inconsistent sizing between Button and ImageButton

[pozemka]

Version/Branch of Dear ImGui:

Version: v1.89.9
Branch: https://github.com/thedmd/imgui/tree/layouts

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_opengl3.h, imgui_impl_glfw.h
Compiler: msvc
Operating System: windows 10

My Issue/Question:
Hello. When displaying buttons with this code:

ImGuiIO& io = ImGui::GetIO();
ImTextureID my_tex_id = io.Fonts->TexID;

ImGui::Button("Hi1", { 32,32 });
ImGui::ImageButton("Hi2", my_tex_id, { 32, 32 });

their sizes are different:

Screenshots/Video

Standalone, minimal, complete and verifiable example:

// Here's some code anyone can copy and paste to reproduce your issue
ImGuiIO& io = ImGui::GetIO();
ImTextureID my_tex_id = io.Fonts->TexID;

ImGui::Button("Hi1", { 32,32 });
ImGui::ImageButton("Hi2", my_tex_id, { 32, 32 });

Is this expected behavior? If yes how should I correct size of the ImageButton to match size of regular Button?

[ocornut]

Is this expected behavior? If yes how should I correct size of the ImageButton to match size of regular Butto

Yes.
When passing a size to most widgets it is a total size and include the FramePadding.

ImageButton() adds FramePadding over the passed size. It makes sense but I do agree it should be clarified in the documentation.

The difference is (style.FramePadding * 2.0f)

So those will be equivalent:

ImGui::Button("Hi1", { 32,32 } + ImGui::GetStyle().FramePadding * 2.0f );
ImGui::ImageButton("Hi2", my_tex_id, { 32, 32 });

Those will also be equivalent:

ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, { 0, 0 });
ImGui::Button("Hi1", { 32,32 } );
ImGui::ImageButton("Hi2", my_tex_id, { 32, 32 });
ImGui::PopStyleVar();

[pozemka]

Thank you. That was unexpected for me.

If this is intended despite not very obvious (at least for me) behavior I wouldn't suggest to change calculations since many could rely on this sizing. Hope adding information about sizing to documentation would help future users.

Feel free to close this ticket.

[ocornut]

What happened is the following:

• prior to August 2022 we had a different API to ImageButton() which was less consistent with others API has it had both size and padding parameter, and it possible to set or override padding via a parameter.
• we switched it to a new logic and kept old redirecting one (see 4a2ae06) but as a side-effect of being more consistent it got a little more error-prone/misleading on this specific topic. I admit I didn't consider this aspect back then.

Unlike e.g. Button() where automatic size may be referred from the text contents we cannot do the same with ImageButton().

I have now renamed the argument to image_size and added various comments to clarify this. See commit 0312a29