Font: Internals: make used page maps smaller. Since it's extremely ra…

…rely used and for iterations only. ~34->16 bytes with ImWchar32.

imgui.cpp

@@ -16177,9 +16177,9 @@ void ImGui::DebugNodeFont(ImFont* font)
             // Skip ahead if a large bunch of glyphs are not present in the font (test in chunks of 4k)
             // This is only a small optimization to reduce the number of iterations when IM_UNICODE_MAX_CODEPOINT
             // is large // (if ImWchar==ImWchar32 we will do at least about 272 queries here)
-            if (!(base & 4095) && font->IsGlyphRangeUnused(base, base + 4095))
+            if (!(base & 8191) && font->IsGlyphRangeUnused(base, base + 8191))
             {
-                base += 4096 - 256;
+                base += 8192 - 256;
                 continue;
             }
 

imgui.h

@@ -3461,7 +3461,7 @@ struct ImFont
     float                       Scale;              // 4     // in  // = 1.f      // Base font scale, multiplied by the per-window font scale which you can adjust with SetWindowFontScale()
     float                       Ascent, Descent;    // 4+4   // out //            // Ascent: distance from top to bottom of e.g. 'A' [0..FontSize] (unscaled)
     int                         MetricsTotalSurface;// 4     // out //            // Total surface in pixels to get an idea of the font rasterization/texture cost (not exact, we approximate the cost of padding between glyphs)
-    ImU8                        Used4kPagesMap[(IM_UNICODE_CODEPOINT_MAX+1)/4096/8]; // 2 bytes if ImWchar=ImWchar16, 34 bytes if ImWchar==ImWchar32. Store 1-bit for each block of 4K codepoints that has one active glyph. This is mainly used to facilitate iterations across all used codepoints.
+    ImU8                        Used8kPagesMap[(IM_UNICODE_CODEPOINT_MAX+1)/8192/8]; // 1 bytes if ImWchar=ImWchar16, 16 bytes if ImWchar==ImWchar32. Store 1-bit for each block of 4K codepoints that has one active glyph. This is mainly used to facilitate iterations across all used codepoints.
 
     // Methods
     IMGUI_API ImFont();

imgui_draw.cpp

@@ -3689,7 +3689,7 @@ ImFont::ImFont()
     Scale = 1.0f;
     Ascent = Descent = 0.0f;
     MetricsTotalSurface = 0;
-    memset(Used4kPagesMap, 0, sizeof(Used4kPagesMap));
+    memset(Used8kPagesMap, 0, sizeof(Used8kPagesMap));
 }
 
 ImFont::~ImFont()
@@ -3709,7 +3709,7 @@ void    ImFont::ClearOutputData()
     DirtyLookupTables = true;
     Ascent = Descent = 0.0f;
     MetricsTotalSurface = 0;
-    memset(Used4kPagesMap, 0, sizeof(Used4kPagesMap));
+    memset(Used8kPagesMap, 0, sizeof(Used8kPagesMap));
 }
 
 static ImWchar FindFirstExistingGlyph(ImFont* font, const ImWchar* candidate_chars, int candidate_chars_count)
@@ -3732,7 +3732,7 @@ void ImFont::BuildLookupTable()
     IndexAdvanceX.clear();
     IndexLookup.clear();
     DirtyLookupTables = false;
-    memset(Used4kPagesMap, 0, sizeof(Used4kPagesMap));
+    memset(Used8kPagesMap, 0, sizeof(Used8kPagesMap));
     GrowIndex(max_codepoint + 1);
     for (int i = 0; i < Glyphs.Size; i++)
     {
@@ -3741,8 +3741,8 @@ void ImFont::BuildLookupTable()
         IndexLookup[codepoint] = (ImWchar)i;
 
         // Mark 4K page as used
-        const int page_n = codepoint / 4096;
-        Used4kPagesMap[page_n >> 3] |= 1 << (page_n & 7);
+        const int page_n = codepoint / 8192;
+        Used8kPagesMap[page_n >> 3] |= 1 << (page_n & 7);
     }
 
     // Create a glyph to handle TAB
@@ -3804,15 +3804,15 @@ void ImFont::BuildLookupTable()
     }
 }
 
-// API is designed this way to avoid exposing the 4K page size
+// API is designed this way to avoid exposing the 8K page size
 // e.g. use with IsGlyphRangeUnused(0, 255)
 bool ImFont::IsGlyphRangeUnused(unsigned int c_begin, unsigned int c_last)
 {
-    unsigned int page_begin = (c_begin / 4096);
-    unsigned int page_last = (c_last / 4096);
+    unsigned int page_begin = (c_begin / 8192);
+    unsigned int page_last = (c_last / 8192);
     for (unsigned int page_n = page_begin; page_n <= page_last; page_n++)
-        if ((page_n >> 3) < sizeof(Used4kPagesMap))
-            if (Used4kPagesMap[page_n >> 3] & (1 << (page_n & 7)))
+        if ((page_n >> 3) < sizeof(Used8kPagesMap))
+            if (Used8kPagesMap[page_n >> 3] & (1 << (page_n & 7)))
                 return false;
     return true;
 }