ImDrawList: made AddCallback() user data default to NULL + minor amends/comments.

backends/imgui_impl_dx10.cpp

@@ -16,7 +16,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2026-01-19: DirectX11: Added 'SamplerNearest' in ImGui_ImplDX11_RenderState. Renamed 'SamplerDefault' to 'SamplerLinear'. 
+//  2026-01-19: DirectX10: Added 'SamplerNearest' in ImGui_ImplDX10_RenderState. Renamed 'SamplerDefault' to 'SamplerLinear'. 
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX10: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2025-05-07: DirectX10: Honor draw_data->FramebufferScale to allow for custom backends and experiment using it (consistently with other renderer backends, even though in normal condition it is not set under Windows).

backends/imgui_impl_sdlrenderer2.cpp

@@ -15,7 +15,7 @@
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 
-// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // Learn about Dear ImGui:
 // - FAQ                  https://dearimgui.com/faq

backends/imgui_impl_sdlrenderer3.cpp

@@ -15,7 +15,7 @@
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 
-// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // Learn about Dear ImGui:
 // - FAQ                  https://dearimgui.com/faq

backends/imgui_impl_sdlrenderer3.h

@@ -15,7 +15,7 @@
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 
-// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // Learn about Dear ImGui:
 // - FAQ                  https://dearimgui.com/faq

backends/imgui_impl_vulkan.cpp

@@ -2,7 +2,7 @@
 // This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..)
 
 // Implemented features:
-//  [!] Renderer: User texture binding. Use 'VkDescriptorSet' as texture identifier. Call ImGui_ImplVulkan_AddTexture() to register one. Read the FAQ about ImTextureID/ImTextureRef + https://github.com/ocornut/imgui/pull/914 for discussions.
+//  [!] Renderer: User texture binding. Use a VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE 'VkDescriptorSet' as texture identifier. Call ImGui_ImplVulkan_AddTexture() to register one. Read the FAQ about ImTextureID/ImTextureRef + https://github.com/ocornut/imgui/pull/914 for discussions.
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.

backends/imgui_impl_vulkan.h

@@ -2,7 +2,7 @@
 // This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..)
 
 // Implemented features:
-//  [!] Renderer: User texture binding. Use 'VkDescriptorSet' as texture identifier. Call ImGui_ImplVulkan_AddTexture() to register one. Read the FAQ about ImTextureID/ImTextureRef + https://github.com/ocornut/imgui/pull/914 for discussions.
+//  [!] Renderer: User texture binding. Use a VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE 'VkDescriptorSet' as texture identifier. Call ImGui_ImplVulkan_AddTexture() to register one. Read the FAQ about ImTextureID/ImTextureRef + https://github.com/ocornut/imgui/pull/914 for discussions.
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.

backends/imgui_impl_wgpu.cpp

@@ -83,7 +83,7 @@ struct ImGui_ImplWGPU_Texture
 
 struct RenderResources
 {
-    WGPUSampler         Sampler = nullptr;              // Sampler for textures
+    WGPUSampler         SamplerLinear = nullptr;        // Sampler for textures
     WGPUBuffer          Uniforms = nullptr;             // Shader uniforms
     WGPUBindGroup       CommonBindGroup = nullptr;      // Resources bind-group to bind the common resources to pipeline
     ImGuiStorage        ImageBindGroups;                // Resources bind-group to bind the font/image resources to pipeline (this is a key->value map)
@@ -296,7 +296,7 @@ static void SafeRelease(WGPUShaderModule& res)
 }
 static void SafeRelease(RenderResources& res)
 {
-    SafeRelease(res.Sampler);
+    SafeRelease(res.SamplerLinear);
     SafeRelease(res.Uniforms);
     SafeRelease(res.CommonBindGroup);
     SafeRelease(res.ImageBindGroupLayout);
@@ -538,6 +538,7 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
             {
                 // User callback, registered via ImDrawList::AddCallback()
                 // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
+                IM_ASSERT(pcmd->UserCallback != ImDrawCallback_SetSamplerLinear && pcmd->UserCallback != ImDrawCallback_SetSamplerNearest); // Unsupported.
                 if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
                     ImGui_ImplWGPU_SetupRenderState(draw_data, pass_encoder, fr);
                 else
@@ -824,13 +825,13 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
     sampler_desc.addressModeV = WGPUAddressMode_ClampToEdge;
     sampler_desc.addressModeW = WGPUAddressMode_ClampToEdge;
     sampler_desc.maxAnisotropy = 1;
-    bd->renderResources.Sampler = wgpuDeviceCreateSampler(bd->wgpuDevice, &sampler_desc);
+    bd->renderResources.SamplerLinear = wgpuDeviceCreateSampler(bd->wgpuDevice, &sampler_desc);
 
     // Create resource bind group
     WGPUBindGroupEntry common_bg_entries[] =
     {
         { nullptr, 0, bd->renderResources.Uniforms, 0, MEMALIGN(sizeof(Uniforms), 16), 0, 0 },
-        { nullptr, 1, 0, 0, 0, bd->renderResources.Sampler, 0 },
+        { nullptr, 1, 0, 0, 0, bd->renderResources.SamplerLinear, 0 },
     };
     WGPUBindGroupDescriptor common_bg_descriptor = {};
     common_bg_descriptor.layout = bg_layouts[0];
@@ -896,7 +897,7 @@ bool ImGui_ImplWGPU_Init(ImGui_ImplWGPU_InitInfo* init_info)
     bd->numFramesInFlight = init_info->NumFramesInFlight;
     bd->frameIndex = UINT_MAX;
 
-    bd->renderResources.Sampler = nullptr;
+    bd->renderResources.SamplerLinear = nullptr;
     bd->renderResources.Uniforms = nullptr;
     bd->renderResources.CommonBindGroup = nullptr;
     bd->renderResources.ImageBindGroups.Data.reserve(100);

docs/CHANGELOG.txt

@@ -113,6 +113,8 @@ Other Changes:
     reporting the common clipper error over a table sanity check assert). (#9350)
   - Tweaked assert triggering when first item height measurement fails, and made it
     a better recoverable error. (#9350)
+- DrawList:
+  - Made AddCallback() user data default parameter.
 - Misc:
   - Minor optimization: reduce redudant label scanning in common widgets.
   - Added missing Test Engine hooks for PlotXXX(), VSliderXXX(), TableHeader().

imgui.h

@@ -3385,7 +3385,7 @@ struct ImDrawList
     //   - If userdata_size == 0: we copy/store the 'userdata' argument as-is. It will be available unmodified in ImDrawCmd::UserCallbackData during render.
     //   - If userdata_size > 0,  we copy/store 'userdata_size' bytes pointed to by 'userdata'. We store them in a buffer stored inside the drawlist. ImDrawCmd::UserCallbackData will point inside that buffer so you have to retrieve data from there. Your callback may need to use ImDrawCmd::UserCallbackDataSize if you expect dynamically-sized data.
     //   - Support for userdata_size > 0 was added in v1.91.4, October 2024. So earlier code always only allowed to copy/store a simple void*.
-    IMGUI_API void  AddCallback(ImDrawCallback callback, void* userdata, size_t userdata_size = 0);
+    IMGUI_API void  AddCallback(ImDrawCallback callback, void* userdata = NULL, size_t userdata_size = 0);
 
     // Advanced: Miscellaneous
     IMGUI_API void  AddDrawCmd();                                               // This is useful if you need to forcefully create a new draw call (to allow for dependent rendering / blending). Otherwise primitives are merged into the same draw-call as much as possible