diff options
| -rw-r--r-- | alphagen.c | 72 |
1 files changed, 60 insertions, 12 deletions
@@ -37,6 +37,7 @@ struct image { /* Main functionality of AlphaGen. */
bool alphagen(char *black_name, char *white_name, char *alpha_name);
+bool alphagen_check_inputs(struct image *b, struct image *w);
/* image_* functions, so the libpng stuff is kept hidden */
bool image_init(struct image *img, int width, int height, int channels);
@@ -77,18 +78,17 @@ bool alphagen(char *black_name, char *white_name, char *alpha_name) /* Load input PNGs */
if (!image_read_png(black_name, &b)) {
- printf("Could not load \"%s\" as black background input.\n",
+ printf("Couldn't load \"%s\" as black background input.\n",
black_name);
return false;
}
if (!image_read_png(white_name, &w)) {
- printf("Could not load \"%s\" as white background input.\n",
+ printf("Couldn't 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");
+
+ if (!alphagen_check_inputs(&b, &w)) {
return false;
}
@@ -136,30 +136,78 @@ bool alphagen(char *black_name, char *white_name, char *alpha_name) }
+/* Check input images for problems */
+bool alphagen_check_inputs(struct image *b, struct image *w)
+{
+ unsigned int data_size;
+ bool opaque = true;
+
+ /* Check both input images are the same size */
+ if (b->width != w->width || b->height != w->height) {
+ printf("Error: Input images have different dimensions.\n");
+ return false;
+ }
+
+ /* Check input images are both the same bit depth */
+ if (b->channels != w->channels || b->channels != 3) {
+ /* AlphaGen should load both as 24bpp, so it's not an input
+ * error, but an internal error. */
+ printf("Error: Internal error.\n");
+ return false;
+ }
+
+ /* Check that black background image is darker than white and check
+ * for opaque image (identical input images). */
+ data_size = b->height * b->width * b->channels;
+ for (unsigned int i = 0; i < data_size; i++) {
+ if (b->d[0][i] > w->d[0][i]) {
+ /* Black bg image is brighter than white bg image. */
+ printf("Error: Black background input image has pixel "
+ "brighter than White background\n"
+ "input image.\n");
+ return false;
+ }
+ if (b->d[0][i] < w->d[0][i]) {
+ /* White bg image data brighter than black bg image. */
+ opaque = false;
+ }
+ }
+
+ /* If input images were identical, the image is opaque and there
+ * is no alpha channel to recover. */
+ if (opaque) {
+ printf("Error: Input images are identical. "
+ "No alpha channel to recover.\n");
+ return false;
+ }
+
+ 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**);
int row_data_width;
- // Set frame dimensions
+ /* Set frame dimensions */
img->width = width;
img->height = height;
img->channels = channels;
- // Allocate memory for row pointers
- img->d = (uint8_t**)malloc(height * size);
+ /* Allocate memory for row pointers */
+ img->d = malloc(height * sizeof(uint8_t*));
if (img->d == NULL)
return false;
- // Allocate memory for image data
+ /* Allocate memory for image data */
row_data_width = width * channels;
- img->d[0] = (uint8_t*)malloc(height * row_data_width * size);
+ img->d[0] = malloc(height * row_data_width * sizeof(uint8_t));
if (img->d[0] == NULL)
return false;
for (int i = 1; i < height; i++) {
- // Set pointers to each row
+ /* Set pointers to each row */
img->d[i] = img->d[i - 1] + row_data_width;
}
return true;
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