Backends: Win32: Removed silent return when calling ImGui_ImplWin32_WndProcHandler() with no active context! (#6275)

Better standardized similar checks in other backends.

backends/imgui_impl_allegro5.cpp

@@ -490,8 +490,9 @@ static void ImGui_ImplAllegro5_UpdateKeyModifiers()
 // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
 bool ImGui_ImplAllegro5_ProcessEvent(ALLEGRO_EVENT* ev)
 {
-    ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplAllegro5_Data* bd = ImGui_ImplAllegro5_GetBackendData();
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplAllegro5_Init()?");
+    ImGuiIO& io = ImGui::GetIO();
 
     switch (ev->type)
     {
@@ -586,7 +587,7 @@ static void ImGui_ImplAllegro5_UpdateMouseCursor()
 void ImGui_ImplAllegro5_NewFrame()
 {
     ImGui_ImplAllegro5_Data* bd = ImGui_ImplAllegro5_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplAllegro5_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplAllegro5_Init()?");
 
     if (!bd->Texture)
         ImGui_ImplAllegro5_CreateDeviceObjects();

backends/imgui_impl_dx10.cpp

@@ -578,7 +578,7 @@ void ImGui_ImplDX10_Shutdown()
 void ImGui_ImplDX10_NewFrame()
 {
     ImGui_ImplDX10_Data* bd = ImGui_ImplDX10_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplDX10_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplDX10_Init()?");
 
     if (!bd->pFontSampler)
         ImGui_ImplDX10_CreateDeviceObjects();

backends/imgui_impl_dx11.cpp

@@ -594,7 +594,7 @@ void ImGui_ImplDX11_Shutdown()
 void ImGui_ImplDX11_NewFrame()
 {
     ImGui_ImplDX11_Data* bd = ImGui_ImplDX11_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplDX11_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplDX11_Init()?");
 
     if (!bd->pFontSampler)
         ImGui_ImplDX11_CreateDeviceObjects();

backends/imgui_impl_dx12.cpp

@@ -750,7 +750,7 @@ void ImGui_ImplDX12_Shutdown()
 void ImGui_ImplDX12_NewFrame()
 {
     ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplDX12_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplDX12_Init()?");
 
     if (!bd->pPipelineState)
         ImGui_ImplDX12_CreateDeviceObjects();

backends/imgui_impl_dx9.cpp

@@ -399,7 +399,7 @@ void ImGui_ImplDX9_InvalidateDeviceObjects()
 void ImGui_ImplDX9_NewFrame()
 {
     ImGui_ImplDX9_Data* bd = ImGui_ImplDX9_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplDX9_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplDX9_Init()?");
 
     if (!bd->FontTexture)
         ImGui_ImplDX9_CreateDeviceObjects();

backends/imgui_impl_glfw.cpp

@@ -787,7 +787,7 @@ void ImGui_ImplGlfw_NewFrame()
 {
     ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplGlfw_InitForXXX()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplGlfw_InitForXXX()?");
 
     // Setup display size (every frame to accommodate for window resizing)
     int w, h;
@@ -838,7 +838,7 @@ void ImGui_ImplGlfw_InstallEmscriptenCanvasResizeCallback(const char* canvas_sel
 {
     IM_ASSERT(canvas_selector != nullptr);
     ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplGlfw_InitForXXX()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplGlfw_InitForXXX()?");
 
     bd->CanvasSelector = canvas_selector;
     emscripten_set_resize_callback(EMSCRIPTEN_EVENT_TARGET_WINDOW, bd, false, ImGui_ImplGlfw_OnCanvasSizeChange);

backends/imgui_impl_metal.mm

@@ -153,7 +153,7 @@ void ImGui_ImplMetal_Shutdown()
 void ImGui_ImplMetal_NewFrame(MTLRenderPassDescriptor* renderPassDescriptor)
 {
     ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
-    IM_ASSERT(bd->SharedMetalContext != nil && "No Metal context. Did you call ImGui_ImplMetal_Init() ?");
+    IM_ASSERT(bd != nil && "Context or backend not initialized! Did you call ImGui_ImplMetal_Init()?");
     bd->SharedMetalContext.framebufferDescriptor = [[FramebufferDescriptor alloc] initWithRenderPassDescriptor:renderPassDescriptor];
 
     if (bd->SharedMetalContext.depthStencilState == nil)

backends/imgui_impl_opengl2.cpp

@@ -108,7 +108,7 @@ void    ImGui_ImplOpenGL2_Shutdown()
 void    ImGui_ImplOpenGL2_NewFrame()
 {
     ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplOpenGL2_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplOpenGL2_Init()?");
 
     if (!bd->FontTexture)
         ImGui_ImplOpenGL2_CreateDeviceObjects();

backends/imgui_impl_opengl3.cpp

@@ -396,7 +396,7 @@ void    ImGui_ImplOpenGL3_Shutdown()
 void    ImGui_ImplOpenGL3_NewFrame()
 {
     ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplOpenGL3_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplOpenGL3_Init()?");
 
     if (!bd->ShaderHandle)
         ImGui_ImplOpenGL3_CreateDeviceObjects();

backends/imgui_impl_osx.mm

@@ -600,6 +600,7 @@ static void ImGui_ImplOSX_UpdateImePosWithView(NSView* view)
 void ImGui_ImplOSX_NewFrame(NSView* view)
 {
     ImGui_ImplOSX_Data* bd = ImGui_ImplOSX_GetBackendData();
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplOSX_Init()?");
     ImGuiIO& io = ImGui::GetIO();
 
     // Setup display size

backends/imgui_impl_sdl2.cpp

@@ -306,8 +306,9 @@ static void ImGui_ImplSDL2_UpdateKeyModifiers(SDL_Keymod sdl_key_mods)
 // If you have multiple SDL events and some of them are not meant to be used by dear imgui, you may need to filter events based on their windowID field.
 bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
 {
-    ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDL2_Init()?");
+    ImGuiIO& io = ImGui::GetIO();
 
     switch (event->type)
     {
@@ -704,7 +705,7 @@ static void ImGui_ImplSDL2_UpdateGamepads()
 void ImGui_ImplSDL2_NewFrame()
 {
     ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplSDL2_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDL2_Init()?");
     ImGuiIO& io = ImGui::GetIO();
 
     // Setup display size (every frame to accommodate for window resizing)

backends/imgui_impl_sdl3.cpp

@@ -269,8 +269,9 @@ static void ImGui_ImplSDL3_UpdateKeyModifiers(SDL_Keymod sdl_key_mods)
 // If you have multiple SDL events and some of them are not meant to be used by dear imgui, you may need to filter events based on their windowID field.
 bool ImGui_ImplSDL3_ProcessEvent(const SDL_Event* event)
 {
-    ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDL3_Init()?");
+    ImGuiIO& io = ImGui::GetIO();
 
     switch (event->type)
     {
@@ -658,7 +659,7 @@ static void ImGui_ImplSDL3_UpdateGamepads()
 void ImGui_ImplSDL3_NewFrame()
 {
     ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplSDL3_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDL3_Init()?");
     ImGuiIO& io = ImGui::GetIO();
 
     // Setup display size (every frame to accommodate for window resizing)

backends/imgui_impl_sdlrenderer2.cpp

@@ -104,7 +104,7 @@ static void ImGui_ImplSDLRenderer2_SetupRenderState()
 void ImGui_ImplSDLRenderer2_NewFrame()
 {
     ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplSDLRenderer2_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDLRenderer2_Init()?");
 
     if (!bd->FontTexture)
         ImGui_ImplSDLRenderer2_CreateDeviceObjects();

backends/imgui_impl_sdlrenderer3.cpp

@@ -100,7 +100,7 @@ static void ImGui_ImplSDLRenderer3_SetupRenderState()
 void ImGui_ImplSDLRenderer3_NewFrame()
 {
     ImGui_ImplSDLRenderer3_Data* bd = ImGui_ImplSDLRenderer3_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplSDLRenderer3_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDLRenderer3_Init()?");
 
     if (!bd->FontTexture)
         ImGui_ImplSDLRenderer3_CreateDeviceObjects();

backends/imgui_impl_vulkan.cpp

@@ -1133,7 +1133,7 @@ void ImGui_ImplVulkan_Shutdown()
 void ImGui_ImplVulkan_NewFrame()
 {
     ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplVulkan_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplVulkan_Init()?");
 
     if (!bd->FontDescriptorSet)
         ImGui_ImplVulkan_CreateFontsTexture();

backends/imgui_impl_win32.cpp

@@ -21,6 +21,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-05-07: Removed silent return when calling ImGui_ImplWin32_WndProcHandler() with no active context! If you don't always have an active context, check that ImGui::GetCurrentContext() != nullptr before calling this.
 //  2023-10-05: Inputs: Added support for extra ImGuiKey values: F13 to F24 function keys, app back/forward keys.
 //  2023-09-25: Inputs: Synthesize key-down event on key-up for VK_SNAPSHOT / ImGuiKey_PrintScreen as Windows doesn't emit it (same behavior as GLFW/SDL).
 //  2023-09-07: Inputs: Added support for keyboard codepage conversion for when application is compiled in MBCS mode and using a non-Unicode window.
@@ -382,9 +383,9 @@ static void ImGui_ImplWin32_UpdateGamepads()
 
 void    ImGui_ImplWin32_NewFrame()
 {
-    ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
-    IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplWin32_Init()?");
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized? Did you call ImGui_ImplWin32_Init()?");
+    ImGuiIO& io = ImGui::GetIO();
 
     // Setup display size (every frame to accommodate for window resizing)
     RECT rect = { 0, 0, 0, 0 };
@@ -580,11 +581,12 @@ static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
 
 IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
-    if (ImGui::GetCurrentContext() == nullptr)
+    // Before 2024-05-07 we were silently returning if ImGui::GetCurrentContext() == nullptr,
-        return 0;
+    // which was inconsistent with other backends. Make sure you call this after initializing the imgui context,
-
+    // other add an 'if (ImGui::GetCurrentContext() != NULL)` check before calling ImGui_ImplWin32_WndProcHandler().
-    ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplWin32_Init()?");
+    ImGuiIO& io = ImGui::GetIO();
 
     switch (msg)
     {

docs/CHANGELOG.txt

@@ -70,15 +70,18 @@ Other changes:
   duplicate with this fix. (#7399, #7404) [@GamingMinds-DanielC]
 - TreeNode: Added ImGuiTreeNodeFlags_SpanTextWidth to make hitbox and highlight only
   cover the label. (#6937) [@dimateos]
-- ProgressBar: Added support for indeterminate progress bar by passing an animated
-  negative fraction, e.g. ProgressBar(-1.0f * GetTime()). (#5316, #5370, #1901)[@gan74]
 - Tables: Angled headers: fixed multi-line label display when angle is flipped. (#6917)
 - Tables: Angled headers: added style.TableAngledHeadersTextAlign and corresponding
   ImGuiStyleVar_TableAngledHeadersTextAlign variable. Default to horizontal center. (#6917)
   [@thedmd, @ocornut]
+- ProgressBar: Added support for indeterminate progress bar by passing an animated
+  negative fraction, e.g. ProgressBar(-1.0f * GetTime()). (#5316, #5370, #1901)[@gan74]
 - Text, DrawList: Improved handling of long single-line wrapped text. Faster and
   mitigitate issues with reading vertex indexing limits with 16-bit indices. (#7496, #5720)
-- Backends: OpenGL: Detect ES3 contexts on desktop based on version string,
+- Backends: Win32: Removed silent return when calling ImGui_ImplWin32_WndProcHandler() with
+  no active context! If you don't always have an active context, you can check that
+  ImGui::GetCurrentContext() != nullptr before calling ImGui_ImplWin32_WndProcHandler(). (#6275)
+- Backends: OpenGL3: Detect ES3 contexts on desktop based on version string,
   to e.g. avoid calling glPolygonMode() on them. (#7447) [@afraidofdark, @ocornut]
 - Backends: Vulkan: Added convenience support for Volk via IMGUI_IMPL_VULKAN_USE_VOLK define.
   (you could always use IMGUI_IMPL_VULKAN_NO_PROTOTYPES + ImGui_ImplVulkan_LoadFunctions() as well).