tidy up legend DND

implot.cpp

@@ -1474,13 +1474,13 @@ void EndPlot() {
             label_bb.Min = legend_content_bb.Min + legend_spacing + ImVec2(0, i * txt_ht) + ImVec2(2, 2);
             label_bb.Max = legend_content_bb.Min + legend_spacing + ImVec2(0, i * txt_ht) + ImVec2(legend_content_bb.Max.x, legend_icon_size - 2);
             ImU32 col_hl_txt;
-            if (ImHasFlag(plot.Flags, ImPlotFlags_Highlight) && hov_legend && (icon_bb.Contains(IO.MousePos) || label_bb.Contains(IO.MousePos))) {
-                item->Highlight = true;
+            if (hov_legend && (icon_bb.Contains(IO.MousePos) || label_bb.Contains(IO.MousePos))) {
+                item->LegendHovered = true;
                 col_hl_txt = ImGui::GetColorU32(ImLerp(col_txt, item->Color, 0.25f));
             }
             else
             {
-               item->Highlight = false;
+               item->LegendHovered = false;
                col_hl_txt = ImGui::GetColorU32(col_txt);
             }
             ImU32 iconColor;
@@ -1820,10 +1820,7 @@ bool IsLegendEntryHovered(const char* label_id) {
     IM_ASSERT_USER_ERROR(gp.CurrentPlot != NULL, "IsPlotItemHighlight() needs to be called between BeginPlot() and EndPlot()!");
     ImGuiID id = ImGui::GetID(label_id);
     ImPlotItem* item = gp.CurrentPlot->Items.GetByKey(id);
-    if (item && item->Highlight)
-        return true;
-    else
-        return false;
+    return item && item->LegendHovered;
 }
 
 bool BeginLegendDragDropSource(const char* label_id, ImGuiDragDropFlags flags) {
@@ -1831,7 +1828,7 @@ bool BeginLegendDragDropSource(const char* label_id, ImGuiDragDropFlags flags) {
     IM_ASSERT_USER_ERROR(gp.CurrentPlot != NULL, "BeginLegendDragDropSource() needs to be called between BeginPlot() and EndPlot()!");
     ImGuiID source_id = ImGui::GetID(label_id);
     ImPlotItem* item = gp.CurrentPlot->Items.GetByKey(source_id);
-    bool is_hovered = item && item->Highlight;
+    bool is_hovered = item && item->LegendHovered;
 
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
@@ -1891,7 +1888,7 @@ bool BeginLegendDragDropSource(const char* label_id, ImGuiDragDropFlags flags) {
     return false;
 }
 
-void EndDragDropSource() {
+void EndLegendDragDropSource() {
     ImGui::EndDragDropSource();
 }
 

implot.h

@@ -422,8 +422,6 @@ ImPlotLimits GetPlotLimits(int y_axis = IMPLOT_AUTO);
 bool IsPlotQueried();
 // Returns the current plot query bounds.
 ImPlotLimits GetPlotQuery(int y_axis = IMPLOT_AUTO);
-// Returns true if a plot item legend entry is hovered.
-bool IsLegendEntryHovered(const char* label_id);
 
 //-----------------------------------------------------------------------------
 // Plot and Item Styling
@@ -513,6 +511,17 @@ void ShowColormapScale(double scale_min, double scale_max, float height);
 // Returns a null terminated string name for a built-in colormap.
 const char* GetColormapName(ImPlotColormap colormap);
 
+//-----------------------------------------------------------------------------
+// Legend Utils
+//-----------------------------------------------------------------------------
+
+// Returns true if a plot item legend entry is hovered.
+bool IsLegendEntryHovered(const char* label_id);
+// Begin a drag and drop source from a legend entry. The only supported flag is SourceNoPreviewTooltip
+bool BeginLegendDragDropSource(const char* label_id, ImGuiDragDropFlags flags = 0);
+// End legend drag and drop source.
+void EndLegendDragDropSource();
+
 //-----------------------------------------------------------------------------
 // Miscellaneous
 //-----------------------------------------------------------------------------
@@ -534,11 +543,6 @@ void PushPlotClipRect();
 // Pop plot clip rect.
 void PopPlotClipRect();
 
-// Begin a drag and drop source from a legend entry.  The only supported flag is SourceNoPreviewTooltip
-bool BeginLegendDragDropSource(const char* label_id, ImGuiDragDropFlags flags = 0);
-// End drag and drop source.
-void EndDragDropSource();
-
 //-----------------------------------------------------------------------------
 // Demo (add implot_demo.cpp to your sources!)
 //-----------------------------------------------------------------------------

implot_demo.cpp

@@ -715,7 +715,7 @@ void ShowDemoWindow(bool* p_open) {
             init = false;
         }
         ImGui::BulletText("Drag data items from the left column onto the plot or onto a specific y-axis.");
-        ImGui::BulletText("Drag data items from the legend onto a specific y-axis.");
+        ImGui::BulletText("Redrag data items from the legend onto other y-axes.");
         ImGui::BeginGroup();
         if (ImGui::Button("Clear", ImVec2(100, 0))) {
             for (int i = 0; i < K_CHANNELS; ++i) {
@@ -755,17 +755,21 @@ void ShowDemoWindow(bool* p_open) {
                     sprintf(label, "data_%d", i);
 					ImPlot::SetPlotYAxis(yAxis[i]);
                     ImPlot::PlotLine(label, &data[i].Data[0].x, &data[i].Data[0].y, data[i].Data.size(), data[i].Offset, 2 * sizeof(t_float));
+                    // allow legend labels to be dragged and dropped
                     if (ImPlot::BeginLegendDragDropSource(label)) {
                         ImGui::SetDragDropPayload("DND_PLOT", &i, sizeof(int));
                         ImGui::TextUnformatted(label);
-                        ImPlot::EndDragDropSource();
+                        ImPlot::EndLegendDragDropSource();
                     }
                 }
             }
+            // make our plot a drag and drop target
 			if (ImGui::BeginDragDropTarget()) {
 				if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload("DND_PLOT")) {
 					int i = *(int*)payload->Data;
 					show[i] = true;
+                    yAxis[i] = 0;
+                    // set specific y-axis if hovered
 					for (int y = 0; y < 3; y++) {
 						if (ImPlot::IsPlotYAxisHovered(y))
 							yAxis[i] = y;

implot_internal.h

@@ -301,7 +301,7 @@ struct ImPlotItem
     ImVec4       Color;
     int          NameOffset;
     bool         Show;
-    bool         Highlight;
+    bool         LegendHovered;
     bool         SeenThisFrame;
 
     ImPlotItem() {
@@ -310,7 +310,7 @@ struct ImPlotItem
         NameOffset    = -1;
         Show          = true;
         SeenThisFrame = false;
-        Highlight     = false;
+        LegendHovered = false;
     }
 
     ~ImPlotItem() { ID = 0; }

implot_items.cpp

@@ -145,7 +145,7 @@ bool BeginItem(const char* label_id, ImPlotCol recolor_from) {
         s.Colors[ImPlotCol_Fill].w       *= s.FillAlpha;
         // s.Colors[ImPlotCol_MarkerFill].w *= s.FillAlpha; // TODO: this should be separate, if it at all
         // apply highlight mods
-        if (item->Highlight) {
+        if (item->LegendHovered && ImHasFlag(gp.CurrentPlot->Flags, ImPlotFlags_Highlight)) {
             s.LineWeight   *= 2;
             s.MarkerWeight *= 2;
             // TODO: highlight fills?