Fix on image layer with error

- simplify the too big images generation
- manage the download error

core/src/main/java/org/mapfish/print/map/image/ImageLayer.java

@@ -39,6 +39,8 @@
 import org.mapfish.print.map.geotools.StyleSupplier;
 import org.mapfish.print.parser.HasDefaultValue;
 import org.opengis.referencing.crs.CoordinateReferenceSystem;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.client.ClientHttpRequest;
@@ -50,11 +52,14 @@
  */
 public final class ImageLayer extends AbstractSingleImageLayer {
   private final ImageParam params;
+  private final boolean failOnError;
   private final StyleSupplier<GridCoverage2D> styleSupplier;
   private final ExecutorService executorService;
   private final RenderType renderType;
   private double imageBufferScaling;
   private BufferedImage image;
+  private boolean imageLoadError = false;
+  private static final Logger LOGGER = LoggerFactory.getLogger(ImageLayer.class);
 
   /**
    * Constructor.
@@ -73,6 +78,8 @@ protected ImageLayer(
       @Nonnull final MetricRegistry registry) {
     super(executorService, styleSupplier, params, registry, configuration);
     this.params = params;
+    this.failOnError = params.failOnError;
+    params.failOnError = true;
     this.styleSupplier = styleSupplier;
     this.executorService = executorService;
     this.renderType = RenderType.fromMimeType(params.imageFormat);
@@ -83,7 +90,12 @@ protected BufferedImage loadImage(
       final MfClientHttpRequestFactory requestFactory, final MapfishMapContext transformer) {
     final ReferencedEnvelope envelopeOrig =
         transformer.getBounds().toReferencedEnvelope(transformer.getPaintArea());
-    final Rectangle paintArea = calculateNewBounds(image, envelopeOrig);
+    final Rectangle paintArea;
+    if (imageLoadError) {
+      paintArea = transformer.getPaintArea();
+    } else {
+      paintArea = calculateNewBounds(image, envelopeOrig);
+    }
     final ReferencedEnvelope envelope = transformer.getBounds().toReferencedEnvelope(paintArea);
     final BufferedImage bufferedImage =
         new BufferedImage(paintArea.width, paintArea.height, TYPE_INT_ARGB_PRE);
@@ -157,30 +169,47 @@ public double getImageBufferScaling() {
   public void prepareRender(
       final MapfishMapContext transformer,
       final MfClientHttpRequestFactory clientHttpRequestFactory) {
-    image = fetchImage(transformer, clientHttpRequestFactory);
+    try {
+      image = fetchImage(transformer, clientHttpRequestFactory);
+    } catch (Exception e) {
+      if (failOnError) {
+        throw new RuntimeException(e);
+      } else {
+        LOGGER.error("Error while fetching image", e);
+        image = createErrorImage(new Rectangle(1, 1));
+        imageLoadError = true;
+        imageBufferScaling = 1;
+        return;
+      }
+    }
+    imageLoadError = false;
+
     final ReferencedEnvelope envelopeOrig =
         transformer.getBounds().toReferencedEnvelope(transformer.getPaintArea());
     final Rectangle paintArea = calculateNewBounds(image, envelopeOrig);
 
+    double widthImageBufferScaling = paintArea.getWidth() / transformer.getMapSize().getWidth();
+    double heightImageBufferScaling = paintArea.getHeight() / transformer.getMapSize().getHeight();
     imageBufferScaling =
-        ((paintArea.getWidth() / transformer.getMapSize().getWidth())
-                + (paintArea.getHeight() / transformer.getMapSize().getHeight()))
-            / 2;
+        Math.sqrt(
+            (Math.pow(widthImageBufferScaling, 2) + Math.pow(heightImageBufferScaling, 2)) / 2);
+    if (imageBufferScaling >= 2) {
+      // Simplify the image by multiple of 2
+      imageBufferScaling =
+          imageBufferScaling
+              / Math.pow((int) (Math.floor(Math.log(imageBufferScaling) / Math.log(2))), 2);
+    }
   }
 
   private BufferedImage fetchImage(
       final MapfishMapContext transformer,
-      final MfClientHttpRequestFactory clientHttpRequestFactory) {
+      final MfClientHttpRequestFactory clientHttpRequestFactory)
+      throws URISyntaxException, IOException {
     BufferedImage image;
-    try {
-      final URI commonUri = new URI(this.params.getBaseUrl());
-      final ClientHttpRequest request =
-          clientHttpRequestFactory.createRequest(commonUri, HttpMethod.GET);
-      image = fetchImage(request, transformer);
-    } catch (URISyntaxException | IOException e) {
-      throw new RuntimeException(e);
-    }
-    return image;
+    final URI commonUri = new URI(this.params.getBaseUrl());
+    final ClientHttpRequest request =
+        clientHttpRequestFactory.createRequest(commonUri, HttpMethod.GET);
+    return fetchImage(request, transformer);
   }
 
   /**

examples/src/test/resources/examples/image_layer_test/requestData-with-error.json

@@ -0,0 +1,22 @@
+{
+  "layout": "A4 landscape",
+  "outputFormat": "pdf",
+  "attributes": {
+    "map": {
+      "bbox": [4150836.3839982115, 7600898.092677928, 5703147.34969658, 8257645.039704161],
+      "dpi": 300,
+      "layers": [
+        {
+          "baseURL": "http://geoserver:8080/does-not-exist.png",
+          "extent": [4392836.015549079, 7861166.1739889495, 4481502.968359884, 7888169.291435877],
+          "name": "image",
+          "opacity": 1,
+          "type": "image"
+        }
+      ],
+      "longitudeFirst": true,
+      "projection": "EPSG:3857",
+      "rotation": 0
+    }
+  }
+}

examples/src/test/resources/examples/image_layer_test/requestData.json

@@ -7,7 +7,7 @@
       "dpi": 300,
       "layers": [
         {
-          "baseURL": "http://geoserver:8080/geoserver/GeoServer.png",
+          "baseURL": "http://geoserver:8080/geoserver/www/GeoServer.png",
           "extent": [4392836.015549079, 7861166.1739889495, 4481502.968359884, 7888169.291435877],
           "name": "image",
           "opacity": 1,