106 lines
3.0 KiB
TypeScript
106 lines
3.0 KiB
TypeScript
namespace pxsim.image {
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function DMESG(msg: string) {
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control.dmesg(msg)
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}
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const NULL: RefBuffer = null;
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export function unpackPNG(png: RefBuffer) {
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function memcmp(off: number, mark: string) {
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for (let i = 0; i < mark.length; ++i) {
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if (mark.charCodeAt(i) != png.data[off + i])
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return 1
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}
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return 0
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}
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function readInt(off: number) {
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return ((png.data[off] << 24) | (png.data[off + 1] << 16) |
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(png.data[off + 2] << 8) | (png.data[off + 3])) >>> 0
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}
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if (!png) {
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DMESG("PNG: Missing image");
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return NULL;
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}
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if (png.data.length < 45) {
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DMESG("PNG: File too small");
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return NULL;
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}
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if (memcmp(0, "\x89PNG\r\n\x1A\n") != 0) {
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DMESG("PNG: Invalid header");
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return NULL;
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}
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if (memcmp(12, "IHDR") != 0) {
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DMESG("PNG: missing IHDR");
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return NULL;
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}
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const lenIHDR = readInt(8);
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const width = readInt(16);
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const height = readInt(20);
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const lenIDAT = readInt(33);
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const sizeOfHD = 41;
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if (lenIHDR != 13) {
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DMESG("PNG: bad IHDR len");
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return NULL;
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}
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if (memcmp(24, "\x01\x00\x00\x00\x00") != 0) {
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DMESG("PNG: not 1-bit grayscale");
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return NULL;
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}
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if (memcmp(37, "IDAT") != 0) {
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DMESG("PNG: missing IDAT");
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return NULL;
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}
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if (lenIDAT + sizeOfHD >= png.data.length) {
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DMESG("PNG: buffer too short");
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return NULL;
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}
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if (width > 300 || height > 300) {
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DMESG("PNG: too big");
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return NULL;
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}
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const byteW = (width + 7) >> 3;
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const sz = (byteW + 1) * height;
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const tmp = new Uint8Array(sz + 1);
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// uncompress doesn't take the zlib header, hence + 2
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const two = tinf.uncompress(png.data.slice(sizeOfHD + 2, sizeOfHD + lenIDAT), tmp);
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if (two.length != sz) {
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DMESG("PNG: invalid compressed size");
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return NULL;
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}
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const res = output.createBuffer(3 + byteW * height);
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res.data[0] = 0xf1;
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res.data[1] = width;
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res.data[2] = height;
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let dst = 3
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let src = 0
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let lastMask = (1 << (width & 7)) - 1;
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if (lastMask == 0)
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lastMask = 0xff;
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for (let i = 0; i < height; ++i) {
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if (two[src++] != 0) {
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DMESG("PNG: unsupported filter");
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decr(res);
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return NULL;
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}
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for (let j = 0; j < byteW; ++j) {
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res.data[dst] = ~(two[src++]);
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if (j == byteW - 1) {
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res.data[dst] &= lastMask;
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}
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dst++;
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}
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}
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return image.ofBuffer(res)
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}
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}
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namespace pxsim.pxtcore {
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export function updateStats(str: string) {
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// TODO
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}
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} |