--- /dev/null
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Support for `TileSet`, `TileSetFont` and drawing text with `TextSprites`
+module tileset
+
+import flat
+
+# Efficiently retrieve tiles in a big texture
+class TileSet
+ # Texture containing the tileset
+ var texture: Texture
+
+ # Width of a tile
+ var width: Numeric
+
+ # Height of a tile
+ var height: Numeric
+
+ # Number of columns of tiles in the texture
+ var nb_cols: Int = (texture.width / width.to_f).to_i is lazy
+
+ # Number of rows of tiles in the texture
+ var nb_rows: Int = (texture.height / height.to_f).to_i is lazy
+
+ # Cache of the subtextures of tiles
+ var subtextures: Array[Texture] is lazy do
+ var subtextures = new Array[Texture]
+ for j in [0..nb_rows[ do
+ for i in [0..nb_cols[ do
+ subtextures.add texture.subtexture(
+ i.to_f*width.to_f, j.to_f*height.to_f, width.to_f, height.to_f)
+ end
+ end
+ return subtextures
+ end
+
+ # Subtexture for the tile at `x, y`
+ #
+ # Require: `x < nb_cols and y < nb_rows`
+ fun [](x,y: Int): Texture
+ do
+ assert x >= 0 and x < nb_cols and y >= 0 and y <= nb_rows else print "{x}x{y}<?{nb_cols}x{nb_rows}"
+ var idx = x + y * nb_cols
+ return subtextures[idx]
+ end
+end
+
+# A monospace bitmap font where glyphs are stored in a tileset
+class TileSetFont
+ super TileSet
+
+ # Set the characters present in `texture`
+ #
+ # Last all characters from left to right, then top to bottom.
+ # Line skip `\n`, are ignored and space ' ' skips holes in the tileset.
+ fun chars=(chars: Text)
+ is autoinit do
+ chars_cleaned = chars.replace("\n", "")
+ end
+
+ # Character present in the texture, set by `chars=`
+ private var chars_cleaned: Text is noautoinit
+
+ # Additional space to insert horizontally between characters
+ #
+ # A negative value may display overlapped tiles.
+ var hspace: Numeric = 0.0 is writable
+
+ # Additional space to insert vertically between characters
+ #
+ # A negative value may display overlapped tiles.
+ var vspace: Numeric = 0.0 is writable
+
+ # The glyph/tile/texture associated to `char`
+ #
+ # Returns null if `char` is not in `chars`.
+ fun char(char: Char): nullable Texture
+ do
+ var i = chars_cleaned.index_of(char)
+ if i == -1 then return null
+ return subtextures[i]
+ end
+
+ # Distance between the beginning of a letter tile and the beginning of the next letter tile
+ fun advance: Float do return width.to_f + hspace.to_f
+
+ # Distance between the beginning and the end of the longest line of `text`
+ fun text_width(text: Text): Numeric
+ do
+ var lines = text.split('\n')
+ if lines.is_empty then return 0
+
+ var longest = 0
+ for line in lines do longest = longest.max(line.length)
+
+ return longest.mul(advance)
+ end
+
+ # Distance between the top of the first line to the bottom of the last line in `text`
+ fun text_height(text: Text): Numeric
+ do
+ if text.is_empty then return 0
+
+ var n_lines = text.chars.count('\n')
+ return (n_lines+1).mul(height.add(vspace)).sub(vspace)
+ end
+end
+
+# Manage a set of sprites to display some text
+class TextSprites
+
+ # Font used to draw text
+ var font: TileSetFont
+
+ # Top left of the first character in UI coordinates
+ var anchor: Point3d[Float]
+
+ # Last set of sprites generated to display `text=`
+ var sprites = new Array[Sprite]
+
+ # Sprite set where to put created sprites
+ #
+ # Defaults to `app::ui_sprites`, but it could also be set to a
+ # `app::sprites` or a custom collection.
+ var target_sprite_set: Sequence[Sprite] = app.ui_sprites is lazy, writable
+
+ private var cached_text: nullable Text = ""
+
+ # Last text drawn
+ fun text: nullable Text do return cached_text
+
+ # Update the text displayed by inserting new sprites into `app.ui_sprites`
+ #
+ # Does not redraw if `text` has not changed.
+ fun text=(text: nullable Text)
+ is autoinit do
+ # Don't redraw if text hasn't changed
+ if text == cached_text then return
+ cached_text = text
+
+ # Clean up last used sprites
+ for s in sprites do if target_sprite_set.has(s) then target_sprite_set.remove s
+ sprites.clear
+
+ if text == null then return
+
+ # Build new sprites
+ var dx = font.vspace.to_f/2.0
+ var dy = font.hspace.to_f/2.0
+ for c in text do
+ if c == '\n' then
+ dy -= font.height.to_f + font.vspace.to_f
+ dx = font.vspace.to_f/2.0
+ continue
+ else if c.is_whitespace then
+ dx += font.advance
+ continue
+ end
+
+ var tex = font.char(c)
+ if tex == null then
+ # Try to fallback to '?'
+ tex = font.char('?')
+ if tex == null then continue
+ end
+
+ sprites.add new Sprite(tex, anchor.offset(dx, dy, 0))
+ dx += font.advance
+ end
+
+ # Register sprites to be drawn by `app.ui_camera`
+ target_sprite_set.add_all sprites
+ end
+end
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