Paragraph+TextDocument: Added GetText() method

* GetText() extracts the text from a certain range as BString.
 * Probably fixed TextDocument::ParagraphAt(), though it is still untested.

src/apps/haiku-depot/textview/Paragraph.cpp

@@ -5,6 +5,8 @@
 
 #include "Paragraph.h"
 
+#include <algorithm>
+
 
 Paragraph::Paragraph()
 	:
@@ -149,3 +151,47 @@ Paragraph::IsEmpty() const
 {
 	return fTextSpans.CountItems() == 0;
 }
+
+
+BString
+Paragraph::GetText(int32 start, int32 length) const
+{
+	if (start < 0)
+		start = 0;
+	
+	BString text;
+	
+	int32 count = fTextSpans.CountItems();
+	for (int32 i = 0; i < count; i++) {
+		const TextSpan& span = fTextSpans.ItemAtFast(i);
+		int32 spanLength = span.CharCount();
+		if (spanLength == 0)
+			continue;
+		if (start > spanLength) {
+			// Skip span if its before start
+			start -= spanLength;
+			continue;
+		}
+
+		// Remaining span length after start
+		spanLength -= start;
+		int32 copyLength = std::min(spanLength, length);
+
+		if (start == 0 && length == spanLength) {
+			text << span.Text();
+		} else {
+			BString subString;
+			span.Text().CopyCharsInto(subString, start, copyLength);
+			text << subString;
+		}
+		
+		length -= copyLength;
+		if (length == 0)
+			break;
+
+		// Next span is copied from its beginning
+		start = 0;
+	}
+
+	return text;
+}

src/apps/haiku-depot/textview/Paragraph.h

@@ -37,6 +37,8 @@ public:
 			int32				Length() const;
 			bool				IsEmpty() const;
 
+			BString				GetText(int32 start, int32 length) const;
+
 private:
 			ParagraphStyle		fStyle;
 			TextSpanList		fTextSpans;

src/apps/haiku-depot/textview/TextDocument.cpp

@@ -5,6 +5,8 @@
 
 #include "TextDocument.h"
 
+#include <algorithm>
+
 
 TextDocument::TextDocument()
 	:
@@ -172,9 +174,11 @@ TextDocument::ParagraphAt(int32 textOffset, int32& paragraphOffset) const
 	int32 count = fParagraphs.CountItems();
 	for (int32 i = 0; i < count; i++) {
 		const Paragraph& paragraph = fParagraphs.ItemAtFast(i);
-		paragraphOffset = textLength;
-		if (textLength + paragraph.Length() > textOffset)
+		paragraphOffset = textOffset - textLength;
+		int32 paragraphLength = paragraph.Length();
+		if (textLength + paragraphLength > textOffset)
 			return paragraph;
+		textLength += paragraphLength;
 	}
 	return fEmptyLastParagraph;
 }
@@ -211,3 +215,41 @@ TextDocument::Length() const
 }
 
 
+BString
+TextDocument::GetText(int32 start, int32 length) const
+{
+	if (start < 0)
+		start = 0;
+	
+	BString text;
+	
+	int32 count = fParagraphs.CountItems();
+	for (int32 i = 0; i < count; i++) {
+		const Paragraph& paragraph = fParagraphs.ItemAtFast(i);
+		int32 paragraphLength = paragraph.Length();
+		if (paragraphLength == 0)
+			continue;
+		if (start > paragraphLength) {
+			// Skip paragraph if its before start
+			start -= paragraphLength;
+			continue;
+		}
+
+		// Remaining paragraph length after start
+		paragraphLength -= start;
+		int32 copyLength = std::min(paragraphLength, length);
+		
+		text << paragraph.GetText(start, copyLength);
+		
+		length -= copyLength;
+		if (length == 0)
+			break;
+		else if (i < count - 1)
+			text << '\n';
+
+		// Next paragraph is copied from its beginning
+		start = 0;
+	}
+
+	return text;
+}

src/apps/haiku-depot/textview/TextDocument.h

@@ -65,6 +65,8 @@ public:
 			// Query information
 			int32				Length() const;
 
+			BString				GetText(int32 start, int32 length) const;
+
 private:
 			ParagraphList		fParagraphs;
 			Paragraph			fEmptyLastParagraph;