Custom per-item colors for line and scatter plot

implot.h

@@ -589,6 +589,9 @@ typedef int (*ImPlotFormatter)(double value, char* buff, int size, void* user_da
 // Callback signature for data getter.
 typedef ImPlotPoint (*ImPlotGetter)(int idx, void* user_data);
 
+// Callback signature for color getter.
+typedef ImU32 (*ImPlotColorGetter)(ImPlotCol col, int idx, void* user_data);
+
 // Callback signature for axis transform.
 typedef double (*ImPlotTransform)(double value, void* user_data);
 
@@ -858,11 +861,13 @@ IMPLOT_API void SetNextAxesToFit();
 IMPLOT_TMP void PlotLine(const char* label_id, const T* values, int count, double xscale=1, double xstart=0, ImPlotLineFlags flags=0, int offset=0, int stride=sizeof(T));
 IMPLOT_TMP void PlotLine(const char* label_id, const T* xs, const T* ys, int count, ImPlotLineFlags flags=0, int offset=0, int stride=sizeof(T));
 IMPLOT_API void PlotLineG(const char* label_id, ImPlotGetter getter, void* data, int count, ImPlotLineFlags flags=0);
+IMPLOT_API void PlotLineCG(const char* label_id, ImPlotGetter getter_func, void* data, int count, ImPlotColorGetter color_func, void* color_data, ImPlotLineFlags flags=0);
 
 // Plots a standard 2D scatter plot. Default marker is ImPlotMarker_Circle.
 IMPLOT_TMP void PlotScatter(const char* label_id, const T* values, int count, double xscale=1, double xstart=0, ImPlotScatterFlags flags=0, int offset=0, int stride=sizeof(T));
 IMPLOT_TMP void PlotScatter(const char* label_id, const T* xs, const T* ys, int count, ImPlotScatterFlags flags=0, int offset=0, int stride=sizeof(T));
 IMPLOT_API void PlotScatterG(const char* label_id, ImPlotGetter getter, void* data, int count, ImPlotScatterFlags flags=0);
+IMPLOT_API void PlotScatterCG(const char* label_id, ImPlotGetter getter, void* data, int count, ImPlotColorGetter color_func, void* color_data, ImPlotScatterFlags flags=0);
 
 // Plots a a stairstep graph. The y value is continued constantly to the right from every x position, i.e. the interval [x[i], x[i+1]) has the value y[i]
 IMPLOT_TMP void PlotStairs(const char* label_id, const T* values, int count, double xscale=1, double xstart=0, ImPlotStairsFlags flags=0, int offset=0, int stride=sizeof(T));

implot_demo.cpp

@@ -2158,7 +2158,39 @@ void Demo_CustomPlottersAndTooltips()  {
         MyImPlot::PlotCandlestick("GOOGL",dates, opens, closes, lows, highs, 218, tooltip, 0.25f, bullCol, bearCol);
         ImPlot::EndPlot();
     }
+}
+
+void Demo_CustomColors() {
+
+    if (ImPlot::BeginPlot("Custom Colors")){
+        ImPlot::PlotLineCG("Line Plot", 
+            [](int idx, void* user_data){ 
+                return ImPlotPoint(0.1*idx, sin(0.1*idx)); 
+            }, nullptr, 100, 
+            [](ImPlotCol col, int idx, void* user_data){ 
+                switch (idx % 3){
+                case 0 : return 0xFF0000FFu;
+                case 1 : return 0xFF00FF00u;
+                case 2 : return 0xFFFF0000u;
+                default: return 0u;
+                }
+            }, nullptr);
+        ImPlot::PlotScatterCG("Scatter Plot", 
+            [](int idx, void* user_data){ 
+                srand(idx);
+                return ImPlotPoint(10.0*float(rand())/float(RAND_MAX), -1.0+2.0*float(rand())/float(RAND_MAX));
+            }, nullptr, 20, 
+            [](ImPlotCol col, int idx, void* user_data){ 
+                switch (idx % 3){
+                case 0 : return 0xFF0000FFu;
+                case 1 : return 0xFF00FF00u;
+                case 2 : return 0xFFFF0000u;
+                default: return 0u;
+                }
+            }, nullptr);
+        ImPlot::EndPlot();
     }
+}
 
 //-----------------------------------------------------------------------------
 // DEMO WINDOW
@@ -2247,6 +2279,7 @@ void ShowDemoWindow(bool* p_open) {
             DemoHeader("Images", Demo_Images);
             DemoHeader("Markers and Text", Demo_MarkersAndText);
             DemoHeader("NaN Values", Demo_NaNValues);
+            DemoHeader("Custom Colors", Demo_CustomColors);
             ImGui::EndTabItem();
         }
         if (ImGui::BeginTabItem("Subplots")) {