Improve SVG preview generation

dao/src/main/java/org/thingsboard/server/dao/util/ImageUtils.java

@@ -20,8 +20,10 @@ import com.drew.metadata.Directory;
 import com.drew.metadata.Metadata;
 import com.drew.metadata.Tag;
 import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
+import lombok.With;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.batik.anim.dom.SAXSVGDocumentFactory;
 import org.apache.batik.bridge.BridgeContext;
@@ -121,7 +123,7 @@ public class ImageUtils {
         image.setHeight(bufferedImage.getHeight());
 
         ProcessedImage preview = new ProcessedImage();
-        int[] thumbnailDimensions = getThumbnailDimensions(image.getWidth(), image.getHeight(), thumbnailMaxDimension);
+        int[] thumbnailDimensions = getThumbnailDimensions(image.getWidth(), image.getHeight(), thumbnailMaxDimension, true);
         preview.setWidth(thumbnailDimensions[0]);
         preview.setHeight(thumbnailDimensions[1]);
 
@@ -191,8 +193,18 @@ public class ImageUtils {
         image.setSize(data.length);
 
         PNGTranscoder transcoder = new PNGTranscoder();
-        transcoder.addTranscodingHint(PNGTranscoder.KEY_MAX_WIDTH, (float) thumbnailMaxDimension);
-        transcoder.addTranscodingHint(PNGTranscoder.KEY_MAX_HEIGHT, (float) thumbnailMaxDimension);
+        if (image.getSize() < 10240) { // if SVG is smaller than 10kB (average 250x250 PNG preview size)
+            return withPreviewAsOriginalImage(image);
+        } else if (image.getSize() > 102400 && image.getWidth() != 0) { // considering SVG image detailed after 100kB
+            // increasing preview dimensions
+            thumbnailMaxDimension = 512;
+            int[] thumbnailDimensions = getThumbnailDimensions(image.getWidth(), image.getHeight(), thumbnailMaxDimension, false);
+            transcoder.addTranscodingHint(PNGTranscoder.KEY_WIDTH, (float) thumbnailDimensions[0]);
+            transcoder.addTranscodingHint(PNGTranscoder.KEY_HEIGHT, (float) thumbnailDimensions[1]);
+        } else {
+            transcoder.addTranscodingHint(PNGTranscoder.KEY_MAX_WIDTH, (float) thumbnailMaxDimension);
+            transcoder.addTranscodingHint(PNGTranscoder.KEY_MAX_HEIGHT, (float) thumbnailMaxDimension);
+        }
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         transcoder.transcode(new TranscoderInput(new ByteArrayInputStream(data)), new TranscoderOutput(out));
         byte[] pngThumbnail = out.toByteArray();
@@ -214,18 +226,16 @@ public class ImageUtils {
         image.setSize(data.length);
         image.setWidth(0);
         image.setHeight(0);
-        ProcessedImage preview = new ProcessedImage();
-        preview.setMediaType(mediaType);
-        preview.setData(null);
-        preview.setSize(data.length);
-        preview.setWidth(0);
-        preview.setHeight(0);
-        image.setPreview(preview);
-        return image;
+        return withPreviewAsOriginalImage(image);
+    }
+
+    public static ProcessedImage withPreviewAsOriginalImage(ProcessedImage originalImage) {
+        originalImage.setPreview(originalImage.withData(null));
+        return originalImage;
     }
 
-    private static int[] getThumbnailDimensions(int originalWidth, int originalHeight, int maxDimension) {
-        if (originalWidth <= maxDimension && originalHeight <= maxDimension) {
+    private static int[] getThumbnailDimensions(int originalWidth, int originalHeight, int maxDimension, boolean originalIfSmaller) {
+        if (originalWidth <= maxDimension && originalHeight <= maxDimension && originalIfSmaller) {
             return new int[]{originalWidth, originalHeight};
         }
         int thumbnailWidth;
@@ -242,10 +252,13 @@ public class ImageUtils {
     }
 
     @Data
+    @AllArgsConstructor
+    @NoArgsConstructor
     public static class ProcessedImage {
         private String mediaType;
         private int width;
         private int height;
+        @With
         private byte[] data;
         private long size;
         private ProcessedImage preview;