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[libpng16] Trivial editing of comments in contrib/examples/simpleover.c

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Glenn Randers-Pehrson 2015-05-04 20:25:31 -05:00
parent 0f12df19a1
commit d6b1375bf5
1 changed files with 18 additions and 18 deletions
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34
contrib/examples/simpleover.c
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@ -11,8 +11,8 @@
* combine the alpha channels and corresponding data.
*
* Finally read an output (background) PNG using the 24-bit RGB format (the
* PNG will be composited on green (0x00ff00) by default if it has an alpha
* channel) and apply the intermediate image generated above to specified
* PNG will be composited on green (#00ff00) by default if it has an alpha
* channel), and apply the intermediate image generated above to specified
* locations in the image.
*
* The command line has the general format:
@ -21,7 +21,7 @@
* {--sprite=width,height,name {[--at=x,y] {sprite.png}}}
* {--add=name {x,y}}
*
* The --sprite and --add options may occur multiple times, they are executed
* The --sprite and --add options may occur multiple times. They are executed
* in order. --add may refer to any sprite already read.
*
* This code is intended to show how to composite multiple images together
@ -107,8 +107,8 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
*/
/* Check for an x or y offset that pushes the image beyond the right or
* bottom of the sprite:
/* Check for an x or y offset that pushes any part of the image beyond the
* right or bottom of the sprite:
*/
if ((y_offset < 0 || (unsigned)/*SAFE*/y_offset < sprite->height) &&
(x_offset < 0 || (unsigned)/*SAFE*/x_offset < sprite->width))
@ -153,7 +153,7 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
*
* This is exact (and does not overflow) for all values of
* x in the range 0..65535*65535. (Note that the calculation
* produces the closest integer, the maximum error is <0.5).
* produces the closest integer; the maximum error is <0.5).
*/
png_uint_32 tmp;
@ -185,7 +185,7 @@ sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
static int
create_sprite(struct sprite *sprite, int *argc, const char ***argv)
{
/* Read the arguments and create this sprite, the sprite buffer has already
/* Read the arguments and create this sprite. The sprite buffer has already
* been allocated. This reads the input PNGs one by one in linear format,
* composes them onto the sprite buffer (the code in the function above)
* then saves the result, converting it on the fly to PNG RGBA 8-bit format.
@ -226,8 +226,8 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
0/*row_stride*/,
NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
{
/* This is the place were the Porter-Duff 'Over' operator
* needs to be done by this code. In fact any image
/* This is the place where the Porter-Duff 'Over' operator
* needs to be done by this code. In fact, any image
* processing required can be done here; the data is in
* the correct format (linear, 16-bit) and source and
* destination are in memory.
@ -270,7 +270,7 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
}
}
/* All the sprite operations have completed successfully, save the RGBA
/* All the sprite operations have completed successfully. Save the RGBA
* buffer as a PNG using the simplified write API.
*/
sprite->file = tmpfile();
@ -291,7 +291,7 @@ create_sprite(struct sprite *sprite, int *argc, const char ***argv)
if (png_image_write_to_stdio(&save, sprite->file, 1/*convert_to_8_bit*/,
sprite->buffer, 0/*row_stride*/, NULL/*colormap*/))
{
/* Success, the buffer is no longer needed: */
/* Success; the buffer is no longer needed: */
free(sprite->buffer);
sprite->buffer = NULL;
return 1; /* ok */
@ -313,7 +313,7 @@ static int
add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
int *argc, const char ***argv)
{
/* Given a --add argument naming this sprite perform the operations listed
/* Given a --add argument naming this sprite, perform the operations listed
* in the following arguments. The arguments are expected to have the form
* (x,y), which is just an offset at which to add the sprite to the
* output.
@ -423,14 +423,14 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
if (sprites[nsprites].name[0] == 0)
sprintf(sprites[nsprites].name, "sprite-%d", nsprites+1);
/* Allocate a buffer for the sprite, calculate the buffer
/* Allocate a buffer for the sprite and calculate the buffer
* size:
*/
buf_size = sizeof (png_uint_16 [4]);
buf_size *= sprites[nsprites].width;
buf_size *= sprites[nsprites].height;
/* This can overflow a (size_t), check for this: */
/* This can overflow a (size_t); check for this: */
tmp = buf_size;
tmp /= sprites[nsprites].width;
tmp /= sprites[nsprites].height;
@ -488,7 +488,7 @@ simpleover_process(png_imagep output, png_bytep out_buf, int argc,
if (strcmp(sprites[isprite].name, name) == 0)
{
if (!add_sprite(output, out_buf, sprites+isprite, &argc, &argv))
goto out; /* error in addspite */
goto out; /* error in addsprite */
break;
}
@ -553,7 +553,7 @@ int main(int argc, const char **argv)
if (buffer != NULL)
{
png_color background = {0, 0xff, 0}; /* green (aka "lime") */
png_color background = {0, 0xff, 0}; /* fully saturated green */
if (png_image_finish_read(&image, &background, buffer,
0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
@ -619,7 +619,7 @@ int main(int argc, const char **argv)
"simpleover: usage: simpleover background.png [output.png]\n"
" Output 'background.png' as a 24-bit RGB PNG file in 'output.png'\n"
" or, if not given, stdout. 'background.png' will be composited\n"
" on green.\n"
" on fully saturated green.\n"
"\n"
" Optionally, before output, process additional PNG files:\n"
"\n"