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cocoa: SDL_GetDisplayDPI() should account for Retina displays.

Fixes Bugzilla #4856.
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icculus committed Dec 4, 2019
1 parent b757602 commit ca2c8609e1eef465c340c32ce00f3a271b6c6180
Showing with 21 additions and 7 deletions.
  1. +21 −7 src/video/cocoa/SDL_cocoamodes.m
@@ -443,27 +443,41 @@

int
Cocoa_GetDisplayDPI(_THIS, SDL_VideoDisplay * display, float * ddpi, float * hdpi, float * vdpi)
{ @autoreleasepool
{
const float MM_IN_INCH = 25.4f;

SDL_DisplayData *data = (SDL_DisplayData *) display->driverdata;

CGSize displaySize = CGDisplayScreenSize(data->display);
int pixelWidth = (int) CGDisplayPixelsWide(data->display);
int pixelHeight = (int) CGDisplayPixelsHigh(data->display);
/* we need the backingScaleFactor for Retina displays, which is only exposed through NSScreen, not CGDisplay, afaik, so find our screen... */
CGFloat scaleFactor = 1.0f;
NSArray<NSScreen *> *screens = [NSScreen screens];
for (NSScreen *screen in screens) {
const CGDirectDisplayID dpyid = (const CGDirectDisplayID ) [[[screen deviceDescription] objectForKey:@"NSScreenNumber"] unsignedIntValue];
if (dpyid == data->display) {
if ([screen respondsToSelector:@selector(backingScaleFactor)]) { // Mac OS X 10.7 and later
scaleFactor = [screen backingScaleFactor];
break;
}
}
}

const CGSize displaySize = CGDisplayScreenSize(data->display);
const int pixelWidth = (int) CGDisplayPixelsWide(data->display);
const int pixelHeight = (int) CGDisplayPixelsHigh(data->display);

if (ddpi) {
*ddpi = SDL_ComputeDiagonalDPI(pixelWidth, pixelHeight, displaySize.width / MM_IN_INCH, displaySize.height / MM_IN_INCH);
*ddpi = (SDL_ComputeDiagonalDPI(pixelWidth, pixelHeight, displaySize.width / MM_IN_INCH, displaySize.height / MM_IN_INCH)) * scaleFactor;
}
if (hdpi) {
*hdpi = pixelWidth * MM_IN_INCH / displaySize.width;
*hdpi = (pixelWidth * MM_IN_INCH / displaySize.width) * scaleFactor;
}
if (vdpi) {
*vdpi = pixelHeight * MM_IN_INCH / displaySize.height;
*vdpi = (pixelHeight * MM_IN_INCH / displaySize.height) * scaleFactor;
}

return 0;
}
}}

void
Cocoa_GetDisplayModes(_THIS, SDL_VideoDisplay * display)

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