IFF: read only support to Interchange Format Files

Read-only support for most common Interchange Format Files (IFF). Supports IFF saved by Photoshop for the Amiga and Maya platform and HAM6 coded files. Closes #29
2026-07-24 08:40:58 -04:00 · 2025-07-01 23:59:03 +02:00
parent e6357c22f7
commit 4f2f2425d3
38 changed files with 2770 additions and 43 deletions
--- a/src/imageformats/packbits_p.h
+++ b/src/imageformats/packbits_p.h
@@ -0,0 +1,111 @@
+/*
+    Packbits compression used on many legacy formats (IFF, PSD, TIFF).
+
+    SPDX-FileCopyrightText: 2025 Mirco Miranda <mircomir@outlook.com>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+#ifndef PACKBITS_P_H
+#define PACKBITS_P_H
+
+#include <QIODevice>
+
+/*!
+ * \brief packbitsDecompress
+ * Fast PackBits decompression.
+ * \param input The compressed input buffer.
+ * \param ilen The input buffer size.
+ * \param output The uncompressed target buffer.
+ * \param olen The target buffer size.
+ * \param allowN128 If true, -128 is a valid run length size (false for PSD / TIFF, true for IFF) .
+ * \return The number of valid bytes in the target buffer.
+ */
+inline qint64 packbitsDecompress(const char *input, qint64 ilen, char *output, qint64 olen, bool allowN128 = false)
+{
+    qint64  j = 0;
+    for (qint64 ip = 0, rr = 0, available = olen; j < olen && ip < ilen; available = olen - j) {
+        signed char n = static_cast<signed char>(input[ip++]);
+        if (n == -128 && !allowN128)
+            continue;
+
+        if (n >= 0) {
+            rr = qint64(n) + 1;
+            if (available < rr) {
+                --ip;
+                break;
+            }
+
+            if (ip + rr > ilen)
+                return -1;
+            memcpy(output + j, input + ip, size_t(rr));
+            ip += rr;
+        } else if (ip < ilen) {
+            rr = qint64(1-n);
+            if (available < rr) {
+                --ip;
+                break;
+            }
+            memset(output + j, input[ip++], size_t(rr));
+        }
+
+        j += rr;
+    }
+    return j;
+}
+
+/*!
+ * \brief packbitsDecompress
+ * PackBits decompression.
+ * \param input The input device.
+ * \param output The uncompressed target buffer.
+ * \param olen The target buffer size.
+ * \param allowN128 If true, -128 is a valid run length size (false for PSD / TIFF, true for IFF) .
+ * \return The number of valid bytes in the target buffer.
+ */
+inline qint64 packbitsDecompress(QIODevice *input, char *output, qint64 olen, bool allowN128 = false)
+{
+    qint64  j = 0;
+    for (qint64 rr = 0, available = olen; j < olen; available = olen - j) {
+        char n;
+
+        // check the output buffer space for the next run
+        if (available < 129) {
+            if (input->peek(&n, 1) != 1) { // end of data (or error)
+                break;
+            }
+            if (static_cast<signed char>(n) != -128 || allowN128)
+                if ((static_cast<signed char>(n) >= 0 ? qint64(n) + 1 : qint64(1 - n)) > available)
+                    break;
+        }
+
+        // decompress
+        if (input->read(&n, 1) != 1) { // end of data (or error)
+            break;
+        }
+
+        if (static_cast<signed char>(n) == -128 && !allowN128) {
+            continue;
+        }
+
+        if (static_cast<signed char>(n) >= 0) {
+            rr = input->read(output + j, qint64(n) + 1);
+            if (rr == -1) {
+                return -1;
+            }
+        }
+        else {
+            char b;
+            if (input->read(&b, 1) != 1) {
+                break;
+            }
+            rr = qint64(1 - static_cast<signed char>(n));
+            std::memset(output + j, b, size_t(rr));
+        }
+
+        j += rr;
+    }
+    return j;
+}
+
+
+#endif // PACKBITS_P_H