InputScalar, InputInt, InputFloat: added ImGuiInputTextFlags_ParseEmptyRefVal, ImGuiInputTextFlags_DisplayEmptyRefVal. (#7305)

docs/CHANGELOG.txt

@@ -62,6 +62,10 @@ Other changes:
   previous scrollbar width would be accounted for. (#5920)
 - Combo: simplified Combo() API uses a list clipper (due to its api it wasn't
   previously trivial before we added clipper.IncludeItemByIndex() function).
+- InputScalar, InputInt, InputFloat: added ImGuiInputTextFlags_ParseEmptyRefVal
+  to parse an empty field as zero-value. (#7305) [@supermerill, @ocornut]
+- InputScalar, InputInt, InputFloat: added ImGuiInputTextFlags_DisplayEmptyRefVal
+  to display a zero-value as empty. (#7305) [@supermerill, @ocornut]
 - Disabled: nested tooltips or other non-child window within a BeginDisabled()
   block disable the disabled state. (#211, #7640)
 - Misc: made ImGuiDir and ImGuiSortDirection stronger-typed enums.

imgui.h

@@ -1104,6 +1104,8 @@ enum ImGuiInputTextFlags_
     ImGuiInputTextFlags_CallbackResize      = 1 << 18,  // Callback on buffer capacity changes request (beyond 'buf_size' parameter value), allowing the string to grow. Notify when the string wants to be resized (for string types which hold a cache of their Size). You will be provided a new BufSize in the callback and NEED to honor it. (see misc/cpp/imgui_stdlib.h for an example of using this)
     ImGuiInputTextFlags_CallbackEdit        = 1 << 19,  // Callback on any edit (note that InputText() already returns true on edit, the callback is useful mainly to manipulate the underlying buffer while focus is active)
     ImGuiInputTextFlags_EscapeClearsAll     = 1 << 20,  // Escape key clears content if not empty, and deactivate otherwise (contrast to default behavior of Escape to revert)
+    ImGuiInputTextFlags_ParseEmptyRefVal    = 1 << 21,  // InputFloat(), InputInt(), InputScalar() etc. only: parse empty string as zero value.
+    ImGuiInputTextFlags_DisplayEmptyRefVal  = 1 << 22,  // InputFloat(), InputInt(), InputScalar() etc. only: when value is zero, do not display it. Generally used with ImGuiInputTextFlags_ParseEmptyRefVal.
 
     // Obsolete names
     //ImGuiInputTextFlags_AlwaysInsertMode  = ImGuiInputTextFlags_AlwaysOverwrite   // [renamed in 1.82] name was not matching behavior

imgui_demo.cpp

@@ -2273,20 +2273,24 @@ static void ShowDemoWindowWidgets()
 
         IMGUI_DEMO_MARKER("Widgets/Data Types/Inputs");
         static bool inputs_step = true;
+        static ImGuiInputTextFlags flags = ImGuiInputTextFlags_None;
         ImGui::SeparatorText("Inputs");
         ImGui::Checkbox("Show step buttons", &inputs_step);
-        ImGui::InputScalar("input s8",      ImGuiDataType_S8,     &s8_v,  inputs_step ? &s8_one  : NULL, NULL, "%d");
-        ImGui::InputScalar("input u8",      ImGuiDataType_U8,     &u8_v,  inputs_step ? &u8_one  : NULL, NULL, "%u");
-        ImGui::InputScalar("input s16",     ImGuiDataType_S16,    &s16_v, inputs_step ? &s16_one : NULL, NULL, "%d");
-        ImGui::InputScalar("input u16",     ImGuiDataType_U16,    &u16_v, inputs_step ? &u16_one : NULL, NULL, "%u");
-        ImGui::InputScalar("input s32",     ImGuiDataType_S32,    &s32_v, inputs_step ? &s32_one : NULL, NULL, "%d");
-        ImGui::InputScalar("input s32 hex", ImGuiDataType_S32,    &s32_v, inputs_step ? &s32_one : NULL, NULL, "%04X");
-        ImGui::InputScalar("input u32",     ImGuiDataType_U32,    &u32_v, inputs_step ? &u32_one : NULL, NULL, "%u");
-        ImGui::InputScalar("input u32 hex", ImGuiDataType_U32,    &u32_v, inputs_step ? &u32_one : NULL, NULL, "%08X");
-        ImGui::InputScalar("input s64",     ImGuiDataType_S64,    &s64_v, inputs_step ? &s64_one : NULL);
-        ImGui::InputScalar("input u64",     ImGuiDataType_U64,    &u64_v, inputs_step ? &u64_one : NULL);
-        ImGui::InputScalar("input float",   ImGuiDataType_Float,  &f32_v, inputs_step ? &f32_one : NULL);
-        ImGui::InputScalar("input double",  ImGuiDataType_Double, &f64_v, inputs_step ? &f64_one : NULL);
+        ImGui::CheckboxFlags("ImGuiInputTextFlags_ReadOnly", &flags, ImGuiInputTextFlags_ReadOnly);
+        ImGui::CheckboxFlags("ImGuiInputTextFlags_ParseEmptyRefVal", &flags, ImGuiInputTextFlags_ParseEmptyRefVal);
+        ImGui::CheckboxFlags("ImGuiInputTextFlags_DisplayEmptyRefVal", &flags, ImGuiInputTextFlags_DisplayEmptyRefVal);
+        ImGui::InputScalar("input s8",      ImGuiDataType_S8,     &s8_v,  inputs_step ? &s8_one  : NULL, NULL, "%d", flags);
+        ImGui::InputScalar("input u8",      ImGuiDataType_U8,     &u8_v,  inputs_step ? &u8_one  : NULL, NULL, "%u", flags);
+        ImGui::InputScalar("input s16",     ImGuiDataType_S16,    &s16_v, inputs_step ? &s16_one : NULL, NULL, "%d", flags);
+        ImGui::InputScalar("input u16",     ImGuiDataType_U16,    &u16_v, inputs_step ? &u16_one : NULL, NULL, "%u", flags);
+        ImGui::InputScalar("input s32",     ImGuiDataType_S32,    &s32_v, inputs_step ? &s32_one : NULL, NULL, "%d", flags);
+        ImGui::InputScalar("input s32 hex", ImGuiDataType_S32,    &s32_v, inputs_step ? &s32_one : NULL, NULL, "%04X", flags);
+        ImGui::InputScalar("input u32",     ImGuiDataType_U32,    &u32_v, inputs_step ? &u32_one : NULL, NULL, "%u", flags);
+        ImGui::InputScalar("input u32 hex", ImGuiDataType_U32,    &u32_v, inputs_step ? &u32_one : NULL, NULL, "%08X", flags);
+        ImGui::InputScalar("input s64",     ImGuiDataType_S64,    &s64_v, inputs_step ? &s64_one : NULL, NULL, NULL, flags);
+        ImGui::InputScalar("input u64",     ImGuiDataType_U64,    &u64_v, inputs_step ? &u64_one : NULL, NULL, NULL, flags);
+        ImGui::InputScalar("input float",   ImGuiDataType_Float,  &f32_v, inputs_step ? &f32_one : NULL, NULL, NULL, flags);
+        ImGui::InputScalar("input double",  ImGuiDataType_Double, &f64_v, inputs_step ? &f64_one : NULL, NULL, NULL, flags);
 
         ImGui::TreePop();
     }

imgui_internal.h

@@ -1211,6 +1211,7 @@ enum ImGuiNextItemDataFlags_
     ImGuiNextItemDataFlags_HasWidth     = 1 << 0,
     ImGuiNextItemDataFlags_HasOpen      = 1 << 1,
     ImGuiNextItemDataFlags_HasShortcut  = 1 << 2,
+    ImGuiNextItemDataFlags_HasRefVal    = 1 << 3,
 };
 
 struct ImGuiNextItemData
@@ -1224,6 +1225,7 @@ struct ImGuiNextItemData
     ImGuiInputFlags             ShortcutFlags;      // Set by SetNextItemShortcut()
     bool                        OpenVal;            // Set by SetNextItemOpen()
     ImU8                        OpenCond;           // Set by SetNextItemOpen()
+    ImGuiDataTypeStorage        RefVal;             // Not exposed yet, for ImGuiInputTextFlags_ParseEmptyAsRefVal
 
     ImGuiNextItemData()         { memset(this, 0, sizeof(*this)); SelectionUserData = -1; }
     inline void ClearFlags()    { Flags = ImGuiNextItemDataFlags_None; ItemFlags = ImGuiItemFlags_None; } // Also cleared manually by ItemAdd()!
@@ -2154,6 +2156,7 @@ struct ImGuiContext
     ImGuiInputTextDeactivatedState InputTextDeactivatedState;
     ImFont                  InputTextPasswordFont;
     ImGuiID                 TempInputId;                        // Temporary text input when CTRL+clicking on a slider, etc.
+    ImGuiDataTypeStorage    DataTypeZeroValue;                  // 0 for all data types
     int                     BeginMenuDepth;
     int                     BeginComboDepth;
     ImGuiColorEditFlags     ColorEditOptions;                   // Store user options for color edit widgets
@@ -2376,6 +2379,7 @@ struct ImGuiContext
         MouseStationaryTimer = 0.0f;
 
         TempInputId = 0;
+        memset(&DataTypeZeroValue, 0, sizeof(DataTypeZeroValue));
         BeginMenuDepth = BeginComboDepth = 0;
         ColorEditOptions = ImGuiColorEditFlags_DefaultOptions_;
         ColorEditCurrentID = ColorEditSavedID = 0;
@@ -3458,7 +3462,7 @@ namespace ImGui
     IMGUI_API const ImGuiDataTypeInfo*  DataTypeGetInfo(ImGuiDataType data_type);
     IMGUI_API int           DataTypeFormatString(char* buf, int buf_size, ImGuiDataType data_type, const void* p_data, const char* format);
     IMGUI_API void          DataTypeApplyOp(ImGuiDataType data_type, int op, void* output, const void* arg_1, const void* arg_2);
-    IMGUI_API bool          DataTypeApplyFromText(const char* buf, ImGuiDataType data_type, void* p_data, const char* format);
+    IMGUI_API bool          DataTypeApplyFromText(const char* buf, ImGuiDataType data_type, void* p_data, const char* format, void* p_data_when_empty = NULL);
     IMGUI_API int           DataTypeCompare(ImGuiDataType data_type, const void* arg_1, const void* arg_2);
     IMGUI_API bool          DataTypeClamp(ImGuiDataType data_type, void* p_data, const void* p_min, const void* p_max);
 

imgui_widgets.cpp

@@ -2141,18 +2141,25 @@ void ImGui::DataTypeApplyOp(ImGuiDataType data_type, int op, void* output, const
 
 // User can input math operators (e.g. +100) to edit a numerical values.
 // NB: This is _not_ a full expression evaluator. We should probably add one and replace this dumb mess..
-bool ImGui::DataTypeApplyFromText(const char* buf, ImGuiDataType data_type, void* p_data, const char* format)
+bool ImGui::DataTypeApplyFromText(const char* buf, ImGuiDataType data_type, void* p_data, const char* format, void* p_data_when_empty)
 {
-    while (ImCharIsBlankA(*buf))
-        buf++;
-    if (!buf[0])
-        return false;
-
     // Copy the value in an opaque buffer so we can compare at the end of the function if it changed at all.
     const ImGuiDataTypeInfo* type_info = DataTypeGetInfo(data_type);
     ImGuiDataTypeStorage data_backup;
     memcpy(&data_backup, p_data, type_info->Size);
 
+    while (ImCharIsBlankA(*buf))
+        buf++;
+    if (!buf[0])
+    {
+        if (p_data_when_empty != NULL)
+        {
+            memcpy(p_data, p_data_when_empty, type_info->Size);
+            return memcmp(&data_backup, p_data, type_info->Size) != 0;
+        }
+        return false;
+    }
+
     // Sanitize format
     // - For float/double we have to ignore format with precision (e.g. "%.2f") because sscanf doesn't take them in, so force them into %f and %lf
     // - In theory could treat empty format as using default, but this would only cover rare/bizarre case of using InputScalar() + integer + format string without %.
@@ -3475,7 +3482,7 @@ bool ImGui::TempInputScalar(const ImRect& bb, ImGuiID id, const char* label, ImG
         memcpy(&data_backup, p_data, data_type_size);
 
         // Apply new value (or operations) then clamp
-        DataTypeApplyFromText(data_buf, data_type, p_data, format);
+        DataTypeApplyFromText(data_buf, data_type, p_data, format, NULL);
         if (p_clamp_min || p_clamp_max)
         {
             if (p_clamp_min && p_clamp_max && DataTypeCompare(data_type, p_clamp_min, p_clamp_max) > 0)
@@ -3505,8 +3512,13 @@ bool ImGui::InputScalar(const char* label, ImGuiDataType data_type, void* p_data
     if (format == NULL)
         format = DataTypeGetInfo(data_type)->PrintFmt;
 
+    void* p_data_default = (g.NextItemData.Flags & ImGuiNextItemDataFlags_HasRefVal) ? &g.NextItemData.RefVal : &g.DataTypeZeroValue;
+
     char buf[64];
-    DataTypeFormatString(buf, IM_ARRAYSIZE(buf), data_type, p_data, format);
+    if ((flags & ImGuiInputTextFlags_DisplayEmptyRefVal) && DataTypeCompare(data_type, p_data, p_data_default) == 0)
+        buf[0] = 0;
+    else
+        DataTypeFormatString(buf, IM_ARRAYSIZE(buf), data_type, p_data, format);
 
     flags |= ImGuiInputTextFlags_AutoSelectAll | (ImGuiInputTextFlags)ImGuiInputTextFlags_NoMarkEdited; // We call MarkItemEdited() ourselves by comparing the actual data rather than the string.
     flags |= (ImGuiInputTextFlags)ImGuiInputTextFlags_LocalizeDecimalPoint;
@@ -3515,7 +3527,7 @@ bool ImGui::InputScalar(const char* label, ImGuiDataType data_type, void* p_data
     if (p_step == NULL)
     {
         if (InputText(label, buf, IM_ARRAYSIZE(buf), flags))
-            value_changed = DataTypeApplyFromText(buf, data_type, p_data, format);
+            value_changed = DataTypeApplyFromText(buf, data_type, p_data, format, (flags & ImGuiInputTextFlags_ParseEmptyRefVal) ? p_data_default : NULL);
     }
     else
     {
@@ -3525,7 +3537,7 @@ bool ImGui::InputScalar(const char* label, ImGuiDataType data_type, void* p_data
         PushID(label);
         SetNextItemWidth(ImMax(1.0f, CalcItemWidth() - (button_size + style.ItemInnerSpacing.x) * 2));
         if (InputText("", buf, IM_ARRAYSIZE(buf), flags)) // PushId(label) + "" gives us the expected ID from outside point of view
-            value_changed = DataTypeApplyFromText(buf, data_type, p_data, format);
+            value_changed = DataTypeApplyFromText(buf, data_type, p_data, format, (flags & ImGuiInputTextFlags_ParseEmptyRefVal) ? p_data_default : NULL);
         IMGUI_TEST_ENGINE_ITEM_INFO(g.LastItemData.ID, label, g.LastItemData.StatusFlags | ImGuiItemStatusFlags_Inputable);
 
         // Step buttons