Bug 1693688 - Make the non-native theme not return minimum sizes for checkboxes (and most other widgets). r=spohl,mstange

This matches closer what Chrome and Safari do (Safari paints outside of
the box when this happens, but the layout box still respects the
author), see:

  data:text/html,<button style="padding: 0; width: 0">
  data:text/html,<input type=checkbox style="width: 0">

Etc. For checkboxes, this matches what OSX does, too.

Since we still want checkboxes to be slightly larger than what they'd be
otherwise, we add a hook to tweak it when non-native theme is enabled.

Differential Revision: https://phabricator.services.mozilla.com/D105798

gfx/src/nsITheme.h

@@ -150,6 +150,14 @@ class nsITheme : public nsISupports {
     return false;
   }
 
+  /**
+   * Get the preferred content-box size of a checkbox / radio button, in app
+   * units.  Historically 9px.
+   */
+  virtual nscoord GetCheckboxRadioPrefSize() {
+    return mozilla::CSSPixel::ToAppUnits(9);
+  }
+
   /**
    * Get the minimum border-box size of a widget, in *pixels* (in
    * |aResult|).  If |aIsOverridable| is set to true, this size is a

layout/forms/nsCheckboxRadioFrame.cpp

@@ -14,7 +14,6 @@
 #include "nsStyleConsts.h"
 
 using namespace mozilla;
-using mozilla::dom::Element;
 using mozilla::dom::HTMLInputElement;
 
 //#define FCF_NOISY
@@ -37,6 +36,13 @@ NS_QUERYFRAME_HEAD(nsCheckboxRadioFrame)
   NS_QUERYFRAME_ENTRY(nsIFormControlFrame)
 NS_QUERYFRAME_TAIL_INHERITING(nsAtomicContainerFrame)
 
+nscoord nsCheckboxRadioFrame::DefaultSize() {
+  if (StyleDisplay()->HasAppearance()) {
+    return PresContext()->Theme()->GetCheckboxRadioPrefSize();
+  }
+  return CSSPixel::ToAppUnits(9);
+}
+
 /* virtual */
 nscoord nsCheckboxRadioFrame::GetMinISize(gfxContext* aRenderingContext) {
   nscoord result;

layout/forms/nsCheckboxRadioFrame.h

@@ -86,12 +86,7 @@ class nsCheckboxRadioFrame final : public nsAtomicContainerFrame,
  protected:
   virtual ~nsCheckboxRadioFrame();
 
-  static nscoord DefaultSize() {
-    // XXXmats We have traditionally always returned 9px for GetMin/PrefISize
-    // but we might want to factor in what the theme says, something like:
-    // GetMinimumWidgetSize - GetWidgetPadding - GetWidgetBorder.
-    return nsPresContext::CSSPixelsToAppUnits(9);
-  }
+  nscoord DefaultSize();
 
   /**
    * Get the state of the checked attribute.

layout/reftests/forms/input/checkbox/reftest.list

@@ -11,9 +11,9 @@
 != indeterminate-native-checked.html indeterminate-native-checked-notref.html
 != indeterminate-native-unchecked.html indeterminate-native-unchecked-notref.html
 == indeterminate-selector.html indeterminate-selector-ref.html
-skip-if(!gtkWidget) == gtk-theme-width-height.html gtk-theme-width-height-ref.html
+skip-if(!gtkWidget||!nativeThemePref) == gtk-theme-width-height.html gtk-theme-width-height-ref.html
 == checkbox-baseline.html checkbox-baseline-ref.html
 == checkbox-radio-color.html checkbox-radio-color-ref.html
 skip-if(gtkWidget&&nativeThemePref) == checkbox-clamp-01.html checkbox-clamp-01-ref.html
 skip-if(OSX||winWidget) fails-if(geckoview&&webrender) fuzzy-if(gtkWidget&&nativeThemePref,25-25,32-32) fails-if(Android&&nativeThemePref) == checkbox-clamp-02.html checkbox-clamp-02-ref.html
-fails-if(OSX&&nativeThemePref) == checkbox-minimum-size.html checkbox-minimum-size-ref.html
+fails-if(!OSX&&nativeThemePref) != checkbox-minimum-size.html checkbox-minimum-size-notref.html

layout/reftests/forms/input/radio/reftest.list

@@ -4,7 +4,7 @@
 == unchecked-appearance-none.html about:blank
 != checked-native.html about:blank
 != checked-native-notref.html about:blank
-skip-if(!gtkWidget) == gtk-theme-width-height.html gtk-theme-width-height-ref.html
+skip-if(!gtkWidget||!nativeThemePref) == gtk-theme-width-height.html gtk-theme-width-height-ref.html
 skip-if(gtkWidget&&nativeThemePref) == radio-clamp-01.html radio-clamp-01-ref.html
 skip-if(OSX||winWidget||Android) fuzzy-if(gtkWidget&&nativeThemePref,24-24,16-16) == radio-clamp-02.html radio-clamp-02-ref.html # gtkWidget, Bug 1599622
-fails-if(OSX&&nativeThemePref) == radio-minimum-size.html radio-minimum-size-ref.html
+fails-if(!OSX&&nativeThemePref) != radio-minimum-size.html radio-minimum-size-notref.html

widget/nsNativeBasicTheme.cpp

@@ -655,9 +655,12 @@ void nsNativeBasicTheme::PaintCheckboxControl(DrawTarget* aDrawTarget,
   }
 }
 
-// Returns the right scale to cover aRect in the smaller dimension.
-static float ScaleToWidgetRect(const LayoutDeviceRect& aRect) {
-  return std::min(aRect.width, aRect.height) / kMinimumWidgetSize;
+
+// Returns the right scale for points in a 14x14 unit box centered at 0x0 to
+// fill aRect in the smaller dimension.
+static float ScaleToFillRect(const LayoutDeviceRect& aRect) {
+  static constexpr float kPathPointsScale = 14.0f;
+  return std::min(aRect.width, aRect.height) / kPathPointsScale;
 }
 
 void nsNativeBasicTheme::PaintCheckMark(DrawTarget* aDrawTarget,
@@ -669,7 +672,7 @@ void nsNativeBasicTheme::PaintCheckMark(DrawTarget* aDrawTarget,
   const float checkPolygonY[] = {0.5f,  4.0f, 4.0f,  -2.5f, -4.0f,
                                  -4.0f, 1.0f, 1.25f, -1.0f};
   const int32_t checkNumPoints = sizeof(checkPolygonX) / sizeof(float);
-  const float scale = ScaleToWidgetRect(aRect);
+  const float scale = ScaleToFillRect(aRect);
   auto center = aRect.Center().ToUnknownPoint();
 
   RefPtr<PathBuilder> builder = aDrawTarget->CreatePathBuilder();
@@ -689,7 +692,7 @@ void nsNativeBasicTheme::PaintIndeterminateMark(DrawTarget* aDrawTarget,
                                                 const LayoutDeviceRect& aRect,
                                                 const EventStates& aState) {
   const CSSCoord borderWidth = 2.0f;
-  const float scale = ScaleToWidgetRect(aRect);
+  const float scale = ScaleToFillRect(aRect);
 
   Rect rect = aRect.ToUnknownRect();
   rect.y += (rect.height / 2) - (borderWidth * scale / 2);
@@ -788,7 +791,7 @@ void nsNativeBasicTheme::PaintRadioCheckmark(DrawTarget* aDrawTarget,
                                              const EventStates& aState,
                                              DPIRatio aDpiRatio) {
   const CSSCoord borderWidth = 2.0f;
-  const float scale = ScaleToWidgetRect(aRect);
+  const float scale = ScaleToFillRect(aRect);
   auto [backgroundColor, checkColor] = ComputeRadioCheckmarkColors(aState);
 
   LayoutDeviceRect rect(aRect);
@@ -853,7 +856,7 @@ void nsNativeBasicTheme::PaintArrow(DrawTarget* aDrawTarget,
                                     const float aArrowPolygonY[],
                                     const int32_t aArrowNumPoints,
                                     const sRGBColor aFillColor) {
-  const float scale = ScaleToWidgetRect(aRect);
+  const float scale = ScaleToFillRect(aRect);
 
   auto center = aRect.Center().ToUnknownPoint();
 
@@ -900,7 +903,7 @@ void nsNativeBasicTheme::PaintSpinnerButton(nsIFrame* aFrame,
   const float arrowPolygonY[] = {-1.875f, 2.625f, 2.625f, -1.875f, -4.125f,
                                  -4.125f, 0.375f, 0.375f, -4.125f, -4.125f};
   const int32_t arrowNumPoints = ArrayLength(arrowPolygonX);
-  const float scaleX = ScaleToWidgetRect(aRect);
+  const float scaleX = ScaleToFillRect(aRect);
   const float scaleY =
       aAppearance == StyleAppearance::SpinnerDownbutton ? scaleX : -scaleX;
 
@@ -1546,6 +1549,10 @@ auto nsNativeBasicTheme::GetScrollbarSizes(nsPresContext* aPresContext,
   return {s, s};
 }
 
+nscoord nsNativeBasicTheme::GetCheckboxRadioPrefSize() {
+  return CSSPixel::ToAppUnits(10);
+}
+
 NS_IMETHODIMP
 nsNativeBasicTheme::GetMinimumWidgetSize(nsPresContext* aPresContext,
                                          nsIFrame* aFrame,
@@ -1554,7 +1561,8 @@ nsNativeBasicTheme::GetMinimumWidgetSize(nsPresContext* aPresContext,
                                          bool* aIsOverridable) {
   DPIRatio dpiRatio = GetDPIRatio(aFrame, aAppearance);
 
-  aResult->width = aResult->height = (kMinimumWidgetSize * dpiRatio).Rounded();
+  aResult->width = aResult->height = 0;
+  *aIsOverridable = true;
 
   switch (aAppearance) {
     case StyleAppearance::Button:
@@ -1621,7 +1629,6 @@ nsNativeBasicTheme::GetMinimumWidgetSize(nsPresContext* aPresContext,
       break;
   }
 
-  *aIsOverridable = true;
   return NS_OK;
 }
 

widget/nsNativeBasicTheme.h

@@ -83,7 +83,6 @@ static const gfx::sRGBColor sScrollbarButtonHoverColor(gfx::sRGBColor(0.86f,
                                                                       0.86f,
                                                                       0.86f));
 
-static const CSSCoord kMinimumWidgetSize = 14.0f;
 static const CSSCoord kMinimumScrollbarSize = 17.0f;
 static const CSSCoord kMinimumThinScrollbarSize = 6.0f;
 static const CSSCoord kMinimumColorPickerHeight = 32.0f;
@@ -175,6 +174,8 @@ class nsNativeBasicTheme : protected nsNativeTheme, public nsITheme {
                                    Overlay) override;
   static nscolor AdjustUnthemedScrollbarThumbColor(nscolor, EventStates);
 
+  nscoord GetCheckboxRadioPrefSize() override;
+
  protected:
   nsNativeBasicTheme() = default;
   virtual ~nsNativeBasicTheme() = default;