Font loading before rendering

[wusikijeronii]

Hello,
I cache some data during the resources preparation stage to reduce the number of calls per frame. Today I ran into an error trying to get the text size. To determine the size, I use the ImGui::CalcTextSize function. But as I found out, it uses font data (which is logical), but this font itself is not loaded at the initialization stage (through the AddFontFromFileTTF function), and it is NULL. Initialization occurs in the first frame. Is there a way to load the font before the first call to ImGui::New Frame? I will add that for non-GUI tasks, I use my implementation of text atlases. And I prepare the data in advance. So I don't see a problem with that.

[PathogenDavid]

Yes and no. You can build the font atlas and associated data before ImGui::NewFrame using ImFontAtlas::Build, but ImGui::CalcTextSize still won't work as it relies on other state in ImGuiContext to be set up by NewFrame.

You can however use ImFont::CalcTextSizeA instead, which is slightly different from ImGui::CalcTextSize but not in ways that'd likely affect your use-case.

Here's an example:

ImGuiIO& io = ImGui::GetIO();
io.Fonts->Build();
ImFont* font = io.Fonts->Fonts[0];
ImVec2 size = font->CalcTextSizeA(font->FontSize, FLT_MAX, 0.f, "Hello, world!");

[wusikijeronii]

Yes, it can work. Thanks, I just had to ask. In case there was a direct way to do this.