iOS scale conversion 1mm equals how many pixels understand

Tag: Is the IMG demo conversion sqrt a wide high height post

Just see a scale article, realize the mobile phone screen painting scale.

Then there is a question: how does the actual 1mm (1 mm) length compare to cell phone pixels?

Looked at the demo code, found this write:

CGFloat Sc_w =[[UIScreen mainscreen] bounds].size.width; CGFloat Sc_h=[[UIScreen mainscreen] bounds].size.height;    CGFloat sc_s; CGFloat FF=[[UIScreen mainscreen] nativebounds].size.height; if(ff = =1136) {sc_s=4.0; }Else if(ff = =1334.0) {sc_s=4.7; }Else if(ff==1920x1080) {sc_s=5.5; }Else if(ff==2436) {sc_s=5.8; }Else{sc_s=3.5; }        //1mm m Pixel pointPMM = sqrt (sc_w * sc_w + sc_h * sc_h)/(sc_s *25.4);//mm

The above PMM is obtained 1mm = PMM pixels

What's the solution?

The original is this:

1, according to cell phone pixel value: [UIScreen mainscreen] nativebounds, get phone size in inches (4, 4.7, 5.5, etc.)

2, according to the width of the mobile phone, according to the Triangle Hook stock Law, calculate the hypotenuse length xiebian= sqrt (sc_w * sc_w + sc_h * sc_h)

3, the focus is this 25.4, has not understood this number, and finally found that because: 1 inches = 2.54 centimeters, that is, 25.4mm, you can get a hypotenuse corresponding to the millimeter value: (sc_s * 25.4)

4, then is used to get the hypotenuse length pixel/millimeter value, to get 1mm corresponding pixel value

5, finally, according to this value slowly draw the scale ~

soga~

iOS scale conversion 1mm equals how many pixels understand