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- /*
- * Copyright 2014 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #ifndef SkDistanceFieldGen_DEFINED
- #define SkDistanceFieldGen_DEFINED
- #include "include/core/SkTypes.h"
- // the max magnitude for the distance field
- // distance values are limited to the range (-SK_DistanceFieldMagnitude, SK_DistanceFieldMagnitude]
- #define SK_DistanceFieldMagnitude 4
- // we need to pad around the original glyph to allow our maximum distance of
- // SK_DistanceFieldMagnitude texels away from any edge
- #define SK_DistanceFieldPad 4
- // the rect we render with is inset from the distance field glyph size to allow for bilerp
- #define SK_DistanceFieldInset 2
- // For the fragment shader:
- // The distance field is constructed as unsigned char values,
- // so that the zero value is at 128, and the supported range of distances is [-4 * 127/128, 4].
- // Hence our multiplier (width of the range) is 4 * 255/128 and zero threshold is 128/255.
- #define SK_DistanceFieldMultiplier "7.96875"
- #define SK_DistanceFieldThreshold "0.50196078431"
- /** Given 8-bit mask data, generate the associated distance field
- * @param distanceField The distance field to be generated. Should already be allocated
- * by the client with the padding above.
- * @param image 8-bit mask we're using to generate the distance field.
- * @param w Width of the original image.
- * @param h Height of the original image.
- * @param rowBytes Size of each row in the image, in bytes
- */
- bool SkGenerateDistanceFieldFromA8Image(unsigned char* distanceField,
- const unsigned char* image,
- int w, int h, size_t rowBytes);
- /** Given LCD16 mask data (not a 16-bit image), generate the associated distance field
- * @param distanceField The distance field to be generated. Should already be allocated
- * by the client with the padding above.
- * @param image 16-bit LCD data we're using to generate the distance field.
- * @param w Width of the original image.
- * @param h Height of the original image.
- * @param rowBytes Size of each row in the image, in bytes
- */
- bool SkGenerateDistanceFieldFromLCD16Mask(unsigned char* distanceField,
- const unsigned char* image,
- int w, int h, size_t rowBytes);
- /** Given 1-bit mask data, generate the associated distance field
- * @param distanceField The distance field to be generated. Should already be allocated
- * by the client with the padding above.
- * @param image 1-bit mask we're using to generate the distance field.
- * @param w Width of the original image.
- * @param h Height of the original image.
- * @param rowBytes Size of each row in the image, in bytes
- */
- bool SkGenerateDistanceFieldFromBWImage(unsigned char* distanceField,
- const unsigned char* image,
- int w, int h, size_t rowBytes);
- /** Given width and height of original image, return size (in bytes) of distance field
- * @param w Width of the original image.
- * @param h Height of the original image.
- */
- inline size_t SkComputeDistanceFieldSize(int w, int h) {
- return (w + 2*SK_DistanceFieldPad) * (h + 2*SK_DistanceFieldPad) * sizeof(unsigned char);
- }
- #endif
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