(svn r25465) -Codechange: add the concept of a layouting engine for text

1 files changed, 109 insertions, 0 deletions

diff --git a/src/gfx_layout.h b/src/gfx_layout.h
new file mode 100644
index 000000000..cf4f1f90a
--- /dev/null
+++ b/src/gfx_layout.h
@@ -0,0 +1,109 @@
+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file gfx_layout.h Functions related to laying out the texts. */
+
+#ifndef GFX_LAYOUT_H
+#define GFX_LAYOUT_H
+
+#include "fontcache.h"
+#include "gfx_func.h"
+#include "core/smallmap_type.hpp"
+
+/**
+ * Container with information about a font.
+ */
+class Font {
+public:
+	FontCache *fc;     ///< The font we are using.
+	TextColour colour; ///< The colour this font has to be.
+
+	Font(FontSize size, TextColour colour);
+};
+
+/** Mapping from index to font. */
+typedef SmallMap<int, Font *> FontMap;
+
+/**
+ * Class handling the splitting of a paragraph of text into lines and
+ * visual runs.
+ *
+ * One constructs this class with the text that needs to be split into
+ * lines. Then nextLine is called with the maximum with until NULL is
+ * returned. Each nextLine call creates VisualRuns which contain the
+ * length of text that are to be drawn with the same font. In other
+ * words, the result of this class is a list of sub strings with their
+ * font. The sub strings are then already fully laid out, and only
+ * need actual drawing.
+ *
+ * The positions in a visual run are sequential pairs of X,Y of the
+ * begin of each of the glyphs plus an extra pair to mark the end.
+ *
+ * @note This variant does not handle left-to-right properly. This
+ *       is supported in the one ParagraphLayout coming from ICU.
+ * @note Does not conform to function naming style as it provides a
+ *       fallback for the ICU class.
+ */
+class ParagraphLayout {
+public:
+	/** Visual run contains data about the bit of text with the same font. */
+	class VisualRun {
+		Font *font;       ///< The font used to layout these.
+		GlyphID *glyphs;  ///< The glyphs we're drawing.
+		float *positions; ///< The positions of the glyphs.
+		int glyph_count;  ///< The number of glyphs.
+
+	public:
+		VisualRun(Font *font, const WChar *chars, int glyph_count, int x);
+		~VisualRun();
+		Font *getFont() const;
+		int getGlyphCount() const;
+		const GlyphID *getGlyphs() const;
+		float *getPositions() const;
+		int getLeading() const;
+	};
+
+	/** A single line worth of VisualRuns. */
+	class Line : public AutoDeleteSmallVector<VisualRun *, 4> {
+	public:
+		int getLeading() const;
+		int getWidth() const;
+		int countRuns() const;
+		VisualRun *getVisualRun(int run) const;
+	};
+
+	const WChar *buffer_begin; ///< Begin of the buffer.
+	WChar *buffer;             ///< The current location in the buffer.
+	FontMap &runs;             ///< The fonts we have to use for this paragraph.
+
+	ParagraphLayout(WChar *buffer, int length, FontMap &runs);
+	Line *nextLine(int max_width);
+};
+
+/**
+ * The layouter performs all the layout work.
+ *
+ * It also accounts for the memory allocations and frees.
+ */
+class Layouter : public AutoDeleteSmallVector<ParagraphLayout::Line *, 4> {
+	typedef WChar CharType; ///< The type of character used within the layouter.
+
+	size_t AppendToBuffer(CharType *buff, const CharType *buffer_last, WChar c);
+	ParagraphLayout *GetParagraphLayout(CharType *buff);
+
+	CharType buffer[DRAW_STRING_BUFFER]; ///< Buffer for the text that is going to be drawn.
+	FontMap fonts;                       ///< The fonts needed for drawing.
+
+public:
+	Layouter(const char *str, int maxw = INT32_MAX, TextColour colour = TC_FROMSTRING, FontSize fontsize = FS_NORMAL);
+	~Layouter();
+	Dimension GetBounds();
+};
+
+#endif /* GFX_LAYOUT_H */