Reduce CPU usage when font fallback in not needed

microsoft · Oct 2, 2019 · e566a4a · e566a4a
1 parent abf3ee5
commit e566a4a
Showing 1 changed file with 24 additions and 7 deletions.
diff --git a/src/renderer/dx/CustomTextLayout.cpp b/src/renderer/dx/CustomTextLayout.cpp
@@ -129,13 +129,30 @@ CustomTextLayout::CustomTextLayout(gsl::not_null<IDWriteFactory1*> const factory
         // Allocate enough room to have one breakpoint per code unit.
         _breakpoints.resize(_text.size());
 
-        // Call each of the analyzers in sequence, recording their results.
-        RETURN_IF_FAILED(_analyzer->AnalyzeLineBreakpoints(this, 0, textLength, this));
-        RETURN_IF_FAILED(_analyzer->AnalyzeBidi(this, 0, textLength, this));
-        RETURN_IF_FAILED(_analyzer->AnalyzeScript(this, 0, textLength, this));
-        RETURN_IF_FAILED(_analyzer->AnalyzeNumberSubstitution(this, 0, textLength, this));
-        // Perform our custom font fallback analyzer that mimics the pattern of the real analyzers.
-        RETURN_IF_FAILED(_AnalyzeFontFallback(this, 0, textLength));
+        const bool whiteSpacesOnly = std::all_of(
+            _text.begin(), _text.end(), [](wchar_t c) noexcept {
+            return iswspace(c);
+        });
+
+        if (!whiteSpacesOnly)
+        {
+            // Call each of the analyzers in sequence, recording their results.
+            RETURN_IF_FAILED(_analyzer->AnalyzeLineBreakpoints(this, 0, textLength, this));
+            RETURN_IF_FAILED(_analyzer->AnalyzeBidi(this, 0, textLength, this));
+            RETURN_IF_FAILED(_analyzer->AnalyzeScript(this, 0, textLength, this));
+            RETURN_IF_FAILED(_analyzer->AnalyzeNumberSubstitution(this, 0, textLength, this));
+
+            const bool asciiOnly = std::all_of(
+                _text.begin(), _text.end(), [](wchar_t c) noexcept {
+                return iswascii(c);
+            });
+
+            if (!asciiOnly)
+            {
+                // Perform our custom font fallback analyzer that mimics the pattern of the real analyzers.
+                RETURN_IF_FAILED(_AnalyzeFontFallback(this, 0, textLength));
+            }
+        }
 
         // Ensure that a font face is attached to every run
         for (auto& run : _runs)