1// tLayer.cpp 
2// 
3// A tLayer is a data container for texture pixel data. It is used only by the tTexture class to store image data. It 
4// contains data that may be in a variety of hardware-ready formats, like dxt5. It is primarily used to store the 
5// multiple mipmap layers of a texture. Main members are width, height, pixel format, and a function to compute data 
6// size based on those three variables. It knows how to save and load itself in tChunk format. 
7// 
8// tLayers may have any width and height in [1, MaxLayerDimension]. If the pixel format is block-based (4x4 pixels) 
9// the tLayer still allows smaller than 4 width and height. However, a whole block is still needed so the number of 
10// bytes will be the block size for the particular BC format. For example, a 1x1 BC1 format layer still needs 8 bytes. 
11// A 5x5 BC format layer would need 4 blocks (same as an 8x8). The tLayer does not place further constraints on width 
12// and height. A higher level system, for example, may want to ensure power-of-two sizes, or multiple of 4, but that 
13// shouldn't and doesn't happen here. 
14// 
15// Copyright (c) 2006, 2017, 2022 Tristan Grimmer. 
16// Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby 
17// granted, provided that the above copyright notice and this permission notice appear in all copies. 
18// 
19// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL 
20// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, 
21// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN 
22// AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 
23// PERFORMANCE OF THIS SOFTWARE. 
24 
25#include "Image/tLayer.h" 
26using namespace tImage; 
27 
28 
29bool tLayer::operator==(const tLayer& src) const 
30{ 
31 if (!IsValid() || !src.IsValid()) 
32 return false; 
33 
34 if (PixelFormat != src.PixelFormat) 
35 return false; 
36 
37 if ((Width != src.Width) || (Height != src.Height)) 
38 return false; 
39 
40 int dataSize = GetDataSize(); 
41 return tStd::tMemcmp(a: Data, b: src.Data, numBytes: dataSize) ? false : true; 
42} 
43 
44 
45void tLayer::Save(tChunkWriter& chunk) const 
46{ 
47 chunk.Begin(chunkID: tChunkID::Image_Layer); 
48 { 
49 // This chunk must be saved first. 
50 chunk.Begin(chunkID: tChunkID::Image_LayerProperties); 
51 { 
52 chunk.Write(obj: PixelFormat); 
53 chunk.Write(obj: Width); 
54 chunk.Write(obj: Height); 
55 } 
56 chunk.End(); 
57 
58 chunk.Begin(chunkID: tChunkID::Image_LayerData); 
59 { 
60 int dataSize = GetDataSize(); 
61 chunk.Write(data: Data, numItems: dataSize); 
62 } 
63 chunk.End(); 
64 } 
65 chunk.End(); 
66} 
67 
68 
69void tLayer::Load(const tChunk& chunk, bool ownsData) 
70{ 
71 Clear(); 
72 if (chunk.ID() != tChunkID::Image_Layer) 
73 return; 
74 
75 OwnsData = ownsData; 
76 for (tChunk ch = chunk.First(); ch.IsValid(); ch = ch.Next()) 
77 { 
78 switch (ch.ID()) 
79 { 
80 // This chunk must be loaded first. 
81 case tChunkID::Image_LayerProperties: 
82 { 
83 ch.GetItem(item&: PixelFormat); 
84 ch.GetItem(item&: Width); 
85 ch.GetItem(item&: Height); 
86 break; 
87 } 
88 
89 case tChunkID::Image_LayerData: 
90 { 
91 int dataSize = GetDataSize(); 
92 if (dataSize <= 0) 
93 return; 
94 
95 tAssert(!Data); 
96 if (OwnsData) 
97 { 
98 Data = new uint8[dataSize]; 
99 tStd::tMemcpy(dest: Data, src: ch.Data(), numBytes: dataSize); 
100 } 
101 else 
102 { 
103 Data = (uint8*)ch.Data(); 
104 } 
105 break; 
106 } 
107 } 
108 } 
109} 
110