I'm creating a web service for an iPhone app to interact with.
When my client uploads images server-side, I want my php script to resize the image, whilst maintaining the aspect ratio, so that it will fit onto the iPhone screen. (i.e. the longest side is <= 960 and the shortest <= 640
I've created a mock-up in JS, simply because I find it easier to do quickly.
I'm pretty sure, though I may be wrong, that this isn't the most efficient way of doing it. Could someone correct me with either better logic (especially the bit at the start), or a more mathematical way of approaching this?
var w = 960, h = 960, new_w, new_h;
if (w >= h && w > 960 || h >= w && h > 960 || w >= h && h > 640 || h >= w && w > 640) {
if (w > h) {
if (w>960) {
new_w = 960;
new_h = h*(new_w/w);
}
if (h>640) {
new_h = 640;
new_w = w*(new_h/h);
}
}
else {
if (h>960) {
new_h = 960;
new_w = w*(new_h/h);
}
if (w>640) {
new_w = 640;
new_h = h*(new_w/w);
}
}
}
Maybe a slightly shorter routine would be:
// Calculate resize ratios for resizing
float ratioW = targetWidth / oldWidth;
float ratioH = targetHeight / oldHeight;
// smaller ratio will ensure that the image fits in the view
float ratio = ratioW < ratioH?ratioW:ratioH;
newWidth = oldWidth*ratio;
newHeight = oldHeight*ratio;
Obviously if the ratio is > 1, then it's enlarging, if < 1 then it's shrinking.