34 lines
1.9 KiB
JavaScript
34 lines
1.9 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.PNGColorType = exports.PNGFilterType = void 0;
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/**
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* Filter method is a single-byte integer that indicates the preprocessing method applied to the image data before compression.
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*/
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var PNGFilterType;
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(function (PNGFilterType) {
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PNGFilterType[PNGFilterType["AUTO"] = -1] = "AUTO";
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/** scanline is transmitted unmodified */
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PNGFilterType[PNGFilterType["NONE"] = 0] = "NONE";
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/** filter transmits the difference between each byte and the value of the corresponding byte of the prior pixel */
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PNGFilterType[PNGFilterType["SUB"] = 1] = "SUB";
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/** The Up() filter is just like the Sub() filter except that the pixel immediately above the current pixel, rather than just to its left, is used as the predictor. */
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PNGFilterType[PNGFilterType["UP"] = 2] = "UP";
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/** uses the average of the two neighboring pixels (left and above) to predict the value of a pixel */
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PNGFilterType[PNGFilterType["AVERAGE"] = 3] = "AVERAGE";
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/** computes a simple linear function of the three neighboring pixels (left, above, upper left), then chooses as predictor the neighboring pixel closest to the computed value. */
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PNGFilterType[PNGFilterType["PATH"] = 4] = "PATH";
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})(PNGFilterType || (exports.PNGFilterType = PNGFilterType = {}));
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/**
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* Color type is a single-byte integer that describes the interpretation of the image data.
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* Color type codes represent sums of the following values:
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*
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* 1 (palette used), 2 (color used), and 4 (alpha channel used).
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*/
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var PNGColorType;
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(function (PNGColorType) {
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PNGColorType[PNGColorType["GRAYSCALE"] = 0] = "GRAYSCALE";
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PNGColorType[PNGColorType["COLOR"] = 2] = "COLOR";
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PNGColorType[PNGColorType["GRAYSCALE_ALPHA"] = 4] = "GRAYSCALE_ALPHA";
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PNGColorType[PNGColorType["COLOR_ALPHA"] = 6] = "COLOR_ALPHA";
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})(PNGColorType || (exports.PNGColorType = PNGColorType = {}));
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//# sourceMappingURL=constants.js.map
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