Tables: Angled headers: fixed multi-line label display when angle is flipped. (#6917)

docs/CHANGELOG.txt

@@ -66,6 +66,7 @@ Other changes:
   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)
 - 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,

imgui.cpp

@@ -2334,6 +2334,20 @@ const char* ImTextFindPreviousUtf8Codepoint(const char* in_text_start, const cha
     return in_text_start;
 }
 
+int ImTextCountLines(const char* in_text, const char* in_text_end)
+{
+    if (in_text_end == NULL)
+        in_text_end = in_text + strlen(in_text); // FIXME-OPT: Not optimal approach, discourage use for now.
+    int count = 0;
+    while (in_text < in_text_end)
+    {
+        const char* line_end = (const char*)memchr(in_text, '\n', in_text_end - in_text);
+        in_text = line_end ? line_end + 1 : in_text_end;
+        count++;
+    }
+    return count;
+}
+
 IM_MSVC_RUNTIME_CHECKS_RESTORE
 
 //-----------------------------------------------------------------------------

imgui_internal.h

@@ -407,6 +407,7 @@ IMGUI_API int           ImTextCountCharsFromUtf8(const char* in_text, const char
 IMGUI_API int           ImTextCountUtf8BytesFromChar(const char* in_text, const char* in_text_end);                             // return number of bytes to express one char in UTF-8
 IMGUI_API int           ImTextCountUtf8BytesFromStr(const ImWchar* in_text, const ImWchar* in_text_end);                        // return number of bytes to express string in UTF-8
 IMGUI_API const char*   ImTextFindPreviousUtf8Codepoint(const char* in_text_start, const char* in_text_curr);                   // return previous UTF-8 code-point.
+IMGUI_API int           ImTextCountLines(const char* in_text, const char* in_text_end);                                         // return number of lines taken by text. trailing carriage return doesn't count as an extra line.
 
 // Helpers: File System
 #ifdef IMGUI_DISABLE_FILE_FUNCTIONS

imgui_tables.cpp

@@ -3279,8 +3279,8 @@ void ImGui::TableAngledHeadersRowEx(ImGuiID row_id, float angle, float max_label
                 // - Handle multiple lines manually, as we want each lines to follow on the horizontal border, rather than see a whole block rotated.
                 const char* label_name = TableGetColumnName(table, column_n);
                 const char* label_name_end = FindRenderedTextEnd(label_name);
-                const float line_off_step_x = g.FontSize / -sin_a;
-                float line_off_curr_x = 0.0f;
+                const float line_off_step_x = (g.FontSize / -sin_a) * (flip_label ? -1.0f : 1.0f);
+                float line_off_curr_x = flip_label ? (ImTextCountLines(label_name, label_name_end) - 1) * -line_off_step_x : 0.0f;
                 while (label_name < label_name_end)
                 {
                     const char* label_name_eol = strchr(label_name, '\n');