From 37a4bf86937e4e18c5cce70913b6b90e39df20cc Mon Sep 17 00:00:00 2001

From: Vadim Zeitlin <vadim@wxwidgets.org>

Date: Thu, 27 Jan 2022 15:46:42 +0100

Subject: [PATCH] Add wxColour::Get{Red,Green,Blue,Alpha}() to avoid gcc 12

 warnings

These functions return the colour components as unsigned int and so

promote to this type in arithmetic expressions, unlike unsigned char

returned by the existing accessors without the "Get" prefix, which

promotes to (signed) int and results in gcc 12 -Warith-conversion

warnings when the result is then converted to unsigned, as it happened

in our own wxColour::GetRGB() and GetRGBA() functions and would probably

happen in a lot of code outside wx, which could also be updated to use

the new functions instead of inserting casts.

---

 include/wx/colour.h   | 11 ++++++++--

 interface/wx/colour.h | 51 +++++++++++++++++++++++++++++++++++++++++++

 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/include/wx/colour.h b/include/wx/colour.h

index 4e9e0a185407..22a145ab22d1 100644

--- a/include/wx/colour.h

+++ b/include/wx/colour.h

@@ -125,6 +125,13 @@ class WXDLLIMPEXP_CORE wxColourBase : public

     virtual ChannelType Alpha() const

         { return wxALPHA_OPAQUE ; }

+    // These getters return the values as unsigned int, which avoids promoting

+    // them to (signed) int in arithmetic expressions, unlike the ones above.

+    unsigned int GetRed() const { return Red(); }

+    unsigned int GetGreen() const { return Green(); }

+    unsigned int GetBlue() const { return Blue(); }

+    unsigned int GetAlpha() const { return Alpha(); }

+

     virtual bool IsSolid() const

         { return true; }

@@ -147,10 +154,10 @@ class WXDLLIMPEXP_CORE wxColourBase : public

     }

     wxUint32 GetRGB() const

-        { return Red() | (Green() << 8) | (Blue() << 16); }

+        { return GetRed() | (GetGreen() << 8) | (GetBlue() << 16); }

     wxUint32 GetRGBA() const

-        { return Red() | (Green() << 8) | (Blue() << 16) | (Alpha() << 24); }

+        { return GetRed() | (GetGreen() << 8) | (GetBlue() << 16) | (GetAlpha() << 24); }

 #if !wxCOLOUR_IS_GDIOBJECT

     virtual bool IsOk() const= 0;

diff --git a/interface/wx/colour.h b/interface/wx/colour.h

index 32424f1123c7..9cc0ac7c9dec 100644

--- a/interface/wx/colour.h

+++ b/interface/wx/colour.h

@@ -34,6 +34,20 @@ const unsigned char wxALPHA_OPAQUE = 0xff;

     You can retrieve the current system colour settings with wxSystemSettings.

+

+    @section colour_accessors Channel Accessor Functions

+

+    Note that this class provides pairs of functions for each of the colour

+    channels, i.e. red, green, blue and alpha values. The one word functions

+    Red(), Green(), Blue() and Alpha() return the values of type @c unsigned @c

+    char, while GetRed(), GetGreen(), GetBlue() and GetAlpha() returns the same

+    value as @c unsigned @c int. According to the C++ integer promotion rules,

+    the result of any arithmetic expression involving the former will be

+    (signed) @c int, while that of the latter will be @c unsigned, which is

+    what would be commonly expected, so the latter family of functions should

+    be typically preferred (but they are only available since wxWidgets 3.1.6).

+

+

     @library{wxcore}

     @category{gdi}

@@ -94,14 +108,47 @@ class wxColour : public wxObject

     /**

         Returns the alpha value, on platforms where alpha is not yet supported, this

         always returns wxALPHA_OPAQUE.

+

+        @see GetAlpha()

     */

     virtual unsigned char Alpha() const;

     /**

         Returns the blue intensity.

+

+        @see GetBlue()

     */

     virtual unsigned char Blue() const;

+    /**

+        Returns the alpha value, on platforms where alpha is not yet supported, this

+        always returns wxALPHA_OPAQUE.

+

+        @since 3.1.6

+     */

+    unsigned int GetAlpha() const;

+

+    /**

+        Returns the blue intensity as unsigned int.

+

+        @since 3.1.6

+     */

+    unsigned int GetBlue() const;

+

+    /**

+        Returns the green intensity as unsigned int.

+

+        @since 3.1.6

+     */

+    unsigned int GetGreen() const;

+

+    /**

+        Returns the red intensity as unsigned int.

+

+        @since 3.1.6

+     */

+    unsigned int GetRed() const;

+

     /**

         Converts this colour to a wxString using the given flags.

@@ -184,6 +231,8 @@ class wxColour : public wxObject

     /**

         Returns the green intensity.

+

+        @see GetGreen()

     */

     virtual unsigned char Green() const;

@@ -195,6 +244,8 @@ class wxColour : public wxObject

     /**

         Returns the red intensity.

+

+        @see GetRed()

     */

     virtual unsigned char Red() const;