Allow drawing the selected text bg earlier

Add new methods to DrawTextDelegate to allow drawing the background
of the selected text before drawing each character. This fixes an issue
when the glyphs used by a TTF were overlapped.

Author: martincapello

text/draw_text.h

@@ -1,5 +1,5 @@
 // LAF Text Library
-// Copyright (c) 2022-2024  Igara Studio S.A.
+// Copyright (c) 2022-2025  Igara Studio S.A.
 // Copyright (C) 2017  David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -32,6 +32,20 @@ class DrawTextDelegate {
 public:
   virtual ~DrawTextDelegate() {}
 
+  // This is called before processing and drawing character by character.
+  // Returns true if the character index is in the range of selected characters.
+  virtual bool isSelectedChar(const int index)
+  {
+    // Do nothing
+    return false;
+  }
+
+  // This is called before processing and drawing character by character.
+  virtual void drawSelectionBg(const gfx::RectF& bounds)
+  {
+    // Do nothing
+  }
+
   // This is called before drawing the character.
   virtual void preProcessChar(const int index,
                               const codepoint_t codepoint,

text/draw_text_shaper.cpp

@@ -1,5 +1,5 @@
 // LAF Text Library
-// Copyright (c) 2024  Igara Studio S.A.
+// Copyright (c) 2024-2025  Igara Studio S.A.
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -49,11 +49,31 @@ class AdapterBuilder : public TextBlob::RunHandler {
   void commitRunBuffer(TextBlob::RunInfo& info) override
   {
     if (info.clusters && info.glyphCount > 0) {
-      float advanceX = 0.0f;
+      gfx::RectF selectionBounds;
+      gfx::RectF textBounds;
+      std::vector<gfx::RectF> glyphsBounds;
+      for (int i = 0; i < info.glyphCount; ++i) {
+        auto bounds = info.getGlyphBounds(i);
+        glyphsBounds.push_back(bounds);
+        textBounds |= bounds;
+
+        if (m_delegate && m_delegate->isSelectedChar(i))
+          selectionBounds |= bounds;
+      }
 
       os::Paint paint;
       paint.style(os::Paint::Fill);
 
+      if (m_surface && m_bg != gfx::ColorNone) {
+        paint.color(m_bg);
+        m_surface->drawRect(textBounds.offset(m_origin), paint);
+      }
+
+      if (m_delegate && !selectionBounds.isEmpty())
+        m_delegate->drawSelectionBg(selectionBounds.offset(m_origin));
+
+      float advanceX = 0.0f;
+
       for (int i = 0; i < info.glyphCount; ++i) {
         int utf8Begin, utf8End;
 
@@ -71,7 +91,7 @@ class AdapterBuilder : public TextBlob::RunHandler {
 
         const std::string utf8text = m_text.substr(utf8Begin, utf8End - utf8Begin);
 
-        gfx::RectF bounds = info.getGlyphBounds(i);
+        gfx::RectF bounds = glyphsBounds[i];
         bounds.offset(m_origin);
 
         advanceX += bounds.w;
@@ -100,11 +120,6 @@ class AdapterBuilder : public TextBlob::RunHandler {
         if (m_delegate)
           m_delegate->preDrawChar(bounds);
 
-        if (m_bg != gfx::ColorNone) {
-          paint.color(m_bg);
-          m_surface->drawRect(bounds, paint);
-        }
-
         if (m_surface && info.font) {
           if (info.font->type() == FontType::SpriteSheet) {
             const auto* spriteFont = static_cast<const SpriteSheetFont*>(info.font.get());