Improve indent and kerning handling.

1 files changed, 95 insertions, 60 deletions

diff --git a/mcs/class/System.Windows.Forms/System.Windows.Forms/Line.cs b/mcs/class/System.Windows.Forms/System.Windows.Forms/Line.cs
index f4eea8893df..008a2aabc4e 100644
--- a/mcs/class/System.Windows.Forms/System.Windows.Forms/Line.cs
+++ b/mcs/class/System.Windows.Forms/System.Windows.Forms/Line.cs
@@ -51,7 +51,7 @@ namespace System.Windows.Forms
 		internal HorizontalAlignment	alignment;		// Alignment of the line

 		internal int			align_shift;		// Pixel shift caused by the alignment

 		internal float			indent;			// Left indent for the first line

-		internal float			hanging_indent;		// Hanging indent (difference between first line indent and other lines, cannot be less than -indent)

+		internal float			hanging_indent;		// Hanging indent (difference between first line indent and other lines)

 		internal float			right_indent;		// Right indent for all lines

 		internal LineEnding		ending;

 		internal float			spacing_before;

@@ -181,10 +181,7 @@ namespace System.Windows.Forms
 		internal float HangingIndent {

 			get { return hanging_indent; }

 			set {

-				if (hanging_indent >= -indent)

-					this.hanging_indent = value;

-				else

-					this.hanging_indent = -indent;

+				this.hanging_indent = value;

 				recalc = true;

 			}

 		}

@@ -583,14 +580,11 @@ namespace System.Windows.Forms
 		/// </summary>

 		internal bool RecalculateLine (Graphics g, Document doc)

 		{

-			return RecalculateLine (g, doc, kerning_fonts.ContainsKey (tags.Font.GetHashCode ()));

-		}

-

-		private bool RecalculateLine (Graphics g, Document doc, bool handleKerning)

-		{

 			LineTag tag;

 			int pos;

 			int len;

+			Font currentFont;

+			int currentFontStart;

 			SizeF size;

 			float w;

 			int prev_offset;

@@ -603,7 +597,6 @@ namespace System.Windows.Forms
 			int prev_height;

 			int prev_ascent;

 			float prev_spacing_before;

-			float add_width;

 			int max_above_baseline;

 			int max_below_baseline;

 			int total_ascent;

@@ -611,9 +604,13 @@ namespace System.Windows.Forms
 			TabStop lastTab;

 			int lastTabPos;

 			char c;

+			bool handleKerning;

+			float right_indent;

 

 			pos = 0;

 			len = this.text.Length;

+			currentFont = tags.FontToDisplay;

+			currentFontStart = 0;

 			tag = this.tags;

 			prev_offset = this.offset;	// For drawing optimization calculations

 			prev_height = this.height;

@@ -628,6 +625,7 @@ namespace System.Windows.Forms
 			this.height = 0;		// Reset line height

 			this.ascent = 0;		// Reset the ascent for the line

 			tag.Shift = 0;			// Reset shift (which should be stored as pixels, not as points)

+			right_indent = Math.Max(this.right_indent, 0); // Ignore any negative right indent.

 

 			if (line_no > 0) {

 				line = doc.GetLine (LineNo - 1);

@@ -637,9 +635,14 @@ namespace System.Windows.Forms
 			}

 

 			if (first_in_para)

-				widths[0] = document.left_margin + indent;

+				widths[0] = indent;

 			else

-				widths[0] = document.left_margin + indent + hanging_indent;

+				widths[0] = indent + hanging_indent;

+			

+			if (widths[0] < 0)

+				widths[0] = 0; // Don't allow a negative indent to take the line to a negative position.

+			

+			widths[0] += document.left_margin;

 

 			this.recalc = false;

 			retval = false;

@@ -647,7 +650,8 @@ namespace System.Windows.Forms
 

 			wrap_pos = 0;

 			prev_wrap_pos = 0;

-			add_width = 0;

+			

+			handleKerning = kerning_fonts.ContainsKey (currentFont.GetHashCode ());

 

 			while (pos < len) {

 

@@ -655,8 +659,16 @@ namespace System.Windows.Forms
 					//tag.Ascent = 0;

 					tag.Shift = (tag.Line.ascent - tag.Ascent); // / 72;

 					tag = tag.Next;

+					if (tag.Length != 0 && tag.FontToDisplay != currentFont) {

+						CheckKerning(g, currentFont, currentFontStart, pos - currentFontStart);

+						currentFont = tag.FontToDisplay;

+						currentFontStart = pos;

+						handleKerning = kerning_fonts.ContainsKey (currentFont.GetHashCode ());

+					}

 				}

 

+				c = text[pos];

+

 				// kerning is a problem.  The original code in this method assumed that the

 				// width of a string equals the sum of the widths of its characters.  This is

 				// not true when kerning takes place during the display process.  Since it's

@@ -673,17 +685,18 @@ namespace System.Windows.Forms
 					// MeasureText doesn't measure trailing spaces, so we do the best we can for those

 					// in the else branch.

 					// It doesn't measure /t characters either, we need to add it manually with add_width.

-					size = TextBoxTextRenderer.MeasureText (g, text.ToString (0, pos + 1), tag.Font);

-					newWidth = widths[0] + size.Width + add_width;

+					size = TextBoxTextRenderer.MeasureText (g, text.ToString (currentFontStart, pos + 1 - currentFontStart), currentFont);

+					newWidth = widths[currentFontStart] + size.Width;

 				}

-				else

-				{

-				c = text[pos];

-

-				if (c != '\t') {

+				else if (c != '\t') {

 					size = tag.SizeOfPosition(g, pos);

+					size = tag.SizeOfPosition (g, pos);

 					w = size.Width;

+					newWidth = widths[pos] + w;

 				} else {

+					CheckKerning(g, currentFont, currentFontStart, pos - currentFontStart);

+					currentFontStart = pos + 1; // Don't try handling the tab along with kerned text.

+					

 					if (lastTab != null) {

 						ProcessLastTab(lastTab, lastTabPos, pos);

 						lastTab = null;

@@ -703,25 +716,27 @@ namespace System.Windows.Forms
 					if (w < 0) {

 						w = tag.SizeOfPosition(g, pos).Width;

 					}

+					

+					newWidth = widths[pos] + w;

 				}

 

-				// FIXME: Technically there are multiple no-break spaces, not just the main one.

-				if ((Char.IsWhiteSpace (c) && c != '\u00A0') || c == '-' || c == '\u2013' || c == '\u2014') {

-					// Primarily break on whitespace except a no-break space, or dashes.

-					prev_wrap_pos = wrap_pos;

-					if (c == '\t') {

-						wrap_pos = pos; // Wrap before tabs for some reason.

-					} else {

-						wrap_pos = pos + 1;

+				if (doc.Wrap) {

+					// FIXME: Technically there are multiple no-break spaces, not just the main one.

+					if ((Char.IsWhiteSpace (c) && c != '\u00A0') || c == '-' || c == '\u2013' || c == '\u2014') {

+						// Primarily break on dashes or whitespace other than a no-break space.

+						prev_wrap_pos = wrap_pos;

+						if (c == '\t') {

+							wrap_pos = pos; // Wrap before tabs for some reason.

+						} else {

+							wrap_pos = pos + 1;

+						}

 					}

-				}

 

-				if (doc.wrap) {

-					if ((wrap_pos > 0) && (wrap_pos != len) && (newWidth + 5) > (doc.viewport_width - this.right_indent)) {

+					if ((newWidth) > (doc.viewport_width - this.right_indent)) {

 						LineTag split_tag = null;

 						if (wrap_pos > 0) {

 							// Make sure to set the last width of the line before wrapping

-						widths[pos + 1] = newWidth;

+							widths[pos + 1] = newWidth;

 

 							if (wrap_pos > pos && Char.IsWhiteSpace(c)) {

 								while (wrap_pos < text.Length && Char.IsWhiteSpace(text[wrap_pos]) && text[wrap_pos] != '\t') {

@@ -731,6 +746,8 @@ namespace System.Windows.Forms
 								wrapped = true; // don't try pulling more into this line, but keep looping to deal with the rest of the widths and tags

 							} else {

 								if (wrap_pos > pos) {

+									// We're at a dash (otherwise we'd be above), but don't have room to fit it in.

+									// Wrap at the previous wrap point if possible.

 									wrap_pos = prev_wrap_pos > 0 ? prev_wrap_pos : pos;

 								}

 								split_tag = tag;

@@ -740,7 +757,7 @@ namespace System.Windows.Forms
 							// No suitable wrap position was found so break right in the middle of a word

 

 							// Make sure to set the last width of the line before wrapping

-						widths[pos + 1] = newWidth;

+							widths[pos + 1] = newWidth;

 

 							split_tag = tag;

 						} // Else don't wrap -- pos == 0, so we'd infinite loop adding blank lines before this.

@@ -775,9 +792,11 @@ namespace System.Windows.Forms
 						line = doc.GetLine (this.line_no + 1);

 						do {

 							if ((line != null) && (ending == LineEnding.Wrap || ending == LineEnding.None) &&

-							    (widths[pos] < doc.viewport_width || line.text.Length == 0)) { // Only do this if the line isn't already full, or the next line is empty.

+							    (widths[pos] < (doc.viewport_width - this.right_indent) || line.text.Length == 0)) { // Only do this if the line isn't already full, or the next line is empty.

 								// Pull the two lines together

+								var h = this.height; // Back up h, because Combine sets it to zero.

 								doc.Combine (this, line);

+								this.height = h; // And restore it. There's no point starting at the start again.

 								tag = FindTag (pos - 1); // Document.Combine() called Line.Streamline(), so this is necessary in case tag points to one of the tags that got removed.

 								len = this.text.Length;

 								line = doc.GetLine (this.line_no + 1);

@@ -826,36 +845,24 @@ namespace System.Windows.Forms
 

 					tag = tag.Next;

 					if (tag != null) {

+						if (tag.Length != 0 && tag.FontToDisplay != currentFont) {

+							CheckKerning(g, currentFont, currentFontStart, pos - currentFontStart);

+							currentFont = tag.FontToDisplay;

+							currentFontStart = pos;

+							handleKerning = kerning_fonts.ContainsKey (currentFont.GetHashCode ());

+						}

 						tag.Shift = 0;

-						//wrap_pos = pos; //No, we can't just wrap on tag boundaries -- e.g. if the first letter of the word has a different colour / font.

+						// We can't just wrap on tag boundaries -- e.g. if the first letter of the word has a different colour / font.

 					}

 				}

 			}

 

-			var fullText = text.ToString();

-			if (!handleKerning && fullText.Length > 1 && !wrapped)

-			{

-				// Check whether kerning takes place for this string and font.

-				var realSize = TextBoxTextRenderer.MeasureText(g, fullText, tags.Font);

-				float realWidth = realSize.Width + widths[0];

-				// MeasureText ignores trailing whitespace, so we will too at this point.

-				int length = fullText.TrimEnd().Length;

-				float sumWidth = widths[length];

-				if (realWidth != sumWidth)

-				{

-					kerning_fonts.Add(tags.Font.GetHashCode (), true);

-					// Using a slightly incorrect width this time around isn't that bad. All that happens

-					// is that the cursor is a pixel or two off until the next character is typed.  It's

-					// the accumulation of pixel after pixel that causes display problems.

-				}

-			}

-

 			if (lastTab != null) {

 				ProcessLastTab(lastTab, lastTabPos, pos);

 				lastTab = null;

 			}

 

-			while (tag != null) {	

+			while (tag != null) {

 				tag.Shift = (tag.Line.ascent - tag.Ascent); // / 72;

 				tag = tag.Next;

 			}

@@ -885,6 +892,27 @@ namespace System.Windows.Forms
 				widths[i] += change;

 			}

 		}

+		

+		private void CheckKerning(Graphics g, Font font, int start, int length) {

+			if (length > 1) {

+				if (!kerning_fonts.ContainsKey (tags.Font.GetHashCode ())) {

+					// Check whether kerning takes place for this string and font.

+					var partText = text.ToString(start, length);

+					var realSize = TextBoxTextRenderer.MeasureText(g, partText, font);

+					float realWidth = realSize.Width + widths[start + 1];

+					// MeasureText ignores trailing whitespace, so we will too at this point.

+					int textLength = partText.TrimEnd().Length;

+					float sumWidth = widths[textLength + start + 1];

+					if (realWidth != sumWidth)

+					{

+						kerning_fonts.Add(tags.Font.GetHashCode (), true);

+						// Using a slightly incorrect width this time around isn't that bad. All that happens

+						// is that the cursor is a pixel or two off until the next character is typed.  It's

+						// the accumulation of pixel after pixel that causes display problems.

+					}

+				}

+			}

+		}

 

 		/// <summary>

 		/// Recalculate a single line using the same char for every character in the line

@@ -928,20 +956,25 @@ namespace System.Windows.Forms
 		}

 

 		internal void CalculateAlignment() {

-			switch (alignment) {

+            var alignmentWidth = document.ViewPortWidth - document.left_margin - document.right_margin;

+			var alignmentLineWidth = GetAlignmentLineWidth();

+

+            switch (alignment) {

 			case HorizontalAlignment.Left:

 				align_shift = 0;

 				break;

 			case HorizontalAlignment.Center:

-				align_shift = (document.viewport_width - GetLineWidth()) / 2;

+                    align_shift = (alignmentWidth - alignmentLineWidth) / 2;

 				break;

 			case HorizontalAlignment.Right:

-				align_shift = document.viewport_width - GetLineWidth() - document.right_margin - (int)right_indent;

+                    align_shift = alignmentWidth - alignmentLineWidth;

 				break;

 			}

+

+			align_shift = Math.Max(align_shift, 0); // Don't allow negative shifts.

 		}

 

-		private int GetLineWidth() {

+		private int GetAlignmentLineWidth() {

 			int last = text.Length - 1;

 			if (last < 0)

 				return 0;

@@ -950,7 +983,9 @@ namespace System.Windows.Forms
 			while (last > 0 && Char.IsWhiteSpace(c) && c != '\t' && c != '\u00A0') {

 				c = text[--last];

 			}

-			return (int)(widths[last + 1] - document.left_margin - indent);

+			// widths[0] has both the left margin and the left indents.

+			// Remove the margin (it is part of the viewport) and add the right indents (part of the line width, for alignment purposes).

+			return (int)(widths[last + 1] - document.left_margin + Math.Max(right_indent, 0));

 		}

 		

 		internal void Streamline (int lines)