MemoryEditor does not allow editing

[learn-more]

TLDR: I can't get the memory editor to 'edit' anything, and I am unsure how to debug this.

Observed issue: When selecting a byte (both in the hex or ascii columns) the byte is briefly selected, after which the selection seems to get lost again?
See screen recording:

example_glfw_vulkan_2024-02-21_22-20-34.mp4

This occurs in a (minimally) edited branch of Dear ImGui, details:

Version: v1.90.3-docking
Backend: imgui_impl_glfw.cpp + imgui_impl_vulkan.cpp
Compiler/OS: Win10 22H2 + MSVC 2022 (17.7.4)
Full config/build information:

Dear ImGui 1.90.3 (19030)
--------------------------------
sizeof(size_t): 4, sizeof(ImDrawIdx): 2, sizeof(ImDrawVert): 20
define: __cplusplus=199711
define: IMGUI_DISABLE_OBSOLETE_FUNCTIONS
define: IMGUI_DISABLE_OBSOLETE_KEYIO
define: _WIN32
define: _MSC_VER=1900
define: _MSVC_LANG=201402
define: IMGUI_HAS_VIEWPORT
define: IMGUI_HAS_DOCK
--------------------------------
io.BackendPlatformName: imgui_impl_glfw
io.BackendRendererName: imgui_impl_vulkan
io.ConfigFlags: 0x00000443
 NavEnableKeyboard
 NavEnableGamepad
 DockingEnable
 ViewportsEnable
io.ConfigViewportsNoDecoration
io.ConfigInputTextCursorBlink
io.ConfigWindowsResizeFromEdges
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x0000140E
 HasMouseCursors
 HasSetMousePos
 PlatformHasViewports
 RendererHasVtxOffset
 RendererHasViewports
--------------------------------
io.Fonts: 1 fonts, Flags: 0x00000000, TexSize: 512,64
io.DisplaySize: 1280.00,720.00
io.DisplayFramebufferScale: 1.00,1.00
--------------------------------
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00

To reproduce:

• Download imgui_memory_editor.h from ea49dd3 and drop it next to imgui.h
• Enable the attached patch
• Open Another Window
• Click on a byte

Patch :

$ git diff
diff --git a/examples/example_glfw_vulkan/main.cpp b/examples/example_glfw_vulkan/main.cpp
index c852e5f4d..47dd787c6 100644
--- a/examples/example_glfw_vulkan/main.cpp
+++ b/examples/example_glfw_vulkan/main.cpp
@@ -16,6 +16,7 @@
 #include "imgui.h"
 #include "imgui_impl_glfw.h"
 #include "imgui_impl_vulkan.h"
+#include "imgui_memory_editor.h"
 #include <stdio.h>          // printf, fprintf
 #include <stdlib.h>         // abort
 #define GLFW_INCLUDE_NONE
@@ -539,6 +540,9 @@ int main(int, char**)
             ImGui::Text("Hello from another window!");
             if (ImGui::Button("Close Me"))
                 show_another_window = false;
+            static MemoryEditor edit;
+            static unsigned char data[100];
+            edit.DrawContents(data, sizeof data);
             ImGui::End();
         }

[ocornut]

Indeed there was a bug.

In "Debug Log" I could see active id is being taken and cleared:

With io.ConfigDebugIsDebuggerPresent = true I can hover the value and break on the item:

And notice the window itself seems to be taking ActiveID, not the InputText().

Then I followed the trail of calling SetKeyboardFocusHere() -> InputText() and stepped into it, into ItemAdd()->NavProcessItem().
Recalled the implementation of SetKeyboardFocusHere() changed with better tabbing support in 1.89.4, and understood the issue in NavProcessItem():

// This is the code that is relied on for `SetKeyboardFocusHere()`.
if (g.NavMoveScoringItems && (item_flags & ImGuiItemFlags_Disabled) == 0 && (window->Flags & ImGuiWindowFlags_NoNavInputs) == 0)
{

Memory Editor uses ImGuiWindowFlags_NoNavInputs (via ImGuiWindowFlags_NoNav)

In other word, main lib broke SetKeyboardFocusHere() for windows using ImGuiWindowFlags_NoNavInputs.
I will work on a fix.

[ocornut]

Bug was introduced on February 8 with ocornut/imgui@3a07846

[ocornut]

This is fixed in main line by ocornut/imgui@13d91ff
I will make a release tonight or tomorrow with this.
Thank you for reporting!

[ocornut]

That'll teach me for not always running tests locally, as soon as I ran them I realized the typo and fixed it: ocornut/imgui@f5be905

[learn-more]

Thanks for the detailed explanation and the fast fix!