Struct Context

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pub struct Context { /* private fields */ }

Expand description

An imgui context.

A context needs to be created to access most library functions. Due to current Dear ImGui design choices, at most one active Context can exist at any time. This limitation will likely be removed in a future Dear ImGui version.

If you need more than one context, you can use suspended contexts. As long as only one context is active at a time, it’s possible to have multiple independent contexts.

§Examples

Creating a new active context:

let ctx = dear_imgui_rs::Context::create();
// ctx is dropped naturally when it goes out of scope, which deactivates and destroys the
// context

Never try to create an active context when another one is active:

let ctx1 = dear_imgui_rs::Context::create();

let ctx2 = dear_imgui_rs::Context::create(); // PANIC

Implementations§

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impl Context

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pub fn try_create() -> Result<Context, ImGuiError>

Tries to create a new active Dear ImGui context.

Returns an error if another context is already active or creation fails.

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pub fn try_create_with_shared_font_atlas( shared_font_atlas: SharedFontAtlas, ) -> Result<Context, ImGuiError>

Tries to create a new active Dear ImGui context with a shared font atlas.

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pub fn create() -> Context

Creates a new active Dear ImGui context (panics on error).

This aligns with imgui-rs behavior. For fallible creation use try_create().

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pub fn create_with_shared_font_atlas( shared_font_atlas: SharedFontAtlas, ) -> Context

Creates a new active Dear ImGui context with a shared font atlas (panics on error).

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pub fn as_raw(&self) -> *mut ImGuiContext

Returns the raw ImGuiContext* for FFI integrations.

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pub fn alive_token(&self) -> ContextAliveToken

Returns a token that can be used to check whether this context is still alive.

Useful for extension crates that store raw pointers and need to avoid calling into FFI after the owning Context has been dropped.

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pub fn io_mut(&mut self) -> &mut Io

Returns a mutable reference to the active context’s IO object

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pub fn io(&self) -> &Io

Get access to the IO structure

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pub fn style(&self) -> &Style

Get access to the Style structure

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pub fn style_mut(&mut self) -> &mut Style

Get mutable access to the Style structure

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pub fn frame(&mut self) -> &mut Ui

Creates a new frame and returns a Ui object for building the interface

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pub fn frame_with<F, R>(&mut self, f: F) -> R
where F: FnOnce(&Ui) -> R,

Create a new frame with a callback

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pub fn render(&mut self) -> &DrawData

Renders the frame and returns a reference to the resulting draw data

This finalizes the Dear ImGui frame and prepares all draw data for rendering. The returned draw data contains all the information needed to render the frame.

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pub fn draw_data(&self) -> Option<&DrawData>

Gets the draw data for the current frame

This returns the draw data without calling render. Only valid after render() has been called and before the next new_frame().

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pub fn register_user_texture(&mut self, texture: &mut TextureData)

Register a user-created texture in ImGui’s global texture list (ImGui 1.92+).

Dear ImGui builds DrawData::textures() from its internal PlatformIO.Textures[] list. If you create a TextureData yourself (e.g. OwnedTextureData::new()), you must register it for renderer backends (with BackendFlags::RENDERER_HAS_TEXTURES) to receive Create/Update/Destroy requests automatically.

Note: RegisterUserTexture() is currently an experimental ImGui API.

§Safety & Lifetime

The underlying ImTextureData must remain alive and registered until you call unregister_user_texture(). Unregister before dropping the texture to avoid leaving a dangling pointer inside ImGui.

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pub fn register_user_texture_token( &mut self, texture: &mut TextureData, ) -> RegisteredUserTexture

Register a user-created texture and return an RAII token which unregisters on drop.

This is a convenience wrapper around register_user_texture().

§Safety & Drop Ordering

The returned token must be dropped before the underlying ImGuiContext is destroyed. If you store it in a struct alongside Context, ensure the token is dropped first.

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pub fn unregister_user_texture(&mut self, texture: &mut TextureData)

Unregister a user texture previously registered with register_user_texture().

This removes the ImTextureData* from ImGui’s internal texture list.

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pub fn set_ini_filename( &mut self, filename: Option, ) -> Result<(), ImGuiError>
where P: Into<PathBuf>,

Sets the INI filename for settings persistence

§Errors

Returns an error if the filename contains null bytes

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pub fn set_log_filename( &mut self, filename: Option, ) -> Result<(), ImGuiError>
where P: Into<PathBuf>,

Sets the log filename

§Errors

Returns an error if the filename contains null bytes

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pub fn set_platform_name<S>( &mut self, name: Option<S>, ) -> Result<(), ImGuiError>
where S: Into<String>,

Sets the platform name

§Errors

Returns an error if the name contains null bytes

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pub fn set_renderer_name<S>( &mut self, name: Option<S>, ) -> Result<(), ImGuiError>
where S: Into<String>,

Sets the renderer name

§Errors

Returns an error if the name contains null bytes

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pub fn platform_io_mut(&mut self) -> &mut PlatformIo

Get mutable access to the platform IO.

Note: ImGuiPlatformIO exists even when multi-viewport is disabled. We expose it unconditionally so callers can use ImGui 1.92+ texture management via PlatformIO.Textures[].

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