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macOS: Calculate correct DPI by not using backingScaleFactor

This commit is contained in:
Edward Li 2021-12-25 03:47:59 +08:00 committed by Sam Lantinga
parent 724468ae2c
commit 1c41b53551
1 changed files with 48 additions and 6 deletions
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54
src/video/cocoa/SDL_cocoamodes.m
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@ -454,28 +454,70 @@ Cocoa_GetDisplayDPI(_THIS, SDL_VideoDisplay * display, float * ddpi, float * hdp
/* 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 *screens = [NSScreen screens];
NSSize displayNativeSize;
displayNativeSize.width = (int) CGDisplayPixelsWide(data->display);
displayNativeSize.height = (int) CGDisplayPixelsHigh(data->display);
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
/* Neither CGDisplayScreenSize(description's NSScreenNumber) nor [NSScreen backingScaleFactor] can calculate the correct dpi in macOS. E.g. backingScaleFactor is always 2 in all display modes for rMBP 16" */
if (@available(macOS 10.8, *)) {
CFStringRef dmKeys[1] = { kCGDisplayShowDuplicateLowResolutionModes };
CFBooleanRef dmValues[1] = { kCFBooleanTrue };
CFDictionaryRef dmOptions = CFDictionaryCreate(kCFAllocatorDefault, (const void**) dmKeys, (const void**) dmValues, 1, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks );
CFArrayRef allDisplayModes = CGDisplayCopyAllDisplayModes(dpyid, dmOptions);
CFIndex n = CFArrayGetCount(allDisplayModes);
for(CFIndex i = 0; i < n; ++i) {
CGDisplayModeRef m = (CGDisplayModeRef)CFArrayGetValueAtIndex(allDisplayModes, i);
CGFloat width = CGDisplayModeGetPixelWidth(m);
CGFloat height = CGDisplayModeGetPixelHeight(m);
CGFloat HiDPIWidth = CGDisplayModeGetWidth(m);
BOOL isNative = (CGDisplayModeGetIOFlags(m) & kDisplayModeNativeFlag) ? true : false;
CFRelease(m);
//Only check 1x mode
if(width == HiDPIWidth) {
if(isNative) {
displayNativeSize.width = width;
displayNativeSize.height = height;
break;
}
//Get the largest size even if kDisplayModeNativeFlag is not present e.g. iMac 27-Inch with 5K Retina
if(width > displayNativeSize.width) {
displayNativeSize.width = width;
displayNativeSize.height = height;
}
}
}
CFRelease(allDisplayModes);
CFRelease(dmOptions);
} else if (@available(macOS 10.7, *)) {
// fallback for 10.7
scaleFactor = [screen backingScaleFactor];
displayNativeSize.width = displayNativeSize.width * scaleFactor;
displayNativeSize.height = displayNativeSize.height * scaleFactor;
break;
}
}
}
const CGSize displaySize = CGDisplayScreenSize(data->display);
const int pixelWidth = (int) CGDisplayPixelsWide(data->display);
const int pixelHeight = (int) CGDisplayPixelsHigh(data->display);
const int pixelWidth = displayNativeSize.width;
const int pixelHeight = displayNativeSize.height;
if (ddpi) {
*ddpi = (SDL_ComputeDiagonalDPI(pixelWidth, pixelHeight, displaySize.width / MM_IN_INCH, displaySize.height / MM_IN_INCH)) * scaleFactor;
*ddpi = (SDL_ComputeDiagonalDPI(pixelWidth, pixelHeight, displaySize.width / MM_IN_INCH, displaySize.height / MM_IN_INCH));
}
if (hdpi) {
*hdpi = (pixelWidth * MM_IN_INCH / displaySize.width) * scaleFactor;
*hdpi = (pixelWidth * MM_IN_INCH / displaySize.width);
}
if (vdpi) {
*vdpi = (pixelHeight * MM_IN_INCH / displaySize.height) * scaleFactor;
*vdpi = (pixelHeight * MM_IN_INCH / displaySize.height);
}
return 0;