ImGui: create dedicated file for wrappers and implement RenderText

All future wrappers go here.

src/thirdparty/imgui/CMakeLists.txt

@@ -42,6 +42,8 @@ add_sources( SOURCE_GROUP "Misc"
 	"misc/imgui_style.h"
 	"misc/imgui_utility.cpp"
 	"misc/imgui_utility.h"
+	"misc/imgui_wrapper.cpp"
+	"misc/imgui_wrapper.h"
 	"misc/cpp/imgui_stdlib.cpp"
 	"misc/cpp/imgui_stdlib.h"
 )

src/thirdparty/imgui/misc/imgui_wrapper.cpp

@@ -0,0 +1,34 @@
+//============================================================================//
+// 
+// Purpose: Set of Dear ImGui wrappers
+// 
+//============================================================================//
+#include "imgui.h"
+#include "imgui_wrapper.h"
+
+#include "stdio.h"
+
+void ImGui_RenderText(const ImGuiTextAlign_e align, const ImVec2 pos, const ImVec4& color, const char* const fmt, ...)
+{
+	ImDrawList* const drawList = ImGui::GetBackgroundDrawList();
+	assert(drawList);
+
+	va_list argsCopy;
+	va_start(argsCopy, fmt);
+
+	char textBuffer[2048];
+
+	const int numChars = vsnprintf(textBuffer, sizeof(textBuffer), fmt, argsCopy);
+	va_end(argsCopy);
+
+	// nb(amos): 'vsnprintf' does not count the terminating null, so no -1 here.
+	const char* const textEnd = &textBuffer[numChars];
+	ImVec2 alignedPos = pos;
+
+	if (align == ImGuiTextAlign_e::kAlignCenter)
+		alignedPos.x -= ImGui::CalcTextSize(textBuffer, textEnd).x / 2;
+	else if (align == ImGuiTextAlign_e::kAlignRight)
+		alignedPos.x -= ImGui::CalcTextSize(textBuffer, textEnd).x;
+
+	drawList->AddText(alignedPos, ImGui::ColorConvertFloat4ToU32(color), textBuffer, textEnd);
+}

src/thirdparty/imgui/misc/imgui_wrapper.h

@@ -0,0 +1,13 @@
+#ifndef IMGUI_WRAPPER_H
+#define IMGUI_WRAPPER_H
+
+enum class ImGuiTextAlign_e
+{
+	kAlignLeft,
+	kAlignCenter,
+	kAlignRight,
+};
+
+extern void ImGui_RenderText(const ImGuiTextAlign_e align, const ImVec2 pos, const ImVec4& color, const char* const fmt, ...);
+
+#endif // IMGUI_WRAPPER_H