fix text width and caret positioning in text boxes

src/graphics/core/Font.cpp

@@ -29,6 +29,10 @@ Font::Font(
     if (this->fontFile.has_value()) {
         if (auto fontPtr = this->fontFile->lock()) {
             monospace = fontPtr->isMonospace();
+            if (monospace && this->glyphs.size() > '0' &&
+                this->glyphs['0'].xAdvance > 0) {
+                glyphInterval = this->glyphs['0'].xAdvance;
+            }
         }
     }
 }
@@ -62,21 +66,13 @@ bool Font::isPrintableChar(uint codepoint) const {
 
 int FontMetrics::calcWidth(std::wstring_view text, size_t offset, size_t length) const {
     auto font = this->font.has_value() ? this->font->lock() : nullptr;
-    if (font == nullptr || font->isMonospace()) {
-        return std::min(text.length() - offset, length) * _glyphInterval;
+    if (font != nullptr) {
+        return font->calcWidth(text, offset, length);
     }
-    int totalWidth = 0;
-    for (int i = offset; i < offset + length && i < text.length(); i++) {
-        auto codepoint = text[i];
-        if (!font->isPrintableChar(codepoint)) {
-            totalWidth += _glyphInterval;
-        } else if (auto glyph = font->getGlyph(codepoint)) {
-            totalWidth += glyph->xAdvance;
-        } else {
-            totalWidth += _glyphInterval;
-        }
+    if (offset >= text.length()) {
+        return 0;
     }
-    return totalWidth;
+    return std::min(text.length() - offset, length) * _glyphInterval;
 }
 
 int Font::calcWidth(std::wstring_view text, size_t length) const {
@@ -84,7 +80,24 @@ int Font::calcWidth(std::wstring_view text, size_t length) const {
 }
 
 int Font::calcWidth(std::wstring_view text, size_t offset, size_t length) const {
-    return std::min(text.length()-offset, length) * glyphInterval;
+    if (offset >= text.length()) {
+        return 0;
+    }
+    size_t end = offset + std::min(text.length() - offset, length);
+    int width = 0;
+    for (size_t i = offset; i < end; i++) {
+        width += getAdvance(text[i]);
+    }
+    return width;
+}
+
+int Font::getAdvance(uint codepoint) const {
+    if (isPrintableChar(codepoint)) {
+        if (auto glyph = getGlyph(codepoint)) {
+            return glyph->xAdvance;
+        }
+    }
+    return glyphInterval;
 }
 
 static inline void draw_glyph(
@@ -194,11 +207,10 @@ static inline void draw_text(
             }
             int yOffset = 0;
             int xOffset = 0;
-            float advance = 1.0f;
+            float advance = font.getAdvance(c) / cellAdvance;
             if (auto glyph = font.getGlyph(c)) {
                 yOffset = glyph->yOffset;
                 xOffset = glyph->xOffset;
-                advance = glyph->xAdvance / cellAdvance;
             }
             uint charpage = c >> 8;
             if (charpage == page){
@@ -325,7 +337,7 @@ std::unique_ptr<Font> Font::createBitmapFont(
     return std::make_unique<Font>(std::move(textures), std::move(glyphs), res, 4);
 }
 
-const Glyph* Font::getGlyph(int codepoint) {
+const Glyph* Font::getGlyph(int codepoint) const {
     if (codepoint < 0) {
         return nullptr;
     }

src/graphics/core/Font.hpp

@@ -57,6 +57,10 @@ public:
     /// @return pixel width of the substring
     int calcWidth(std::wstring_view text, size_t offset, size_t length) const;
 
+    /// @brief Get the horizontal advance of a character in pixels
+    /// @param codepoint character unicode codepoint
+    int getAdvance(uint codepoint) const;
+
     /// @brief Check if character is visible (non-whitespace)
     /// @param codepoint character unicode codepoint
     bool isPrintableChar(uint codepoint) const;
@@ -87,7 +91,7 @@ public:
         return {std::nullopt, lineHeight, yoffset, glyphInterval};
     }
  
-    const Glyph* getGlyph(int codepoint);
+    const Glyph* getGlyph(int codepoint) const;
 
     static std::unique_ptr<Font> createBitmapFont(
         std::vector<std::unique_ptr<ImageData>> pages
@@ -97,7 +101,7 @@ private:
     int yoffset;
     int glyphInterval;
     bool monospace = true;
-    std::vector<std::unique_ptr<Texture>> pages;
-    std::vector<Glyph> glyphs;
+    mutable std::vector<std::unique_ptr<Texture>> pages;
+    mutable std::vector<Glyph> glyphs;
     std::optional<std::weak_ptr<vector_fonts::FontFile>> fontFile;
 };

src/graphics/ui/elements/TextBox.cpp

@@ -255,9 +255,9 @@ void TextBox::draw(const DrawContext& pctx, const Assets& assets) {
     // drawing caret here
     if (isFocused() && editable && static_cast<int>((time - caretLastMove) * 2) % 2 == 0) {
         uint line = label->getLineByTextIndex(caret);
-        auto linestart = label->getTextLineOffset(line);
-        uint lcaret = caret - label->getTextLineOffset(line);
-        int width = rawTextCache.metrics.calcWidth(input.substr(linestart), 0, lcaret);
+        size_t lineStart = label->getTextLineOffset(line);
+        size_t lineCaret = caret - lineStart;
+        int width = rawTextCache.metrics.calcWidth(input, lineStart, lineCaret);
 
         batch->rect(
             lcoord.x + width,
@@ -275,11 +275,13 @@ void TextBox::draw(const DrawContext& pctx, const Assets& assets) {
         uint endLine = label->getLineByTextIndex(selectionEnd);
 
         batch->setColor(glm::vec4(0.8f, 0.9f, 1.0f, 0.25f));
+        size_t startLineOffset = label->getTextLineOffset(startLine);
+        size_t endLineOffset = label->getTextLineOffset(endLine);
         int start = rawTextCache.metrics.calcWidth(
-            labelText, 0, selectionStart - label->getTextLineOffset(startLine)
+            labelText, startLineOffset, selectionStart - startLineOffset
         );
         int end = rawTextCache.metrics.calcWidth(
-            labelText, 0, selectionEnd - label->getTextLineOffset(endLine)
+            labelText, endLineOffset, selectionEnd - endLineOffset
         );
         int lineY = label->getLineYOffset(startLine);
 
@@ -352,6 +354,11 @@ void TextBox::draw(const DrawContext& pctx, const Assets& assets) {
 }
 
 void TextBox::drawBackground(const DrawContext& pctx, const Assets& assets) {
+    if (lineNumbersLabel->getFontName() != label->getFontName()) {
+        lineNumbersLabel->setFontName(label->getFontName());
+    }
+    lineNumbersLabel->setLineInterval(label->getLineInterval());
+
     auto font = assets.getShared<Font>(label->getFontName());
     if (font != nullptr) {
         rawTextCache.prepare(font, font->getMetrics(), label->getSize().x);
@@ -681,13 +688,19 @@ int TextBox::calcIndexAt(int x, int y) const {
     uint line = label->getLineByYOffset(y - lcoord.y);
     line = std::min(line, label->getLinesNumber() - 1);
     size_t lineLength = getLineLength(line);
+    size_t lineStart = label->getTextLineOffset(line);
     uint offset = 0;
-    while (lcoord.x + rawTextCache.metrics.calcWidth(labelText, 0, offset) < x &&
-           offset < lineLength - 1) {
+    while (offset < lineLength - 1) {
+        int width = rawTextCache.metrics.calcWidth(
+            labelText, lineStart, offset
+        );
+        if (lcoord.x + width >= x) {
+            break;
+        }
         offset++;
     }
     return std::min(
-        offset + label->getTextLineOffset(line), labelText.length()
+        offset + lineStart, labelText.length()
     );
 }
 
@@ -1224,9 +1237,12 @@ void TextBox::setCaret(size_t position) {
         offset -= getSize().y;
         scrolled(-glm::ceil(offset / static_cast<double>(scrollStep) + 0.5f));
     }
-    int lcaret = caret - rawTextCache.getTextLineOffset(line);
-    int realoffset = rawTextCache.metrics.calcWidth(labelText, 0, lcaret) -
-                     static_cast<int>(textOffset);
+    size_t lineStart = rawTextCache.getTextLineOffset(line);
+    size_t lineCaret = caret - lineStart;
+    int caretWidth = rawTextCache.metrics.calcWidth(
+        labelText, lineStart, lineCaret
+    );
+    int realoffset = caretWidth - static_cast<int>(textOffset);
 
     if (realoffset - width > 0) {
         setTextOffset(textOffset + realoffset - width);