WRaster: Add optional support to JPEG XL

Detect if libjxl is intalled, and build-in support in raster lib.
Feature can be disabled/enabled at configure time.

wrlib/load_jxl.c

@@ -0,0 +1,211 @@
+/* load_jxl.c - load JXL (JPEG XL) image from file
+ *
+ * Raster graphics library
+ *
+ * Copyright (c) 2025 Window Maker Team
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is 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
+ *  Library General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Library General Public
+ *  License along with this library; if not, write to the Free
+ *  Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ *  MA 02110-1301, USA.
+ */
+
+#include <config.h>
+
+#ifdef USE_JXL
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include <jxl/decode.h>
+
+#include "wraster.h"
+#include "imgformat.h"
+#include "wr_i18n.h"
+
+static unsigned char *do_read_file(const char *filename, size_t *size)
+{
+	FILE *file;
+	struct stat st;
+	unsigned char *data;
+
+	if (stat(filename, &st) != 0) {
+		RErrorCode = RERR_OPEN;
+		return NULL;
+	}
+
+	file = fopen(filename, "rb");
+	if (!file) {
+		RErrorCode = RERR_OPEN;
+		return NULL;
+	}
+
+	*size = st.st_size;
+	data = malloc(*size);
+	if (!data) {
+		RErrorCode = RERR_NOMEMORY;
+		fclose(file);
+		return NULL;
+	}
+
+	if (fread(data, 1, *size, file) != *size) {
+		RErrorCode = RERR_READ;
+		free(data);
+		fclose(file);
+		return NULL;
+	}
+
+	fclose(file);
+	return data;
+}
+
+RImage *RLoadJXL(const char *file)
+{
+	RImage *image = NULL;
+	unsigned char *data = NULL, *pixels = NULL;
+	size_t size;
+	JxlDecoder *dec = NULL;
+	JxlDecoderStatus status;
+	JxlBasicInfo info;
+	JxlPixelFormat format;
+	size_t buffer_size;
+	int width = 0, height = 0;
+	int has_alpha = 0;
+
+	/* Load file data */
+	data = do_read_file(file, &size);
+	if (!data)
+		return NULL;
+
+	/* Create decoder */
+	dec = JxlDecoderCreate(NULL);
+	if (!dec) {
+		RErrorCode = RERR_NOMEMORY;
+		goto error;
+	}
+
+	/* Subscribe to basic info and full image */
+	if (JxlDecoderSubscribeEvents(dec, JXL_DEC_BASIC_INFO | JXL_DEC_FULL_IMAGE) != JXL_DEC_SUCCESS) {
+		RErrorCode = RERR_BADIMAGEFILE;
+		goto error;
+	}
+
+	/* Set input data */
+	if (JxlDecoderSetInput(dec, data, size) != JXL_DEC_SUCCESS) {
+		RErrorCode = RERR_BADIMAGEFILE;
+		goto error;
+	}
+
+	/* Process events */
+	for (;;) {
+		status = JxlDecoderProcessInput(dec);
+
+		if (status == JXL_DEC_ERROR) {
+			RErrorCode = RERR_BADIMAGEFILE;
+			goto error;
+		}
+
+		if (status == JXL_DEC_NEED_MORE_INPUT) {
+			RErrorCode = RERR_BADIMAGEFILE;
+			goto error;
+		}
+
+		if (status == JXL_DEC_BASIC_INFO) {
+			if (JxlDecoderGetBasicInfo(dec, &info) != JXL_DEC_SUCCESS) {
+				RErrorCode = RERR_BADIMAGEFILE;
+				goto error;
+			}
+
+			width = info.xsize;
+			height = info.ysize;
+
+			if (width < 1 || height < 1) {
+				RErrorCode = RERR_BADIMAGEFILE;
+				goto error;
+			}
+
+			/* Check if image has alpha channel */
+			has_alpha = (info.alpha_bits > 0);
+			
+			/* Set pixel format based on alpha channel presence */
+			if (has_alpha) {
+				format.num_channels = 4;  /* RGBA */
+			} else {
+				format.num_channels = 3;  /* RGB */
+			}
+			format.data_type = JXL_TYPE_UINT8;
+			format.endianness = JXL_NATIVE_ENDIAN;
+			format.align = 0;
+
+		} else if (status == JXL_DEC_NEED_IMAGE_OUT_BUFFER) {
+			/* Allocate image with or without alpha */
+			image = RCreateImage(width, height, has_alpha ? True : False);
+			if (!image) {
+				RErrorCode = RERR_NOMEMORY;
+				goto error;
+			}
+
+			/* Determine buffer size */
+			if (JxlDecoderImageOutBufferSize(dec, &format, &buffer_size) != JXL_DEC_SUCCESS) {
+				RErrorCode = RERR_BADIMAGEFILE;
+				goto error;
+			}
+
+			/* Allocate buffer */
+			pixels = malloc(buffer_size);
+			if (!pixels) {
+				RErrorCode = RERR_NOMEMORY;
+				goto error;
+			}
+
+			/* Set output buffer */
+			if (JxlDecoderSetImageOutBuffer(dec, &format, pixels, buffer_size) != JXL_DEC_SUCCESS) {
+				RErrorCode = RERR_BADIMAGEFILE;
+				goto error;
+			}
+		} else if (status == JXL_DEC_FULL_IMAGE) {
+			/* Image is ready, copy data directly for RGB or RGBA */
+			if (has_alpha) {
+				/* RGBA format - copy directly */
+				memcpy(image->data, pixels, width * height * 4);
+			} else {
+				/* RGB format - copy directly */
+				memcpy(image->data, pixels, width * height * 3);
+			}
+			break;
+		} else if (status == JXL_DEC_SUCCESS) {
+			/* All done */
+			break;
+		}
+	}
+
+	free(data);
+	free(pixels);
+	JxlDecoderDestroy(dec);
+	return image;
+
+error:
+	if (data)
+		free(data);
+	if (pixels)
+		free(pixels);
+	if (image)
+		RReleaseImage(image);
+	if (dec)
+		JxlDecoderDestroy(dec);
+	return NULL;
+}
+
+#endif /* USE_JXL */