1// tImageGIF.cpp 
2// 
3// This knows how to load gifs. It knows the details of the gif file format and loads the data into multiple tPixel 
4// arrays, one for each frame (gifs may be animated). These arrays may be 'stolen' by tPictures. 
5// 
6// Copyright (c) 2020 Tristan Grimmer. 
7// Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby 
8// granted, provided that the above copyright notice and this permission notice appear in all copies. 
9// 
10// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL 
11// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, 
12// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN 
13// AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 
14// PERFORMANCE OF THIS SOFTWARE. 
15 
16#include <Foundation/tStandard.h> 
17#include <Foundation/tString.h> 
18#include <System/tFile.h> 
19#include <GifLoad/gif_load.h> 
20#include "Image/tImageGIF.h" 
21 
22using namespace tSystem; 
23namespace tImage 
24{ 
25 
26 
27// This callback is a essentially the example code from gif_load. 
28void tImageGIF::FrameCallback(struct GIF_WHDR* whdr) 
29{ 
30 #define RGBA(i) \ 
31 ( \ 
32 (whdr->bptr[i] == whdr->tran) ? 0x00000000 : \ 
33 ( \ 
34 uint32_t(whdr->cpal[whdr->bptr[i]].B << 16) | \ 
35 uint32_t(whdr->cpal[whdr->bptr[i]].G << 8) | \ 
36 uint32_t(whdr->cpal[whdr->bptr[i]].R << 0) | \ 
37 0xFF000000 \ 
38 ) \ 
39 ) 
40 
41 // Is first frame? 
42 if (whdr->ifrm == 0) 
43 { 
44 Width = whdr->xdim; 
45 Height = whdr->ydim; 
46 FrmPict = new tPixel[Width * Height]; 
47 FrmPrev = new tPixel[Width * Height]; 
48 } 
49 
50 int numPixels = Width * Height; 
51 tPixel* pict = FrmPict; 
52 tPixel* prev = nullptr; 
53 
54 uint32 ddst = uint32(whdr->xdim * whdr->fryo + whdr->frxo); 
55 
56 // Interlacing support. 
57 uint32 iter = whdr->intr ? 0 : 4; 
58 uint32 ifin = !iter ? 4 : 5; 
59 
60 int y = 0; 
61 for (uint32 dsrc = (uint32)-1; iter < ifin; iter++) 
62 for (int yoff = 16U >> ((iter > 1) ? iter : 1), y = (8 >> iter) & 7; y < whdr->fryd; y += yoff) 
63 for (int x = 0; x < whdr->frxd; x++) 
64 if (whdr->tran != (long)whdr->bptr[++dsrc]) 
65 pict[whdr->xdim * y + x + ddst].BP = RGBA(dsrc); 
66 
67 tImageGIF::Frame* frame = new tImageGIF::Frame(); 
68 Frames.Append(frame); 
69 frame->Pixels = new tPixel[numPixels]; 
70 frame->Duration = float(whdr->time) / 100.0f; 
71 
72 // We store rows starting from the bottom (lower left is 0,0). 
73 for (int row = Height-1; row >= 0; row--) 
74 tStd::tMemcpy(frame->Pixels + (row*Width), pict + ((Height-row-1)*Width), Width*sizeof(tPixel)); 
75 
76 if ((whdr->mode == GIF_PREV) && !FrmLast) 
77 { 
78 whdr->frxd = whdr->xdim; 
79 whdr->fryd = whdr->ydim; 
80 whdr->mode = GIF_BKGD; 
81 ddst = 0; 
82 } 
83 else 
84 { 
85 FrmLast = (whdr->mode == GIF_PREV) ? FrmLast : (whdr->ifrm + 1); 
86 pict = (whdr->mode == GIF_PREV) ? FrmPict : FrmPrev; 
87 prev = (whdr->mode == GIF_PREV) ? FrmPrev : FrmPict; 
88 for (int x = whdr->xdim * whdr->ydim; --x; 
89 pict[x - 1].BP = prev[x - 1].BP); 
90 } 
91 
92 // Cutting a hole for the next frame. 
93 if (whdr->mode == GIF_BKGD) 
94 { 
95 int y = 0; 
96 for 
97 ( 
98 whdr->bptr[0] = ((whdr->tran >= 0) ? uint8(whdr->tran) : uint8(whdr->bkgd)), y = 0, pict = FrmPict; 
99 y < whdr->fryd; 
100 y++ 
101 ) 
102 { 
103 for (int x = 0; x < whdr->frxd; x++) 
104 pict[whdr->xdim * y + x + ddst].BP = RGBA(0); 
105 } 
106 } 
107} 
108 
109 
110bool tImageGIF::Load(const tString& gifFile) 
111{ 
112 Clear(); 
113 
114 if (tSystem::tGetFileType(gifFile) != tSystem::tFileType::GIF) 
115 return false; 
116 
117 if (!tFileExists(gifFile)) 
118 return false; 
119 
120 int numBytes = 0; 
121 uint8* gifFileInMemory = tLoadFile(gifFile, nullptr, &numBytes); 
122 
123 // This call allocated scratchpad memory pointed to by FrmPict and FrmPrev. 
124 // They are set to null just in case GIF_Load fails to allocate. 
125 FrmPict = nullptr; 
126 FrmPrev = nullptr; 
127 int result = GIF_Load(gifFileInMemory, numBytes, FrameCallbackBridge, nullptr, (void*)this, 0); 
128 delete[] FrmPict; 
129 delete[] FrmPrev; 
130 delete[] gifFileInMemory; 
131 if (result <= 0) 
132 return false; 
133 
134 SrcPixelFormat = tPixelFormat::PAL_8BIT; 
135 return true; 
136} 
137 
138 
139} 
140