Optimisation for drawing of large TextLayouts that go beyond the top and bottom of the graphics clip region

modules/juce_graphics/fonts/juce_TextLayout.cpp

@@ -27,7 +27,7 @@
 namespace juce
 {
 
-TextLayout::Glyph::Glyph (const int glyph, Point<float> anch, float w) noexcept
+TextLayout::Glyph::Glyph (int glyph, Point<float> anch, float w) noexcept
     : glyphCode (glyph), anchor (anch), width (w)
 {
 }
@@ -69,6 +69,29 @@ TextLayout::Run::Run (const Run& other)
 
 TextLayout::Run::~Run() noexcept {}
 
+Range<float> TextLayout::Run::getRunBoundsX() const noexcept
+{
+    Range<float> range;
+    bool isFirst = true;
+
+    for (auto& glyph : glyphs)
+    {
+        Range<float> r (glyph.anchor.x, glyph.anchor.x + glyph.width);
+
+        if (isFirst)
+        {
+            isFirst = false;
+            range = r;
+        }
+        else
+        {
+            range = range.getUnionWith (r);
+        }
+    }
+
+    return range;
+}
+
 //==============================================================================
 TextLayout::Line::Line() noexcept
     : ascent (0.0f), descent (0.0f), leading (0.0f)
@@ -101,19 +124,16 @@ Range<float> TextLayout::Line::getLineBoundsX() const noexcept
 
     for (auto* run : runs)
     {
-        for (auto& glyph : run->glyphs)
-        {
-            Range<float> runRange (glyph.anchor.x, glyph.anchor.x + glyph.width);
+        auto runRange = run->getRunBoundsX();
 
-            if (isFirst)
-            {
-                isFirst = false;
-                range = runRange;
-            }
-            else
-            {
-                range = range.getUnionWith (runRange);
-            }
+        if (isFirst)
+        {
+            isFirst = false;
+            range = runRange;
+        }
+        else
+        {
+            range = range.getUnionWith (runRange);
         }
     }
 
@@ -177,7 +197,7 @@ TextLayout::~TextLayout()
 {
 }
 
-TextLayout::Line& TextLayout::getLine (const int index) const
+TextLayout::Line& TextLayout::getLine (int index) const noexcept
 {
     return *lines.getUnchecked (index);
 }
@@ -194,12 +214,23 @@ void TextLayout::addLine (Line* line)
 
 void TextLayout::draw (Graphics& g, Rectangle<float> area) const
 {
-    auto origin = justification.appliedToRectangle (Rectangle<float> (width, getHeight()), area).getPosition();
+    auto origin = justification.appliedToRectangle ({ width, getHeight() }, area).getPosition();
 
-    auto& context = g.getInternalContext();
+    auto& context   = g.getInternalContext();
+    auto clip       = context.getClipBounds();
+    auto clipTop    = (float) clip.getY();
+    auto clipBottom = (float) clip.getBottom();
 
     for (auto* line : lines)
     {
+        auto lineRangeY = line->getLineBoundsY();
+
+        if (lineRangeY.getEnd() < clipTop)
+            continue;
+
+        if (lineRangeY.getStart() > clipBottom)
+            break;
+
         auto lineOrigin = origin + line->lineOrigin;
 
         for (auto* run : line->runs)
@@ -213,16 +244,7 @@ void TextLayout::draw (Graphics& g, Rectangle<float> area) const
 
             if (run->font.isUnderlined())
             {
-                Range<float> runExtent;
-
-                for (auto& glyph : run->glyphs)
-                {
-                    Range<float> glyphRange (glyph.anchor.x, glyph.anchor.x + glyph.width);
-
-                    runExtent = runExtent.isEmpty() ? glyphRange
-                                                    : runExtent.getUnionWith (glyphRange);
-                }
-
+                auto runExtent = run->getRunBoundsX();
                 auto lineThickness = run->font.getDescent() * 0.3f;
 
                 context.fillRect ({ runExtent.getStart() + lineOrigin.x, lineOrigin.y + lineThickness * 2.0f,
@@ -385,7 +407,7 @@ namespace TextLayoutHelpers
                             currentRun = new TextLayout::Run();
 
                         addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
-                        currentLine->stringRange = Range<int> (lineStartPosition, charPosition);
+                        currentLine->stringRange = { lineStartPosition, charPosition };
 
                         if (! needToSetLineOrigin)
                             layout.addLine (currentLine.release());
@@ -398,7 +420,7 @@ namespace TextLayoutHelpers
                 else
                 {
                     addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
-                    currentLine->stringRange = Range<int> (lineStartPosition, charPosition);
+                    currentLine->stringRange = { lineStartPosition, charPosition };
 
                     if (! needToSetLineOrigin)
                         layout.addLine (currentLine.release());
@@ -426,7 +448,7 @@ namespace TextLayoutHelpers
 
     private:
         static void addRun (TextLayout::Line& glyphLine, TextLayout::Run* glyphRun,
-                            const Token& t, const int start, const int end)
+                            const Token& t, int start, int end)
         {
             glyphRun->stringRange = { start, end };
             glyphRun->font = t.font;
@@ -436,7 +458,7 @@ namespace TextLayoutHelpers
             glyphLine.runs.add (glyphRun);
         }
 
-        static int getCharacterType (const juce_wchar c) noexcept
+        static int getCharacterType (juce_wchar c) noexcept
         {
             if (c == '\r' || c == '\n')
                 return 0;
@@ -482,7 +504,7 @@ namespace TextLayoutHelpers
                 tokens.add (new Token (currentString, font, colour, lastCharType == 2));
         }
 
-        void layoutRuns (const float maxWidth, const float extraLineSpacing, const AttributedString::WordWrap wordWrap)
+        void layoutRuns (float maxWidth, float extraLineSpacing, AttributedString::WordWrap wordWrap)
         {
             float x = 0, y = 0, h = 0;
             int i;
@@ -500,7 +522,7 @@ namespace TextLayoutHelpers
                 if (nextTok == nullptr)
                     break;
 
-                const bool tokenTooLarge = (x + nextTok->area.getWidth() > maxWidth);
+                bool tokenTooLarge = (x + nextTok->area.getWidth() > maxWidth);
 
                 if (t.isNewLine || ((! nextTok->isWhitespace) && (tokenTooLarge && wordWrap != AttributedString::none)))
                 {
@@ -516,7 +538,7 @@ namespace TextLayoutHelpers
             ++totalLines;
         }
 
-        void setLastLineHeight (int i, const float height) noexcept
+        void setLastLineHeight (int i, float height) noexcept
         {
             while (--i >= 0)
             {

modules/juce_graphics/fonts/juce_TextLayout.h

@@ -119,6 +119,9 @@ public:
         Run (Range<int> stringRange, int numGlyphsToPreallocate);
         ~Run() noexcept;
 
+        /** Returns the X position range which contains all the glyphs in this run. */
+        Range<float> getRunBoundsX() const noexcept;
+
         Font font;              /**< The run's font. */
         Colour colour;          /**< The run's colour. */
         Array<Glyph> glyphs;    /**< The glyphs in this run. */
@@ -171,7 +174,7 @@ public:
     int getNumLines() const noexcept    { return lines.size(); }
 
     /** Returns one of the lines. */
-    Line& getLine (int index) const;
+    Line& getLine (int index) const noexcept;
 
     /** Adds a line to the layout. The layout will take ownership of this line object
         and will delete it when it is no longer needed. */