initial heatmap prototype working

implot.cpp

@@ -31,6 +31,7 @@ Below is a change-log of API breaking changes only. If you are using one of the
 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.
 
+- 2020/06/01 (0.3) - SetPalette/RestorePalette were changed to SetColormap/RestoreColormap for consistency with other plotting libraries.
 - 2020/05/31 (0.3) - Plot functions taking custom ImVec2* getters were removed. Use the ImPlotPoint* getter versions instead.
 - 2020/05/29 (0.3) - The signature of ImPlotLimits::Contains was changed to take two doubles instead of ImVec2
 - 2020/05/16 (0.2) - All plotting functions were reverted to being prefixed with "Plot" to maintain a consistent VerbNoun style. `Plot` was split into `PlotLine`
@@ -152,8 +153,9 @@ inline void FlipFlag(TSet& set, TFlag flag) {
     HasFlag(set, flag) ? set &= ~flag : set |= flag;
 }
 
-/// Linearly remaps float x from [x0 x1] to [y0 y1].
+/// Linearly remaps x from [x0 x1] to [y0 y1].
-inline float Remap(float x, float x0, float x1, float y0, float y1) {
+template <typename T>
+inline T Remap(T x, T x0, T x1, T y0, T y1) {
     return y0 + (x - x0) * (y1 - y0) / (x1 - x0);
 }
 
@@ -334,7 +336,7 @@ struct ImPlotContext {
     ImPlotContext() : RenderX(), RenderY() {
         CurrentPlot = NULL;
         FitThisFrame = FitX = false;
-        RestorePalette();
+        RestoreColormap();
     }
 
     /// ALl Plots
@@ -385,7 +387,7 @@ struct ImPlotContext {
     // Mouse pos
     ImPlotPoint LastMousePos[MAX_Y_AXES];
     // Style
-    ImVector<ImVec4> ColorMap;
+    ImVector<ImVec4> Colormap;
     ImPlotStyle Style;
     ImVector<ImGuiColorMod> ColorModifiers;  // Stack for PushStyleColor()/PopStyleColor()
     ImVector<ImGuiStyleMod> StyleModifiers;  // Stack for PushStyleVar()/PopStyleVar()
@@ -404,7 +406,7 @@ static ImPlotContext gp;
 
 /// Returns the next unused default plot color
 ImVec4 NextColor() {
-    ImVec4 col  = gp.ColorMap[gp.CurrentPlot->ColorIdx % gp.ColorMap.size()];
+    ImVec4 col  = gp.Colormap[gp.CurrentPlot->ColorIdx % gp.Colormap.size()];
     gp.CurrentPlot->ColorIdx++;
     return col;
 }
@@ -1078,8 +1080,8 @@ bool BeginPlot(const char* title, const char* x_label, const char* y_label, cons
         float zoom_rate = 0.1f;
         if (IO.MouseWheel > 0)
             zoom_rate = (-zoom_rate) / (1.0f + (2.0f * zoom_rate));
-        float tx = Remap(IO.MousePos.x, gp.BB_Grid.Min.x, gp.BB_Grid.Max.x, 0, 1);
+        float tx = Remap(IO.MousePos.x, gp.BB_Grid.Min.x, gp.BB_Grid.Max.x, 0.0f, 1.0f);
-        float ty = Remap(IO.MousePos.y, gp.BB_Grid.Min.y, gp.BB_Grid.Max.y, 0, 1);
+        float ty = Remap(IO.MousePos.y, gp.BB_Grid.Min.y, gp.BB_Grid.Max.y, 0.0f, 1.0f);
         if (hov_x_axis_region && !x.lock) {
             ImPlotAxisScale axis_scale(0, tx, ty, zoom_rate);
             const ImPlotPoint& plot_tl = axis_scale.Min;
@@ -1866,17 +1868,18 @@ ImPlotStyle& GetStyle() {
     return gp.Style;
 }
 
-void SetPalette(const ImVec4* colors, int num_colors) {
+void SetColormap(const ImVec4* colors, int num_colors) {
-    gp.ColorMap.shrink(0);
+    gp.Colormap.shrink(0);
-    gp.ColorMap.reserve(num_colors);
+    gp.Colormap.reserve(num_colors);
     for (int i = 0; i < num_colors; ++i) {
-        gp.ColorMap.push_back(colors[i]);
+        gp.Colormap.push_back(colors[i]);
     }
 }
 
-/// Returns the next unused default plot color
+void SetColormap(ImPlotColormap colormap) {
-void RestorePalette() {
+    static ImVec4 maps[ImPlotColormap_COUNT][10] {
-    static ImVec4 default_colors[10] = {
+        // ImPlotColormap_Default
+        {
             ImVec4((0.0F), (0.7490196228F), (1.0F), (1.0F)),                    // Blues::DeepSkyBlue,
             ImVec4((1.0F), (0.0F), (0.0F), (1.0F)),                             // Reds::Red,
             ImVec4((0.4980392158F), (1.0F), (0.0F), (1.0F)),                    // Greens::Chartreuse,
@@ -1887,8 +1890,83 @@ void RestorePalette() {
             ImVec4((0.5411764979F), (0.1686274558F), (0.8862745166F), (1.0F)),  // Purples::BlueViolet,
             ImVec4((0.5f), (0.5f), (0.5f), (1.0F)),                             // Grays::Gray50,
             ImVec4((0.8235294223F), (0.7058823705F), (0.5490196347F), (1.0F))   // Browns::Tan
+        },
+        // ImPlotColormap_Viridis
+        {
+            ImVec4(0.267004f, 0.004874f, 0.329415f, 1.f),
+            ImVec4(0.281412f, 0.155834f, 0.469201f, 1.f),
+            ImVec4(0.244972f, 0.287675f, 0.53726f,  1.f),
+            ImVec4(0.190631f, 0.407061f, 0.556089f, 1.f),
+            ImVec4(0.147607f, 0.511733f, 0.557049f, 1.f),
+            ImVec4(0.119699f, 0.618490f, 0.536347f, 1.f),
+            ImVec4(0.208030f, 0.718701f, 0.472873f, 1.f),
+            ImVec4(0.430983f, 0.808473f, 0.346476f, 1.f),
+            ImVec4(0.709898f, 0.868751f, 0.169257f, 1.f),
+            ImVec4(0.993248f, 0.906157f, 0.143936f, 1.f )
+        },
+        // ImPlotColormap_Plasma
+        {
+            ImVec4(0.050383f, 0.029803f, 0.527975f, 1.f),
+            ImVec4(0.274191f, 0.012109f, 0.622722f, 1.f),
+            ImVec4(0.447714f, 0.002080f, 0.660240f, 1.f),
+            ImVec4(0.610667f, 0.090204f, 0.619951f, 1.f),
+            ImVec4(0.740143f, 0.213864f, 0.524216f, 1.f),
+            ImVec4(0.846788f, 0.342551f, 0.420579f, 1.f),
+            ImVec4(0.928329f, 0.472975f, 0.326067f, 1.f),
+            ImVec4(0.983041f, 0.624131f, 0.227937f, 1.f),
+            ImVec4(0.991209f, 0.790537f, 0.149377f, 1.f),
+            ImVec4(0.940015f, 0.975158f, 0.131326f, 1.f)
+        },
+        // ImPlotColormap_Hot
+        {
+            ImVec4(0.3333f,    0.0f,    0.0f, 1.0f),
+            ImVec4(0.6667f,    0.0f,    0.0f, 1.0f),
+            ImVec4(1.0000f,    0.0f,    0.0f, 1.0f),
+            ImVec4(1.0000f, 0.3333f,    0.0f, 1.0f),
+            ImVec4(1.0000f, 0.6667f,    0.0f, 1.0f),
+            ImVec4(1.0000f, 1.0000f,    0.0f, 1.0f),
+            ImVec4(1.0000f, 1.0000f, 0.2500f, 1.0f),
+            ImVec4(1.0000f, 1.0000f, 0.5000f, 1.0f),
+            ImVec4(1.0000f, 1.0000f, 0.7500f, 1.0f),
+            ImVec4(1.0000f, 1.0000f, 1.0000f, 1.0f)
+        },
+        // ImPlotColormap_Cool
+        {
+            ImVec4(   0.0f, 1.0000f, 1.0000f, 1.0f),
+            ImVec4(0.1111f, 0.8889f, 1.0000f, 1.0f),
+            ImVec4(0.2222f, 0.7778f, 1.0000f, 1.0f),
+            ImVec4(0.3333f, 0.6667f, 1.0000f, 1.0f),
+            ImVec4(0.4444f, 0.5556f, 1.0000f, 1.0f),
+            ImVec4(0.5556f, 0.4444f, 1.0000f, 1.0f),
+            ImVec4(0.6667f, 0.3333f, 1.0000f, 1.0f),
+            ImVec4(0.7778f, 0.2222f, 1.0000f, 1.0f),
+            ImVec4(0.8889f, 0.1111f, 1.0000f, 1.0f),
+            ImVec4(1.0000f,    0.0f, 1.0000f, 1.0f)
+        }
+        // ImPlotColormap_Spring
+        // ImPlotColormap_Summer
+        // ImPlotColormap_Autumn
+        // ImPlotColormap_Winter
     };
-    SetPalette(default_colors, 10);
+    SetColormap(maps[colormap], 10);
+}
+
+/// Returns the next unused default plot color
+void RestoreColormap() {
+    SetColormap(ImPlotColormap_Default);
+}
+
+ImVec4 SampleColormap(float t) {
+    t = ImClamp(t,0.0f,1.0f);
+    int i1 = (int)((gp.Colormap.Size-1) * t);
+    int i2 = i1 + 1;
+
+    if (i2 == gp.Colormap.Size)
+        return gp.Colormap[i1];
+    float t1 = (float)i1 / (float)gp.Colormap.Size;
+    float t2 = (float)i2 / (float)gp.Colormap.Size;
+    t = Remap(t, t1, t2, 0.0f, 1.0f);
+    return ImLerp(gp.Colormap[i1],gp.Colormap[i2],t);
 }
 
 void PushStyleColor(ImPlotCol idx, ImU32 col) {
@@ -2515,8 +2593,7 @@ void PlotBarsEx(const char* label_id, Getter getter, int count, TWidth width, in
 
     int idx = offset;
     for (int i = 0; i < count; ++i) {
-        ImPlotPoint p;
+        ImPlotPoint p = getter(idx);
-        p = getter(idx);
         idx = (idx + 1) % count;
         if (p.y == 0)
             continue;
@@ -2606,8 +2683,7 @@ void PlotBarsHEx(const char* label_id, Getter getter, int count, THeight height,
 
     int idx = offset;
     for (int i = 0; i < count; ++i) {
-        ImPlotPoint p;
+        ImPlotPoint p = getter(idx);
-        p = getter(idx);
         idx = (idx + 1) % count;
         if (p.x == 0)
             continue;
@@ -2828,9 +2904,42 @@ void PlotPieChart(const char** label_ids, double* values, int count, double x, d
 //-----------------------------------------------------------------------------
 
 void PlotHeatmap(const char* label_id, const double* values, int rows, int cols, double scale_min, double scale_max, bool show_labels) {
+    IM_ASSERT_USER_ERROR(gp.CurrentPlot != NULL, "PlotHeatmap() Needs to be called between BeginPlot() and EndPlot()!");
     ImPlotItem* item = RegisterItem(label_id);
     if (!item->Show)
         return;
+    if (gp.FitThisFrame) {
+        FitPoint(ImPlotPoint(0, 0));
+        FitPoint(ImPlotPoint(1, 1));        
+    }
+
+    ImDrawList& DrawList = *ImGui::GetWindowDrawList();
+    double w = 1.0 / cols;
+    double h = 1.0 / rows;
+    const ImPlotPoint half_size(w*0.5,h*0.5);
+    ImGui::PushClipRect(gp.BB_Grid.Min, gp.BB_Grid.Max, true);
+    int i = 0;
+    for (int r = 0; r < rows; ++r) {
+        for (int c = 0; c < cols; ++c) {
+            ImPlotPoint p;
+            p.x = 0.5*w + c*w;
+            p.y = 1 - (0.5*h + r*h);
+            ImVec2 px = PlotToPixels(p);
+            ImVec2 a  = PlotToPixels(p.x - half_size.x, p.y - half_size.y);
+            ImVec2 b  = PlotToPixels(p.x + half_size.x, p.y + half_size.y);
+            float t = (float)Remap(values[i], scale_min, scale_max, 0.0, 1.0);
+            ImVec4 color = SampleColormap(t);
+            DrawList.AddRectFilled(a, b, ImGui::GetColorU32(color));
+            if (show_labels) {
+                char buff[32];
+                sprintf(buff, "%g", values[i]);
+                ImVec2 size = ImGui::CalcTextSize(buff);
+                DrawList.AddText(px - size * 0.5f, ImGui::GetColorU32(ImGuiCol_Text), buff);
+            }
+            i++;
+        }
+    }
+    ImGui::PopClipRect();
 }
 
 //-----------------------------------------------------------------------------

implot.h

@@ -34,6 +34,7 @@ typedef int ImPlotAxisFlags;
 typedef int ImPlotCol;
 typedef int ImPlotStyleVar;
 typedef int ImPlotMarker;
+typedef int ImPlotColormap;
 
 // Options for plots.
 enum ImPlotFlags_ {
@@ -114,7 +115,25 @@ enum ImPlotMarker_ {
     ImPlotMarker_Asterisk    = 1 << 10, // a asterisk marker will be rendered at each point (not filled)
 };
 
-/// Double precision version of ImVec2 used by ImPlot. Extensible by end users.
+// Built-in colormaps
+enum ImPlotColormap_ {
+    // Qualitative
+    ImPlotColormap_Default,
+    // Sequential
+    ImPlotColormap_Viridis,
+    ImPlotColormap_Plasma,
+    ImPlotColormap_Hot,
+    ImPlotColormap_Cool,
+    // ImPlotColormap_Spring,
+    // ImPlotColormap_Summer,
+    // ImPlotColormap_Autumn,
+    // ImPlotColormap_Winter,
+    // Diverging
+    // ...
+    ImPlotColormap_COUNT
+};
+
+// Double precision version of ImVec2 used by ImPlot. Extensible by end users.
 struct ImPlotPoint {
     double x, y;
     ImPlotPoint()  { x = y = 0.0; }
@@ -226,7 +245,7 @@ void PlotErrorBars(const char* label_id, const double* xs, const double* ys, con
 void PlotPieChart(const char** label_ids, float* values, int count, float x, float y, float radius, bool show_percents = true, float angle0 = 90);
 void PlotPieChart(const char** label_ids, double* values, int count, double x, double y, double radius, bool show_percents = true, double angle0 = 90);
 
-// Plots a 2D heatmap chart.
+// Plots a 2D heatmap chart. Values are expected to be in row-major order.
 void PlotHeatmap(const char* label_id, const double* values, int rows, int cols, double scale_min, double scale_max, bool show_labels = true);
 
 // Plots digital data.
@@ -242,15 +261,15 @@ void PlotText(const char* text, double x, double y, bool vertical = false, const
 // Plot Queries
 //-----------------------------------------------------------------------------
 
-/// Returns true if the plot area in the current or most recent plot is hovered.
+// Returns true if the plot area in the current or most recent plot is hovered.
 bool IsPlotHovered();
-/// Returns the mouse position in x,y coordinates of the current or most recent plot. A negative y_axis uses the current value of SetPlotYAxis (0 initially).
+// Returns the mouse position in x,y coordinates of the current or most recent plot. A negative y_axis uses the current value of SetPlotYAxis (0 initially).
 ImPlotPoint GetPlotMousePos(int y_axis = -1);
-/// Returns the current or most recent plot axis range. A negative y_axis uses the current value of SetPlotYAxis (0 initially).
+// Returns the current or most recent plot axis range. A negative y_axis uses the current value of SetPlotYAxis (0 initially).
 ImPlotLimits GetPlotLimits(int y_axis = -1);
-/// Returns true if the current or most recent plot is being queried.
+// Returns true if the current or most recent plot is being queried.
 bool IsPlotQueried();
-/// Returns the current or most recent plot query bounds.
+// Returns the current or most recent plot query bounds.
 ImPlotLimits GetPlotQuery(int y_axis = -1);
 
 //-----------------------------------------------------------------------------
@@ -260,10 +279,14 @@ ImPlotLimits GetPlotQuery(int y_axis = -1);
 // Provides access to plot style structure for permanant modifications to colors, sizes, etc.
 ImPlotStyle& GetStyle();
 
-// Sets the color palette to be used for plot items.
+// Switch to one of the built-in colormaps for plot items.
-void SetPalette(const ImVec4* colors, int num_colors);
+void SetColormap(ImPlotColormap colormap);
+// Sets a custom colormap to be used for plot items.
+void SetColormap(const ImVec4* colors, int num_colors);
 // Restores the default ImPlot colormap.
-void RestorePalette();
+void RestoreColormap();
+// Linearly interpolates a color from the current colormap/
+ImVec4 SampleColormap(float t);
 
 // Temporarily modify a plot color. Don't forget to call PopStyleColor!
 void PushStyleColor(ImPlotCol idx, ImU32 col);
@@ -283,14 +306,14 @@ void PopStyleVar(int count = 1);
 // Plot Utils
 //-----------------------------------------------------------------------------
 
-/// Set the axes range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the axes limits will be locked.
+// Set the axes range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the axes limits will be locked.
 void SetNextPlotLimits(double x_min, double x_max, double y_min, double y_max, ImGuiCond cond = ImGuiCond_Once);
-/// Set the X axis range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the X axis limits will be locked.
+// Set the X axis range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the X axis limits will be locked.
 void SetNextPlotLimitsX(double x_min, double x_max, ImGuiCond cond = ImGuiCond_Once);
-/// Set the Y axis range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the Y axis limits will be locked.
+// Set the Y axis range limits of the next plot. Call right before BeginPlot(). If ImGuiCond_Always is used, the Y axis limits will be locked.
 void SetNextPlotLimitsY(double y_min, double y_max, ImGuiCond cond = ImGuiCond_Once, int y_axis = 0);
 
-/// Select which Y axis will be used for subsequent plot elements. The default is '0', or the first (left) Y axis.
+// Select which Y axis will be used for subsequent plot elements. The default is '0', or the first (left) Y axis.
 void SetPlotYAxis(int y_axis);
 
 // Get the current Plot position (top-left) in pixels.

implot_demo.cpp

@@ -129,7 +129,7 @@ void ShowDemoWindow(bool* p_open) {
     if (show_app_metrics)             { ImGui::ShowMetricsWindow(&show_app_metrics); }
     if (show_app_style_editor)        { ImGui::Begin("Style Editor", &show_app_style_editor); ImGui::ShowStyleEditor(); ImGui::End(); }
     ImGui::SetNextWindowPos(ImVec2(50, 50), ImGuiCond_FirstUseEver);
-    ImGui::SetNextWindowSize(ImVec2(520, 750), ImGuiCond_FirstUseEver);
+    ImGui::SetNextWindowSize(ImVec2(530, 750), ImGuiCond_FirstUseEver);
     ImGui::Begin("ImPlot Demo", p_open, ImGuiWindowFlags_MenuBar);
     if (ImGui::BeginMenuBar()) {
         if (ImGui::BeginMenu("Tools")) {
@@ -307,7 +307,7 @@ void ShowDemoWindow(bool* p_open) {
             ImVec4(0.9882f,    0.3059f,    0.1647f, 1.0f),
             ImVec4(0.7412f,       0.0f,    0.1490f, 1.0f),
         };
-        ImPlot::SetPalette(YlOrRd, 5);
+        ImPlot::SetColormap(YlOrRd, 5);
         SetNextPlotLimits(0,1,0,1,ImGuiCond_Always);
         static const char* labels2[]   = {"One","Two","Three","Four","Five"};
         static t_float not_normalized[] = {1,2,3,4,5};
@@ -315,7 +315,38 @@ void ShowDemoWindow(bool* p_open) {
             ImPlot::PlotPieChart(labels2, not_normalized, 5, 0.5f, 0.5f, 0.4f);
             ImPlot::EndPlot();
         }
-        ImPlot::RestorePalette();
+        ImPlot::RestoreColormap();
+    }
+    //-------------------------------------------------------------------------
+    if (ImGui::CollapsingHeader("Heatmaps")) {
+        static double values1[7][7] = {{0.8, 2.4, 2.5, 3.9, 0.0, 4.0, 0.0},
+                                     {2.4, 0.0, 4.0, 1.0, 2.7, 0.0, 0.0},
+                                     {1.1, 2.4, 0.8, 4.3, 1.9, 4.4, 0.0},
+                                     {0.6, 0.0, 0.3, 0.0, 3.1, 0.0, 0.0},
+                                     {0.7, 1.7, 0.6, 2.6, 2.2, 6.2, 0.0},
+                                     {1.3, 1.2, 0.0, 0.0, 0.0, 3.2, 5.1},
+                                     {0.1, 2.0, 0.0, 1.4, 0.0, 1.9, 6.3}};
+        static double values2[100*100];
+        for (int i = 0; i < 100*100; ++i) {
+            values2[i] = RandomRange(0,1);
+        }
+        static ImPlotColormap map = ImPlotColormap_Viridis;
+        if (ImGui::Button("Cycle Colormaps"))
+            map = (map + 1) % ImPlotColormap_COUNT;
+        static ImPlotAxisFlags axes_flags = ImPlotAxisFlags_LockMin | ImPlotAxisFlags_LockMax;
+        if (ImPlot::BeginPlot("##Heatmap1",NULL,NULL,ImVec2(250,250),0,axes_flags,axes_flags)) {
+            ImPlot::SetColormap(map);
+            ImPlot::PlotHeatmap("heat",values1[0],7,7,0,6.3);
+            ImPlot::EndPlot();
+            ImPlot::RestoreColormap();
+        }
+        ImGui::SameLine();
+        if (ImPlot::BeginPlot("##Heatmap2",NULL,NULL,ImVec2(250,250),0,axes_flags,axes_flags)) {
+            ImPlot::SetColormap(map);
+            ImPlot::PlotHeatmap("heat",values2,100,100,0,1,false);
+            ImPlot::EndPlot();
+            ImPlot::RestoreColormap();
+        }
     }
     //-------------------------------------------------------------------------
     if (ImGui::CollapsingHeader("Realtime Plots")) {
@@ -783,12 +814,12 @@ void ShowDemoWindow(bool* p_open) {
     }
     //-------------------------------------------------------------------------
     if (ImGui::CollapsingHeader("Custom Styles")) {
-        static ImVec4 my_palette[3] = {
+        static ImVec4 my_map[3] = {
             ImVec4(0.000f, 0.980f, 0.604f, 1.0f),
             ImVec4(0.996f, 0.278f, 0.380f, 1.0f),
             ImVec4(0.1176470593f, 0.5647059083f, 1.0f, 1.0f),
         };
-        ImPlot::SetPalette(my_palette, 3);
+        ImPlot::SetColormap(my_map, 3);
         ImPlot::PushStyleColor(ImPlotCol_FrameBg, IM_COL32(32,51,77,255));
         ImPlot::PushStyleColor(ImPlotCol_PlotBg, ImVec4(0,0,0,0));
         ImPlot::PushStyleColor(ImPlotCol_PlotBorder, ImVec4(0,0,0,0));
@@ -810,7 +841,7 @@ void ShowDemoWindow(bool* p_open) {
         }
         ImPlot::PopStyleColor(5);
         ImPlot::PopStyleVar();
-        ImPlot::RestorePalette();
+        ImPlot::RestoreColormap();
     }
     //-------------------------------------------------------------------------
     if (ImGui::CollapsingHeader("Custom Rendering")) {