Draw text line by line (diasurgical#8379)

Author: BLooperZ

CMake/Tests.cmake

@@ -170,6 +170,16 @@ if(DEVILUTIONX_SCREENSHOT_FORMAT STREQUAL DEVILUTIONX_SCREENSHOT_FORMAT_PNG AND
       kerning_fit_spacing__align_right.png
       vertical_overflow.png
       vertical_overflow-colors.png
+      cursor-start.png
+      cursor-middle.png
+      cursor-end.png
+      multiline_cursor-end_first_line.png
+      multiline_cursor-start_second_line.png
+      multiline_cursor-middle_second_line.png
+      multiline_cursor-end_second_line.png
+      highlight-partial.png
+      highlight-full.png
+      multiline_highlight.png
     SRC_PREFIX test/fixtures/text_render_integration_test/
     OUTPUT_DIR "${DEVILUTIONX_TEST_FIXTURES_OUTPUT_DIRECTORY}/text_render_integration_test"
     OUTPUT_VARIABLE _text_render_integration_test_fixtures

Source/engine/render/text_render.cpp

@@ -437,6 +437,88 @@ int GetLineStartX(UiFlags flags, const Rectangle &rect, int lineWidth)
 	return rect.position.x;
 }
 
+void DrawLine(
+    const Surface &out,
+    std::string_view text,
+    Point characterPosition,
+    Rectangle rect,
+    UiFlags flags,
+    int curSpacing,
+    GameFontTables size,
+    text_color color,
+    bool outline,
+    const TextRenderOptions &opts,
+    size_t lineStartPos,
+    int totalWidth)
+{
+	CurrentFont currentFont;
+
+	std::string_view lineCopy = text;
+
+	size_t currentPos = 0;
+
+	size_t cpLen;
+
+	const auto maybeDrawCursor = [&]() {
+		const auto byteIndex = static_cast<int>(lineStartPos + currentPos);
+		Point position = characterPosition;
+		if (opts.cursorPosition == byteIndex) {
+			if (GetAnimationFrame(2, 500) != 0 || opts.cursorStatic) {
+				FontStack baseFont = LoadFont(size, color, 0);
+				if (baseFont.has_value()) {
+					DrawFont(out, position, baseFont.glyph('|'), color, outline);
+				}
+			}
+			if (opts.renderedCursorPositionOut != nullptr) {
+				*opts.renderedCursorPositionOut = position;
+			}
+		}
+	};
+
+	// Start from the beginning of the line
+	characterPosition.x = GetLineStartX(flags, rect, totalWidth);
+
+	while (!lineCopy.empty()) {
+		char32_t c = DecodeFirstUtf8CodePoint(lineCopy, &cpLen);
+		if (c == Utf8DecodeError) break;
+		if (c == ZWSP) {
+			lineCopy.remove_prefix(cpLen);
+			continue;
+		}
+
+		if (!currentFont.load(size, color, c)) {
+			c = U'?';
+			if (!currentFont.load(size, color, c)) {
+				app_fatal("Missing fonts");
+			}
+		}
+		const uint8_t frame = c & 0xFF;
+
+		const ClxSprite glyph = currentFont.glyph(frame);
+		const int charWidth = glyph.width();
+
+		const auto byteIndex = static_cast<int>(lineStartPos + currentPos);
+
+		// Draw highlight
+		if (byteIndex >= opts.highlightRange.begin && byteIndex < opts.highlightRange.end) {
+			const bool lastInRange = static_cast<int>(byteIndex + cpLen) == opts.highlightRange.end;
+			FillRect(out, characterPosition.x, characterPosition.y,
+			    glyph.width() + (lastInRange ? 0 : curSpacing), glyph.height(),
+			    opts.highlightColor);
+		}
+
+		DrawFont(out, characterPosition, glyph, color, outline);
+		maybeDrawCursor();
+
+		// Move to the next position
+		characterPosition.x += charWidth + curSpacing;
+		currentPos += cpLen;
+		lineCopy.remove_prefix(cpLen);
+	}
+	assert(currentPos == text.size());
+	maybeDrawCursor();
+}
+
 uint32_t DoDrawString(const Surface &out, std::string_view text, Rectangle rect, Point &characterPosition,
     int lineWidth, int charactersInLine, int rightMargin, int bottomMargin, GameFontTables size, text_color color, bool outline,
     TextRenderOptions &opts)
@@ -455,19 +537,26 @@ uint32_t DoDrawString(const Surface &out, std::string_view text, Rectangle rect,
 	std::string_view remaining = text;
 	size_t cpLen;
 
-	const auto maybeDrawCursor = [&]() {
-		if (opts.cursorPosition == static_cast<int>(text.size() - remaining.size())) {
-			Point position = characterPosition;
-			MaybeWrap(position, 2, rightMargin, position.x, opts.lineHeight);
-			if (GetAnimationFrame(2, 500) != 0) {
-				FontStack baseFont = LoadFont(size, color, 0);
-				if (baseFont.has_value()) {
-					DrawFont(out, position, baseFont.glyph('|'), color, outline);
-				}
-			}
-			if (opts.renderedCursorPositionOut != nullptr) {
-				*opts.renderedCursorPositionOut = position;
-			}
+	// Track line boundaries
+	size_t lineStartPos = 0;
+	size_t lineEndPos = 0;
+
+	const auto drawLine = [&]() {
+		std::string_view lineText = text.substr(lineStartPos, lineEndPos - lineStartPos);
+		if (!lineText.empty()) {
+			DrawLine(
+			    out,
+			    lineText,
+			    characterPosition,
+			    rect,
+			    opts.flags,
+			    curSpacing,
+			    size,
+			    color,
+			    outline,
+			    opts,
+			    lineStartPos,
+			    lineWidth);
 		}
 	};
 
@@ -487,8 +576,10 @@ uint32_t DoDrawString(const Surface &out, std::string_view text, Rectangle rect,
 		const uint8_t frame = next & 0xFF;
 		const uint16_t width = currentFont.glyph(frame).width();
 		if (next == U'\n' || characterPosition.x + width > rightMargin) {
-			if (next == '\n')
-				maybeDrawCursor();
+			lineEndPos = text.size() - remaining.size();
+
+			drawLine();
+
 			const int nextLineY = characterPosition.y + opts.lineHeight;
 			if (nextLineY >= bottomMargin)
 				break;
@@ -506,26 +597,26 @@ uint32_t DoDrawString(const Surface &out, std::string_view text, Rectangle rect,
 			}
 			characterPosition.x = GetLineStartX(opts.flags, rect, lineWidth);
 
+			// Start a new line
+			lineStartPos = next == U'\n' ? (text.size() - remaining.size() + cpLen) : (text.size() - remaining.size());
+			lineEndPos = lineStartPos;
+
 			if (next == U'\n')
 				continue;
 		}
 
-		const ClxSprite glyph = currentFont.glyph(frame);
-		const auto byteIndex = static_cast<int>(text.size() - remaining.size());
-
-		// Draw highlight
-		if (byteIndex >= opts.highlightRange.begin && byteIndex < opts.highlightRange.end) {
-			const bool lastInRange = static_cast<int>(byteIndex + cpLen) == opts.highlightRange.end;
-			FillRect(out, characterPosition.x, characterPosition.y,
-			    glyph.width() + (lastInRange ? 0 : curSpacing), glyph.height(),
-			    opts.highlightColor);
-		}
+		// Update end position as we add characters
+		lineEndPos = text.size() - remaining.size() + cpLen;
 
-		DrawFont(out, characterPosition, glyph, color, outline);
-		maybeDrawCursor();
+		// Update position for the next character
 		characterPosition.x += width + curSpacing;
 	}
-	maybeDrawCursor();
+
+	// Draw any remaining characters in the last line
+	if (lineStartPos < lineEndPos) {
+		drawLine();
+	}
+
 	return static_cast<uint32_t>(remaining.data() - text.data());
 }
 

Source/engine/render/text_render.hpp

@@ -155,6 +155,8 @@ struct TextRenderOptions {
 
 	/** @brief If a cursor is rendered, the surface coordinates are saved here. */
 	std::optional<Point> *renderedCursorPositionOut = nullptr;
+
+	bool cursorStatic = false;
 };
 
 /**