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Merge pull request #578 from FlorianRauscha/master
Add image support for worksheets (PNG, JPEG, GIF, SVG)
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‎fastexcel-writer/src/main/java/org/dhatim/fastexcel/ImageType.java‎

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

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

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

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