1/*
2 * Copyright 2017 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "include/core/SkPoint3.h"
9#include "include/core/SkRefCnt.h"
10
11#ifndef SkAtlasTextRenderer_DEFINED
12#define SkAtlasTextRenderer_DEFINED
13
14/**
15 * This is the base class for a renderer implemented by the SkAtlasText client. The
16 * SkAtlasTextContext issues texture creations, deletions, uploads, and vertex draws to the
17 * renderer. The renderer must perform those actions in the order called to correctly render
18 * the text drawn to SkAtlasTextTargets.
19 */
20class SK_API SkAtlasTextRenderer : public SkRefCnt {
21public:
22 enum class AtlasFormat {
23 /** Unsigned normalized 8 bit single channel format. */
24 kA8
25 };
26
27 struct SDFVertex {
28 /** Position in device space (not normalized). The third component is w (not z). */
29 SkPoint3 fPosition;
30 /** Color, same value for all four corners of a glyph quad. */
31 uint32_t fColor;
32 /** Texture coordinate (in texel units, not normalized). */
33 int16_t fTextureCoordX;
34 int16_t fTextureCoordY;
35 };
36
37 virtual ~SkAtlasTextRenderer() = default;
38
39 /**
40 * Create a texture of the provided format with dimensions 'width' x 'height'
41 * and return a unique handle.
42 */
43 virtual void* createTexture(AtlasFormat, int width, int height) = 0;
44
45 /**
46 * Delete the texture with the passed handle.
47 */
48 virtual void deleteTexture(void* textureHandle) = 0;
49
50 /**
51 * Place the pixel data specified by 'data' in the texture with handle
52 * 'textureHandle' in the rectangle ['x', 'x' + 'width') x ['y', 'y' + 'height').
53 * 'rowBytes' specifies the byte offset between successive rows in 'data' and will always be
54 * a multiple of the number of bytes per pixel.
55 * The pixel format of data is the same as that of 'textureHandle'.
56 */
57 virtual void setTextureData(void* textureHandle, const void* data, int x, int y, int width,
58 int height, size_t rowBytes) = 0;
59
60 /**
61 * Draws glyphs using SDFs. The SDF data resides in 'textureHandle'. The array
62 * 'vertices' provides interleaved device-space positions, colors, and
63 * texture coordinates. There are are 4 * 'quadCnt' entries in 'vertices'.
64 */
65 virtual void drawSDFGlyphs(void* targetHandle, void* textureHandle, const SDFVertex vertices[],
66 int quadCnt) = 0;
67
68 /** Called when a SkAtlasTextureTarget is destroyed. */
69 virtual void targetDeleted(void* targetHandle) = 0;
70};
71
72#endif
73