Martin Michelsen
114 lines
3.5 KiB
C++
114 lines
3.5 KiB
C++
#include "GVMEncoder.hh"
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#include <phosg/Encoding.hh>
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#include <phosg/Image.hh>
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#include <phosg/Strings.hh>
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#include "Text.hh"
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using namespace std;
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struct GVMFileEntry {
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be_uint16_t file_num;
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pstring<TextEncoding::ASCII, 0x1C> name;
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uint8_t format_flags; // Same as in GVRHeader
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GVRDataFormat data_format; // Same as in GVRHeader
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be_uint16_t dimensions; // As powers of two in low nybbles (so e.g. 128x128 = 0x0055)
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be_uint32_t global_index;
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} __packed_ws__(GVMFileEntry, 0x26);
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struct GVMFileHeader {
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be_uint32_t signature; // 'GVMH'
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le_uint32_t header_size;
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be_uint16_t flags; // Specifies which fields are present in GVMFileEntries; we always use 0xF (all fields present)
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be_uint16_t num_files;
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} __packed_ws__(GVMFileHeader, 0x0C);
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struct GVRHeader {
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be_uint32_t magic; // 'GVRT'
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le_uint32_t data_size;
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be_uint16_t unknown;
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uint8_t format_flags; // High 4 bits are pixel format, low 4 are data flags
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GVRDataFormat data_format;
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be_uint16_t width;
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be_uint16_t height;
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} __packed_ws__(GVRHeader, 0x10);
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string encode_gvm(const phosg::Image& img, GVRDataFormat data_format, const std::string& internal_name, uint32_t global_index) {
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int8_t dimensions_field = -2;
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{
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size_t h = img.get_height();
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size_t w = img.get_width();
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if ((h != w) || (w & (w - 1)) || (h & (h - 1))) {
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throw runtime_error("image must be square and dimensions must be powers of 2");
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}
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for (w >>= 1; w; w >>= 1, dimensions_field++) {
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}
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if (dimensions_field < 1) {
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throw runtime_error("image is too small");
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}
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if (dimensions_field > 0xF) {
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throw runtime_error("image is too large");
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}
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}
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size_t pixel_count = img.get_width() * img.get_height();
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size_t pixel_bytes = 0;
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switch (data_format) {
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case GVRDataFormat::RGB565:
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case GVRDataFormat::RGB5A3:
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pixel_bytes = pixel_count * 2;
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break;
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case GVRDataFormat::ARGB8888:
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pixel_bytes = pixel_count * 2;
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break;
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default:
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throw invalid_argument("cannot encode pixel format");
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}
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phosg::StringWriter w;
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w.put<GVMFileHeader>({.signature = 0x47564D48, .header_size = 0x48, .flags = 0x000F, .num_files = 1});
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GVMFileEntry file_entry;
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file_entry.file_num = 0;
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file_entry.name.encode(internal_name, 1);
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file_entry.data_format = data_format;
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file_entry.format_flags = 0;
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file_entry.dimensions = (dimensions_field << 4) | dimensions_field;
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file_entry.global_index = global_index;
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w.put(file_entry);
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w.extend_to(0x50, 0x00);
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w.put<GVRHeader>({.magic = 0x47565254,
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.data_size = pixel_bytes + 8,
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.unknown = 0,
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.format_flags = 0,
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.data_format = data_format,
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.width = img.get_width(),
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.height = img.get_height()});
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for (size_t y = 0; y < img.get_height(); y += 4) {
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for (size_t x = 0; x < img.get_width(); x += 4) {
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for (size_t yy = 0; yy < 4; yy++) {
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for (size_t xx = 0; xx < 4; xx++) {
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uint64_t a, r, g, b;
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img.read_pixel(x + xx, y + yy, &r, &g, &b, &a);
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switch (data_format) {
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case GVRDataFormat::RGB565:
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w.put_u16b(encode_rgb565(r, g, b));
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break;
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case GVRDataFormat::RGB5A3:
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w.put_u16b(encode_rgb5a3(r, g, b, a));
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break;
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case GVRDataFormat::ARGB8888:
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w.put_u32b(encode_argb8888(r, g, b, a));
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break;
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default:
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throw logic_error("cannot encode pixel format");
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}
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}
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}
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}
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}
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return std::move(w.str());
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}
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