117 lines
4.0 KiB
JavaScript
117 lines
4.0 KiB
JavaScript
// (c) Dean McNamee <dean@gmail.com>, 2013.
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// Node omggif example to write out a few example images.
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var fs = require('fs');
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var omggif = require('./omggif');
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// Needs to be large enough for the final full file size. Can be any type of
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// buffer that supports [] (an Array, Uint8Array, Node Buffer, etc).
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var buf = new Buffer(1024 * 1024);
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function gen_static_global() {
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var gf = new omggif.GifWriter(buf, 2, 2, {palette: [0xff0000, 0x0000ff]});
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gf.addFrame(0, 0, 2, 2,
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[0, 1, 1, 0]);
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return buf.slice(0, gf.end());
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}
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function gen_static_local() {
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var gf = new omggif.GifWriter(buf, 2, 2);
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gf.addFrame(0, 0, 2, 2,
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[0, 1, 1, 0],
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{palette: [0xff0000, 0x0000ff]});
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return buf.slice(0, gf.end());
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}
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function gen_anim() {
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// The loop parameter is the number of times to loop, or 0 for forever.
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// A value of 1 will play twice (first time, and then one loop time).
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// To play only once do not specify loop or pass null.
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var gf = new omggif.GifWriter(buf, 2, 2, {loop: 1});
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gf.addFrame(0, 0, 2, 2,
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[0, 1, 1, 0],
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{palette: [0xff0000, 0x0000ff]});
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gf.addFrame(0, 0, 2, 2,
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[1, 0, 0, 1],
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{palette: [0xff0000, 0x0000ff],
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delay: 10}); // Delay in hundredths of a sec (100 = 1s).
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return buf.slice(0, gf.end());
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}
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function gen_gray_strip() {
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var gf = new omggif.GifWriter(buf, 256, 1);
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var palette = [ ];
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var indices = [ ];
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for (var i = 0; i < 256; ++i) {
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palette.push(i << 16 | i << 8 | i);
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indices.push(i);
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}
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gf.addFrame(0, 0, 256, 1, indices, {palette: palette});
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return buf.slice(0, gf.end());
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}
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// More than 8-bit color (via tiling of several frames). Browsers seem to
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// treat this as an animation though, with an enforced minimum time between
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// frames which makes it animated instead of the intended static image.
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function gen_color_strip() {
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var gf = new omggif.GifWriter(buf, 256, 256, {palette: [0x000000, 0xff0000],
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background: 1});
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var indices = [ ];
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for (var i = 0; i < 256; ++i) indices.push(i);
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for (var j = 0; j < 256; ++j) {
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var palette = [ ];
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for (var i = 0; i < 256; ++i)
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palette.push(j << 16 | i << 8 | i);
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gf.addFrame(0, j, 256, 1, indices, {palette: palette, disposal: 1});
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}
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return buf.slice(0, gf.end());
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}
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// 1x1 white, generates the same as Google's 35 byte __utm.gif, except for some
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// reason that I'm not sure of they set their background index to 255.
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function gen_empty_white() {
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var gf = new omggif.GifWriter(buf, 1, 1, {palette: [0xffffff, 0x000000]});
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gf.addFrame(0, 0, 1, 1, [0]);
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return buf.slice(0, gf.end());
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}
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// 1x1 transparent 43 bytes.
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function gen_empty_trans() {
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var gf = new omggif.GifWriter(buf, 1, 1, {palette: [0x000000, 0x000000]});
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gf.addFrame(0, 0, 1, 1, [0], {transparent: 0});
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return buf.slice(0, gf.end());
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}
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// with lzw block of 256.
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// see: https://github.com/deanm/omggif/issues/5
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function gen_block256() {
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var width = 4840;
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var gf = new omggif.GifWriter(buf, width, 1, {
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palette: [0x000000, 0x000000, 0x000000, 0x000000,
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0x000000, 0x000000, 0x000000, 0x000000]
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});
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var stream = Array(width);
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for (var i = 0; i < width; ++i) stream[i] = i & 0x7;
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gf.addFrame(0, 0, width, 1, stream, {transparent: 0});
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var data = buf.slice(0, gf.end());
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// Make sure it decodes.
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var gr = new omggif.GifReader(data);
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var fi0 = gr.frameInfo(0);
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/*
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console.log(fi0);
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console.log(buf.slice(fi0.data_offset, fi0.data_offset + fi0.data_length));
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*/
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return data;
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}
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fs.writeFileSync('./test_static_global_palette.gif', gen_static_global());
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fs.writeFileSync('./test_static_local_palette.gif', gen_static_local());
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fs.writeFileSync('./test_anim.gif', gen_anim());
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fs.writeFileSync('./test_gray_strip.gif', gen_gray_strip());
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fs.writeFileSync('./test_color_strip.gif', gen_color_strip());
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fs.writeFileSync('./test_empty_white.gif', gen_empty_white());
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fs.writeFileSync('./test_empty_trans.gif', gen_empty_trans());
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fs.writeFileSync('./test_block256.gif', gen_block256());
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