Rendering U+0305

[evgenydrainov]

Version/Branch of Dear ImGui:

Version 1.90.5 WIP, Branch: docking

Back-ends:

imgui_impl_win32.cpp + imgui_impl_dx9.cpp

Compiler, OS:

Windows 11 + MSVC 2022

Full config/build information:

Dear ImGui 1.90.5 WIP (19042)
--------------------------------
sizeof(size_t): 8, sizeof(ImDrawIdx): 2, sizeof(ImDrawVert): 20
define: __cplusplus=199711
define: IMGUI_DISABLE_OBSOLETE_FUNCTIONS
define: IMGUI_DISABLE_OBSOLETE_KEYIO
define: _WIN32
define: _WIN64
define: _MSC_VER=1939
define: _MSVC_LANG=201402
define: IMGUI_HAS_VIEWPORT
define: IMGUI_HAS_DOCK
--------------------------------
io.BackendPlatformName: imgui_impl_win32
io.BackendRendererName: imgui_impl_dx9
io.ConfigFlags: 0x00000003
 NavEnableKeyboard
 NavEnableGamepad
io.ConfigViewportsNoDecoration
io.ConfigInputTextCursorBlink
io.ConfigWindowsResizeFromEdges
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x00001C0E
 HasMouseCursors
 HasSetMousePos
 PlatformHasViewports
 HasMouseHoveredViewport
 RendererHasVtxOffset
 RendererHasViewports
--------------------------------
io.Fonts: 3 fonts, Flags: 0x00000000, TexSize: 512,1024
io.DisplaySize: 1920.00,1133.00
io.DisplayFramebufferScale: 1.00,1.00
--------------------------------
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00

Details:

Rendering U+0305

Is it possible to render U+0305 (Combining Overline) with imgui? My string is written like this:

std::string result_unicode = "(x\xCC\x85 \xE2\x88\xA7 y\xCC\x85 \xE2\x88\xA7 z\xCC\x85)";

And I render it like this:

ImGui::PushTextWrapPos(0);
ImGui::PushFont(fnt_math);
ImGui::TextUnformatted(result_unicode.c_str());
ImGui::PopFont();
ImGui::PopTextWrapPos();

I've tried several fonts: C:\Windows\Fonts\segoeui.ttf, C:\Windows\Fonts\cambria.ttc, C:\Windows\Fonts\cour.ttf, DroidSans from misc/fonts.
I'm loading 0x3000, 0x036F Combining Diacritical Marks range and 0x2000, 0x206F General Punctuation range.

Screenshots/Video:

With cambria.ttc:

Minimal, Complete and Verifiable Example code:

My full font loading code:

ImGuiIO& io = ImGui::GetIO();

{
	ImVector<ImWchar> fnt_main_ranges;
	{
		ImWchar _ranges[] = {
			0x2000, 0x206F, // General Punctuation (for Overline)
			0x2070, 0x209F, // Superscripts and Subscripts
			0x2200, 0x22FF, // Mathematical Operators (for logical and, or)
			0x3000, 0x036F, // Combining Diacritical Marks (for Combining Overline)
			0,
		};

		ImFontGlyphRangesBuilder builder;
		builder.AddRanges(io.Fonts->GetGlyphRangesDefault());
		builder.AddRanges(io.Fonts->GetGlyphRangesCyrillic());
		builder.AddRanges(_ranges);

		builder.BuildRanges(&fnt_main_ranges);
	}

	fnt_main = AddFontFromFileTTF(io.Fonts, "C:\\Windows\\Fonts\\segoeui.ttf", 24, nullptr, fnt_main_ranges.Data);
	if (!fnt_main) {
		ImFontConfig config;
		config.SizePixels = 20;
		fnt_main = io.Fonts->AddFontDefault(&config);
	}

	fnt_mono = AddFontFromFileTTF(io.Fonts, "C:\\Windows\\Fonts\\cour.ttf", 24);
	if (!fnt_mono) {
		fnt_mono = fnt_main;
	}

	ImVector<ImWchar> fnt_math_ranges;
	{
		ImWchar _ranges[] = {
			0x2000, 0x206F, // General Punctuation (for Overline)
			0x2200, 0x22FF, // Mathematical Operators (for logical and, or)
			0x3000, 0x036F, // Combining Diacritical Marks (for Combining Overline)
			0,
		};

		ImFontGlyphRangesBuilder builder;
		builder.AddRanges(io.Fonts->GetGlyphRangesDefault());
		builder.AddRanges(_ranges);

		builder.BuildRanges(&fnt_math_ranges);
	}

	fnt_math = AddFontFromFileTTF(io.Fonts, "C:\\Windows\\Fonts\\cambria.ttc", 24, nullptr, fnt_math_ranges.Data);
	if (!fnt_math) {
		fnt_math = fnt_main;
	}

	// fnt_math = fnt_main;

	io.Fonts->Build();
}

And rendering:

if (ImGui::Begin("mcve")) {
	std::string result_unicode = "(x\xCC\x85 \xE2\x88\xA7 y\xCC\x85 \xE2\x88\xA7 z\xCC\x85)";

	ImGui::PushTextWrapPos(0);
	ImGui::PushFont(fnt_math);
	ImGui::TextUnformatted(result_unicode.c_str());
	ImGui::PopFont();
	ImGui::PopTextWrapPos();
}
ImGui::End();

[evgenydrainov]

Forgot to tell, AddFontFromFileTTF is a version of ImFontAtlas::AddFontFromFileTTF that doesn't assert on failure:

// 
// Don't assert on fail
// 
static ImFont* AddFontFromFileTTF(ImFontAtlas* atlas, const char* filename, float size_pixels, const ImFontConfig* font_cfg_template = nullptr, const ImWchar* glyph_ranges = nullptr)
{
	size_t data_size = 0;
	void* data = ImFileLoadToMemory(filename, "rb", &data_size, 0);
	if (!data)
	{
		return NULL;
	}
	ImFontConfig font_cfg = font_cfg_template ? *font_cfg_template : ImFontConfig();
	if (font_cfg.Name[0] == '\0')
	{
		// Store a short copy of filename into into the font name for convenience
		const char* p;
		for (p = filename + strlen(filename); p > filename && p[-1] != '/' && p[-1] != '\\'; p--) {}
		ImFormatString(font_cfg.Name, IM_ARRAYSIZE(font_cfg.Name), "%s, %.0fpx", p, size_pixels);
	}
	return atlas->AddFontFromMemoryTTF(data, (int)data_size, size_pixels, &font_cfg, glyph_ranges);
}

[PathogenDavid]

Unfortunately Dear ImGui doesn't support combining characters.

Non-trivial text shaping doesn't mesh well with the architecture or philosophy of the library so this is unlikely to improve.

(See also #4922 #6036 #4227 #1228 #4943)

[evgenydrainov]

Ok got it thanks. I'll try to look for a workaround.