(Breaking) Moved ImDrawCallback_ResetRenderState -> ImGui::GetPlatformIO().DrawCallback_ResetRenderState + added room in ImGuiPlatformIO for more standard backend-agnostic draw callbacks. (#9378)

docs/BACKENDS.md

@@ -255,8 +255,8 @@ void MyImGuiBackend_RenderDrawData(ImDrawData* draw_data)
             const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
             if (pcmd->UserCallback)
             {
-                if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
-                    MyEngineSetupenderState();
+                if (pcmd->UserCallback == platform_io.DrawCallback_ResetRenderState)
+                    MyEngineSetupSenderState();
                 else
                     pcmd->UserCallback(cmd_list, pcmd);
             }

docs/CHANGELOG.txt

@@ -41,6 +41,10 @@ HOW TO UPDATE?
 
 Breaking Changes:
 
+- DrawList:
+  - Obsoleted `ImDrawCallback_ResetRenderState` in favor of using `ImGui::GetPlatformIO().DrawCallback_ResetRenderState`,
+    which is part of our new standard draw callbacks. (#9378)
+    Redirecting the earlier value into the later one when set, so both old and new code should work.
 - Backends:
   - Vulkan: redesigned to use separate ImageView + Sampler instead of Combined Image Sampler. (#914)
     This change allows us to facilitate changing samplers, in line with other backends. [@yaz0r, @ocornut]
@@ -57,6 +61,19 @@ Breaking Changes:
 
 Other Changes:
 
+- DrawList:
+  - Added room in ImGuiPlatformIO for standard backend-agnostic draw callbacks. Those callbacks
+    are setup/provided by the backend and available in most of our standard backends.
+    They allow backend-agnostic code from e.g. switching to a Nearest/Point sampler without
+    messing with custom Renderer-specific callbacks.
+      platform_io.DrawCallback_ResetRenderState;    // Request to reset the graphics/render state.
+      platform_io.DrawCallback_SetSamplerLinear;    // Request to set current texture sampling to Linear
+      platform_io.DrawCallback_SetSamplerNearest;   // Request to set current texture sampling to Nearest/Point
+      platform_io.DrawCallback_SetSamplerCustom;    // Request to set current texture sampling using Backend Specific data.
+    Note that some backends might not support all callbacks.
+    (#9378, #9371, #3590, #8926, #2973, #7485, #7468, #6969, #5118, #7616, #9173, #8322, #7230,
+    #5999, #6452, #5156, #7342, #7592, #7511)
+  - Made AddCallback() user data default to Null for convenience.
 - InputText:
   - InputTextMultiline: fixed an issue processing deactivation logic when an active
     multi-line edit is clipped due to being out of view.
@@ -113,8 +130,6 @@ 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.cpp

@@ -395,6 +395,7 @@ IMPLEMENTING SUPPORT for ImGuiBackendFlags_RendererHasTextures:
  When you are not sure about an old symbol or function name, try using the Search/Find function of your IDE to look for comments or references in all imgui files.
  You can read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2026/04/23 (1.92.8) - Obsoleted `ImDrawCallback_ResetRenderState` in favor of using `ImGui::GetPlatformIO().DrawCallback_ResetRenderState`, which is part of our new standard draw callbacks. (#9378)
  - 2026/04/22 (1.92.8) - Backends: Vulkan: redesigned to use separate ImageView + Sampler instead of Combined Image Sampler.
                          - When registering custom textures: changed ImGui_ImplVulkan_AddTexture() signature to remove Sampler.
                          - When creating your own descriptor pool (instead of letting backend creates its own): need at least IMGUI_IMPL_VULKAN_MINIMUM_SAMPLED_IMAGE_POOL_SIZE descriptors of type VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE + IMGUI_IMPL_VULKAN_MINIMUM_SAMPLER_POOL_SIZE descriptors of type VK_DESCRIPTOR_TYPE_SAMPLER.
@@ -15816,6 +15817,7 @@ void ImGuiPlatformIO::ClearRendererHandlers()
 {
     Renderer_TextureMaxWidth = Renderer_TextureMaxHeight = 0;
     Renderer_RenderState = NULL;
+    DrawCallback_ResetRenderState = DrawCallback_SetSamplerLinear = DrawCallback_SetSamplerNearest = DrawCallback_SetSamplerCustom = NULL;
 }
 
 ImGuiViewport* ImGui::GetMainViewport()

imgui.h

@@ -3166,12 +3166,6 @@ typedef unsigned short ImDrawIdx;   // Default: 16-bit (for maximum compatibilit
 typedef void (*ImDrawCallback)(const ImDrawList* parent_list, const ImDrawCmd* cmd);
 #endif
 
-// Special Draw callback value to request renderer backend to reset the graphics/render state.
-// The renderer backend needs to handle this special value, otherwise it will crash trying to call a function at this address.
-// This is useful, for example, if you submitted callbacks which you know have altered the render state and you want it to be restored.
-// Render state is not reset by default because they are many perfectly useful way of altering render state (e.g. changing shader/blending settings before an Image call).
-#define ImDrawCallback_ResetRenderState     (ImDrawCallback)(-8)
-
 // Typically, 1 command = 1 GPU draw call (unless command is a callback)
 // - VtxOffset: When 'io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset' is enabled,
 //   this fields allow us to render meshes larger than 64K vertices while keeping 16-bit indices.
@@ -3378,7 +3372,8 @@ struct ImDrawList
 
     // Advanced: Draw Callbacks
     // - May be used to alter render state (change sampler, blending, current shader). May be used to emit custom rendering commands (difficult to do correctly, but possible).
-    // - Use special ImDrawCallback_ResetRenderState callback to instruct backend to reset its render state to the default.
+    // - Use special GetPlatformIO().DrawCallback_ResetRenderState callback to instruct backend to reset its render state to the default.
+    // - See other standard callbacks in GetPlatformIO(), which may or not be supported by your backend.
     // - Your rendering loop must check for 'UserCallback' in ImDrawCmd and call the function instead of rendering triangles. All standard backends are honoring this.
     // - For some backends, the callback may access selected render-states exposed by the backend in a ImGui_ImplXXXX_RenderState structure pointed to by platform_io.Renderer_RenderState.
     // - IMPORTANT: please be mindful of the different level of indirection between using size==0 (copying argument) and using size>0 (copying pointed data into a buffer).
@@ -4022,6 +4017,12 @@ struct ImGuiPlatformIO
     // Written by some backends during ImGui_ImplXXXX_RenderDrawData() call to point backend_specific ImGui_ImplXXXX_RenderState* structure.
     void*       Renderer_RenderState;
 
+    // Standard draw callbacks
+    ImDrawCallback  DrawCallback_ResetRenderState;      // Request to reset the graphics/render state.
+    ImDrawCallback  DrawCallback_SetSamplerLinear;      // Request to set current texture sampling to Linear
+    ImDrawCallback  DrawCallback_SetSamplerNearest;     // Request to set current texture sampling to Nearest/Point
+    ImDrawCallback  DrawCallback_SetSamplerCustom;      // Request to set current texture sampling using Backend Specific data.
+
     //------------------------------------------------------------------
     // Output
     //------------------------------------------------------------------
@@ -4150,6 +4151,8 @@ namespace ImGui
     //static inline void  SetScrollPosHere()                    { SetScrollHere(); }                                                // OBSOLETED in 1.42
 }
 
+#define ImDrawCallback_ResetRenderState     (ImDrawCallback)(-8)    // OBSOLETED in 1.92.8: Use ImGui::GetPlatformIO().DrawCallback_ResetRenderState
+
 //-- OBSOLETED in 1.92.0: ImFontAtlasCustomRect becomes ImTextureRect
 // - ImFontAtlasCustomRect::X,Y          --> ImTextureRect::x,y
 // - ImFontAtlasCustomRect::Width,Height --> ImTextureRect::w,h

imgui_draw.cpp

@@ -528,9 +528,14 @@ void ImDrawList::_PopUnusedDrawCmd()
 
 void ImDrawList::AddCallback(ImDrawCallback callback, void* userdata, size_t userdata_size)
 {
+    IM_ASSERT(callback != NULL);
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    if (callback == ImDrawCallback_ResetRenderState && _Data->Context != NULL && _Data->Context->PlatformIO.DrawCallback_ResetRenderState != NULL)
+        callback = _Data->Context->PlatformIO.DrawCallback_ResetRenderState; // == ImGui::GetPlatformIO().DrawCallback_ResetRenderState
+#endif
+
     IM_ASSERT_PARANOID(CmdBuffer.Size > 0);
     ImDrawCmd* curr_cmd = &CmdBuffer.Data[CmdBuffer.Size - 1];
-    IM_ASSERT(callback != NULL);
     IM_ASSERT(curr_cmd->UserCallback == NULL);
     if (curr_cmd->ElemCount != 0)
     {