From d384b2b902b55f8de9fdbb826175711f4f61547f Mon Sep 17 00:00:00 2001
From: Daniel Eklöf <daniel@ekloef.se>
Date: Sun, 20 Sep 2020 12:20:46 +0200
Subject: jpeg: initial support for JPEG images, using libjpeg
---
jpg.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 119 insertions(+)
create mode 100644 jpg.c
(limited to 'jpg.c')
diff --git a/jpg.c b/jpg.c
new file mode 100644
index 0000000..d4784e8
--- /dev/null
+++ b/jpg.c
@@ -0,0 +1,119 @@
+#include "jpg.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include <setjmp.h>
+
+#include <jpeglib.h>
+
+#define LOG_MODULE "jpg"
+#define LOG_ENABLE_DBG 1
+#include "log.h"
+#include "stride.h"
+
+struct my_error_mgr {
+ struct jpeg_error_mgr mgr;
+ jmp_buf setjmp_buffer;
+};
+
+static void
+error_exit(j_common_ptr cinfo)
+{
+ struct my_error_mgr *err_handler = (struct my_error_mgr *)cinfo->err;
+ longjmp(err_handler->setjmp_buffer, 1);
+}
+
+pixman_image_t *
+jpg_load(const char *path)
+{
+ struct jpeg_decompress_struct cinfo = {0};
+ struct my_error_mgr err_handler;
+
+ uint8_t *image_data = NULL;
+ pixman_image_t *pix = NULL;
+
+ FILE *fp = fopen(path, "rb");
+ if (fp == NULL)
+ goto err;
+
+ cinfo.err = jpeg_std_error(&err_handler.mgr);
+ err_handler.mgr.error_exit = &error_exit;
+ if (setjmp(err_handler.setjmp_buffer)) {
+ char err_string[JMSG_LENGTH_MAX];
+ cinfo.err->format_message((j_common_ptr)&cinfo, err_string);
+ LOG_ERR("%s: %s", path, err_string);
+ goto err;
+ }
+
+ jpeg_create_decompress(&cinfo);
+ jpeg_stdio_src(&cinfo, fp);
+ jpeg_read_header(&cinfo, true);
+ jpeg_calc_output_dimensions(&cinfo);
+
+ if (cinfo.output_components != 1 && cinfo.output_components != 3) {
+ LOG_ERR("%s: unsupported number of color components: %d",
+ path, cinfo.output_components);
+ goto err;
+ }
+
+ pixman_format_code_t format = PIXMAN_b8g8r8;
+ int width = cinfo.output_width;
+ int height = cinfo.output_height;
+ int stride = stride_for_format_and_width(format, width);
+
+ LOG_DBG("width=%d, height=%d, stride=%d, components=%d",
+ width, height, stride, cinfo.output_components);
+
+ image_data = malloc(height * width * stride);
+ if (image_data == NULL)
+ goto err;
+
+ jpeg_start_decompress(&cinfo);
+
+ for (int row_no = 0; cinfo.output_scanline < height; row_no++) {
+ uint8_t *row = &image_data[row_no * stride];
+
+ if (cinfo.output_components == 3) {
+ /* Read directly info our to-be pixman image buffer */
+ jpeg_read_scanlines(&cinfo, (JSAMPARRAY)&row, 1);
+ }
+
+ else {
+ /* Read into temporary buffer, then expand to rgb */
+ assert(cinfo.output_components == 1);
+
+ uint8_t buf[cinfo.output_width];
+ uint8_t *scanline = &buf[0];
+ jpeg_read_scanlines(&cinfo, (JSAMPARRAY)&scanline, 1);
+
+ for (size_t i = 0; i < cinfo.output_width; i++) {
+ row[i * 3 + 0] = buf[i];
+ row[i * 3 + 1] = buf[i];
+ row[i * 3 + 2] = buf[i];
+ }
+ }
+ }
+
+ jpeg_finish_decompress(&cinfo);
+ jpeg_destroy_decompress(&cinfo);
+ fclose(fp);
+
+ pix = pixman_image_create_bits_no_clear(
+ format, width, height, (uint32_t *)image_data, stride);
+
+ if (pix == NULL) {
+ LOG_ERR("%s: failed to instantiate pixman image", path);
+ goto err;
+ }
+
+ return pix;
+
+err:
+ if (pix != NULL)
+ pixman_image_unref(pix);
+ free(image_data);
+ jpeg_destroy_decompress(&cinfo);
+ if (fp != NULL)
+ fclose(fp);
+ return NULL;
+}
--
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