Bug 1120 - Refine HiDPI Support ( Part-2 ) (API CHANGE)

- Use float[2] for pixel-scale.
  Utilize simple integer rounding:
    int-pixel-units = (int) ( int-window-units * pixel-scale + 0.5f )

- Provide minimum and maximum allowed pixel-scale values
  to be set by platform, supporting generic pixel-scale validation.

- Remove 'OSXUtil.GetPixelScale(final RectangleImmutable r, final int[] screenIndexOut)',
  implementation for all platforms would cause huge redundancy of
  Screen and MonitorDevice code (duplication of NEWT).

- instead, add 'float[2] pixelScale' to NEWT's MonitorDevice

- Detect change of pixel-scale and propagate accordingly.
  This allows GLCanvas, GLJPanel and NewtCanvasAWT instances
  to be dragged between monitor devices w/ different pixel-scale.

- OSX: Handle native triggered reshape events off-thread to avoid EDT congestion
       due to locked window when consuming deferred events on EDT.

2 files changed, 17 insertions, 7 deletions

diff --git a/src/newt/native/MacWindow.m b/src/newt/native/MacWindow.m
index 2bd11da3c..1dbe2b7bd 100644
--- a/src/newt/native/MacWindow.m
+++ b/src/newt/native/MacWindow.m
@@ -420,7 +420,7 @@ NS_ENDHANDLER
 
 
 CGDirectDisplayID NewtScreen_getCGDirectDisplayIDByNSScreen(NSScreen *screen) {
-    // Mind: typedef uint32_t CGDirectDisplayID; - however, we assume it's 64bit on 64bit ?!
+    // Mind: typedef uint32_t CGDirectDisplayID;
     NSDictionary * dict = [screen deviceDescription];
     NSNumber * val = (NSNumber *) [dict objectForKey: @"NSScreenNumber"];
     // [NSNumber integerValue] returns NSInteger which is 32 or 64 bit native size
diff --git a/src/newt/native/NewtMacWindow.m b/src/newt/native/NewtMacWindow.m
index caf9e54e0..7b3df391d 100644
--- a/src/newt/native/NewtMacWindow.m
+++ b/src/newt/native/NewtMacWindow.m
@@ -784,11 +784,21 @@ static jmethodID windowRepaintID = NULL;
     [super viewDidChangeBackingProperties];
 
     // HiDPI scaling
-    BOOL useHiDPI = [self wantsBestResolutionOpenGLSurface];
-    CGFloat pixelScaleNative = [[self window] backingScaleFactor];
-    CGFloat pixelScaleUse = useHiDPI ? pixelScaleNative : 1.0;
-    DBG_PRINT("viewDidChangeBackingProperties: PixelScale: HiDPI %d, native %f -> use %f\n", useHiDPI, (float)pixelScaleNative, (float)pixelScaleUse);
-    [[self layer] setContentsScale: pixelScaleUse];
+    BOOL useHiDPI = false;
+    CGFloat maxPixelScale = 1.0;
+    CGFloat winPixelScale = 1.0;
+    NSWindow* window = [self window];
+    NSScreen* screen = [window screen];
+NS_DURING
+    maxPixelScale = [screen backingScaleFactor];
+    useHiDPI = [self wantsBestResolutionOpenGLSurface];
+    if( useHiDPI ) {
+        winPixelScale = [window backingScaleFactor];
+    }
+NS_HANDLER
+NS_ENDHANDLER
+    DBG_PRINT("viewDidChangeBackingProperties: PixelScale: HiDPI %d, max %f, window %f\n", useHiDPI, (float)maxPixelScale, (float)winPixelScale);
+    [[self layer] setContentsScale: winPixelScale];
 
     if (javaWindowObject == NULL) {
         DBG_PRINT("viewDidChangeBackingProperties: null javaWindowObject\n");
@@ -801,7 +811,7 @@ static jmethodID windowRepaintID = NULL;
         return;
     }
 
-    (*env)->CallVoidMethod(env, javaWindowObject, updatePixelScaleID, JNI_TRUE, (jfloat)pixelScaleUse, (jfloat)pixelScaleNative); // defer 
+    (*env)->CallVoidMethod(env, javaWindowObject, updatePixelScaleID, JNI_TRUE, (jfloat)winPixelScale, (jfloat)maxPixelScale); // defer 
 
     // detaching thread not required - daemon
     // NewtCommon_ReleaseJNIEnv(shallBeDetached);