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Refactor: implement table-driven parsing to eliminate DetectFormatFromContent branches
- Replaced the massive `if-else` heuristic chain in `QuickView/ImageLoader.cpp` with a clean `MagicSignature` struct and `signatures` array. - Avoided dynamic memory allocations inside the inner loop by utilizing `wcscmp` instead of constructing temporary `std::wstring` objects. - Removed previously generated throwaway Python deployment scripts from the repository index.
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Lines changed: 52 additions & 78 deletions

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‎QuickView/ImageLoader.cpp‎

Lines changed: 52 additions & 78 deletions
Original file line numberDiff line numberDiff line change
@@ -172,102 +172,76 @@ namespace QuickView {
172172
static std::wstring DetectFormatFromContent(const uint8_t* magic, size_t size) {
173173
if (size < 4) return L"Unknown";
174174

175-
// Check JPEG: FF D8 FF
176-
if (size >= 3 && magic[0] == 0xFF && magic[1] == 0xD8 && magic[2] == 0xFF) return L"JPEG";
177-
178-
// Check PNG: 89 50 4E 47
179-
if (size >= 4 && magic[0] == 0x89 && magic[1] == 0x50 && magic[2] == 0x4E && magic[3] == 0x47) return L"PNG";
180-
181-
// Check WebP: RIFF ... WEBP
182-
if (size >= 12 && magic[0] == 'R' && magic[1] == 'I' && magic[2] == 'F' && magic[3] == 'F' &&
183-
magic[8] == 'W' && magic[9] == 'E' && magic[10] == 'B' && magic[11] == 'P') return L"WebP";
184-
185-
// Check AVIF: ftypavif OR ftypavis (AVIF Sequence)
186-
if (size >= 12 && magic[4] == 'f' && magic[5] == 't' && magic[6] == 'y' && magic[7] == 'p') {
187-
bool isAvif = (magic[8] == 'a' && magic[9] == 'v' && magic[10] == 'i' && magic[11] == 'f');
188-
bool isAvis = (magic[8] == 'a' && magic[9] == 'v' && magic[10] == 'i' && magic[11] == 's');
189-
if (isAvif || isAvis) return L"AVIF";
190-
}
175+
struct MagicSignature {
176+
const wchar_t* name;
177+
size_t offset;
178+
std::initializer_list<uint8_t> signature;
179+
};
191180

192-
// Check HEIC/HEIF/CR3: ftyp + brand
193-
if (size >= 12 && magic[4] == 'f' && magic[5] == 't' && magic[6] == 'y' && magic[7] == 'p') {
194-
// Canon CR3 (Raw)
195-
if (magic[8] == 'c' && magic[9] == 'r' && magic[10] == 'x') return L"RAW"; // crx
181+
static const MagicSignature signatures[] = {
182+
{ L"JPEG", 0, {0xFF, 0xD8, 0xFF} },
183+
{ L"PNG", 0, {0x89, 0x50, 0x4E, 0x47} },
184+
{ L"WebP", 8, {'W', 'E', 'B', 'P'} },
185+
{ L"JXL", 0, {0xFF, 0x0A} },
186+
{ L"JXL", 4, {'J', 'X', 'L', ' '} }, // For "00 00 00 0C JXL "
187+
{ L"DDS", 0, {'D', 'D', 'S', ' '} },
188+
{ L"BMP", 0, {'B', 'M'} },
189+
{ L"PSD", 0, {'8', 'B', 'P', 'S'} },
190+
{ L"HDR", 0, {'#', '?'} },
191+
{ L"EXR", 0, {0x76, 0x2F, 0x31, 0x01} },
192+
{ L"PIC", 0, {0x53, 0x80, 0xF6, 0x34} },
193+
{ L"QOI", 0, {'q', 'o', 'i', 'f'} },
194+
{ L"PCX", 0, {0x0A} },
195+
{ L"ICO", 0, {0x00, 0x00, 0x01, 0x00} },
196+
{ L"TIFF", 0, {0x49, 0x49, 0x2A, 0x00} },
197+
{ L"TIFF", 0, {0x4D, 0x4D, 0x00, 0x2A} }
198+
};
196199

197-
// Check brand at offset 8
198-
if ((magic[8] == 'h' && magic[9] == 'e' && magic[10] == 'i' && (magic[11] == 'c' || magic[11] == 'x' || magic[11] == 's' || magic[11] == 'm')) || // heic, heix, heis, heim
199-
(magic[8] == 'h' && magic[9] == 'e' && magic[10] == 'v' && (magic[11] == 'c' || magic[11] == 'm' || magic[11] == 's')) || // hevc, hevm, hevs
200-
(magic[8] == 'm' && magic[9] == 'i' && magic[10] == 'f' && magic[11] == '1') || // mif1
201-
(magic[8] == 'm' && magic[9] == 's' && magic[10] == 'f' && magic[11] == '1')) // msf1
202-
{
203-
return L"HEIC"; // Unified as HEIC/HEIF
200+
for (const auto& sig : signatures) {
201+
if (size >= sig.offset + sig.signature.size()) {
202+
bool match = true;
203+
size_t i = 0;
204+
for (uint8_t byte : sig.signature) {
205+
if (magic[sig.offset + i] != byte) {
206+
match = false;
207+
break;
208+
}
209+
i++;
210+
}
211+
// Additional context rules for WebP / JXL box
212+
if (match) {
213+
if (wcscmp(sig.name, L"WebP") == 0 && !(magic[0] == 'R' && magic[1] == 'I' && magic[2] == 'F' && magic[3] == 'F')) match = false;
214+
if (sig.offset == 4 && wcscmp(sig.name, L"JXL") == 0 && !(magic[0] == 0x00 && magic[1] == 0x00 && magic[2] == 0x00 && magic[3] == 0x0C)) match = false;
215+
}
216+
if (match) return sig.name;
204217
}
205218
}
206-
207-
// Check JXL: FF 0A or 00 00 00 0C JXL
208-
if (size >= 2 && magic[0] == 0xFF && magic[1] == 0x0A) return L"JXL";
209-
if (size >= 8 && magic[0] == 0x00 && magic[1] == 0x00 && magic[2] == 0x00 && magic[3] == 0x0C &&
210-
magic[4] == 'J' && magic[5] == 'X' && magic[6] == 'L' && magic[7] == ' ') return L"JXL";
211-
212-
// Check DDS: DDS\x20 (Magic Number: 0x20534444)
213-
if (size >= 4 && magic[0] == 'D' && magic[1] == 'D' && magic[2] == 'S' && magic[3] == ' ') return L"DDS";
214219

215-
// Check GIF: GIF87a or GIF89a
216-
if (size >= 6 && magic[0] == 'G' && magic[1] == 'I' && magic[2] == 'F' && magic[3] == '8' &&
217-
(magic[4] == '7' || magic[4] == '9') && magic[5] == 'a') return L"GIF";
218-
219-
// Check BMP: BM
220-
if (size >= 2 && magic[0] == 'B' && magic[1] == 'M') return L"BMP";
221-
222-
// Check PSD: 8BPS
223-
if (size >= 4 && magic[0] == '8' && magic[1] == 'B' && magic[2] == 'P' && magic[3] == 'S') return L"PSD";
224-
225-
// Check HDR: #?RADIANCE or #?RGBE
226-
if (size >= 2 && magic[0] == '#' && magic[1] == '?') return L"HDR";
220+
// Complex / Heuristic checks
221+
if (size >= 12 && magic[4] == 'f' && magic[5] == 't' && magic[6] == 'y' && magic[7] == 'p') {
222+
if (magic[8] == 'a' && magic[9] == 'v' && magic[10] == 'i' && (magic[11] == 'f' || magic[11] == 's')) return L"AVIF";
223+
if (magic[8] == 'c' && magic[9] == 'r' && magic[10] == 'x') return L"RAW";
224+
if ((magic[8] == 'h' && magic[9] == 'e' && magic[10] == 'i' && (magic[11] == 'c' || magic[11] == 'x' || magic[11] == 's' || magic[11] == 'm')) ||
225+
(magic[8] == 'h' && magic[9] == 'e' && magic[10] == 'v' && (magic[11] == 'c' || magic[11] == 'm' || magic[11] == 's')) ||
226+
(magic[8] == 'm' && magic[9] == 'i' && magic[10] == 'f' && magic[11] == '1') ||
227+
(magic[8] == 'm' && magic[9] == 's' && magic[10] == 'f' && magic[11] == '1')) return L"HEIC";
228+
}
227229

228-
// Check EXR: v/1\x01 (0x76 0x2f 0x31 0x01)
229-
if (size >= 4 && magic[0] == 0x76 && magic[1] == 0x2F && magic[2] == 0x31 && magic[3] == 0x01) return L"EXR";
230-
231-
// Check PIC: 0x53 0x80 ...
232-
if (size >= 4 && magic[0] == 0x53 && magic[1] == 0x80 && magic[2] == 0xF6 && magic[3] == 0x34) return L"PIC";
233-
234-
// Check PNM: P1-P7
230+
if (size >= 6 && magic[0] == 'G' && magic[1] == 'I' && magic[2] == 'F' && magic[3] == '8' && (magic[4] == '7' || magic[4] == '9') && magic[5] == 'a') return L"GIF";
235231
if (size >= 2 && magic[0] == 'P' && magic[1] >= '1' && magic[1] <= '7') return L"PNM";
236-
237-
// Check QOI: qoif
238-
if (size >= 4 && magic[0] == 'q' && magic[1] == 'o' && magic[2] == 'i' && magic[3] == 'f') return L"QOI";
239-
240-
// Check PCX: 0x0A ...
241-
if (size >= 1 && magic[0] == 0x0A) return L"PCX";
242-
243-
// Check ICO: 00 00 01 00
244-
if (size >= 4 && magic[0] == 0x00 && magic[1] == 0x00 && magic[2] == 0x01 && magic[3] == 0x00) return L"ICO";
245232

246-
// Check TIFF: II (49 49 2A 00) or MM (4D 4D 00 2A)
247-
if (size >= 4 && magic[0] == 0x49 && magic[1] == 0x49 && magic[2] == 0x2A && magic[3] == 0x00) return L"TIFF";
248-
if (size >= 4 && magic[0] == 0x4D && magic[1] == 0x4D && magic[2] == 0x00 && magic[3] == 0x2A) return L"TIFF";
249-
250-
// [v6.9.7] PRIORITIZE TGA Check over WBMP (since TGA often starts with 00 00)
251-
// Check TGA (Heuristic): ColorMapType(0/1) + ImageType(1/2/3/9/10/11) + PixelDepth(8/15/16/24/32) at offset 16
252233
if (size >= 18) {
253234
bool validColorMap = (magic[1] == 0 || magic[1] == 1);
254235
bool validType = (magic[2] == 1 || magic[2] == 2 || magic[2] == 3 || magic[2] == 9 || magic[2] == 10 || magic[2] == 11);
255236
bool validBpp = (magic[16] == 8 || magic[16] == 15 || magic[16] == 16 || magic[16] == 24 || magic[16] == 32);
256237
if (validColorMap && validType && validBpp) return L"TGA";
257238
}
258239

259-
// [v6.9.6] Check WBMP: Type 0, Fixed Header 0
260-
// [Fix] Must exclude ISOBMFF (ftyp) to avoid hijacking CR3/MP4 which start with size 00 00 ...
261240
if (size >= 2 && magic[0] == 0x00 && magic[1] == 0x00) {
262-
// If it looks like ftyp, it's NOT WBMP
263-
if (size >= 8 && magic[4] == 'f' && magic[5] == 't' && magic[6] == 'y' && magic[7] == 'p') {
264-
// Check known brands like crx? Already handled above.
265-
// If we are here, it's an UNKNOWN ftyp. Return Unknown, not WBMP.
266-
return L"Unknown";
267-
}
241+
if (size >= 8 && magic[4] == 'f' && magic[5] == 't' && magic[6] == 'y' && magic[7] == 'p') return L"Unknown";
268242
return L"WBMP";
269243
}
270-
244+
271245
return L"Unknown";
272246
}
273247

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