Bug 1370757 - Improve widget overflow calculation. r=mattwoodrow

This fixes HiDPI and adds overflow for meter bars.

Meter bars should probably have their intrinsic size fixed instead, but
keeping the existing behavior for them is less risky.

MozReview-Commit-ID: xF83bqdDlz

--HG--
extra : rebase_source : d28b4c265298e870d7cc03b11038da605d920b49

widget/cocoa/nsNativeThemeCocoa.mm

@@ -2273,10 +2273,10 @@ nsNativeThemeCocoa::IsParentScrollbarRolledOver(nsIFrame* aFrame)
 }
 
 static bool
-IsHiDPIContext(nsPresContext* aContext)
+IsHiDPIContext(nsDeviceContext* aContext)
 {
   return nsPresContext::AppUnitsPerCSSPixel() >=
-    2 * aContext->DeviceContext()->AppUnitsPerDevPixelAtUnitFullZoom();
+    2 * aContext->AppUnitsPerDevPixelAtUnitFullZoom();
 }
 
 NS_IMETHODIMP
@@ -2311,7 +2311,7 @@ nsNativeThemeCocoa::DrawWidgetBackground(nsRenderingContext* aContext,
 
   AutoRestoreTransform autoRestoreTransform(&aDrawTarget);
 
-  bool hidpi = IsHiDPIContext(aFrame->PresContext());
+  bool hidpi = IsHiDPIContext(aFrame->PresContext()->DeviceContext());
   if (hidpi) {
     // Use high-resolution drawing.
     nativeWidgetRect.Scale(0.5f);
@@ -3093,7 +3093,7 @@ nsNativeThemeCocoa::GetWidgetBorder(nsDeviceContext* aContext,
       break;
   }
 
-  if (IsHiDPIContext(aFrame->PresContext())) {
+  if (IsHiDPIContext(aContext)) {
     *aResult = *aResult + *aResult; // doubled
   }
 
@@ -3130,7 +3130,7 @@ bool
 nsNativeThemeCocoa::GetWidgetOverflow(nsDeviceContext* aContext, nsIFrame* aFrame,
                                       uint8_t aWidgetType, nsRect* aOverflowRect)
 {
-  int32_t p2a = aFrame->PresContext()->AppUnitsPerDevPixel();
+  nsIntMargin overflow;
   switch (aWidgetType) {
     case NS_THEME_BUTTON:
     case NS_THEME_MAC_DISCLOSURE_BUTTON_OPEN:
@@ -3148,34 +3148,42 @@ nsNativeThemeCocoa::GetWidgetOverflow(nsDeviceContext* aContext, nsIFrame* aFram
     case NS_THEME_CHECKBOX:
     case NS_THEME_RADIO:
     case NS_THEME_TAB:
+    case NS_THEME_FOCUS_OUTLINE:
     {
-      // We assume that the above widgets can draw a focus ring that will be less than
-      // or equal to 4 pixels thick.
-      nsIntMargin extraSize = nsIntMargin(kMaxFocusRingWidth,
-                                          kMaxFocusRingWidth,
-                                          kMaxFocusRingWidth,
-                                          kMaxFocusRingWidth);
-      nsMargin m(NSIntPixelsToAppUnits(extraSize.top, p2a),
-                 NSIntPixelsToAppUnits(extraSize.right, p2a),
-                 NSIntPixelsToAppUnits(extraSize.bottom, p2a),
-                 NSIntPixelsToAppUnits(extraSize.left, p2a));
-      aOverflowRect->Inflate(m);
-      return true;
+      overflow.SizeTo(kMaxFocusRingWidth,
+                      kMaxFocusRingWidth,
+                      kMaxFocusRingWidth,
+                      kMaxFocusRingWidth);
+      break;
     }
     case NS_THEME_PROGRESSBAR:
     {
-      // Progress bars draw a 2 pixel white shadow under their progress indicators
-      nsMargin m(0, 0, NSIntPixelsToAppUnits(2, p2a), 0);
-      aOverflowRect->Inflate(m);
-      return true;
+      // Progress bars draw a 2 pixel white shadow under their progress indicators.
+      overflow.bottom = 2;
+      break;
     }
-    case NS_THEME_FOCUS_OUTLINE:
+    case NS_THEME_METERBAR:
     {
-      aOverflowRect->Inflate(NSIntPixelsToAppUnits(2, p2a));
-      return true;
+      // Meter bars overflow their boxes by about 2 pixels.
+      overflow.SizeTo(2, 2, 2, 2);
+      break;
     }
   }
 
+  if (IsHiDPIContext(aContext)) {
+    // Double the number of device pixels.
+    overflow += overflow;
+  }
+
+  if (overflow != nsIntMargin()) {
+    int32_t p2a = aFrame->PresContext()->AppUnitsPerDevPixel();
+    aOverflowRect->Inflate(nsMargin(NSIntPixelsToAppUnits(overflow.top, p2a),
+                                    NSIntPixelsToAppUnits(overflow.right, p2a),
+                                    NSIntPixelsToAppUnits(overflow.bottom, p2a),
+                                    NSIntPixelsToAppUnits(overflow.left, p2a)));
+    return true;
+  }
+
   return false;
 }
 
@@ -3497,7 +3505,7 @@ nsNativeThemeCocoa::GetMinimumWidgetSize(nsPresContext* aPresContext,
     }
   }
 
-  if (IsHiDPIContext(aPresContext)) {
+  if (IsHiDPIContext(aPresContext->DeviceContext())) {
     *aResult = *aResult * 2;
   }