Backends: SDL2, SDL3: changed GetClipboardText() handler to return NULL on error aka clipboard contents is not text. (#9168)

Consistent with other backends.

backends/imgui_impl_sdl2.cpp

@@ -21,6 +21,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-01-15: Changed GetClipboardText() handler to return nullptr on error aka clipboard contents is not text. Consistent with other backends. (#9168)
 //  2025-09-24: Skip using the SDL_GetGlobalMouseState() state when one of our window is hovered, as the SDL_MOUSEMOTION data is reliable. Fix macOS notch mouse coordinates issue in fullscreen mode + better perf on X11. (#7919, #7786)
 //  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-09-15: Content Scales are always reported as 1.0 on Wayland. (#8921)
@@ -178,7 +179,10 @@ static const char* ImGui_ImplSDL2_GetClipboardText(ImGuiContext*)
     ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
     if (bd->ClipboardTextData)
         SDL_free(bd->ClipboardTextData);
-    bd->ClipboardTextData = SDL_GetClipboardText();
+    if (SDL_HasClipboardText())
+        bd->ClipboardTextData = SDL_GetClipboardText();
+    else
+        bd->ClipboardTextData = nullptr;
     return bd->ClipboardTextData;
 }
 

backends/imgui_impl_sdl3.cpp

@@ -20,6 +20,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-01-15: Changed GetClipboardText() handler to return nullptr on error aka clipboard contents is not text. Consistent with other backends. (#9168)
 //  2025-11-05: Fixed an issue with missing characters events when an already active text field changes viewports. (#9054)
 //  2025-10-22: Fixed Platform_OpenInShellFn() return value (unused in core).
 //  2025-09-24: Skip using the SDL_GetGlobalMouseState() state when one of our window is hovered, as the SDL_EVENT_MOUSE_MOTION data is reliable. Fix macOS notch mouse coordinates issue in fullscreen mode + better perf on X11. (#7919, #7786)
@@ -151,7 +152,10 @@ static const char* ImGui_ImplSDL3_GetClipboardText(ImGuiContext*)
     ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
     if (bd->ClipboardTextData)
         SDL_free(bd->ClipboardTextData);
-    bd->ClipboardTextData = SDL_GetClipboardText();
+    if (SDL_HasClipboardText())
+        bd->ClipboardTextData = SDL_GetClipboardText();
+    else
+        bd->ClipboardTextData = nullptr;
     return bd->ClipboardTextData;
 }
 

docs/CHANGELOG.txt

@@ -195,6 +195,8 @@ Other Changes:
     forcefully disable either. (#9109, #9116)
   - OpenGL3: Fixed embedded loader multiple init/shutdown cycles broken on some
     platforms. (#8792, #9112)
+  - SDL2, SDL3: changed GetClipboardText() handler to return NULL on error aka
+    clipboard contents is not text. Consistent with other backends. (#9168)
   - SDL_GPU3: macOS version can use MSL shaders in order to support macOS 10.14+
     (vs Metallib shaders requiring macOS 14+). Requires application calling
     SDL_CreateGPUDevice() with SDL_GPU_SHADERFORMAT_MSL. (#9076) [@Niminem]

imgui.cpp

@@ -5091,10 +5091,11 @@ void ImGui::DebugAllocHook(ImGuiDebugAllocInfo* info, int frame_count, void* ptr
     }
 }
 
+// A conformant backend should return NULL on failure (e.g. clipboard data is not text).
 const char* ImGui::GetClipboardText()
 {
     ImGuiContext& g = *GImGui;
-    return g.PlatformIO.Platform_GetClipboardTextFn ? g.PlatformIO.Platform_GetClipboardTextFn(&g) : "";
+    return g.PlatformIO.Platform_GetClipboardTextFn ? g.PlatformIO.Platform_GetClipboardTextFn(&g) : NULL;
 }
 
 void ImGui::SetClipboardText(const char* text)

imgui.h

@@ -3956,7 +3956,7 @@ struct ImGuiPlatformIO
 
     // Optional: Access OS clipboard
     // (default to use native Win32 clipboard on Windows, otherwise uses a private clipboard. Override to access OS clipboard on other architectures)
-    const char* (*Platform_GetClipboardTextFn)(ImGuiContext* ctx);
+    const char* (*Platform_GetClipboardTextFn)(ImGuiContext* ctx);                      // Should return NULL on failure (e.g. clipboard data is not text).
     void        (*Platform_SetClipboardTextFn)(ImGuiContext* ctx, const char* text);
     void*       Platform_ClipboardUserData;