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WRaster: add function to save image in memory

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This patch adds the RSaveRawImage() function to the WRaster lib
to be able to save image structure in memory.
The WRaster lib version is bumped.
This commit is contained in:
David Maciejak
2026-01-17 16:09:37 -05:00
committed by Carlos R. Mafra
parent 72942267aa
commit 7cfdf6bd68
8 changed files with 266 additions and 42 deletions
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130
wrlib/save_png.c
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@@ -2,7 +2,7 @@
*
* Raster graphics library
*
* Copyright (c) 2023 Window Maker Team
* Copyright (c) 2023-2025 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
@@ -33,12 +33,51 @@
#include "imgformat.h"
#include "wr_i18n.h"
/*
* Save RImage to PNG image
*/
Bool RSavePNG(RImage *img, const char *filename, char *title)
/* Structure to hold PNG data in memory */
struct png_mem_data {
unsigned char *buffer;
size_t size;
size_t capacity;
};
/* Callback function to write PNG data to memory buffer */
static void png_write_to_memory(png_structp png_ptr, png_bytep data, png_size_t length)
{
struct png_mem_data *p = (struct png_mem_data *)png_get_io_ptr(png_ptr);
size_t new_size = p->size + length;
/* Expand buffer if necessary */
if (new_size > p->capacity) {
size_t new_capacity = p->capacity ? p->capacity * 2 : 8192;
while (new_capacity < new_size)
new_capacity *= 2;
unsigned char *new_buffer = realloc(p->buffer, new_capacity);
if (!new_buffer) {
png_error(png_ptr, "Out of memory");
return;
}
p->buffer = new_buffer;
p->capacity = new_capacity;
}
/* Copy data to buffer */
memcpy(p->buffer + p->size, data, length);
p->size += length;
}
/* Dummy flush function for memory I/O */
static void png_flush_memory(png_structp png_ptr)
{
/* No-op for memory I/O */
(void)png_ptr;
}
/*
* Save RImage to PNG data in memory
*/
Bool RSaveRawPNG(RImage *img, char *title, unsigned char **out_buf, size_t *out_size)
{
FILE *file;
png_structp png_ptr;
png_infop png_info_ptr;
png_bytep png_row;
@@ -46,17 +85,14 @@ Bool RSavePNG(RImage *img, const char *filename, char *title)
int x, y;
int width = img->width;
int height = img->height;
struct png_mem_data png_data = {NULL, 0, 0};
file = fopen(filename, "wb");
if (file == NULL) {
RErrorCode = RERR_OPEN;
return False;
}
*out_buf = NULL;
*out_size = 0;
/* Initialize write structure */
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (png_ptr == NULL) {
fclose(file);
RErrorCode = RERR_NOMEMORY;
return False;
}
@@ -64,19 +100,22 @@ Bool RSavePNG(RImage *img, const char *filename, char *title)
/* Initialize info structure */
png_info_ptr = png_create_info_struct(png_ptr);
if (png_info_ptr == NULL) {
fclose(file);
png_destroy_write_struct(&png_ptr, NULL);
RErrorCode = RERR_NOMEMORY;
return False;
}
/* Setup Exception handling */
if (setjmp(png_jmpbuf (png_ptr))) {
fclose(file);
if (setjmp(png_jmpbuf(png_ptr))) {
if (png_data.buffer)
free(png_data.buffer);
png_destroy_write_struct(&png_ptr, &png_info_ptr);
RErrorCode = RERR_INTERNAL;
return False;
}
png_init_io(png_ptr, file);
/* Set up memory I/O */
png_set_write_fn(png_ptr, &png_data, png_write_to_memory, png_flush_memory);
/* Write header (8 bit colour depth) */
png_set_IHDR(png_ptr, png_info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB,
@@ -96,6 +135,13 @@ Bool RSavePNG(RImage *img, const char *filename, char *title)
/* Allocate memory for one row (3 bytes per pixel - RGB) */
png_row = (png_bytep) malloc(3 * width * sizeof(png_byte));
if (!png_row) {
if (png_data.buffer)
free(png_data.buffer);
png_destroy_write_struct(&png_ptr, &png_info_ptr);
RErrorCode = RERR_NOMEMORY;
return False;
}
/* Write image data */
for (y = 0; y < height; y++) {
@@ -114,8 +160,7 @@ Bool RSavePNG(RImage *img, const char *filename, char *title)
/* End write */
png_write_end(png_ptr, NULL);
/* Clean */
fclose(file);
/* Clean up structures */
if (png_info_ptr != NULL)
png_free_data(png_ptr, png_info_ptr, PNG_FREE_ALL, -1);
if (png_ptr != NULL)
@@ -123,5 +168,54 @@ Bool RSavePNG(RImage *img, const char *filename, char *title)
if (png_row != NULL)
free(png_row);
/* Return the buffer */
*out_buf = png_data.buffer;
*out_size = png_data.size;
return True;
}
/*
* Save RImage to PNG image
*/
Bool RSavePNG(RImage *img, const char *filename, char *title)
{
FILE *file;
unsigned char *png_data = NULL;
size_t png_size = 0;
size_t written;
if (!img || !filename) {
RErrorCode = RERR_BADIMAGEFILE;
return False;
}
/* Use RSaveRawPNG to generate PNG data in memory */
if (!RSaveRawPNG(img, title, &png_data, &png_size)) {
/* Error code already set by RSaveRawPNG */
return False;
}
/* Open file for writing */
file = fopen(filename, "wb");
if (file == NULL) {
free(png_data);
RErrorCode = RERR_OPEN;
return False;
}
/* Write PNG data to file */
written = fwrite(png_data, 1, png_size, file);
fclose(file);
/* Check if all data was written */
if (written != png_size) {
free(png_data);
RErrorCode = RERR_WRITE;
return False;
}
/* Clean up */
free(png_data);
return True;
}