/**
* File: Cropping
*
* Crop an image
*
* Some functions to crop images, automatically (auto detection of the border
* color), using a given color (with or without tolerance) or using a given
* rectangle.
*
* Example:
* (start code)
* im2 = gdImageAutoCrop(im, GD_CROP_SIDES);
* if (im2) {
* gdImageDestroy(im); // unless you need the original image subsequently
* // do something with the cropped image
* }
* gdImageDestroy(im2);
* (end code)
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include "gd.h"
#include "gd_color.h"
static int gdGuessBackgroundColorFromCorners(gdImagePtr im, int *color);
/**
* Function: gdImageCrop
*
* Crop an image to a given rectangle
*
* Parameters:
* src - The image.
* crop - The cropping rectangle, see <gdRect>.
*
* Returns:
* The newly created cropped image, or NULL on failure.
*
* See also:
* - <gdImageCropAuto>
* - <gdImageCropThreshold>
*/
BGD_DECLARE(gdImagePtr) gdImageCrop(gdImagePtr src, const gdRect *crop)
{
gdImagePtr dst;
if (gdImageTrueColor(src)) {
dst = gdImageCreateTrueColor(crop->width, crop->height);
} else {
dst = gdImageCreate(crop->width, crop->height);
}
if (!dst) return NULL;
gdImageCopy(dst, src, 0, 0, crop->x, crop->y, crop->width, crop->height);
return dst;
}
/**
* Function: gdImageCropAuto
*
* Crop an image automatically
*
* This function detects the cropping area according to the given _mode_.
*
* Parameters:
* im - The image.
* mode - The cropping mode, see <gdCropMode>.
*
* Returns:
* The newly created cropped image, or NULL on failure.
*
* See also:
* - <gdImageCrop>
* - <gdImageCropThreshold>
*/
BGD_DECLARE(gdImagePtr) gdImageCropAuto(gdImagePtr im, const unsigned int mode)
{
const int width = gdImageSX(im);
const int height = gdImageSY(im);
int x,y;
int color, match;
gdRect crop;
crop.x = 0;
crop.y = 0;
crop.width = 0;
crop.height = 0;
switch (mode) {
case GD_CROP_TRANSPARENT:
color = gdImageGetTransparent(im);
break;
case GD_CROP_BLACK:
color = gdImageColorClosestAlpha(im, 0, 0, 0, 0);
break;
case GD_CROP_WHITE:
color = gdImageColorClosestAlpha(im, 255, 255, 255, 0);
break;
case GD_CROP_SIDES:
gdGuessBackgroundColorFromCorners(im, &color);
break;
case GD_CROP_DEFAULT:
default:
color = gdImageGetTransparent(im);
break;
}
/* TODO: Add gdImageGetRowPtr and works with ptr at the row level
* for the true color and palette images
* new formats will simply work with ptr
*/
match = 1;
for (y = 0; match && y < height; y++) {
for (x = 0; match && x < width; x++) {
match = (color == gdImageGetPixel(im, x,y));
}
}
/* Nothing to do > bye
* Duplicate the image?
*/
if (y == height - 1) {
return NULL;
}
crop.y = y -1;
match = 1;
for (y = height - 1; match && y >= 0; y--) {
for (x = 0; match && x < width; x++) {
match = (color == gdImageGetPixel(im, x,y));
}
}
if (y == 0) {
crop.height = height - crop.y + 1;
} else {
crop.height = y - crop.y + 2;
}
match = 1;
for (x = 0; match && x < width; x++) {
for (y = 0; match && y < crop.y + crop.height - 1; y++) {
match = (color == gdImageGetPixel(im, x,y));
}
}
crop.x = x - 1;
match = 1;
for (x = width - 1; match && x >= 0; x--) {
for (y = 0; match && y < crop.y + crop.height - 1; y++) {
match = (color == gdImageGetPixel(im, x,y));
}
}
crop.width = x - crop.x + 2;
return gdImageCrop(im, &crop);
}
/**
* Function: gdImageCropThreshold
*
* Crop an image using a given color
*
* The _threshold_ defines the tolerance to be used while comparing the image
* color and the color to crop. The method used to calculate the color
* difference is based on the color distance in the RGB(A) cube.
*
* Parameters:
* im - The image.
* color - The crop color.
* threshold - The crop threshold.
*
* Returns:
* The newly created cropped image, or NULL on failure.
*
* See also:
* - <gdImageCrop>
* - <gdImageCropAuto>
*/
BGD_DECLARE(gdImagePtr) gdImageCropThreshold(gdImagePtr im, const unsigned int color, const float threshold)
{
const int width = gdImageSX(im);
const int height = gdImageSY(im);
int x,y;
int match;
gdRect crop;
crop.x = 0;
crop.y = 0;
crop.width = 0;
crop.height = 0;
/* Pierre: crop everything sounds bad */
if (threshold > 100.0) {
return NULL;
}
if (!gdImageTrueColor(im) && color >= gdImageColorsTotal(im)) {
return NULL;
}
/* TODO: Add gdImageGetRowPtr and works with ptr at the row level
* for the true color and palette images
* new formats will simply work with ptr
*/
match = 1;
for (y = 0; match && y < height; y++) {
for (x = 0; match && x < width; x++) {
match = (gdColorMatch(im, color, gdImageGetPixel(im, x,y), threshold)) > 0;
}
}
/* Pierre
* Nothing to do > bye
* Duplicate the image?
*/
if (y == height - 1) {
return NULL;
}
crop.y = y -1;
match = 1;
for (y = height - 1; match && y >= 0; y--) {
for (x = 0; match && x < width; x++) {
match = (gdColorMatch(im, color, gdImageGetPixel(im, x, y), threshold)) > 0;
}
}
if (y == 0) {
crop.height = height - crop.y + 1;
} else {
crop.height = y - crop.y + 2;
}
match = 1;
for (x = 0; match && x < width; x++) {
for (y = 0; match && y < crop.y + crop.height - 1; y++) {
match = (gdColorMatch(im, color, gdImageGetPixel(im, x,y), threshold)) > 0;
}
}
crop.x = x - 1;
match = 1;
for (x = width - 1; match && x >= 0; x--) {
for (y = 0; match && y < crop.y + crop.height - 1; y++) {
match = (gdColorMatch(im, color, gdImageGetPixel(im, x,y), threshold)) > 0;
}
}
crop.width = x - crop.x + 2;
return gdImageCrop(im, &crop);
}
/* This algorithm comes from pnmcrop (http://netpbm.sourceforge.net/)
* Three steps:
* - if 3 corners are equal.
* - if two are equal.
* - Last solution: average the colors
*/
static int gdGuessBackgroundColorFromCorners(gdImagePtr im, int *color)
{
const int tl = gdImageGetPixel(im, 0, 0);
const int tr = gdImageGetPixel(im, gdImageSX(im) - 1, 0);
const int bl = gdImageGetPixel(im, 0, gdImageSY(im) -1);
const int br = gdImageGetPixel(im, gdImageSX(im) - 1, gdImageSY(im) -1);
if (tr == bl && tr == br) {
*color = tr;
return 3;
} else if (tl == bl && tl == br) {
*color = tl;
return 3;
} else if (tl == tr && tl == br) {
*color = tl;
return 3;
} else if (tl == tr && tl == bl) {
*color = tl;
return 3;
} else if (tl == tr || tl == bl || tl == br) {
*color = tl;
return 2;
} else if (tr == bl) {
*color = tr;
return 2;
} else if (br == bl) {
*color = bl;
return 2;
} else {
register int r,b,g,a;
r = (int)(0.5f + (gdImageRed(im, tl) + gdImageRed(im, tr) + gdImageRed(im, bl) + gdImageRed(im, br)) / 4);
g = (int)(0.5f + (gdImageGreen(im, tl) + gdImageGreen(im, tr) + gdImageGreen(im, bl) + gdImageGreen(im, br)) / 4);
b = (int)(0.5f + (gdImageBlue(im, tl) + gdImageBlue(im, tr) + gdImageBlue(im, bl) + gdImageBlue(im, br)) / 4);
a = (int)(0.5f + (gdImageAlpha(im, tl) + gdImageAlpha(im, tr) + gdImageAlpha(im, bl) + gdImageAlpha(im, br)) / 4);
*color = gdImageColorClosestAlpha(im, r, g, b, a);
return 0;
}
}