Add image support for worksheets (PNG, JPEG, GIF, SVG)

fastexcel-writer/src/main/java/org/dhatim/fastexcel/ImageType.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2016 Dhatim.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.dhatim.fastexcel;
+
+/**
+ * Supported image types for embedding in worksheets.
+ */
+public enum ImageType {
+    PNG("png", "image/png", false),
+    JPEG("jpeg", "image/jpeg", false),
+    GIF("gif", "image/gif", false),
+    SVG("svg", "image/svg+xml", true);
+
+    private final String extension;
+    private final String contentType;
+    private final boolean vector;
+
+    ImageType(String extension, String contentType, boolean vector) {
+        this.extension = extension;
+        this.contentType = contentType;
+        this.vector = vector;
+    }
+
+    /**
+     * Check if this is a vector image format (e.g., SVG).
+     *
+     * @return true if vector format, false if raster
+     */
+    public boolean isVector() {
+        return vector;
+    }
+
+    /**
+     * Get the file extension for this image type.
+     *
+     * @return File extension without the dot (e.g., "png", "jpeg")
+     */
+    public String getExtension() {
+        return extension;
+    }
+
+    /**
+     * Get the MIME content type for this image type.
+     *
+     * @return MIME content type (e.g., "image/png")
+     */
+    public String getContentType() {
+        return contentType;
+    }
+
+    /**
+     * Detect image type from byte array header.
+     *
+     * @param data Image bytes
+     * @return Detected ImageType
+     * @throws IllegalArgumentException if the image format is not supported or data is invalid
+     */
+    public static ImageType fromBytes(byte[] data) {
+        if (data == null || data.length < 8) {
+            throw new IllegalArgumentException("Invalid image data: data is null or too short");
+        }
+        // PNG signature: 89 50 4E 47 0D 0A 1A 0A
+        if (data[0] == (byte) 0x89 && data[1] == 0x50 && data[2] == 0x4E && data[3] == 0x47
+                && data[4] == 0x0D && data[5] == 0x0A && data[6] == 0x1A && data[7] == 0x0A) {
+            return PNG;
+        }
+        // JPEG signature: FF D8 FF
+        if (data[0] == (byte) 0xFF && data[1] == (byte) 0xD8 && data[2] == (byte) 0xFF) {
+            return JPEG;
+        }
+        // GIF signature: 47 49 46 38 (GIF8)
+        if (data[0] == 0x47 && data[1] == 0x49 && data[2] == 0x46 && data[3] == 0x38) {
+            return GIF;
+        }
+        // SVG detection: look for <?xml or <svg in the beginning (text-based format)
+        String header = new String(data, 0, Math.min(data.length, 256), java.nio.charset.StandardCharsets.UTF_8);
+        if (header.contains("<svg") || (header.contains("<?xml") && header.contains("<svg"))) {
+            return SVG;
+        }
+        throw new IllegalArgumentException("Unsupported image format. Supported formats: PNG, JPEG, GIF, SVG");
+    }
+}

fastexcel-writer/src/main/java/org/dhatim/fastexcel/Picture.java

@@ -0,0 +1,158 @@
+/*
+ * Copyright 2016 Dhatim.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.dhatim.fastexcel;
+
+import java.io.IOException;
+
+/**
+ * Represents an image embedded in a worksheet.
+ */
+public class Picture {
+
+    private final int id;
+    private final String name;
+    private final PictureAnchor anchor;
+    private final byte[] imageData;
+    private final ImageType imageType;
+    private final boolean lockAspectRatio;
+
+    // Relationship ID (set when writing)
+    private String relationshipId;
+
+    Picture(int id, String name, PictureAnchor anchor, byte[] imageData, ImageType imageType,
+            boolean lockAspectRatio) {
+        this.id = id;
+        this.name = name != null ? name : "Picture " + id;
+        this.anchor = anchor;
+        this.imageData = imageData;
+        this.imageType = imageType;
+        this.lockAspectRatio = lockAspectRatio;
+    }
+
+    void setRelationshipId(String relationshipId) {
+        this.relationshipId = relationshipId;
+    }
+
+    String getRelationshipId() {
+        return relationshipId;
+    }
+
+    int getId() {
+        return id;
+    }
+
+    byte[] getImageData() {
+        return imageData;
+    }
+
+    ImageType getImageType() {
+        return imageType;
+    }
+
+    PictureAnchor getAnchor() {
+        return anchor;
+    }
+
+    /**
+     * Get the name of this picture.
+     *
+     * @return Picture name
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Write the picture element to the drawing XML.
+     */
+    void write(Writer w) throws IOException {
+        if (anchor.isTwoCellAnchor()) {
+            writeTwoCellAnchor(w);
+        } else {
+            writeOneCellAnchor(w);
+        }
+    }
+
+    private void writeOneCellAnchor(Writer w) throws IOException {
+        w.append("<xdr:oneCellAnchor>");
+        anchor.writeFrom(w);
+        anchor.writeExt(w);
+        writePicElement(w);
+        w.append("<xdr:clientData/>");
+        w.append("</xdr:oneCellAnchor>");
+    }
+
+    private void writeTwoCellAnchor(Writer w) throws IOException {
+        w.append("<xdr:twoCellAnchor>");
+        anchor.writeFrom(w);
+        anchor.writeTo(w);
+        writePicElement(w);
+        w.append("<xdr:clientData/>");
+        w.append("</xdr:twoCellAnchor>");
+    }
+
+    private void writePicElement(Writer w) throws IOException {
+        w.append("<xdr:pic>");
+
+        // Non-visual properties
+        w.append("<xdr:nvPicPr>");
+        w.append("<xdr:cNvPr id=\"").append(id).append("\" name=\"");
+        w.appendEscaped(name);
+        w.append("\"/>");
+        w.append("<xdr:cNvPicPr>");
+        if (lockAspectRatio) {
+            w.append("<a:picLocks noChangeAspect=\"1\"/>");
+        }
+        w.append("</xdr:cNvPicPr>");
+        w.append("</xdr:nvPicPr>");
+
+        // Blip fill (image reference)
+        w.append("<xdr:blipFill>");
+        if (imageType == ImageType.SVG) {
+            // SVG uses extension element with svgBlip (Office 2016+)
+            w.append("<a:blip xmlns:r=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships\">");
+            w.append("<a:extLst>");
+            w.append("<a:ext uri=\"{96DAC541-7B7A-43D3-8B79-37D633B846F1}\">");
+            w.append("<asvg:svgBlip xmlns:asvg=\"http://schemas.microsoft.com/office/drawing/2016/SVG/main\" ");
+            w.append("r:embed=\"").append(relationshipId).append("\"/>");
+            w.append("</a:ext>");
+            w.append("</a:extLst>");
+            w.append("</a:blip>");
+        } else {
+            // Raster images (PNG, JPEG, GIF)
+            w.append("<a:blip xmlns:r=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships\" ");
+            w.append("r:embed=\"").append(relationshipId).append("\"/>");
+        }
+        w.append("<a:stretch><a:fillRect/></a:stretch>");
+        w.append("</xdr:blipFill>");
+
+        // Shape properties
+        w.append("<xdr:spPr>");
+        w.append("<a:xfrm>");
+        w.append("<a:off x=\"0\" y=\"0\"/>");
+        if (anchor.isTwoCellAnchor()) {
+            w.append("<a:ext cx=\"0\" cy=\"0\"/>");
+        } else {
+            w.append("<a:ext cx=\"").append(anchor.getWidthEmu()).append("\" cy=\"")
+              .append(anchor.getHeightEmu()).append("\"/>");
+        }
+        w.append("</a:xfrm>");
+        w.append("<a:prstGeom prst=\"rect\"><a:avLst/></a:prstGeom>");
+        w.append("</xdr:spPr>");
+
+        w.append("</xdr:pic>");
+    }
+}