Support font files.

This only works with the userspace build of SharedGraphics so far.
It's also very slow at loading fonts, but that's easy to fix.

Let's put fonts in /res/fonts/.

SharedGraphics/Font.cpp

@@ -2,6 +2,15 @@
 #include "Peanut8x10.h"
 #include "Liza8x10.h"
 #include <AK/kmalloc.h>
+#include <AK/BufferStream.h>
+#include <AK/StdLibExtras.h>
+
+#ifdef USERLAND
+#include <LibC/unistd.h>
+#include <LibC/stdio.h>
+#include <LibC/fcntl.h>
+#include <LibC/errno.h>
+#endif
 
 #define DEFAULT_FONT_NAME Liza8x10
 
@@ -29,8 +38,15 @@ void Font::initialize()
 
 Font& Font::default_font()
 {
-    if (!s_default_font)
-        s_default_font = adopt(*new Font(DEFAULT_FONT_NAME::glyphs, DEFAULT_FONT_NAME::glyph_width, DEFAULT_FONT_NAME::glyph_height, DEFAULT_FONT_NAME::first_glyph, DEFAULT_FONT_NAME::last_glyph)).leak_ref();
+    if (!s_default_font) {
+#ifdef USERLAND
+        s_default_font = Font::load_from_file("/res/fonts/Liza8x10.font").leak_ref();
+        ASSERT(s_default_font);
+#else
+
+        s_default_font = adopt(*new Font(DEFAULT_FONT_NAME::name, DEFAULT_FONT_NAME::glyphs, DEFAULT_FONT_NAME::glyph_width, DEFAULT_FONT_NAME::glyph_height, DEFAULT_FONT_NAME::first_glyph, DEFAULT_FONT_NAME::last_glyph)).leak_ref();
+#endif
+    }
     return *s_default_font;
 }
 
@@ -47,11 +63,12 @@ RetainPtr<Font> Font::clone() const
             memset(new_glyphs[i], ' ', bytes_per_glyph);
         }
     }
-    return adopt(*new Font(new_glyphs, m_glyph_width, m_glyph_height, 0, 255));
+    return adopt(*new Font(m_name, new_glyphs, m_glyph_width, m_glyph_height, 0, 255));
 }
 
-Font::Font(const char* const* glyphs, byte glyph_width, byte glyph_height, byte first_glyph, byte last_glyph)
-    : m_glyphs(glyphs)
+Font::Font(const String& name, const char* const* glyphs, byte glyph_width, byte glyph_height, byte first_glyph, byte last_glyph)
+    : m_name(name)
+    , m_glyphs(glyphs)
     , m_glyph_width(glyph_width)
     , m_glyph_height(glyph_height)
     , m_first_glyph(first_glyph)
@@ -73,3 +90,108 @@ Font::Font(const char* const* glyphs, byte glyph_width, byte glyph_height, byte
 Font::~Font()
 {
 }
+
+#ifdef USERLAND
+struct FontFileHeader {
+    char magic[4];
+    byte glyph_width;
+    byte glyph_height;
+    byte type;
+    byte unused[7];
+    char name[64];
+} PACKED;
+
+RetainPtr<Font> Font::load_from_file(const String& path)
+{
+    int fd = open(path.characters(), O_RDONLY, 0644);
+    if (fd < 0) {
+        dbgprintf("open(%s) got fd=%d, failed: %s\n", path.characters(), fd, strerror(errno));
+        perror("open");
+        return nullptr;
+    }
+
+    FontFileHeader header;
+    ssize_t nread = read(fd, &header, sizeof(FontFileHeader));
+    if (nread != sizeof(FontFileHeader)) {
+        dbgprintf("nread != sizeof(FontFileHeader)=%u\n", sizeof(FontFileHeader));
+        return nullptr;
+    }
+
+    if (memcmp(header.magic, "!Fnt", 4)) {
+        dbgprintf("header.magic != '!Fnt'\n");
+        return nullptr;
+    }
+
+    if (header.name[63] != '\0') {
+        dbgprintf("Font name not fully null-terminated\n");
+        return nullptr;
+    }
+
+    char** new_glyphs = static_cast<char**>(kmalloc(sizeof(char*) * 256));
+    for (unsigned glyph_index = 0; glyph_index < 256; ++glyph_index) {
+        new_glyphs[glyph_index] = static_cast<char*>(kmalloc(header.glyph_width * header.glyph_height));
+        char* bitptr = new_glyphs[glyph_index];
+        for (unsigned y = 0; y < header.glyph_height; ++y) {
+            unsigned pattern;
+            ssize_t nread = read(fd, &pattern, sizeof(unsigned));
+            if (nread != sizeof(unsigned)) {
+                // FIXME: free() things and return nullptr.
+                ASSERT_NOT_REACHED();
+            }
+            for (unsigned x = 0; x < header.glyph_width; ++x) {
+                if (pattern & (1u << x)) {
+                    *(bitptr++) = '#';
+                } else {
+                    *(bitptr++) = ' ';
+                }
+            }
+        }
+    }
+
+    return adopt(*new Font(String(header.name), new_glyphs, header.glyph_width, header.glyph_height, 0, 255));
+}
+
+bool Font::write_to_file(const String& path)
+{
+    int fd = open(path.characters(), O_WRONLY | O_CREAT, 0644);
+    if (fd < 0) {
+        perror("open");
+        return false;
+    }
+
+    FontFileHeader header;
+    memset(&header, 0, sizeof(FontFileHeader));
+    memcpy(header.magic, "!Fnt", 4);
+    header.glyph_width = m_glyph_width;
+    header.glyph_height = m_glyph_height;
+    header.type = 0;
+    memcpy(header.name, m_name.characters(), min(m_name.length(), 63u));
+
+    size_t bytes_per_glyph = sizeof(unsigned) * m_glyph_height;
+
+    auto buffer = ByteBuffer::create_uninitialized(sizeof(FontFileHeader) + (256 * bytes_per_glyph));
+    BufferStream stream(buffer);
+
+    stream << ByteBuffer::wrap((byte*)&header, sizeof(FontFileHeader));
+
+    for (unsigned glyph_index = 0; glyph_index < 256; ++glyph_index) {
+        auto* glyph_bits = (byte*)m_glyphs[glyph_index];
+        for (unsigned y = 0; y < m_glyph_height; ++y) {
+            unsigned pattern = 0;
+            for (unsigned x = 0; x < m_glyph_width; ++x) {
+                if (glyph_bits[y * m_glyph_width + x] == '#') {
+                    pattern |= 1 << x;
+                }
+            }
+            stream << pattern;
+        }
+    }
+
+    ASSERT(stream.at_end());
+    ssize_t nwritten = write(fd, buffer.pointer(), buffer.size());
+    ASSERT(nwritten == (ssize_t)buffer.size());
+    int rc = close(fd);
+    ASSERT(rc == 0);
+    return true;
+}
+#endif