[937] Add diagram to SVG service

Bug: eclipse-sirius#937
Signed-off-by: Raphaël Pagé <raphael.page@obeo.fr>

backend/sirius-components-collaborative-diagrams/src/main/java/org/eclipse/sirius/components/collaborative/diagrams/dto/ExportRepresentationInput.java

@@ -0,0 +1,44 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.sirius.components.collaborative.diagrams.dto;
+
+import java.util.Objects;
+import java.util.UUID;
+
+import org.eclipse.sirius.components.collaborative.diagrams.api.IDiagramInput;
+
+/**
+ * The input object for the export representation service.
+ *
+ * @author rpage
+ */
+public final class ExportRepresentationInput implements IDiagramInput {
+    private final UUID id;
+
+    private final String representationId;
+
+    public ExportRepresentationInput(UUID id, String representationId) {
+        this.id = Objects.requireNonNull(id);
+        this.representationId = Objects.requireNonNull(representationId);
+    }
+
+    @Override
+    public String getRepresentationId() {
+        return this.representationId;
+    }
+
+    @Override
+    public UUID getId() {
+        return this.id;
+    }
+}

backend/sirius-components-collaborative-diagrams/src/main/java/org/eclipse/sirius/components/collaborative/diagrams/dto/ExportRepresentationPayload.java

@@ -0,0 +1,57 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.sirius.components.collaborative.diagrams.dto;
+
+import java.text.MessageFormat;
+import java.util.Objects;
+import java.util.UUID;
+
+import org.eclipse.sirius.components.core.api.IPayload;
+
+/**
+ * The payload of the export representation handler.
+ *
+ * @author rpage
+ */
+public final class ExportRepresentationPayload implements IPayload {
+    private final UUID id;
+
+    private final String name;
+
+    private final String content;
+
+    public ExportRepresentationPayload(UUID id, String name, String svgExport) {
+        this.id = Objects.requireNonNull(id);
+        this.name = Objects.requireNonNull(name);
+        this.content = Objects.requireNonNull(svgExport);
+    }
+
+    @Override
+    public UUID getId() {
+        return this.id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public String getContent() {
+        return this.content;
+    }
+
+    @Override
+    public String toString() {
+        String pattern = "{0} '{'id: {1}, name: {2}, content: {3} '}'"; //$NON-NLS-1$
+        return MessageFormat.format(pattern, this.getClass().getSimpleName(), this.id, this.name, this.content);
+    }
+}

backend/sirius-components-collaborative-diagrams/src/main/java/org/eclipse/sirius/components/collaborative/diagrams/export/api/ISVGDiagramExportService.java

@@ -0,0 +1,24 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.sirius.components.collaborative.diagrams.export.api;
+
+import org.eclipse.sirius.components.diagrams.Diagram;
+
+/**
+ * Interface of the service used to export a diagram to SVG.
+ *
+ * @author rpage
+ */
+public interface ISVGDiagramExportService {
+    String export(Diagram diagram);
+}

backend/sirius-components-collaborative-diagrams/src/main/java/org/eclipse/sirius/components/collaborative/diagrams/export/svg/DiagramElementExportService.java

@@ -0,0 +1,181 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.sirius.components.collaborative.diagrams.export.svg;
+
+import java.util.Optional;
+
+import org.eclipse.sirius.components.diagrams.Label;
+import org.eclipse.sirius.components.diagrams.LabelStyle;
+import org.eclipse.sirius.components.diagrams.LineStyle;
+import org.eclipse.sirius.components.diagrams.Node;
+import org.eclipse.sirius.components.diagrams.Position;
+import org.eclipse.sirius.components.diagrams.Size;
+import org.springframework.stereotype.Service;
+
+/**
+ * Contains methods used when exporting diagram elements.
+ *
+ * @author rpage
+ */
+@Service
+@SuppressWarnings("checkstyle:MultipleStringLiterals")
+public class DiagramElementExportService {
+    public StringBuilder exportLabel(Label label) {
+        StringBuilder labelExport = new StringBuilder();
+        Position position = label.getPosition();
+        Position alignment = label.getAlignment();
+        LabelStyle style = label.getStyle();
+
+        labelExport.append("<g "); //$NON-NLS-1$
+        labelExport.append("transform=\""); //$NON-NLS-1$
+        labelExport.append("translate(" + position.getX() + ", " + position.getY() + ") "); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+        labelExport.append("translate(" + alignment.getX() + ", " + alignment.getY() + ")\""); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+        labelExport.append(">"); //$NON-NLS-1$
+
+        if (!(style.getIconURL().isEmpty())) {
+            labelExport.append(this.exportImageElement(style.getIconURL(), -20, -12, Optional.empty()));
+        }
+
+        labelExport.append(this.exportTextElement(label.getText(), style));
+
+        return labelExport.append("</g>"); //$NON-NLS-1$
+    }
+
+    public StringBuilder exportImageElement(String imageURL, int x, int y, Optional<Size> size) {
+        StringBuilder imageExport = new StringBuilder();
+
+        imageExport.append("<image "); //$NON-NLS-1$
+        imageExport.append("href=\"" + imageURL + "\" "); //$NON-NLS-1$ //$NON-NLS-2$
+        imageExport.append("x=\"0\" "); //$NON-NLS-1$
+        imageExport.append("y=\"0\" "); //$NON-NLS-1$
+        size.ifPresent(it -> imageExport.append(this.addSizeParam(it)));
+
+        return imageExport.append("/>"); //$NON-NLS-1$
+    }
+
+    /**
+     * Export the g element containing the position of a diagram element.
+     *
+     * @param node
+     *            The diagram element
+     * @return The g element containing its position
+     */
+    public StringBuilder exportGNodeElement(Node node) {
+        StringBuilder gExport = new StringBuilder();
+
+        gExport.append("<g "); //$NON-NLS-1$
+        gExport.append("transform=\"translate(" + node.getPosition().getX() + ", " + node.getPosition().getY() + ")\" "); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+
+        return gExport.append(">"); //$NON-NLS-1$
+    }
+
+    public StringBuilder exportRectangleElement(Size size, Optional<Integer> borderRadius, Optional<String> color, Optional<String> borderColor, Optional<Integer> borderSize,
+            Optional<LineStyle> borderStyle) {
+        StringBuilder rectangle = new StringBuilder();
+
+        rectangle.append("<rect "); //$NON-NLS-1$
+        rectangle.append("x=\"0\" "); //$NON-NLS-1$
+        rectangle.append("y=\"0\" "); //$NON-NLS-1$
+        borderRadius.ifPresent(radius -> rectangle.append("rx=\"" + radius + "\" ")); //$NON-NLS-1$ //$NON-NLS-2$
+        rectangle.append(this.addSizeParam(size));
+        rectangle.append(this.exportRectangleStyleParam(color, borderColor, borderSize, borderStyle));
+
+        return rectangle.append("/> "); //$NON-NLS-1$
+    }
+
+    private StringBuilder addSizeParam(Size size) {
+        StringBuilder sizeParam = new StringBuilder();
+        sizeParam.append("width=\"" + size.getWidth() + "\" "); //$NON-NLS-1$ //$NON-NLS-2$
+        return sizeParam.append("height=\"" + size.getHeight() + "\" "); //$NON-NLS-1$ //$NON-NLS-2$
+    }
+
+    private StringBuilder exportTextElement(String text, LabelStyle labelStyle) {
+        StringBuilder textExport = new StringBuilder();
+
+        textExport.append("<text "); //$NON-NLS-1$
+        textExport.append("style=\""); //$NON-NLS-1$
+        textExport.append("fill: " + labelStyle.getColor() + "; "); //$NON-NLS-1$ //$NON-NLS-2$
+        textExport.append(this.exportFont(labelStyle));
+        textExport.append("\">"); //$NON-NLS-1$
+
+        textExport.append(text);
+
+        return textExport.append("</text>"); //$NON-NLS-1$
+    }
+
+    private StringBuilder exportFont(LabelStyle labelStyle) {
+        StringBuilder textExport = new StringBuilder();
+
+        textExport.append("font-size: " + labelStyle.getFontSize() + "px; "); //$NON-NLS-1$ //$NON-NLS-2$
+        textExport.append("font-family: Arial, Helvetica, sans-serif; "); //$NON-NLS-1$
+
+        textExport.append("font-weight: "); //$NON-NLS-1$
+        if (labelStyle.isBold()) {
+            textExport.append("bold"); //$NON-NLS-1$
+        } else {
+            textExport.append("normal"); //$NON-NLS-1$
+        }
+        textExport.append("; "); //$NON-NLS-1$
+
+        textExport.append("font-style: "); //$NON-NLS-1$
+        if (labelStyle.isItalic()) {
+            textExport.append("italic"); //$NON-NLS-1$
+        } else {
+            textExport.append("normal"); //$NON-NLS-1$
+        }
+        textExport.append("; "); //$NON-NLS-1$
+
+        textExport.append("text-decoration: "); //$NON-NLS-1$
+        if (labelStyle.isUnderline() || labelStyle.isStrikeThrough()) {
+            if (labelStyle.isUnderline()) {
+                textExport.append("underline "); //$NON-NLS-1$
+            }
+            if (labelStyle.isStrikeThrough()) {
+                textExport.append("line-through"); //$NON-NLS-1$
+            }
+        } else {
+            textExport.append("none"); //$NON-NLS-1$
+        }
+        return textExport.append(";"); //$NON-NLS-1$
+    }
+
+    private StringBuilder exportRectangleStyleParam(Optional<String> color, Optional<String> borderColor, Optional<Integer> borderSize, Optional<LineStyle> borderStyle) {
+        StringBuilder styleExport = new StringBuilder();
+
+        styleExport.append("style=\""); //$NON-NLS-1$
+        color.ifPresent(it -> styleExport.append("fill: " + it + "; ")); //$NON-NLS-1$ //$NON-NLS-2$
+        borderColor.ifPresent(it -> styleExport.append("stroke: " + it + "; ")); //$NON-NLS-1$ //$NON-NLS-2$
+        borderSize.ifPresent(it -> styleExport.append("stroke-width: " + it + "px; ")); //$NON-NLS-1$ //$NON-NLS-2$
+        borderStyle.ifPresent(style -> styleExport.append(this.exportBorderStyle(style)));
+
+        return styleExport.append("\""); //$NON-NLS-1$
+    }
+
+    private StringBuilder exportBorderStyle(LineStyle borderStyle) {
+        StringBuilder style = new StringBuilder();
+        switch (borderStyle.toString()) {
+        case "Dash": //$NON-NLS-1$
+            style.append(" stroke-dasharray: 4, 4;"); //$NON-NLS-1$
+            break;
+        case "Dot": //$NON-NLS-1$
+            style.append(" stroke-dasharray: 2, 2;"); //$NON-NLS-1$
+            break;
+        case "Dash_Dot": //$NON-NLS-1$
+            style.append(" stroke-dasharray: 2, 4, 2;"); //$NON-NLS-1$
+            break;
+        default:
+            break;
+        }
+        return style;
+    }
+}