Convert pixels to points for pdf

问题:

I am using php and fpdf to generate a pdf. How can I scale a 400 pixel high image to fit in a 300 point high space? The dimensions are just examples, the image and available space are dynamic.

回答1:

If you want to fit 400 pixels in 300 points, then your resizing factor would simply be 300 / 400 = 0.75. You need to put each pixel in 0.75 of a point.

But there is another story you should know: Each point is 1/72 of an inch. and how many pixels make 1 inch is a matter of choice.

All images have a property called DPI: dots per inch. It specifies how many pixels are there for each inch of the picture. So if you want to convert a 400px * 400px picture to a (say) 96 dpi image, your resizing factor will be 400 / ((72 / 96) * 400). 72 here is for converting inches to points.

回答2:

You can resize the picutre first with imagecopyresampled.

-> Basic Example
-> Adding image to pdf