InputText: Work-around for buggy standard libraries where isprint('\t') returns true. (#2467, #1336)

Not using isprint. + todo items.

docs/CHANGELOG.txt

@@ -38,6 +38,7 @@ Breaking Changes:
 Other Changes:
 - InputText: Fixed selection background starts rendering one frame after the cursor movement
   when first transitioning from no-selection to has-selection. (Bug in 1.69) (#2436) [@Nazg-Gul]
+- InputText: Work-around for buggy standard libraries where isprint('\t') returns true. (#2467, #1336)
 - GetMouseDragDelta(): also returns the delta on the mouse button released frame. (#2419)
 - GetMouseDragDelta(): verify that mouse positions are valid otherwise returns zero.
 - Inputs: Also add support for horizontal scroll with Shift+Mouse Wheel. (#2424, #1463) [@LucaRood]

docs/TODO.txt

@@ -138,7 +138,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - button: provide a button that looks framed. (?)
  - image/image button: misalignment on padded/bordered button?
  - image/image button: parameters are confusing, image() has tint_col,border_col whereas imagebutton() has bg_col/tint_col. Even thou they are different parameters ordering could be more consistent. can we fix that?
- - image button: not taking an explicit id is odd.
+ - image button: not taking an explicit id can be problematic. (#2464, #1390)
  - slider/drag: ctrl+click when format doesn't include a % character.. disable? display underlying value in default format? (see InputScalarAsWidgetReplacement)
  - slider: allow using the [-]/[+] buttons used by InputFloat()/InputInt()
  - slider: initial absolute click is imprecise. change to relative movement slider (same as scrollbar). (#1946)
@@ -329,6 +329,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - examples: glfw: could go idle when minimized? if (glfwGetWindowAttrib(window, GLFW_ICONIFIED)) { glfwWaitEvents(); continue; } // issue: DeltaTime will be super high on resume, perhaps provide a way to let impl know (#440)
  - examples: opengl: rename imgui_impl_opengl2 to impl_opengl_legacy and imgui_impl_opengl3 to imgui_impl_opengl? (#1900)
  - examples: opengl: could use a single vertex buffer and glBufferSubData for uploads?
+ - examples: vulkan: viewport: support for synchronized swapping of multiple swap chains.
  - optimization: replace vsnprintf with stb_printf? or enable the defines/infrastructure to allow it (#1038)
  - optimization: add clipping for multi-component widgets (SliderFloatX, ColorEditX, etc.). one problem is that nav branch can't easily clip parent group when there is a move request.
  - optimization: add a flag to disable most of rendering, for the case where the user expect to skip it (#335)

imgui.cpp

@@ -933,7 +933,7 @@ CODE
 #endif
 #include "imgui_internal.h"
 
-#include <ctype.h>      // toupper, isprint
+#include <ctype.h>      // toupper
 #include <stdio.h>      // vsnprintf, sscanf, printf
 #if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
 #include <stddef.h>     // intptr_t

imgui_demo.cpp

@@ -49,7 +49,7 @@ Index of this file:
 #endif
 
 #include "imgui.h"
-#include <ctype.h>          // toupper, isprint
+#include <ctype.h>          // toupper
 #include <limits.h>         // INT_MIN, INT_MAX
 #include <math.h>           // sqrtf, powf, cosf, sinf, floorf, ceilf
 #include <stdio.h>          // vsnprintf, sscanf, printf
@@ -2571,6 +2571,7 @@ static void ShowDemoWindowMisc()
             ImGui::Text("Keys pressed:");   for (int i = 0; i < IM_ARRAYSIZE(io.KeysDown); i++) if (ImGui::IsKeyPressed(i))             { ImGui::SameLine(); ImGui::Text("%d (0x%X)", i, i); }
             ImGui::Text("Keys release:");   for (int i = 0; i < IM_ARRAYSIZE(io.KeysDown); i++) if (ImGui::IsKeyReleased(i))            { ImGui::SameLine(); ImGui::Text("%d (0x%X)", i, i); }
             ImGui::Text("Keys mods: %s%s%s%s", io.KeyCtrl ? "CTRL " : "", io.KeyShift ? "SHIFT " : "", io.KeyAlt ? "ALT " : "", io.KeySuper ? "SUPER " : "");
+            ImGui::Text("Chars queue:");    for (int i = 0; i < io.InputQueueCharacters.Size; i++) { ImWchar c = io.InputQueueCharacters[i]; ImGui::SameLine();  ImGui::Text("\'%c\' (0x%04X)", (c > ' ' && c <= 255) ? (char)c : '?', c); } // FIXME: We should convert 'c' to UTF-8 here but the functions are not public.
 
             ImGui::Text("NavInputs down:"); for (int i = 0; i < IM_ARRAYSIZE(io.NavInputs); i++) if (io.NavInputs[i] > 0.0f)                    { ImGui::SameLine(); ImGui::Text("[%d] %.2f", i, io.NavInputs[i]); }
             ImGui::Text("NavInputs pressed:"); for (int i = 0; i < IM_ARRAYSIZE(io.NavInputs); i++) if (io.NavInputsDownDuration[i] == 0.0f)    { ImGui::SameLine(); ImGui::Text("[%d]", i); }

imgui_widgets.cpp

@@ -37,7 +37,7 @@ Index of this file:
 #endif
 #include "imgui_internal.h"
 
-#include <ctype.h>      // toupper, isprint
+#include <ctype.h>      // toupper
 #if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
 #include <stddef.h>     // intptr_t
 #else
@@ -3139,7 +3139,8 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
 {
     unsigned int c = *p_char;
 
-    if (c < 128 && c != ' ' && !isprint((int)(c & 0xFF)))
+    // Filter non-printable (NB: isprint is unreliable! see #2467)
+    if (c < 0x20)
     {
         bool pass = false;
         pass |= (c == '\n' && (flags & ImGuiInputTextFlags_Multiline));
@@ -3148,9 +3149,11 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
             return false;
     }
 
-    if (c >= 0xE000 && c <= 0xF8FF) // Filter private Unicode range. I don't imagine anybody would want to input them. GLFW on OSX seems to send private characters for special keys like arrow keys.
+    // Filter private Unicode range. GLFW on OSX seems to send private characters for special keys like arrow keys (FIXME)
+    if (c >= 0xE000 && c <= 0xF8FF)
         return false;
 
+    // Generic named filters
     if (flags & (ImGuiInputTextFlags_CharsDecimal | ImGuiInputTextFlags_CharsHexadecimal | ImGuiInputTextFlags_CharsUppercase | ImGuiInputTextFlags_CharsNoBlank | ImGuiInputTextFlags_CharsScientific))
     {
         if (flags & ImGuiInputTextFlags_CharsDecimal)
@@ -3174,6 +3177,7 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
                 return false;
     }
 
+    // Custom callback filter
     if (flags & ImGuiInputTextFlags_CallbackCharFilter)
     {
         ImGuiInputTextCallbackData callback_data;