Internals: Tidying up internal helpers. Fixed a case ImParseFormatTrimDecorations() can return an off by one (out of bound) pointer if the format string is invalid. Extracted ImParseFormatFindEnd() out of TrimDecorations so we can use it to find the format type and replace the %f in old Int apis.

imgui.cpp

@@ -8631,7 +8631,7 @@ bool ImGui::InputScalarAsWidgetReplacement(const ImRect& bb, ImGuiID id, const c
 
     char fmt_buf[32];
     char data_buf[32];
-    format = ParseFormatTrimDecorations(format, fmt_buf, IM_ARRAYSIZE(fmt_buf));
+    format = ImParseFormatTrimDecorations(format, fmt_buf, IM_ARRAYSIZE(fmt_buf));
     DataTypeFormatString(data_buf, IM_ARRAYSIZE(data_buf), data_type, data_ptr, format);
     ImStrTrimBlanks(data_buf);
     ImGuiInputTextFlags flags = ImGuiInputTextFlags_AutoSelectAll | ((data_type == ImGuiDataType_Float || data_type == ImGuiDataType_Double) ? ImGuiInputTextFlags_CharsScientific : ImGuiInputTextFlags_CharsDecimal);
@@ -8647,7 +8647,8 @@ bool ImGui::InputScalarAsWidgetReplacement(const ImRect& bb, ImGuiID id, const c
     return false;
 }
 
-const char* ImGui::ParseFormatTrimDecorationsLeading(const char* fmt)
+// We don't use strchr() because our strings are usually very short and often start with '%'
+const char* ImParseFormatFindStart(const char* fmt)
 {
     while (char c = fmt[0])
     {
@@ -8660,36 +8661,44 @@ const char* ImGui::ParseFormatTrimDecorationsLeading(const char* fmt)
     return fmt;
 }
 
+const char* ImParseFormatFindEnd(const char* fmt)
+{
+    // Printf/scanf types modifiers: I/L/h/j/l/t/w/z. Other uppercase letters qualify as types aka end of the format.
+    IM_ASSERT(fmt[0] == '%');
+    const unsigned int ignored_uppercase_mask = (1 << ('I'-'A')) | (1 << ('L'-'A'));
+    const unsigned int ignored_lowercase_mask = (1 << ('h'-'a')) | (1 << ('j'-'a')) | (1 << ('l'-'a')) | (1 << ('t'-'a')) | (1 << ('w'-'a')) | (1 << ('z'-'a'));
+    for (char c; (c = *fmt) != 0; fmt++)
+    {
+        if (c >= 'A' && c <= 'Z' && ((1 << (c - 'A')) & ignored_uppercase_mask) == 0) 
+            return fmt + 1;
+        if (c >= 'a' && c <= 'z' && ((1 << (c - 'a')) & ignored_lowercase_mask) == 0)
+            return fmt + 1;
+    }
+    return fmt;
+}
+
 // Extract the format out of a format string with leading or trailing decorations
 //  fmt = "blah blah"  -> return fmt
 //  fmt = "%.3f"       -> return fmt
 //  fmt = "hello %.3f" -> return fmt + 6
 //  fmt = "%.3f hello" -> return buf written with "%.3f"
-const char* ImGui::ParseFormatTrimDecorations(const char* fmt, char* buf, int buf_size)
+const char* ImParseFormatTrimDecorations(const char* fmt, char* buf, int buf_size)
 {
-    // We don't use strchr() because our strings are usually very short and often start with '%'
+    const char* fmt_start = ImParseFormatFindStart(fmt);
-    const char* fmt_start = ParseFormatTrimDecorationsLeading(fmt);
     if (fmt_start[0] != '%')
         return fmt;
-    fmt = fmt_start;
+    const char* fmt_end = ImParseFormatFindEnd(fmt_start);
-    while (char c = *fmt++)
+    if (fmt_end[0] == 0) // If we only have leading decoration, we don't need to copy the data.
-    {
-        if (c >= 'A' && c <= 'Z' && (c != 'L'))  // L is a type modifier, other letters qualify as types aka end of the format
-            break;
-        if (c >= 'a' && c <= 'z' && (c != 'h' && c != 'j' && c != 'l' && c != 't' && c != 'w' && c != 'z'))  // h/j/l/t/w/z are type modifiers, other letters qualify as types aka end of the format
-            break;
-    }
-    if (fmt[0] == 0) // If we only have leading decoration, we don't need to copy the data.
         return fmt_start;
-    ImStrncpy(buf, fmt_start, ImMin((int)(fmt + 1 - fmt_start), buf_size));
+    ImStrncpy(buf, fmt_start, ImMin((int)(fmt_end + 1 - fmt_start), buf_size));
     return buf;
 }
 
 // Parse display precision back from the display format string
 // FIXME: This is still used by some navigation code path to infer a minimum tweak step, but we should aim to rework widgets so it isn't needed.
-int ImGui::ParseFormatPrecision(const char* fmt, int default_precision)
+int ImParseFormatPrecision(const char* fmt, int default_precision)
 {
-    fmt = ParseFormatTrimDecorationsLeading(fmt);
+    fmt = ImParseFormatFindStart(fmt);
     if (fmt[0] != '%')
         return default_precision;
     fmt++;
@@ -8717,13 +8726,6 @@ static float GetMinimumStepAtDecimalPrecision(int decimal_precision)
     return (decimal_precision >= 0 && decimal_precision < 10) ? min_steps[decimal_precision] : powf(10.0f, (float)-decimal_precision);
 }
 
-float ImGui::RoundScalarWithFormat(const char* format, float value)
-{
-    char buf[64];
-    ImFormatString(buf, IM_ARRAYSIZE(buf), ParseFormatTrimDecorationsLeading(format), value);
-    return (float)atof(buf);
-}
-
 static inline float SliderBehaviorCalcRatioFromValue(float v, float v_min, float v_max, float power, float linear_zero_pos)
 {
     if (v_min == v_max)
@@ -8762,7 +8764,7 @@ bool ImGui::SliderBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v
 
     const bool is_non_linear = (power < 1.0f-0.00001f) || (power > 1.0f+0.00001f);
     const bool is_horizontal = (flags & ImGuiSliderFlags_Vertical) == 0;
-    const bool is_decimal = ParseFormatPrecision(format, 3) != 0;
+    const bool is_decimal = ImParseFormatPrecision(format, 3) != 0;
 
     const float grab_padding = 2.0f;
     const float slider_sz = is_horizontal ? (frame_bb.GetWidth() - grab_padding * 2.0f) : (frame_bb.GetHeight() - grab_padding * 2.0f);
@@ -8877,7 +8879,9 @@ bool ImGui::SliderBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v
             }
 
             // Round past decimal precision
-            new_value = RoundScalarWithFormat(format, new_value);
+            char buf[64];
+            ImFormatString(buf, IM_ARRAYSIZE(buf), ImParseFormatFindStart(format), new_value);
+            new_value = (float)atof(buf);
             if (*v != new_value)
             {
                 *v = new_value;
@@ -9155,7 +9159,7 @@ static bool ImGui::DragBehaviorT(ImGuiID id, ImGuiDataType data_type, TYPE* v, f
     }
     if (g.ActiveIdSource == ImGuiInputSource_Nav)
     {
-        int decimal_precision = ParseFormatPrecision(format, 3);
+        int decimal_precision = ImParseFormatPrecision(format, 3);
         adjust_delta = GetNavInputAmount2d(ImGuiNavDirSourceFlags_Keyboard|ImGuiNavDirSourceFlags_PadDPad, ImGuiInputReadMode_RepeatFast, 1.0f/10.0f, 10.0f).x;
         v_speed = ImMax(v_speed, GetMinimumStepAtDecimalPrecision(decimal_precision));
     }
@@ -9198,7 +9202,7 @@ static bool ImGui::DragBehaviorT(ImGuiID id, ImGuiDataType data_type, TYPE* v, f
 
     // Round to user desired precision based on format string
     char v_str[64];
-    ImFormatString(v_str, IM_ARRAYSIZE(v_str), ParseFormatTrimDecorationsLeading(format), v_cur);
+    ImFormatString(v_str, IM_ARRAYSIZE(v_str), ImParseFormatFindStart(format), v_cur);
     if (data_type == ImGuiDataType_Float || data_type == ImGuiDataType_Double)
         v_cur = (TYPE)atof(v_str);
     else

imgui_internal.h

@@ -121,6 +121,10 @@ IMGUI_API const char*   ImStristr(const char* haystack, const char* haystack_end
 IMGUI_API void          ImStrTrimBlanks(char* str);
 IMGUI_API int           ImFormatString(char* buf, size_t buf_size, const char* fmt, ...) IM_FMTARGS(3);
 IMGUI_API int           ImFormatStringV(char* buf, size_t buf_size, const char* fmt, va_list args) IM_FMTLIST(3);
+IMGUI_API const char*   ImParseFormatFindStart(const char* format);
+IMGUI_API const char*   ImParseFormatFindEnd(const char* format);
+IMGUI_API const char*   ImParseFormatTrimDecorations(const char* format, char* buf, int buf_size);
+IMGUI_API int           ImParseFormatPrecision(const char* format, int default_value);
 
 // Helpers: Math
 // We are keeping those not leaking to the user by default, in the case the user has implicit cast operators between ImVec2 and its own types (when IM_VEC2_CLASS_EXTRA is defined)
@@ -1118,11 +1122,6 @@ namespace ImGui
 
     IMGUI_API void          PlotEx(ImGuiPlotType plot_type, const char* label, float (*values_getter)(void* data, int idx), void* data, int values_count, int values_offset, const char* overlay_text, float scale_min, float scale_max, ImVec2 graph_size);
 
-    IMGUI_API const char*   ParseFormatTrimDecorationsLeading(const char* format);
-    IMGUI_API const char*   ParseFormatTrimDecorations(const char* format, char* buf, int buf_size);
-    IMGUI_API int           ParseFormatPrecision(const char* format, int default_value);
-    IMGUI_API float         RoundScalarWithFormat(const char* format, float value);
-
     // Shade functions (write over already created vertices)
     IMGUI_API void          ShadeVertsLinearColorGradientKeepAlpha(ImDrawVert* vert_start, ImDrawVert* vert_end, ImVec2 gradient_p0, ImVec2 gradient_p1, ImU32 col0, ImU32 col1);
     IMGUI_API void          ShadeVertsLinearAlphaGradientForLeftToRightText(ImDrawVert* vert_start, ImDrawVert* vert_end, float gradient_p0_x, float gradient_p1_x);