TreeNode, Style: added style.TreeLinesRounding support. (#2920)

docs/CHANGELOG.txt

@@ -60,9 +60,10 @@ Other changes:
   - ImGuiTreeNodeFlags_DrawLinesNone: No lines drawn (default value in style.TreeLinesFlags).
   - ImGuiTreeNodeFlags_DrawLinesFull: Horizontal lines to child nodes. Vertical line drawn down to TreePop() position: cover full contents.
   - ImGuiTreeNodeFlags_DrawLinesToNodes: Horizontal lines to child nodes. Vertical line drawn down to bottom-most child node.
-  - Added style.TreeLinesFlags which stores the default setting, 
+  - Added style.TreeLinesFlags which stores the default setting,
     which may be overriden in individual TreeNode() calls.
   - Added style.TreeLinesSize (default to 1.0f).
+  - Added style.TreeLinesRadius (default to 0.0f).
   - Added ImGuiCol_TreeLines (in default style this is the same as ImGuiCol_Border).
   - Caveats:
     - Tree nodes may be used in many creative ways (manually positioning openable

imgui.cpp

@@ -1362,6 +1362,7 @@ ImGuiStyle::ImGuiStyle()
     TableAngledHeadersTextAlign = ImVec2(0.5f,0.0f);// Alignment of angled headers within the cell
     TreeLinesFlags              = ImGuiTreeNodeFlags_DrawLinesNone;
     TreeLinesSize               = 1.0f;             // Thickness of outlines when using ImGuiTreeNodeFlags_DrawLines.
+    TreeLinesRounding           = 0.0f;             // Radius of lines connecting child nodes to the vertical line.
     ColorButtonPosition         = ImGuiDir_Right;   // Side of the color button in the ColorEdit4 widget (left/right). Defaults to ImGuiDir_Right.
     ButtonTextAlign             = ImVec2(0.5f,0.5f);// Alignment of button text when button is larger than text.
     SelectableTextAlign         = ImVec2(0.0f,0.0f);// Alignment of selectable text. Defaults to (0.0f, 0.0f) (top-left aligned). It's generally important to keep this left-aligned if you want to lay multiple items on a same line.
@@ -1416,6 +1417,7 @@ void ImGuiStyle::ScaleAllSizes(float scale_factor)
     TabCloseButtonMinWidthSelected = (TabCloseButtonMinWidthSelected > 0.0f && TabCloseButtonMinWidthSelected != FLT_MAX) ? ImTrunc(TabCloseButtonMinWidthSelected * scale_factor) : TabCloseButtonMinWidthSelected;
     TabCloseButtonMinWidthUnselected = (TabCloseButtonMinWidthUnselected > 0.0f && TabCloseButtonMinWidthUnselected != FLT_MAX) ? ImTrunc(TabCloseButtonMinWidthUnselected * scale_factor) : TabCloseButtonMinWidthUnselected;
     TabBarOverlineSize = ImTrunc(TabBarOverlineSize * scale_factor);
+    TreeLinesRounding = ImTrunc(TreeLinesRounding * scale_factor);
     SeparatorTextPadding = ImTrunc(SeparatorTextPadding * scale_factor);
     DisplayWindowPadding = ImTrunc(DisplayWindowPadding * scale_factor);
     DisplaySafeAreaPadding = ImTrunc(DisplaySafeAreaPadding * scale_factor);
@@ -3418,6 +3420,7 @@ static const ImGuiStyleVarInfo GStyleVarsInfo[] =
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, TableAngledHeadersAngle)},    // ImGuiStyleVar_TableAngledHeadersAngle
     { 2, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, TableAngledHeadersTextAlign)},// ImGuiStyleVar_TableAngledHeadersTextAlign
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, TreeLinesSize)},              // ImGuiStyleVar_TreeLinesSize
+    { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, TreeLinesRounding)},          // ImGuiStyleVar_TreeLinesRounding
     { 2, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, ButtonTextAlign) },           // ImGuiStyleVar_ButtonTextAlign
     { 2, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, SelectableTextAlign) },       // ImGuiStyleVar_SelectableTextAlign
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, SeparatorTextBorderSize)},    // ImGuiStyleVar_SeparatorTextBorderSize

imgui.h

@@ -1730,6 +1730,7 @@ enum ImGuiStyleVar_
     ImGuiStyleVar_TableAngledHeadersAngle,  // float     TableAngledHeadersAngle
     ImGuiStyleVar_TableAngledHeadersTextAlign,// ImVec2  TableAngledHeadersTextAlign
     ImGuiStyleVar_TreeLinesSize,            // float     TreeLinesSize
+    ImGuiStyleVar_TreeLinesRounding,        // float     TreeLinesRounding
     ImGuiStyleVar_ButtonTextAlign,          // ImVec2    ButtonTextAlign
     ImGuiStyleVar_SelectableTextAlign,      // ImVec2    SelectableTextAlign
     ImGuiStyleVar_SeparatorTextBorderSize,  // float     SeparatorTextBorderSize
@@ -2190,7 +2191,8 @@ struct ImGuiStyle
     float       TableAngledHeadersAngle;    // Angle of angled headers (supported values range from -50.0f degrees to +50.0f degrees).
     ImVec2      TableAngledHeadersTextAlign;// Alignment of angled headers within the cell
     ImGuiTreeNodeFlags TreeLinesFlags;      // Default way to draw lines connecting TreeNode hierarchy. ImGuiTreeNodeFlags_DrawLinesNone or ImGuiTreeNodeFlags_DrawLinesFull or ImGuiTreeNodeFlags_DrawLinesToNodes.
-    float              TreeLinesSize;       // Thickness of outlines when using ImGuiTreeNodeFlags_DrawLines.
+    float       TreeLinesSize;              // Thickness of outlines when using ImGuiTreeNodeFlags_DrawLines.
+    float       TreeLinesRounding;          // Radius of lines connecting child nodes to the vertical line.
     ImGuiDir    ColorButtonPosition;        // Side of the color button in the ColorEdit4 widget (left/right). Defaults to ImGuiDir_Right.
     ImVec2      ButtonTextAlign;            // Alignment of button text when button is larger than text. Defaults to (0.5f, 0.5f) (centered).
     ImVec2      SelectableTextAlign;        // Alignment of selectable text. Defaults to (0.0f, 0.0f) (top-left aligned). It's generally important to keep this left-aligned if you want to lay multiple items on a same line.

imgui_demo.cpp

@@ -8270,15 +8270,11 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             ImGui::SliderAngle("TableAngledHeadersAngle", &style.TableAngledHeadersAngle, -50.0f, +50.0f);
             ImGui::SliderFloat2("TableAngledHeadersTextAlign", (float*)&style.TableAngledHeadersTextAlign, 0.0f, 1.0f, "%.2f");
 
-            ImGui::SeparatorText("Windows");
+            ImGui::SeparatorText("Trees");
-            ImGui::SliderFloat2("WindowTitleAlign", (float*)&style.WindowTitleAlign, 0.0f, 1.0f, "%.2f");
+            bool combo_open = ImGui::BeginCombo("TreeLinesFlags", GetTreeLinesFlagsName(style.TreeLinesFlags));
-            ImGui::SliderFloat("WindowBorderHoverPadding", &style.WindowBorderHoverPadding, 1.0f, 20.0f, "%.0f");
+            ImGui::SameLine();
-            int window_menu_button_position = style.WindowMenuButtonPosition + 1;
+            HelpMarker("[Experimental] Tree lines may not work in all situations (e.g. using a clipper) and may incurs slight traversal overhead.\n\nImGuiTreeNodeFlags_DrawLinesFull is faster than ImGuiTreeNodeFlags_DrawLinesToNode.");
-            if (ImGui::Combo("WindowMenuButtonPosition", (int*)&window_menu_button_position, "None\0Left\0Right\0"))
+            if (combo_open)
-                style.WindowMenuButtonPosition = (ImGuiDir)(window_menu_button_position - 1);
-
-            ImGui::SeparatorText("Widgets");
-            if (ImGui::BeginCombo("TreeLinesFlags", GetTreeLinesFlagsName(style.TreeLinesFlags)))
             {
                 const ImGuiTreeNodeFlags options[] = { ImGuiTreeNodeFlags_DrawLinesNone, ImGuiTreeNodeFlags_DrawLinesFull, ImGuiTreeNodeFlags_DrawLinesToNodes };
                 for (ImGuiTreeNodeFlags option : options)
@@ -8287,6 +8283,16 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
                 ImGui::EndCombo();
             }
             ImGui::SliderFloat("TreeLinesSize", &style.TreeLinesSize, 0.0f, 2.0f, "%.0f");
+            ImGui::SliderFloat("TreeLinesRounding", &style.TreeLinesRounding, 0.0f, 12.0f, "%.0f");
+
+            ImGui::SeparatorText("Windows");
+            ImGui::SliderFloat2("WindowTitleAlign", (float*)&style.WindowTitleAlign, 0.0f, 1.0f, "%.2f");
+            ImGui::SliderFloat("WindowBorderHoverPadding", &style.WindowBorderHoverPadding, 1.0f, 20.0f, "%.0f");
+            int window_menu_button_position = style.WindowMenuButtonPosition + 1;
+            if (ImGui::Combo("WindowMenuButtonPosition", (int*)&window_menu_button_position, "None\0Left\0Right\0"))
+                style.WindowMenuButtonPosition = (ImGuiDir)(window_menu_button_position - 1);
+
+            ImGui::SeparatorText("Widgets");
             ImGui::Combo("ColorButtonPosition", (int*)&style.ColorButtonPosition, "Left\0Right\0");
             ImGui::SliderFloat2("ButtonTextAlign", (float*)&style.ButtonTextAlign, 0.0f, 1.0f, "%.2f");
             ImGui::SameLine(); HelpMarker("Alignment applies when a button is larger than its text content.");

imgui_widgets.cpp

@@ -6867,9 +6867,22 @@ void ImGui::TreeNodeDrawLineToChildNode(const ImVec2& target_pos)
     float x1 = ImTrunc(parent_data->DrawLinesX1);
     float x2 = ImTrunc(target_pos.x - g.Style.ItemInnerSpacing.x);
     float y = ImTrunc(target_pos.y);
-    parent_data->DrawLinesToNodesY2 = ImMax(parent_data->DrawLinesToNodesY2, y);
+    float rounding = (g.Style.TreeLinesRounding > 0.0f) ? ImMin(x2 - x1, g.Style.TreeLinesRounding) : 0.0f;
-    if (x1 < x2)
+    parent_data->DrawLinesToNodesY2 = ImMax(parent_data->DrawLinesToNodesY2, y - rounding);
+    if (x1 >= x2)
+        return;
+    if (rounding > 0.0f)
+    {
+        x1 += 0.5f + rounding;
+        window->DrawList->PathArcToFast(ImVec2(x1, y - rounding), rounding, 6, 3);
+        if (x1 < x2)
+            window->DrawList->PathLineTo(ImVec2(x2, y));
+        window->DrawList->PathStroke(GetColorU32(ImGuiCol_TreeLines), ImDrawFlags_None, g.Style.TreeLinesSize);
+    }
+    else
+    {
         window->DrawList->AddLine(ImVec2(x1, y), ImVec2(x2, y), GetColorU32(ImGuiCol_TreeLines), g.Style.TreeLinesSize);
+    }
 }
 
 // Draw vertical line of the hierarchy
@@ -6885,7 +6898,7 @@ void ImGui::TreeNodeDrawLineToTreePop(const ImGuiTreeNodeStackData* data)
         if (g.CurrentTable)
             y2_full = ImMax(g.CurrentTable->RowPosY2, y2_full);
         y2_full = ImTrunc(y2_full - g.Style.ItemSpacing.y - g.FontSize * 0.5f);
-        if (y2 + g.Style.ItemSpacing.y < y2_full) // FIXME: threshold to use ToNodes Y2 instead of Full Y2 when close by ItemSpacing.y
+        if (y2 + (g.Style.ItemSpacing.y + g.Style.TreeLinesRounding) < y2_full) // FIXME: threshold to use ToNodes Y2 instead of Full Y2 when close by ItemSpacing.y
             y2 = y2_full;
     }
     y2 = ImMin(y2, window->ClipRect.Max.y);