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authorMichael Drake <tlsa@netsurf-browser.org>2010-09-14 22:07:55 (GMT)
committer Michael Drake <tlsa@netsurf-browser.org>2010-09-14 22:07:55 (GMT)
commit935ac203189b4683ea770244851d598ca5d55774 (patch)
treeb790de78ce8c6d5fe32a523dc733c232d5e75c78
parentf3e5a6c2f53e28755cd42938388668425feca949 (diff)
downloadalphagen-935ac203189b4683ea770244851d598ca5d55774.tar.gz
alphagen-935ac203189b4683ea770244851d598ca5d55774.tar.bz2
Let the input and output filenames be specified on the command line.
svn path=/trunk/tools/alphagen/; revision=10772
-rw-r--r--alphagen.c70
1 files changed, 51 insertions, 19 deletions
diff --git a/alphagen.c b/alphagen.c
index 312edfa..e0411d7 100644
--- a/alphagen.c
+++ b/alphagen.c
@@ -7,15 +7,17 @@
* http://www.opensource.org/licenses/mit-license.php
*
* AlphaGen is a tool for obtaining a bitmap image with an alpha channel from
- * software which lacks this facility itself.
+ * software which lacks this facility itself. It recovers alpha channel
+ * information from two input images; one with a black baground and one with a
+ * white background.
*
- * Input:
- * blackbg.png - The image exported on a black background
- * whitebg.png - The image exported on a white background
+ * Inputs required:
+ * + The input image exported on a _black_ background.
+ * + The input image exported on a _white_ background.
* Output:
- * alpha.png - The resultant image with alpha channel
+ * + The resultant image with an alpha channel.
*
- * Note that blackbg.png and whitebg.png must be the same size.
+ * Note that both images must be the same size.
*/
#include <stdbool.h>
@@ -33,14 +35,38 @@ struct image {
uint8_t **d;
};
+/* Main functionality of AlphaGen. */
+bool alphagen(char *black_name, char *white_name, char *alpha_name);
+
/* image_* functions, so the libpng stuff is kept hidden */
bool image_init(struct image *img, int width, int height, int channels);
void image_free(struct image *img);
bool image_read_png(char *file_name, struct image *img);
bool image_write_png(char *file_name, struct image *img);
+
int main(int argc, char** argv)
{
+ /* Validate execution arguments. */
+ if (argc != 4) {
+ /* Too few arguments */
+ printf("Usage: %s <black> <white> <output>\n", argv[0]);
+ return EXIT_FAILURE;
+ }
+
+ /* Generate the alpha channel bitmap. */
+ if (!alphagen(argv[1], argv[2], argv[3])) {
+ return EXIT_FAILURE;
+ }
+
+ return EXIT_SUCCESS;
+}
+
+
+/* Performs alpha channel recovery on an image provided with black and white
+ * backgrounds. */
+bool alphagen(char *black_name, char *white_name, char *alpha_name)
+{
struct image b, w, a;
unsigned int row_data_width;
unsigned int z;
@@ -50,24 +76,26 @@ int main(int argc, char** argv)
const uint8_t bg = 255;
/* Load input PNGs */
- if (!image_read_png("blackbg.png", &b)) {
- printf("Problem loading blackbg.\n");
- return EXIT_FAILURE;
+ if (!image_read_png(black_name, &b)) {
+ printf("Could not load \"%s\" as black background input.\n",
+ black_name);
+ return false;
}
- if (!image_read_png("whitebg.png", &w)) {
- printf("Problem loading whitebg.\n");
- return EXIT_FAILURE;
+ if (!image_read_png(white_name, &w)) {
+ printf("Could not load \"%s\" as white background input.\n",
+ white_name);
+ return false;
}
/* Check both input images are the same size */
if (b.width != w.width || b.height != w.height) {
printf("Input images have different dimensions.\n");
- return EXIT_FAILURE;
+ return false;
}
/* Prepare output image */
if (!image_init(&a, b.width, b.height, 4)) {
printf("Couldn't create output image.\n");
- return EXIT_FAILURE;
+ return false;
}
/* Recover true image colours and alpha channel for the image */
@@ -94,9 +122,9 @@ int main(int argc, char** argv)
}
/* Save PNG with recovered colour and alpha data */
- if (!image_write_png("alpha.png", &a)) {
- printf("Couldn't write output image.\n");
- return EXIT_FAILURE;
+ if (!image_write_png(alpha_name, &a)) {
+ printf("Couldn't write output file \"%s\".\n", alpha_name);
+ return false;
}
/* Free image memory */
@@ -104,9 +132,11 @@ int main(int argc, char** argv)
image_free(&w);
image_free(&a);
- return EXIT_SUCCESS;
+ return true;
}
+
+/* Initialise an image, allocating memory for it. */
bool image_init(struct image *img, int width, int height, int channels)
{
int size = sizeof(uint8_t**);
@@ -135,12 +165,15 @@ bool image_init(struct image *img, int width, int height, int channels)
return true;
}
+
+/* Free an image. */
void image_free(struct image *img)
{
free(img->d[0]);
free(img->d);
}
+
/* Read RGB PNG with no alpha channel into img. */
bool image_read_png(char *file_name, struct image *img)
{
@@ -221,7 +254,6 @@ bool image_read_png(char *file_name, struct image *img)
}
-
/* Save output PNG file with alpha channel with img data */
bool image_write_png(char *file_name, struct image *img)
{