A new ImageInputStream adapter for InputStream.

2026-04-25 00:00:03 -04:00 · 2022-06-01 22:00:37 +02:00
parent 91493c5145
commit 0cb99feedf
3 changed files with 515 additions and 1 deletions
@@ -0,0 +1,133 @@
+/*
+ * Copyright (c) 2022, Harald Kuhr
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.twelvemonkeys.imageio.stream;
+
+import javax.imageio.stream.ImageInputStreamImpl;
+import java.io.IOException;
+import java.io.InputStream;
+
+import static com.twelvemonkeys.lang.Validate.isTrue;
+import static com.twelvemonkeys.lang.Validate.notNull;
+
+/**
+ * An {@code ImageInputStream} that adapts an {@code InputSteam},
+ * by reading directly from the stream without and form of caching or buffering.
+ * <p>
+ * Note: This is <em>not</em> a general-purpose {@code ImageInputStream}, and is designed for reading large chunks,
+ * typically of pixel data, from an {@code InputStream}.
+ * It does <em>not</em> support backwards seeking, or reading bits.
+ * </p>
+ */
+public final class DirectImageInputStream extends ImageInputStreamImpl {
+    private final InputStream stream;
+    private final long length;
+
+    public DirectImageInputStream(final InputStream stream) {
+        this(stream, -1L);
+    }
+
+    public DirectImageInputStream(final InputStream stream, long length) {
+        this.stream = notNull(stream, "stream");
+        this.length = isTrue(length >= 0L || length == -1L, length, "negative length: %d");
+    }
+
+    @Override
+    public int read() throws IOException {
+        bitOffset = 0;
+        streamPos++;
+        return stream.read();
+    }
+
+    @Override
+    public int read(final byte[] bytes, int off, int len) throws IOException {
+        bitOffset = 0;
+
+        int read = stream.read(bytes, off, len);
+        if (read > 0) {
+            streamPos += read;
+        }
+
+        return read;
+    }
+
+    @Override
+    public void seek(long pos) throws IOException {
+        checkClosed();
+
+        if (pos < streamPos) {
+            // Handle as if flushedPos == streamPos at any time
+            throw new IndexOutOfBoundsException("pos < flushedPos");
+        }
+
+        bitOffset = 0;
+
+        while (streamPos < pos) {
+            long skipped = stream.skip(pos - streamPos);
+
+            if (skipped <= 0) {
+                break;
+            }
+
+            streamPos += skipped;
+        }
+    }
+
+    @Override
+    public long getFlushedPosition() {
+        // Handle as if flushedPos == streamPos at any time
+        return streamPos;
+    }
+
+    @Override
+    public long length() {
+        return length;
+    }
+
+    @SuppressWarnings("RedundantThrows")
+    @Override
+    public int readBit() throws IOException {
+        throw new UnsupportedOperationException("Bit reading not supported");
+    }
+
+    @SuppressWarnings("RedundantThrows")
+    @Override
+    public long readBits(int numBits) throws IOException {
+        throw new UnsupportedOperationException("Bit reading not supported");
+    }
+
+    @Override
+    public void close() throws IOException {
+        // We could seek to EOF here, but the usual case
+
+        stream.close();
+        super.close();
+    }
+}