imagePlaceholder() creates objects that remain in memory #10332

modules/core/core-api/src/main/java/com/enonic/xp/image/ImageHelper.java

@@ -9,7 +9,6 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.Base64;
 import java.util.Iterator;
 
 import javax.imageio.IIOImage;
@@ -31,19 +30,7 @@ private ImageHelper()
 
     public static String createImagePlaceholder( final int width, final int height )
     {
-        try
-        {
-            final BufferedImage image = createImage( width, height, true );
-            final ByteArrayOutputStream out = new ByteArrayOutputStream();
-            writeImage( out, image, "png", 0 );
-            final byte[] bytes = out.toByteArray();
-
-            return "data:image/png;base64," + Base64.getEncoder().encodeToString( bytes );
-        }
-        catch ( final IOException e )
-        {
-            throw Exceptions.newRuntime( "Failed to create image placeholder" ).withCause( e );
-        }
+        return new ImagePlaceholderFactory( width, height ).create();
     }
 
     @Deprecated

modules/core/core-api/src/main/java/com/enonic/xp/image/ImagePlaceholderFactory.java

@@ -0,0 +1,105 @@
+package com.enonic.xp.image;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+import java.util.zip.CRC32;
+import java.util.zip.CheckedOutputStream;
+import java.util.zip.DeflaterOutputStream;
+
+final class ImagePlaceholderFactory
+{
+    private static final byte[] PNG_MAGIC = {(byte) 137, 80, 78, 71, 13, 10, 26, 10};
+
+    private static final byte[] IDAT_TYPE_BYTES = "IDAT".getBytes( StandardCharsets.ISO_8859_1 );
+
+    private static final byte[] IHDR_TYPE_BYTES = "IHDR".getBytes( StandardCharsets.ISO_8859_1 );
+
+    private static final byte[] IHDR_CONST_PART = {(byte) 8, 6, 0, 0, 0};
+
+    private static final byte[] IEND = {(byte) 0, 0, 0, 0, 73, 69, 78, 68, -82, 66, 96, -126};
+
+    private static final byte[] PREFIX = "data:image/png;base64,".getBytes( StandardCharsets.ISO_8859_1 );
+
+    private final int width;
+
+    private final int height;
+
+    ImagePlaceholderFactory( final int width, final int height )
+    {
+        this.width = width;
+        this.height = height;
+    }
+
+    public String create()
+    {
+        ByteArrayOutputStream output = new ByteArrayOutputStream();
+        try
+        {
+            output.write( PREFIX );
+            try (var base64Stream = Base64.getEncoder().wrap( output ))
+            {
+                base64Stream.write( PNG_MAGIC );
+                writeChunk( base64Stream, IHDR_TYPE_BYTES, createIhdr() );
+                writeChunk( base64Stream, IDAT_TYPE_BYTES, createIdat() );
+                base64Stream.write( IEND );
+            }
+        }
+        catch ( IOException e )
+        {
+            throw new UncheckedIOException( e );
+        }
+
+        return output.toString( StandardCharsets.ISO_8859_1 );
+    }
+
+    private byte[] createIhdr()
+        throws IOException
+    {
+        ByteArrayOutputStream ihdr = new ByteArrayOutputStream();
+        writeBigEndianInt( ihdr, width );
+        writeBigEndianInt( ihdr, height );
+        ihdr.write( IHDR_CONST_PART );
+        return ihdr.toByteArray();
+    }
+
+    private byte[] createIdat()
+        throws IOException
+    {
+        final ByteArrayOutputStream idat = new ByteArrayOutputStream();
+
+        final int bufferSize = 512; // DeflaterOutputStream uses this size as a default buffer size
+        byte[] buffer = new byte[bufferSize];
+        int totalBytes = width * height * 5; // 5 bytes per pixel (RGBA)
+        try (DeflaterOutputStream defStream = new DeflaterOutputStream( idat ))
+        {
+            for ( int i = 0; i < totalBytes; i += bufferSize )
+            {
+                defStream.write( buffer, 0, Math.min( bufferSize, totalBytes - i ) );
+            }
+        }
+        return idat.toByteArray();
+    }
+
+    private void writeChunk( final OutputStream outputStream, final byte[] typeBytes, final byte[] data )
+        throws IOException
+    {
+        CheckedOutputStream crcStream = new CheckedOutputStream( outputStream, new CRC32() );
+        writeBigEndianInt( outputStream, data.length );
+        crcStream.write( typeBytes );
+        crcStream.write( data );
+        writeBigEndianInt( outputStream, (int) crcStream.getChecksum().getValue() );
+    }
+
+    private static void writeBigEndianInt( final OutputStream stream, final int value )
+        throws IOException
+    {
+        stream.write( ( value >>> 24 ) & 0xFF );
+        stream.write( ( value >>> 16 ) & 0xFF );
+        stream.write( ( value >>> 8 ) & 0xFF );
+        stream.write( value & 0xFF );
+    }
+}

modules/core/core-api/src/test/java/com/enonic/xp/image/ImageHelperTest.java

@@ -3,16 +3,14 @@
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
 
 class ImageHelperTest
 {
     @Test
     void createImagePlaceholder()
     {
-        final String str = ImageHelper.createImagePlaceholder( 2, 2 );
-        assertNotNull( str );
-        assertEquals( "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAAC0lEQVR42mNgQAcAABIAAeRVjecAAAAASUVORK5CYII=",
+        final String str = ImageHelper.createImagePlaceholder( 2, 3 );
+        assertEquals( "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAADCAYAAAC56t6BAAAAC0lEQVR4nGNgwAcAAB4AAfb96ZYAAAAASUVORK5CYII=",
                       str );
     }
 

modules/lib/lib-portal/src/main/resources/lib/xp/examples/portal/imagePlaceholder.js

@@ -10,7 +10,7 @@ var url = portalLib.imagePlaceholder({
 
 // BEGIN
 // URL returned.
-var expected = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAYCAYAAACbU/80AAAAGUlEQVR42u3BAQEAAACCIP+vbkhAAQAA7wYMGAAB93LuRQAAAABJRU5ErkJggg==';
+var expected = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAYCAYAAACbU/80AAAAGklEQVR4nO3BAQ0AAADCoPdPbQ8HFAAAAPwbDwAAAQUUSzEAAAAASUVORK5CYII=';
 // END
 
 assert.assertEquals(expected, url);

modules/lib/lib-portal/src/test/resources/test/url-test.js

@@ -248,7 +248,7 @@ exports.imagePlaceholderTest = function () {
     });
 
     assert.assertEquals(
-        'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAKCAYAAADVTVykAAAAEklEQVR42mNgGAWjYBSMgpEOAAUKAAEVKR6qAAAAAElFTkSuQmCC',
+        'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAKCAYAAADVTVykAAAAFUlEQVR4nGNgGAWjYBSMglEwCkgHAAZAAAEAAhBgAAAAAElFTkSuQmCC',
         result);
     return true;
 };

modules/portal/portal-impl/src/test/java/com/enonic/xp/portal/impl/view/ImagePlaceholderFunctionTest.java

@@ -19,7 +19,7 @@ protected void setupFunction()
     public void testExecute()
     {
         final Object result = execute( "imagePlaceholder", "width=2", "height=2" );
-        assertEquals( "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAAC0lEQVR42mNgQAcAABIAAeRVjecAAAAASUVORK5CYII=",
+        assertEquals( "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAAC0lEQVR4nGNgwAQAABQAAX3+Hu4AAAAASUVORK5CYII=",
                       result );
     }