PngImageC.java

/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2025, Arnaud Roques
 *
 * Project Info:  https://plantuml.com
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 * PlantUML is free software; you can redistribute it and/or modify it
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 *
 * PlantUML distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
 * License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
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 * Original Author:  Arnaud Roques
 *
 */
package net.sourceforge.plantuml.teavm.c;

/**
 * Encodes a raster image (ARGB pixels) as a PNG in C, losslessly (no palette,
 * no packing of the channels), as javax.imageio does for an image embedded in an
 * SVG (src/teavm-c/native/plantuml_png.h), and decodes an image file into
 * pixels. Only call it when {@code TeaVM.isC()}.
 */
public final class PngImageC {
	// ::remove file when JAVA8

	private PngImageC() {
	}

	/**
	 * @param argb   the pixels, row by row, as 0xAARRGGBB (not premultiplied)
	 * @param opaque whether the alpha channel is ignored (RGB instead of RGBA)
	 */
	public static byte[] encode(int[] argb, int width, int height, boolean opaque) {
		final int size = NativeCanvas.encodeImage(argb, width, height, opaque ? 1 : 0);
		if (size < 0)
			throw new IllegalStateException("PNG encoding failed");
		final byte[] result = new byte[size];
		NativeCanvas.copyImage(result);
		return result;
	}

	/**
	 * Decodes an image file (a PNG), as javax.imageio does.
	 *
	 * @param size receives the width and the height
	 * @return the pixels, row by row, as 0xAARRGGBB (not premultiplied), or null
	 *         when the data is not an image that can be decoded
	 */
	public static int[] decode(byte[] data, int[] size) {
		if (NativeCanvas.decodeImage(data, data.length, size) != 0)
			return null;
		final int[] result = new int[size[0] * size[1]];
		NativeCanvas.copyDecodedImage(result);
		return result;
	}

}