How to merge multiple fonts

[zmdyy0318]

Version/Branch of Dear ImGui:

Version 1.90.1

Back-ends:

imgui_impl_opengl3.cpp

Compiler, OS:

windows 11

Details:

i need use dynamic loading character range to accelerate the font texture loading, for draw diff font text

first, load font1 font2 font3:

ImFontGlyphRangesBuilder builder1; builder1.AddText("qwert"); auto font1 = io.Fonts->AddFontFromFileTTF("font1.ttc", 40, nullptr, builder1.Data);

ImFontGlyphRangesBuilder builder2; builder2.AddText("asdfg"); auto font2 = io.Fonts->AddFontFromFileTTF("font2.ttc", 40, nullptr, builder2.Data);

ImFontGlyphRangesBuilder builder3; builder3.AddText("zxcvb"); auto font3 = io.Fonts->AddFontFromFileTTF("font3.ttc", 40, nullptr, builder3.Data);

so, how to merge "poiuy" text to font2: ImFontConfig.MergeMode only can merge to last font(font3), how to merge to font1 or font2

[aelthalyste]

You must provide ImFontConfig struct to AddFontFromFileTTF function while it's MergeMode set to true. Like this

ImFontConfig merge_config = {};
merge_config.MergeMode = true;

static const ImWchar rangesFixed[] = {
    0x0020, 0x00FF, // Basic Latin + Latin Supplement
    0x2026, 0x2026, // ellipsis
    0
};
static const ImWchar rangesIcons[] = {
    ICON_MIN_FA, ICON_MAX_FA,
    0
};
io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\Consola.ttf", 16, NULL, rangesFixed);
io.Fonts->AddFontFromMemoryCompressedTTF(FontAwesomeSolid_compressed_data, FontAwesomeSolid_compressed_size, 16, &merge_config, rangesIcons);

It shouldn't matter where your glyph ranges are coming from.