Plots
    ImPool<ImPlotState> Plots;
    /// Current Plot
    ImPlotState* CurrentPlot;
    // Legend
    ImVector<int> LegendIndices;
    ImGuiTextBuffer LegendLabels;
    // Bounding regions
    ImRect BB_Frame;
    ImRect BB_Canvas;
    ImRect BB_Grid;
    // Cached Colors
    ImU32 Col_Frame, Col_Bg, Col_Border,
          Col_Txt, Col_TxtDis,
          Col_SlctBg, Col_SlctBd,
          Col_QryBg, Col_QryBd;
    struct AxisColor {
        AxisColor() : Major(), Minor(), Txt() {}
        ImU32 Major, Minor, Txt;
    };
    AxisColor Col_X;
    AxisColor Col_Y[MAX_Y_AXES];
    // Tick marks
    ImVector<ImTick> XTicks,  YTicks[MAX_Y_AXES];
    ImGuiTextBuffer XTickLabels, YTickLabels[MAX_Y_AXES];
    float AxisLabelReference[MAX_Y_AXES];
    // Transformation cache
    ImRect PixelRange[MAX_Y_AXES];
    // linear scale (slope)
    float Mx;
    float My[MAX_Y_AXES];
    // log scale denominator
    float LogDenX;
    float LogDenY[MAX_Y_AXES];
    // Data extents
    ImPlotRange ExtentsX;
    ImPlotRange ExtentsY[MAX_Y_AXES];
    int VisibleItemCount;
    bool FitThisFrame; bool FitX;
    bool FitY[MAX_Y_AXES] = {};
    // Hover states
    bool Hov_Frame;
    bool Hov_Grid;    
    // Render flags
    bool RenderX, RenderY[MAX_Y_AXES];
    // Mouse pos
    ImVec2 LastMousePos[MAX_Y_AXES];
    // Style
    ImVector<ImVec4> ColorMap;
    ImPlotStyle Style;
    ImVector<ImGuiColorMod> ColorModifiers;  // Stack for PushStyleColor()/PopStyleColor()
    ImVector<ImGuiStyleMod> StyleModifiers;  // Stack for PushStyleVar()/PopStyleVar()
    ImNextPlotData NextPlotData;
    // Digital plot item count
    int DigitalPlotItemCnt;
    int DigitalPlotOffset;
};

/// Global plot context
static ImPlotContext gp;

//-----------------------------------------------------------------------------
// Utils
//-----------------------------------------------------------------------------

/// Returns the next unused default plot color
ImVec4 NextColor() {
    ImVec4 col  = gp.ColorMap[gp.CurrentPlot->ColorIdx % gp.ColorMap.size()];
    gp.CurrentPlot->ColorIdx++;
    return col;
}

inline void FitPoint(const ImVec2& p) {
    ImPlotRange* extents_x = &gp.ExtentsX;
    ImPlotRange* extents_y = &gp.ExtentsY[gp.CurrentPlot->CurrentYAxis];
    if (!NanOrInf(p.x)) {
        extents_x->Min = p.x < extents_x->Min ? p.x : extents_x->Min;
        extents_x->Max = p.x > extents_x->Max ? p.x : extents_x->Max;
    }
    if (!NanOrInf(p.y)) {
        extents_y->Min = p.y < extents_y->Min ? p.y : extents_y->Min;
        extents_y->Max = p.y > extents_y->Max ? p.y : extents_y->Max;
    }
}

//-----------------------------------------------------------------------------
// Coordinate Transforms
//-----------------------------------------------------------------------------

inline void UpdateTransformCache() {
    // get pixels for transforms

    for (int i = 0; i < MAX_Y_AXES; i++) {
        gp.PixelRange[i] = ImRect(HasFlag(gp.CurrentPlot->XAxis.Flags, ImPlotAxisFlags_Invert) ? gp.BB_Grid.Max.x : gp.BB_Grid.Min.x,
                                  HasFlag(gp.CurrentPlot->YAxis[i].Flags, ImPlotAxisFlags_Invert) ? gp.BB_Grid.Min.y : gp.BB_Grid.Max.y,
                                  HasFlag(gp.CurrentPlot->XAxis.Flags, ImPlotAxisFlags_Invert) ? gp.BB_Grid.Min.x : gp.BB_Grid.Max.x,
                                  HasFlag(gp.CurrentPlot->YAxis[i].Flags, ImPlotAxisFlags_Invert) ? gp.BB_Grid.Max.y : gp.BB_Grid.Min.y);

        gp.My[i] = (gp.PixelRange[i].Max.y - gp.PixelRange[i].Min.y) / gp.CurrentPlot->YAxis[i].Range.Size();
    }
    gp.LogDenX = log10(gp.CurrentPlot->XAxis.Range.Max / gp.CurrentPlot->XAxis.Range.Min);
    for (int i = 0; i < MAX_Y_AXES; i++) {
        gp.LogDenY[i] = log10(gp.CurrentPlot->YAxis[i].Range.Max / gp.CurrentPlot->YAxis[i].Range.Min);
    }
    gp.Mx = (gp.PixelRange[0].Max.x - gp.PixelRange[0].Min.x) / gp.CurrentPlot->XAxis.Range.Size();
}

inline ImVec2 PixelsToPlot(float x, float y, int y_axis_in = -1) {
    IM_ASSERT_USER_ERROR(gp.CurrentPlot != NULL, "PixelsToPlot() Needs to be called between BeginPlot() and EndPlot()!");
    const int y_axis = y_axis_in >= 0 ? y_axis_in : gp.CurrentPlot->CurrentYAxis;
    ImVec2 plt;
    plt.x = (x - gp.PixelRange[y_axis].Min.x) / gp.Mx + gp.CurrentPlot->XAxis.Range.Min;
    plt.y = (y - gp.PixelRange[y_axis].Min.y) / gp.My[y_axis] + gp.CurrentPlot->YAxis[y_axis].Range.Min;
    if (HasFlag(gp.CurrentPlot->XAxis.Flags, ImPlotAxisFlags_LogScale)) {
        float t = (plt.x - gp.CurrentPlot->XAxis.Range.Min) / gp.CurrentPlot->XAxis.Range.Size();
        plt.x = pow(10.0f, t * gp.LogDenX) * gp.CurrentPlot->XAxis.Range.Min;
    }
    if (HasFlag(gp.CurrentPlot->YAxis[y_axis].Flags, ImPlotAxisFlags_LogScale)) {
        float t = (plt.y - gp.CurrentPlot->YAxis[y_axis].Range.Min) / gp.CurrentPlot->YAxis[y_axis].Range.Size();
        plt.y = pow(10.0f, t * gp.LogDenY[y_axis]) * gp.CurrentPlot->YAxis[y_axis].Range.Min;
    }
    return plt;
}

ImVec2 PixelsToPlot(const ImVec2& pix, int y_axis) {
    return PixelsToPlot(pix.x, pix.y, y_axis);
}

// This function is convenient but should not be used to process a high volume of points. Use the Transformer structs below instead.
inline ImVec2 PlotToPixels(float x, float y, int y_axis_in = -1) {
    IM_ASSERT_USER_ERROR(gp.CurrentPlot != NULL, "PlotToPixels() Needs to be called between BeginPlot() and EndPlot()!");
    const int y_axis = y_axis_in >= 0 ? y_axis_in : gp.CurrentPlot->CurrentYAxis;
    ImVec2 pix;
    if (HasFlag(gp.CurrentPlot->XAxis.Flags, ImPlotAxisFlags_LogScale)) {
        float t = log10(x / gp.CurrentPlot->XAxis.Range.Min) / gp.LogDenX;
        x       = ImLerp(gp.CurrentPlot->XAxis.Range.Min, gp.CurrentPlot->XAxis.Range.Max, t);
    }
    if (HasFlag(gp.CurrentPlot->YAxis[y_axis].Flags, ImPlotAxisFlags_LogScale)) {
        float t = log10(y / gp.CurrentPlot->YAxis[y_axis].Range.Min) / gp.LogDenY[y_axis];
        y       = ImLerp(gp.CurrentPlot->YAxis[y_axis].Range.Min, gp.CurrentPlot->YAxis[y_axis].Range.Max, t);
    }
    pix.x = gp.PixelRange[y_axis].Min.x + gp.Mx * (x - gp.CurrentPlot->XAxis.Range.Min);
    pix.y = gp.PixelRange[y_axis].Min.y + gp.My[y_axis] * (y - gp.CurrentPlot->YAxis[y_axis].Range.Min);
    return pix;
}

// This function is convenient but should not be used to process a high volume of points. Use the Transformer structs below instead.
ImVec2 PlotToPixels(const ImVec2& plt, int y_axis) {
    return PlotToPixels(plt.x, plt.y, y_axis);
}

// Transformer structs

struct Plt2PixLinLin {
    Plt2PixLinLin(int y_axis_in) : y_axis(y_axis_in) {}

    ImVec2 operator()(const ImVec2& plt) { return (*this)(plt.x, plt.y); }
    ImVec2 operator()(float x, float y) {
        return ImVec2( gp.PixelRange[y_axis].Min.x + gp.Mx * (x - gp.CurrentPlot->XAxis.Range.Min),
                 gp.PixelRange[y_axis].Min.y + gp.My[y_axis] * (y - gp.CurrentPlot->YAxis[y_axis].Range.Min) );
    }

    int y_axis;
};

struct Plt2PixLogLin {
    Plt2PixLogLin(int y_axis_in) : y_axis(y_axis_in) {}

    ImVec2 operator()(const ImVec2& plt) { return (*this)(plt.x, plt.y); }
    ImVec2 operator()(float x, float y) {
        float t = log10(x / gp.CurrentPlot->XAxis.Range.Min) / gp.LogDenX;
        x       = ImLerp(gp.CurrentPlot->XAxis.Range.Min, gp.CurrentPlot->XAxis.Range.Max, t);
        return ImVec2( gp.PixelRange[y_axis].Min.x + gp.Mx * (x - gp.CurrentPlot->XAxis.Range.Min),
                 gp.PixelRange[y_axis].Min.y + gp.My[y_axis] * (y - gp.CurrentPlot->YAxis[y_axis].Range.Min) );
    }

    int y_axis;
};

struct Plt2PixLinLog {
    Plt2PixLinLog(int y_axis_in) : y_axis(y_axis_in) {}

    ImVec2 operator()(const ImVec2& plt) { return (*this)(plt.x, plt.y); }
    ImVec2 operator()(float x, float y) {
        float t = log10(y / gp.CurrentPlot->YAxis[y_axis].Range.Min) / gp.LogDenY[y_axis];
        y       = ImLerp(gp.CurrentPlot->YAxis[y_axis].Range.Min, gp.CurrentPlot->YAxis[y_axis].Range.Max, t);
        return ImVec2( gp.PixelRange[y_axis].Min.x + gp.Mx * (x - gp.CurrentPlot->XAxis.Range.Min),
                 gp.PixelRange[y_axis].Min.y + gp.My[y_axis] * (y - gp.CurrentPlot->YAxis[y_axis].Range.Min) );
    }

    int y_axis;
};

struct Plt2PixLogLog {
    Plt2PixLogLog(int y_axis_in) : y_axis(y_axis_in) {}

    ImVec2 operator()(const ImVec2& plt) { return (*this)(plt.x, plt.y); }
    ImVec2 operator()(float x, float y) {
        float t = log10(x / gp.CurrentPlot->XAxis.Range.Min) / gp.LogDenX;
        x       = ImLerp(gp.CurrentPlot->XAxis.Range.Min, gp.CurrentPlot->XAxis.Range.Max, t);
        t       = log10(y / gp.CurrentPlot->YAxis[y_axis].Range.Min) / gp.LogDenY[y_axis];
        y       = ImLerp(gp.CurrentPlot->YAxis[y_axis].Range.Min, gp.CurrentPlot->YAxis[y_axis].Range.Max, t);
        return ImVec2( gp.PixelRange[y_axis].Min.x + gp.Mx * (x - gp.CurrentPlot->XAxis.Range.Min),
                 gp.PixelRange[y_axis].Min.y + gp.My[y_axis] * (y - gp.CurrentPlot->YAxis[y_axis].Range.Min) );
    }

    int y_axis;
};

//-----------------------------------------------------------------------------
// Legend Utils
//-----------------------------------------------------------------------------

ImPlotItem* RegisterItem(const char* label_id) {
    ImGuiID id = ImGui::GetID(label_id);
    ImPlotItem* item = gp.CurrentPlot->Items.GetOrAddByKey(id);
    int idx = gp.CurrentPlot->Items.GetIndex(item);
    item->ID = id;
    gp.LegendIndices.push_back(idx);
    item->NameOffset = gp.LegendLabels.size();
    gp.LegendLabels.append(label_id, label_id + strlen(label_id) + 1);
    if (item->Show)
        gp.VisibleItemCount++;
    return item;
}

int GetLegendCount() {
    return gp.LegendIndices.size();
}

ImPlotItem* GetLegendItem(int i) {
    return gp.CurrentPlot->Items.GetByIndex(gp.LegendIndices[i]);
}

const char* GetLegendLabel(int i) {
    ImPlotItem* item  = gp.CurrentPlot->Items.GetByIndex(gp.LegendIndices[i]);
    IM_ASSERT(item->NameOffset != -1 && item->NameOffset < gp.LegendLabels.Buf.Size);
    return gp.LegendLabels.Buf.Data + item->NameOffset;
}

//-----------------------------------------------------------------------------
// Tick Utils
//-----------------------------------------------------------------------------

inline void GetTicks(const ImPlotRange& scale, int nMajor, int nMinor, bool logscale, ImVector<ImTick> &out) {
    out.shrink(0);
    if (logscale) {
        if (scale.Min <= 0 || scale.Max <= 0)
            return;
        int exp_min = (int)(ImFloor(log10(scale.Min)));
        int exp_max = (int)(ImCeil(log10(scale.Max)));
        for (int e = exp_min - 1; e < exp_max + 1; ++e) {
            double major1 = ImPow(10, (double)(e));
            double major2 = ImPow(10, (double)(e + 1));
            double interval = (major2 - major1) / 9;
            if (major1 >= (scale.Min - FLT_EPSILON) && major1 <= (scale.Max + FLT_EPSILON))
                out.push_back(ImTick(major1, true));
            for (int i = 1; i < 9; ++i) {
                double minor = major1 + i * interval;
                if (minor >= (scale.Min - FLT_EPSILON) && minor <= (scale.Max + FLT_EPSILON))
                    out.push_back(ImTick(minor, false, false));
            }
        }
    }
    else {
        const double range    = NiceNum(scale.Max - scale.Min, 0);
        const double interval = NiceNum(range / (nMajor - 1), 1);
        const double graphmin = floor(scale.Min / interval) * interval;
        const double graphmax = ceil(scale.Max / interval) * interval;
        for (double major = graphmin; major < graphmax + 0.5 * interval; major += interval) {
            if (major >= scale.Min && major <= scale.Max)
                out.push_back(ImTick(major, true));
            for (int i = 1; i < nMinor; ++i) {
                double minor = major + i * interval / nMinor;
                if (minor >= scale.Min && minor <= scale.Max)
                    out.push_back(ImTick(minor, false));
            }
        }
    }
}

inline void LabelTicks(ImVector<ImTick> &ticks, bool scientific, ImGuiTextBuffer& buffer) {
    buffer.Buf.resize(0);
    char temp[32];
    for (int t = 0; t < ticks.Size; t++) {
        ImTick *tk = &ticks[t];
        if (tk->RenderLabel) {
            tk->TextOffset = buffer.size();
            if (scientific)
                sprintf(temp, "%.0e", tk->PlotPos);
            else
                sprintf(temp, "%g", tk->PlotPos);
            buffer.append(temp, temp + strlen(temp) + 1);
            tk->Size = ImGui::CalcTextSize(buffer.Buf.Data + tk->TextOffset);
        }
    }
}

namespace {
struct AxisState {
    ImPlotAxis* axis;
    bool has_range;
    ImGuiCond range_cond;
    bool present;
    int present_so_far;
    bool flip;
    bool lock_min;
    bool lock_max;
    bool lock;

    AxisState(ImPlotAxis& axis_in, bool has_range_in, ImGuiCond range_cond_in,
              bool present_in, int previous_present)
            : axis(&axis_in),
              has_range(has_range_in),
              range_cond(range_cond_in),
              present(present_in),
              present_so_far(previous_present + (present ? 1 : 0)),
              flip(HasFlag(axis->Flags, ImPlotAxisFlags_Invert)),
              lock_min(HasFlag(axis->Flags, ImPlotAxisFlags_LockMin)),
              lock_max(HasFlag(axis->Flags, ImPlotAxisFlags_LockMax)),
              lock(present && ((lock_min && lock_max) || (has_range && range_cond == ImGuiCond_Always))) {}

    AxisState()
            : axis(),
              has_range(),
              range_cond(),
              present(),
              present_so_far(),
              flip(),
              lock_min(),
              lock_max(),
              lock() {}
};

void UpdateAxisColor(int axis_flag, ImPlotContext::AxisColor* col) {
    const ImVec4 col_Axis = gp.Style.Colors[axis_flag].w == -1 ? ImGui::GetStyle().Colors[ImGuiCol_Text] * ImVec4(1, 1, 1, 0.25f) : gp.Style.Colors[axis_flag];
    col->Major = ImGui::GetColorU32(col_Axis);
    col->Minor = ImGui::GetColorU32(col_Axis * ImVec4(1, 1, 1, 0.25f));
    col->Txt   = ImGui::GetColorU32(ImVec4(col_Axis.x, col_Axis.y, col_Axis.z, 1));
}

ImRect GetAxisScale(int y_axis, float tx, float ty, float zoom_rate) {
    return ImRect(
            PixelsToPlot(gp.BB_Grid.Min - gp.BB_Grid.GetSize() * ImVec2(tx * zoom_rate, ty * zoom_rate), y_axis),
            PixelsToPlot(gp.BB_Grid.Max + gp.BB_Grid.GetSize() * ImVec2((1 - tx) * zoom_rate, (1 - ty) * zoom_rate), y_axis));
}

class YPadCalculator {
  public:
    YPadCalculator(const AxisState* axis_states, const float* max_label_widths, float txt_off)
            : AxisStates(axis_states), MaxLabelWidths(max_label_widths), TxtOff(txt_off) {}

    float operator()(int y_axis) {
        ImPlotState& plot = *gp.CurrentPlot;
        if (!AxisStates[y_axis].present) { return 0; }
        // If we have more than 1 axis present before us, then we need
        // extra space to account for our tick bar.
        float pad_result = 0;
        if (AxisStates[y_axis].present_so_far >= 3) {
            pad_result += 6.0f;
        }
        if (!HasFlag(plot.YAxis[y_axis].Flags, ImPlotAxisFlags_TickLabels)) {
            return pad_result;
        }
        pad_result += MaxLabelWidths[y_axis] + TxtOff;
        return pad_result;
    }

  private:
    const AxisState* const AxisStates;
    const float* const MaxLabelWidths;
    const float TxtOff;
};
}  // namespace

//-----------------------------------------------------------------------------
// BeginPlot()
//-----------------------------------------------------------------------------

bool BeginPlot(const char* title, const char* x_label, const char* y_label, const ImVec2& size, ImPlotFlags flags, ImPlotAxisFlags x_flags, ImPlotAxisFlags y_flags, ImPlotAxisFlags y2_flags, ImPlotAxisFlags y3_flags) {

    IM_ASSERT_USER_ERROR(gp.CurrentPlot == NULL, "Mismatched BeginPlot()/EndPlot()!");

    // FRONT MATTER  -----------------------------------------------------------

    ImGuiContext &G      = *GImGui;
    ImGuiWindow * Window = G.CurrentWindow;
    if (Window->SkipItems) {
        gp.NextPlotData = ImNextPlotData();
        return false;
    }

    const ImGuiID     ID       = Window->GetID(title);
    const ImGuiStyle &Style    = G.Style;
    const ImGuiIO &   IO       = ImGui::GetIO();

    bool just_created = gp.Plots.GetByKey(ID) == NULL;
    gp.CurrentPlot = gp.Plots.GetOrAddByKey(ID);
    ImPlotState &plot = *gp.CurrentPlot;

    plot.CurrentYAxis = 0;

    if (just_created) {
        plot.Flags          = flags;
        plot.XAxis.Flags    = x_flags;
        plot.YAxis[0].Flags = y_flags;
        plot.YAxis[1].Flags = y2_flags;
        plot.YAxis[2].Flags = y3_flags;
    }
    else {
        // TODO: Check which individual flags changed, and only reset those!
        // There's probably an easy bit mask trick I'm not aware of.
        if (flags != plot.PreviousFlags)
            plot.Flags = flags;
        if (y_flags != plot.YAxis[0].PreviousFlags)
            plot.YAxis[0].PreviousFlags = y_flags;
        if (y2_flags != plot.YAxis[1].PreviousFlags)
            plot.YAxis[1].PreviousFlags = y2_flags;
        if (y3_flags != plot.YAxis[2].PreviousFlags)
            plot.YAxis[2].PreviousFlags = y3_flags;
    }

    plot.PreviousFlags          = flags;
    plot.XAxis.PreviousFlags    = x_flags;
    plot.YAxis[0].PreviousFlags = y_flags;
    plot.YAxis[1].PreviousFlags = y2_flags;
    plot.YAxis[2].PreviousFlags = y3_flags;

    // capture scroll with a child region
    if (!HasFlag(plot.Flags, ImPlotFlags_NoChild)) {
        ImGui::BeginChild(title, size);
        Window = ImGui::GetCurrentWindow();
        Window->ScrollMax.y = 1.0f;
    }

    ImDrawList &DrawList = *Window->DrawList;

    // NextPlotData -----------------------------------------------------------

    if (gp.NextPlotData.HasXRange) {
        if (just_created || gp.NextPlotData.XRangeCond == ImGuiCond_Always)
        {
            plot.XAxis.Range = gp.NextPlotData.X;
        }
    }

    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (gp.NextPlotData.HasYRange[i]) {
            if (just_created || gp.NextPlotData.YRangeCond[i] == ImGuiCond_Always)
            {
                plot.YAxis[i].Range = gp.NextPlotData.Y[i];
            }
        }
    }

    // AXIS STATES ------------------------------------------------------------
    AxisState x(plot.XAxis, gp.NextPlotData.HasXRange, gp.NextPlotData.XRangeCond, true, 0);
    AxisState y[MAX_Y_AXES];
    y[0] = AxisState(plot.YAxis[0], gp.NextPlotData.HasYRange[0], gp.NextPlotData.YRangeCond[0], true, 0);
    y[1] = AxisState(plot.YAxis[1], gp.NextPlotData.HasYRange[1], gp.NextPlotData.YRangeCond[1],
                     HasFlag(plot.Flags, ImPlotFlags_YAxis2), y[0].present_so_far);
    y[2] = AxisState(plot.YAxis[2], gp.NextPlotData.HasYRange[2], gp.NextPlotData.YRangeCond[2],
                     HasFlag(plot.Flags, ImPlotFlags_YAxis3), y[1].present_so_far);

    const bool lock_plot  = x.lock && y[0].lock && y[1].lock && y[2].lock;

    // CONSTRAINTS ------------------------------------------------------------

    plot.XAxis.Range.Min = ConstrainNan(ConstrainInf(plot.XAxis.Range.Min));
    plot.XAxis.Range.Max = ConstrainNan(ConstrainInf(plot.XAxis.Range.Max));
    for (int i = 0; i < MAX_Y_AXES; i++) {
        plot.YAxis[i].Range.Min = ConstrainNan(ConstrainInf(plot.YAxis[i].Range.Min));
        plot.YAxis[i].Range.Max = ConstrainNan(ConstrainInf(plot.YAxis[i].Range.Max));
    }

    if (HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_LogScale))
        plot.XAxis.Range.Min = ConstrainLog(plot.XAxis.Range.Min);
    if (HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_LogScale))
        plot.XAxis.Range.Max = ConstrainLog(plot.XAxis.Range.Max);
    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_LogScale))
            plot.YAxis[i].Range.Min = ConstrainLog(plot.YAxis[i].Range.Min);
        if (HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_LogScale))
            plot.YAxis[i].Range.Max = ConstrainLog(plot.YAxis[i].Range.Max);
    }

    if (plot.XAxis.Range.Max <= plot.XAxis.Range.Min)
        plot.XAxis.Range.Max = plot.XAxis.Range.Min + FLT_EPSILON;
    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (plot.YAxis[i].Range.Max <= plot.YAxis[i].Range.Min)
            plot.YAxis[i].Range.Max = plot.YAxis[i].Range.Min + FLT_EPSILON;
    }

    // adaptive divisions
    if (HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_Adaptive)) {
        plot.XAxis.Divisions = (int)IM_ROUND(0.003 * gp.BB_Canvas.GetWidth());
        if (plot.XAxis.Divisions < 2)
            plot.XAxis.Divisions = 2;
    }
    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_Adaptive)) {
            plot.YAxis[i].Divisions = (int)IM_ROUND(0.003 * gp.BB_Canvas.GetHeight());
            if (plot.YAxis[i].Divisions < 2)
                plot.YAxis[i].Divisions = 2;
        }
    }

    // COLORS -----------------------------------------------------------------

    gp.Col_Frame  = gp.Style.Colors[ImPlotCol_FrameBg].w     == -1 ? ImGui::GetColorU32(ImGuiCol_FrameBg)    : ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_FrameBg]);
    gp.Col_Bg     = gp.Style.Colors[ImPlotCol_PlotBg].w      == -1 ? ImGui::GetColorU32(ImGuiCol_WindowBg)   : ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_PlotBg]);
    gp.Col_Border = gp.Style.Colors[ImPlotCol_PlotBorder].w  == -1 ? ImGui::GetColorU32(ImGuiCol_Text, 0.5f) : ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_PlotBorder]);

    UpdateAxisColor(ImPlotCol_XAxis, &gp.Col_X);
    UpdateAxisColor(ImPlotCol_YAxis, &gp.Col_Y[0]);
    UpdateAxisColor(ImPlotCol_YAxis2, &gp.Col_Y[1]);
    UpdateAxisColor(ImPlotCol_YAxis3, &gp.Col_Y[2]);

    gp.Col_Txt    = ImGui::GetColorU32(ImGuiCol_Text);
    gp.Col_TxtDis = ImGui::GetColorU32(ImGuiCol_TextDisabled);
    gp.Col_SlctBg = ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_Selection] * ImVec4(1,1,1,0.25f));
    gp.Col_SlctBd = ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_Selection]);
    gp.Col_QryBg =  ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_Query] * ImVec4(1,1,1,0.25f));
    gp.Col_QryBd =  ImGui::GetColorU32(gp.Style.Colors[ImPlotCol_Query]);

    // BB AND HOVER -----------------------------------------------------------

    // frame
    const ImVec2 frame_size = ImGui::CalcItemSize(size, 100, 100);
    gp.BB_Frame = ImRect(Window->DC.CursorPos, Window->DC.CursorPos + frame_size);
    ImGui::ItemSize(gp.BB_Frame);
    if (!ImGui::ItemAdd(gp.BB_Frame, 0, &gp.BB_Frame)) {
        gp.NextPlotData = ImNextPlotData();
        gp.CurrentPlot = NULL;
        if (!HasFlag(plot.Flags, ImPlotFlags_NoChild))
            ImGui::EndChild();
        return false;
    }
    gp.Hov_Frame = ImGui::ItemHoverable(gp.BB_Frame, ID);
    ImGui::RenderFrame(gp.BB_Frame.Min, gp.BB_Frame.Max, gp.Col_Frame, true, Style.FrameRounding);

    // canvas bb
    gp.BB_Canvas = ImRect(gp.BB_Frame.Min + Style.WindowPadding, gp.BB_Frame.Max - Style.WindowPadding);

    gp.RenderX = (HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_GridLines) ||
                    HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_TickMarks) ||
                    HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_TickLabels)) &&  plot.XAxis.Divisions > 1;
    for (int i = 0; i < MAX_Y_AXES; i++) {
        gp.RenderY[i] =
                y[i].present &&
                (HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_GridLines) ||
                 HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_TickMarks) ||
                 HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_TickLabels)) &&  plot.YAxis[i].Divisions > 1;
    }

    // get ticks
    if (gp.RenderX)
        GetTicks(plot.XAxis.Range, plot.XAxis.Divisions, plot.XAxis.Subdivisions, HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_LogScale), gp.XTicks);
    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (gp.RenderY[i]) {
            GetTicks(plot.YAxis[i].Range, plot.YAxis[i].Divisions, plot.YAxis[i].Subdivisions, HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_LogScale), gp.YTicks[i]);
        }
    }

    // label ticks
    if (HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_TickLabels))
        LabelTicks(gp.XTicks, HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_Scientific), gp.XTickLabels);

    float max_label_width[MAX_Y_AXES] = {};
    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (y[i].present && HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_TickLabels)) {
            LabelTicks(gp.YTicks[i], HasFlag(plot.YAxis[i].Flags, ImPlotAxisFlags_Scientific), gp.YTickLabels[i]);
            for (int t = 0; t < gp.YTicks[i].Size; t++) {
                ImTick *yt = &gp.YTicks[i][t];
                max_label_width[i] = yt->Size.x > max_label_width[i] ? yt->Size.x : max_label_width[i];
            }
        }
    }

    // grid bb
    const ImVec2 title_size = ImGui::CalcTextSize(title, NULL, true);
    const float txt_off     = 5;
    const float txt_height  = ImGui::GetTextLineHeight();
    const float pad_top     = title_size.x > 0.0f ? txt_height + txt_off : 0;
    const float pad_bot     = (HasFlag(plot.XAxis.Flags, ImPlotAxisFlags_TickLabels) ? txt_height + txt_off : 0) + (x_label ? txt_height + txt_off : 0);
    YPadCalculator y_axis_pad(y, max_label_width, txt_off);
    const float pad_left    = y_axis_pad(0) + (y_label ? txt_height + txt_off : 0);
    const float pad_right   = y_axis_pad(1) + y_axis_pad(2);
    gp.BB_Grid              = ImRect(gp.BB_Canvas.Min + ImVec2(pad_left, pad_top), gp.BB_Canvas.Max - ImVec2(pad_right, pad_bot));
    gp.Hov_Grid             = gp.BB_Grid.Contains(IO.MousePos);

    // axis region bbs
    const ImRect xAxisRegion_bb(gp.BB_Grid.Min + ImVec2(10, 0), ImVec2(gp.BB_Grid.Max.x, gp.BB_Frame.Max.y) - ImVec2(10, 0));
    const bool   hov_x_axis_region = xAxisRegion_bb.Contains(IO.MousePos);

    // The left labels are referenced to the left of the bounding box.
    gp.AxisLabelReference[0] = gp.BB_Grid.Min.x;
    // If Y axis 1 is present, its labels will be referenced to the
    // right of the bounding box.
    gp.AxisLabelReference[1] = gp.BB_Grid.Max.x;
    // The third axis may be either referenced to the right of the
    // bounding box, or 6 pixels further past the end of the 2nd axis.
    gp.AxisLabelReference[2] =
            !y[1].present ?
            gp.BB_Grid.Max.x :
            (gp.AxisLabelReference[1] + y_axis_pad(1) + 6);

    ImRect yAxisRegion_bb[MAX_Y_AXES];
    yAxisRegion_bb[0] = ImRect(ImVec2(gp.BB_Frame.Min.x, gp.BB_Grid.Min.y), ImVec2(gp.BB_Grid.Min.x + 6, gp.BB_Grid.Max.y - 10));
    // The auxiliary y axes are off to the right of the BB grid.
    yAxisRegion_bb[1] = ImRect(ImVec2(gp.BB_Grid.Max.x - 6, gp.BB_Grid.Min.y),
                               gp.BB_Grid.Max + ImVec2(y_axis_pad(1), 0));
    yAxisRegion_bb[2] = ImRect(ImVec2(gp.AxisLabelReference[2] - 6, gp.BB_Grid.Min.y),
                               yAxisRegion_bb[1].Max + ImVec2(y_axis_pad(2), 0));

    ImRect centralRegion(ImVec2(gp.BB_Grid.Min.x + 6, gp.BB_Grid.Min.y),
                         ImVec2(gp.BB_Grid.Max.x - 6, gp.BB_Grid.Max.y));

    const bool hov_y_axis_region[MAX_Y_AXES] = {
        y[0].present && (yAxisRegion_bb[0].Contains(IO.MousePos) || centralRegion.Contains(IO.MousePos)),
        y[1].present && (yAxisRegion_bb[1].Contains(IO.MousePos) || centralRegion.Contains(IO.MousePos)),
        y[2].present && (yAxisRegion_bb[2].Contains(IO.MousePos) || centralRegion.Contains(IO.MousePos)),
    };
    const bool any_hov_y_axis_region = hov_y_axis_region[0] || hov_y_axis_region[1] || hov_y_axis_region[2];

    // legend hovered from last frame
    const bool hov_legend = HasFlag(plot.Flags, ImPlotFlags_Legend) ? gp.Hov_Frame && plot.BB_Legend.Contains(IO.MousePos) : false;

    bool hov_query = false;
    if (gp.Hov_Frame && gp.Hov_Grid && plot.Queried && !plot.Querying) {
        ImRect bb_query = plot.QueryRect;

        bb_query.Min += gp.BB_Grid.Min;
        bb_query.Max += gp.BB_Grid.Min;

        hov_query = bb_query.Contains(IO.MousePos);
    }

    // QUERY DRAG -------------------------------------------------------------
    if (plot.DraggingQuery && (IO.MouseReleased[0] || !IO.MouseDown[0])) {
        plot.DraggingQuery = false;
    }
    if (plot.DraggingQuery) {
        ImGui::SetMouseCursor(ImGuiMouseCursor_ResizeAll);
        plot.QueryRect.Min += IO.MouseDelta;
        plot.QueryRect.Max += IO.MouseDelta;
    }
    if (gp.Hov_Frame && gp.Hov_Grid && hov_query && !plot.DraggingQuery && !plot.Selecting && !hov_legend) {
        ImGui::SetMouseCursor(ImGuiMouseCursor_ResizeAll);
        const bool any_y_dragging = plot.YAxis[0].Dragging || plot.YAxis[1].Dragging || plot.YAxis[2].Dragging;
        if (IO.MouseDown[0] && !plot.XAxis.Dragging && !any_y_dragging) {
            plot.DraggingQuery = true;
        }
    }

    // DRAG INPUT -------------------------------------------------------------


    // end drags
    if (plot.XAxis.Dragging && (IO.MouseReleased[0] || !IO.MouseDown[0])) {
        plot.XAxis.Dragging             = false;
        G.IO.MouseDragMaxDistanceSqr[0] = 0;
    }
    for (int i = 0; i < MAX_Y_AXES; i++) {
        if (plot.YAxis[i].Dragging && (IO.MouseReleased[0] || !IO.MouseDown[0])) {
            plot.YAxis[i].Dragging             = false;
            G.IO.MouseDragMaxDistanceSqr[0] = 0;
        }
    }
    const bool any_y_dragging = plot.YAxis[0].Dragging || plot.YAxis[1].Dragging || plot.YAxis[2].Dragging;
    bool drag_in_progress = plot.XAxis.Dragging || any_y_dragging;
    // do drag
    if (drag_in_progress) {
        UpdateTransformCache();