+ Add and modify rendering tests

test.lua

@@ -4,21 +4,34 @@
 dofile("init.lua")
 dofile("tga_encoder.lua")
 
-font_1 = unicode_text.hexfont()
+font_1 = unicode_text.hexfont(
+   {
+      kerning = true,
+   }
+)
 font_1:load_glyphs(
    io.lines("/usr/share/unifont/unifont.hex")
 )
-local text = "ABC	123	😀\
+font_1:load_glyphs(
+   io.lines("U+FFFD.hex")
+)
+
+-- The following text purposely contains glyphs not in unifont.hex, to
+-- show that these are rendered like U+FFFD REPLACEMENT CHARACTER (<28>).
+local text = "ABC...	123!!!	😀\
 \
-wð♥𐍈"
+U+0077	w	LATIN SMALL LETTER W\
+U+00F0	ð	LATIN SMALL LETTER ETH\
+U+2665	♥	BLACK HEART SUIT\
+U+10348	𐍈	GOTHIC LETTER HWAIR"
 local pixels = font_1:render_text(text)
 local image = tga_encoder.image(pixels)
 image:save("test.tga")
 
 font_2 = unicode_text.hexfont(
    {
-      background_color = { 0x33, 0x66, 0x99 },
+      background_color = { 1 },
-      foreground_color = { 0xDD, 0x00, 0x00 },
+      foreground_color = { 0 },
    }
 )
 font_2:load_glyphs(
@@ -28,9 +41,55 @@ font_2:load_glyphs(
    io.lines("unifont_upper.hex")
 )
 local file = io.open("UTF-8-demo.txt")
+
+-- encode image with colormap (palette)
 tga_encoder.image(
    font_2:render_text(
       file:read("*all")
    )
-):save("UTF-8-demo.tga")
+):save(
+   "UTF-8-demo.tga",
+   {
+      colormap = {
+         { 0xFF, 0xFF, 0xFF },
+         { 0x00, 0x00, 0xFF },
+      }
+   }
+)
 file:close()
+
+font_2.background_color = { 0, 0, 0 }
+font_2.foreground_color = { 255, 255, 255 }
+font_2.tabulator_size = 4 * 8
+local file = io.open("example.txt")
+local text = file:read("*all")
+file:close()
+local pixels = font_2:render_text(text)
+
+-- colorize text pixels
+for h = 1, #pixels do
+   for w = 1, #pixels[h] do
+      local pixel = pixels[h][w]
+      if (
+         255 == pixel[1] and
+         255 == pixel[2] and
+         255 == pixel[3]
+      ) then
+         pixel = {
+            ( h + w ) % 128 + 128,
+            ( h % w ) % 128 + 128,
+            ( h - w ) % 128 + 128,
+         }
+      end
+      pixels[h][w] = pixel
+   end
+end
+
+-- encode image with 15-bit colors
+tga_encoder.image(pixels):save(
+   "example.tga",
+   {
+      color_format="A1R5G5B5",
+      compression = "RAW",
+   }
+)