Style: added PushStyleVarX(), PushStyleVarY() helpers to modify only one component of a ImVec2 var.

+ tweak existing function to early out on error.

docs/CHANGELOG.txt

@@ -56,7 +56,8 @@ Other changes:
 - InputText: allow callback to update buffer while in read-only mode. (imgui_club/#46)
 - InputText: fixed an issue programmatically refocusing a multi-line input which was just active. (#4761, #7870)
 - TextLink(), TextLinkOpenURL(): change mouse cursor to Hand shape when hovered. (#7885, #7660)
-- Fonts: Made it possible to use PushFont()/PopFont() calls accross Begin() calls. (#3224, #3875, #6398, #7903)
+- Style: added PushStyleVarX(), PushStyleVarY() helpers to modify only one component of a ImVec2 var.
+- Fonts: made it possible to use PushFont()/PopFont() calls accross Begin() calls. (#3224, #3875, #6398, #7903)
 - Backends: GLFW: added ImGui_ImplGlfw_Sleep() helper function because GLFW does not
   provide a way to do a portable sleep. (#7844)
 - Backends: SDL2, SDL3: ignore events of other SDL windows. (#7853) [@madebr, @ocornut]

docs/TODO.txt

@@ -194,7 +194,6 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - settings/persistence: helpers to make TreeNodeBehavior persist (even during dev!) - may need to store some semantic and/or data type in ImGuiStoragePair
 
  - style: better default styles. (#707)
- - style: PushStyleVar: allow direct access to individual float X/Y elements.
  - style: add a highlighted text color (for headers, etc.)
  - style: border types: out-screen, in-screen, etc. (#447)
  - style: add window shadow (fading away from the window. Paint-style calculation of vertices alpha after drawlist would be easier)

imgui.cpp

@@ -3309,28 +3309,56 @@ void ImGui::PushStyleVar(ImGuiStyleVar idx, float val)
 {
     ImGuiContext& g = *GImGui;
     const ImGuiDataVarInfo* var_info = GetStyleVarInfo(idx);
-    if (var_info->Type == ImGuiDataType_Float && var_info->Count == 1)
+    if (var_info->Type != ImGuiDataType_Float || var_info->Count != 1)
     {
-        float* pvar = (float*)var_info->GetVarPtr(&g.Style);
+        IM_ASSERT_USER_ERROR(0, "Calling PushStyleVar() variant with wrong type!");
-        g.StyleVarStack.push_back(ImGuiStyleMod(idx, *pvar));
-        *pvar = val;
         return;
     }
-    IM_ASSERT_USER_ERROR(0, "Calling PushStyleVar() variant with wrong type!");
+    float* pvar = (float*)var_info->GetVarPtr(&g.Style);
+    g.StyleVarStack.push_back(ImGuiStyleMod(idx, *pvar));
+    *pvar = val;
+}
+
+void ImGui::PushStyleVarX(ImGuiStyleVar idx, float val_x)
+{
+    ImGuiContext& g = *GImGui;
+    const ImGuiDataVarInfo* var_info = GetStyleVarInfo(idx);
+    if (var_info->Type != ImGuiDataType_Float || var_info->Count != 2)
+    {
+        IM_ASSERT_USER_ERROR(0, "Calling PushStyleVar() variant with wrong type!");
+        return;
+    }
+    ImVec2* pvar = (ImVec2*)var_info->GetVarPtr(&g.Style);
+    g.StyleVarStack.push_back(ImGuiStyleMod(idx, *pvar));
+    pvar->x = val_x;
+}
+
+void ImGui::PushStyleVarY(ImGuiStyleVar idx, float val_y)
+{
+    ImGuiContext& g = *GImGui;
+    const ImGuiDataVarInfo* var_info = GetStyleVarInfo(idx);
+    if (var_info->Type != ImGuiDataType_Float || var_info->Count != 2)
+    {
+        IM_ASSERT_USER_ERROR(0, "Calling PushStyleVar() variant with wrong type!");
+        return;
+    }
+    ImVec2* pvar = (ImVec2*)var_info->GetVarPtr(&g.Style);
+    g.StyleVarStack.push_back(ImGuiStyleMod(idx, *pvar));
+    pvar->y = val_y;
 }
 
 void ImGui::PushStyleVar(ImGuiStyleVar idx, const ImVec2& val)
 {
     ImGuiContext& g = *GImGui;
     const ImGuiDataVarInfo* var_info = GetStyleVarInfo(idx);
-    if (var_info->Type == ImGuiDataType_Float && var_info->Count == 2)
+    if (var_info->Type != ImGuiDataType_Float || var_info->Count != 2)
     {
-        ImVec2* pvar = (ImVec2*)var_info->GetVarPtr(&g.Style);
+        IM_ASSERT_USER_ERROR(0, "Calling PushStyleVar() variant with wrong type!");
-        g.StyleVarStack.push_back(ImGuiStyleMod(idx, *pvar));
-        *pvar = val;
         return;
     }
-    IM_ASSERT_USER_ERROR(0, "Calling PushStyleVar() variant with wrong type!");
+    ImVec2* pvar = (ImVec2*)var_info->GetVarPtr(&g.Style);
+    g.StyleVarStack.push_back(ImGuiStyleMod(idx, *pvar));
+    *pvar = val;
 }
 
 void ImGui::PopStyleVar(int count)

imgui.h

@@ -438,8 +438,10 @@ namespace ImGui
     IMGUI_API void          PushStyleColor(ImGuiCol idx, ImU32 col);                        // modify a style color. always use this if you modify the style after NewFrame().
     IMGUI_API void          PushStyleColor(ImGuiCol idx, const ImVec4& col);
     IMGUI_API void          PopStyleColor(int count = 1);
-    IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, float val);                     // modify a style float variable. always use this if you modify the style after NewFrame().
+    IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, float val);                     // modify a style float variable. always use this if you modify the style after NewFrame()!
-    IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, const ImVec2& val);             // modify a style ImVec2 variable. always use this if you modify the style after NewFrame().
+    IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, const ImVec2& val);             // modify a style ImVec2 variable. "
+    IMGUI_API void          PushStyleVarX(ImGuiStyleVar idx, float val_x);                  // modify X component of a style ImVec2 variable. "
+    IMGUI_API void          PushStyleVarY(ImGuiStyleVar idx, float val_y);                  // modify Y component of a style ImVec2 variable. "
     IMGUI_API void          PopStyleVar(int count = 1);
     IMGUI_API void          PushItemFlag(ImGuiItemFlags option, bool enabled);              // modify specified shared item flag, e.g. PushItemFlag(ImGuiItemFlags_NoTabStop, true)
     IMGUI_API void          PopItemFlag();

imgui_demo.cpp

@@ -3677,7 +3677,7 @@ static void ShowDemoWindowMultiSelect(ImGuiDemoWindowData* demo_data)
             {
                 ImVec2 color_button_sz(ImGui::GetFontSize(), ImGui::GetFontSize());
                 if (widget_type == WidgetType_TreeNode)
-                    ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(ImGui::GetStyle().ItemSpacing.x, 0.0f));
+                    ImGui::PushStyleVarY(ImGuiStyleVar_ItemSpacing, 0.0f);
 
                 ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags, selection.Size, items.Size);
                 selection.ApplyRequests(ms_io);
@@ -3693,7 +3693,7 @@ static void ShowDemoWindowMultiSelect(ImGuiDemoWindowData* demo_data)
                     ImGui::BeginTable("##Split", 2, ImGuiTableFlags_Resizable | ImGuiTableFlags_NoSavedSettings | ImGuiTableFlags_NoPadOuterX);
                     ImGui::TableSetupColumn("", ImGuiTableColumnFlags_WidthStretch, 0.70f);
                     ImGui::TableSetupColumn("", ImGuiTableColumnFlags_WidthStretch, 0.30f);
-                    //ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(ImGui::GetStyle().ItemSpacing.x, 0.0f));
+                    //ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacingY, 0.0f);
                 }
 
                 ImGuiListClipper clipper;
@@ -5082,8 +5082,8 @@ const ImGuiTableSortSpecs* MyItem::s_current_sort_specs = NULL;
 static void PushStyleCompact()
 {
     ImGuiStyle& style = ImGui::GetStyle();
-    ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(style.FramePadding.x, (float)(int)(style.FramePadding.y * 0.60f)));
+    ImGui::PushStyleVarY(ImGuiStyleVar_FramePadding, (float)(int)(style.FramePadding.y * 0.60f));
-    ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(style.ItemSpacing.x, (float)(int)(style.ItemSpacing.y * 0.60f)));
+    ImGui::PushStyleVarY(ImGuiStyleVar_ItemSpacing, (float)(int)(style.ItemSpacing.y * 0.60f));
 }
 
 static void PopStyleCompact()
@@ -6117,7 +6117,7 @@ static void ShowDemoWindowTables()
             for (int row = 0; row < 8; row++)
             {
                 if ((row % 3) == 2)
-                    ImGui::PushStyleVar(ImGuiStyleVar_CellPadding, ImVec2(style.CellPadding.x, 20.0f));
+                    ImGui::PushStyleVarY(ImGuiStyleVar_CellPadding, 20.0f);
                 ImGui::TableNextRow(ImGuiTableRowFlags_None);
                 ImGui::TableNextColumn();
                 ImGui::Text("CellPadding.y = %.2f", style.CellPadding.y);

imgui_widgets.cpp

@@ -1944,7 +1944,7 @@ bool ImGui::BeginComboPopup(ImGuiID popup_id, const ImRect& bb, ImGuiComboFlags
 
     // We don't use BeginPopupEx() solely because we have a custom name string, which we could make an argument to BeginPopupEx()
     ImGuiWindowFlags window_flags = ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_Popup | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoMove;
-    PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(g.Style.FramePadding.x, g.Style.WindowPadding.y)); // Horizontally align ourselves with the framed text
+    PushStyleVarX(ImGuiStyleVar_WindowPadding, g.Style.FramePadding.x); // Horizontally align ourselves with the framed text
     bool ret = Begin(name, NULL, window_flags);
     PopStyleVar();
     if (!ret)
@@ -8688,7 +8688,7 @@ bool ImGui::BeginMenuEx(const char* label, const char* icon, bool enabled)
         // For ChildMenu, the popup position will be overwritten by the call to FindBestWindowPosForPopup() in Begin()
         popup_pos = ImVec2(pos.x - 1.0f - IM_TRUNC(style.ItemSpacing.x * 0.5f), pos.y - style.FramePadding.y + window->MenuBarHeight);
         window->DC.CursorPos.x += IM_TRUNC(style.ItemSpacing.x * 0.5f);
-        PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(style.ItemSpacing.x * 2.0f, style.ItemSpacing.y));
+        PushStyleVarX(ImGuiStyleVar_ItemSpacing, style.ItemSpacing.x * 2.0f);
         float w = label_size.x;
         ImVec2 text_pos(window->DC.CursorPos.x + offsets->OffsetLabel, window->DC.CursorPos.y + window->DC.CurrLineTextBaseOffset);
         pressed = Selectable("", menu_is_open, selectable_flags, ImVec2(w, label_size.y));
@@ -8895,7 +8895,7 @@ bool ImGui::MenuItemEx(const char* label, const char* icon, const char* shortcut
         float w = label_size.x;
         window->DC.CursorPos.x += IM_TRUNC(style.ItemSpacing.x * 0.5f);
         ImVec2 text_pos(window->DC.CursorPos.x + offsets->OffsetLabel, window->DC.CursorPos.y + window->DC.CurrLineTextBaseOffset);
-        PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(style.ItemSpacing.x * 2.0f, style.ItemSpacing.y));
+        PushStyleVarX(ImGuiStyleVar_ItemSpacing, style.ItemSpacing.x * 2.0f);
         pressed = Selectable("", selected, selectable_flags, ImVec2(w, 0.0f));
         PopStyleVar();
         if (g.LastItemData.StatusFlags & ImGuiItemStatusFlags_Visible)