BTextView: Fixup AdoptSystemColors() and HasSystemColors()

Replace private _UsesSystemColors() with public HasSystemColors()
and make sure to consider the tints when checking if system colors
are used or not.

Document HasSytemColors() in the Haiku Book.

Change-Id: I78de4904d5ddb24b98ad27eb93d4e5ccb330d76a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/8897
Haiku-Format: Haiku-format Bot <[email protected]>
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

docs/user/interface/TextView.dox

@@ -1363,11 +1363,32 @@
 	- \c B_DOCUMENT_BACKGROUND_COLOR for LowUIColor()
 	- \c B_DOCUMENT_TEXT_COLOR for HighUIColor()
 
+	This is reimplemented from BView which uses panel colors.
+
 	View and low colors tinted \c B_DARKEN_1_TINT (inverse on dark) if uneditable.
 
 	Does not alter text color.
 
-	\see BView::AdoptSystemColors(), MakeEditable()
+	\see BView::AdoptSystemColors(), MakeEditable(), HasSystemColors()
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\fn bool BTextView::HasSystemColors() const
+	\brief Tests whether or not the text view is using system colors.
+
+	- \c B_DOCUMENT_BACKGROUND_COLOR for ViewUIColor() either untinted or \c B_DARKEN_1_TINT
+	- \c B_DOCUMENT_BACKGROUND_COLOR for LowUIColor() either untinted or \c B_DARKEN_1_TINT
+	- \c B_DOCUMENT_TEXT_COLOR for HighUIColor() untinted
+
+	Does not consider text color.
+
+	\returns \c true if using system colors either untinted or using uneditable tint
+	         \c false otherwise.
+
+	\see AdoptSystemColors(), MakeEditable()
 
 	\since Haiku R1
 */

headers/os/interface/TextView.h

@@ -132,6 +132,7 @@ public:
 			void				GetSelection(int32* _start, int32* _end) const;
 
 			void				AdoptSystemColors();
+			bool				HasSystemColors() const;
 
 			void				SetFontAndColor(const BFont* font,
 									uint32 mode = B_FONT_ALL,
@@ -428,8 +429,7 @@ private:
 			float				_TextHeight();
 			BRect				_TextRect();
 
-			float				_UneditableTint();
+			float				_UneditableTint() const;
-			bool				_UsesSystemColors();
 
 private:
 			BPrivate::TextGapBuffer*	fText;

src/kits/interface/TextView.cpp

@@ -1601,6 +1601,20 @@ BTextView::AdoptSystemColors()
 }
 
 
+bool
+BTextView::HasSystemColors() const
+{
+	float tint = B_NO_TINT;
+	float uneditableTint = _UneditableTint();
+
+	return ViewUIColor(&tint) == B_DOCUMENT_BACKGROUND_COLOR
+		&& (tint == B_NO_TINT || tint == uneditableTint)
+		&& LowUIColor(&tint) == B_DOCUMENT_BACKGROUND_COLOR
+		&& (tint == B_NO_TINT || tint == uneditableTint)
+		&& HighUIColor(&tint) == B_DOCUMENT_TEXT_COLOR && tint == B_NO_TINT;
+}
+
+
 void
 BTextView::SetFontAndColor(const BFont* font, uint32 mode, const rgb_color* color)
 {
@@ -2385,7 +2399,7 @@ BTextView::MakeEditable(bool editable)
 	fEditable = editable;
 
 	// apply uneditable colors or unapply them
-	if (_UsesSystemColors())
+	if (HasSystemColors())
 		AdoptSystemColors();
 
 	// TextControls change the color of the text when
@@ -6226,23 +6240,12 @@ BTextView::_TextRect()
 
 
 float
-BTextView::_UneditableTint()
+BTextView::_UneditableTint() const
 {
 	return ui_color(B_DOCUMENT_BACKGROUND_COLOR).IsLight() ? B_DARKEN_1_TINT : 0.853;
 }
 
 
-bool
-BTextView::_UsesSystemColors()
-{
-	float tint = B_NO_TINT;
-
-	return ViewUIColor(&tint) == B_DOCUMENT_BACKGROUND_COLOR
-		&& LowUIColor(&tint) == B_DOCUMENT_BACKGROUND_COLOR
-		&& HighUIColor() == B_DOCUMENT_TEXT_COLOR;
-}
-
-
 // #pragma mark - BTextView::TextTrackState