dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-12-27 22:28:22 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

utils/rescaler: add WebPRescalerGetScaledDimensions

Browse Source 
+ use it in WebPPictureRescale()

Change-Id: I491bea8cd56f0eb1ac8bf0829b9f36c77804219a
This commit is contained in:
James Zern 2015-08-13 20:50:38 -07:00
parent 923e8edafb
commit b918724280
3 changed files with 39 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/enc/picture_rescale.c
View File

@ -211,16 +211,10 @@ int WebPPictureRescale(WebPPicture* pic, int width, int height) {
if (pic == NULL) return 0;
prev_width = pic->width;
prev_height = pic->height;
// if width is unspecified, scale original proportionally to height ratio.
if (width == 0) {
width = (prev_width * height + prev_height / 2) / prev_height;
if (!WebPRescalerGetScaledDimensions(
prev_width, prev_height, &width, &height)) {
return 0;
}
// if height is unspecified, scale original proportionally to width ratio.
if (height == 0) {
height = (prev_height * width + prev_width / 2) / prev_width;
}
// Check if the overall dimensions still make sense.
if (width <= 0 || height <= 0) return 0;
PictureGrabSpecs(pic, &tmp);
tmp.width = width;

28
src/utils/rescaler.c
View File

@ -50,6 +50,34 @@ void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
WebPRescalerDspInit();
}
int WebPRescalerGetScaledDimensions(int src_width, int src_height,
int* const scaled_width,
int* const scaled_height) {
assert(scaled_width != NULL);
assert(scaled_height != NULL);
{
int width = *scaled_width;
int height = *scaled_height;
// if width is unspecified, scale original proportionally to height ratio.
if (width == 0) {
width = (src_width * height + src_height / 2) / src_height;
}
// if height is unspecified, scale original proportionally to width ratio.
if (height == 0) {
height = (src_height * width + src_width / 2) / src_width;
}
// Check if the overall dimensions still make sense.
if (width <= 0 || height <= 0) {
return 0;
}
*scaled_width = width;
*scaled_height = height;
return 1;
}
}
//------------------------------------------------------------------------------
// all-in-one calls

8
src/utils/rescaler.h
View File

@ -48,6 +48,14 @@ void WebPRescalerInit(WebPRescaler* const rescaler,
int num_channels,
int32_t* const work);
// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value
// will be calculated preserving the aspect ratio, otherwise the values are
// left unmodified. Returns true on success, false if either value is 0 after
// performing the scaling calculation.
int WebPRescalerGetScaledDimensions(int src_width, int src_height,
int* const scaled_width,
int* const scaled_height);
// Returns the number of input lines needed next to produce one output line,
// considering that the maximum available input lines are 'max_num_lines'.
int WebPRescaleNeededLines(const WebPRescaler* const rescaler,