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terminal/src/buffer/out/TextAttribute.hpp
Dustin L. Howett 1bf4c082b4
Reintroduce a color compatibility hack, but only for PowerShells (#6810) 
There is going to be a very long tail of applications that will
explicitly request VT SGR 40/37 when what they really want is to
SetConsoleTextAttribute() with a black background/white foreground.
Instead of making those applications look bad (and therefore making us
look bad, because we're releasing this as an update to something that
"looks good" already), we're introducing this compatibility quirk.
Before the color reckoning in #6698 + #6506, *every* color was subject
to being spontaneously and erroneously turned into the default color.
Now, only the 16-color palette value that matches the active console
background/foreground color will be destroyed, and only when received
from specific applications.

Removal will be tracked by #6807.

Michael and I discussed what layer this quirk really belonged in. I
originally believed it would be sufficient to detect a background color
that matched the legacy default background, but @j4james provided an
example of where that wouldn't work out (powershell setting the
foreground color to white/gray). In addition, it was too heavyhanded: it
re-broke black backgrounds for every application.

Michael thought that it should live in the server, as a small VT parser
that righted the wrongs coming directly out of the application. On
further investigation, however, I realized that we'd need to push more
information up into the server (so that it could make the decision about
which VT was wrong and which was right) than should be strictly
necessary.

The host knows which colors are right and wrong, and it gets final say
in what ends up in the buffer.

Because of that, I chose to push the quirk state down through
WriteConsole to DoWriteConsole and toggle state on the
SCREEN_INFORMATION that indicates whether the colors coming out of the
application are to be distrusted. This quirk _only applies to pwsh.exe
and powershell.exe._

NOTE: This doesn't work for PowerShell the .NET Global tool, because it
is run as an assembly through dotnet.exe. I have no opinion on how to
fix this, or whether it is worth fixing.

VALIDATION
----------
I configured my terminals to have an incredibly garish color scheme to
show exactly what's going to happen as a result of this. The _default
terminal background_ is purple or red, and the foreground green. I've
printed out a heap of test colors to see how black interacts with them.

Pull request #6810 contains the images generated from this test.

The only color lines that change are the ones where black as a
background or white as a foreground is selected out of the 16-color
palette explicitly. Reverse video still works fine (because black is in
the foreground!), and it's even possible to represent "black on default"
and reverse it into "default on black", despite the black in question
having been `40`.

Fixes #6767.
2020-07-10 15:25:39 -07:00

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/*++
Copyright (c) Microsoft Corporation
Licensed under the MIT license.
Module Name:
- TextAttribute.hpp
Abstract:
- contains data structure for run-length-encoding of text attribute data
Author(s):
- Michael Niksa (miniksa) 10-Apr-2014
- Paul Campbell (paulcam) 10-Apr-2014
Revision History:
- From components of output.h/.c
by Therese Stowell (ThereseS) 1990-1991
- Pulled into its own file from textBuffer.hpp/cpp (AustDi, 2017)
- Pulled each of the fg/bg colors into their own abstraction (migrie, Nov 2018)
--*/
#pragma once
#include "TextColor.h"
#include "../../inc/conattrs.hpp"
#ifdef UNIT_TESTING
#include "WexTestClass.h"
#endif
#pragma pack(push, 1)
class TextAttribute final
{
public:
constexpr TextAttribute() noexcept :
_wAttrLegacy{ 0 },
_foreground{},
_background{},
_extendedAttrs{ ExtendedAttributes::Normal }
{
}
explicit constexpr TextAttribute(const WORD wLegacyAttr) noexcept :
_wAttrLegacy{ gsl::narrow_cast<WORD>(wLegacyAttr & META_ATTRS) },
_foreground{ s_LegacyIndexOrDefault(wLegacyAttr & FG_ATTRS, s_legacyDefaultForeground) },
_background{ s_LegacyIndexOrDefault((wLegacyAttr & BG_ATTRS) >> 4, s_legacyDefaultBackground) },
_extendedAttrs{ ExtendedAttributes::Normal }
{
// If we're given lead/trailing byte information with the legacy color, strip it.
WI_ClearAllFlags(_wAttrLegacy, COMMON_LVB_SBCSDBCS);
}
constexpr TextAttribute(const COLORREF rgbForeground,
const COLORREF rgbBackground) noexcept :
_wAttrLegacy{ 0 },
_foreground{ rgbForeground },
_background{ rgbBackground },
_extendedAttrs{ ExtendedAttributes::Normal }
{
}
static void SetLegacyDefaultAttributes(const WORD defaultAttributes) noexcept;
static TextAttribute StripErroneousVT16VersionsOfLegacyDefaults(const TextAttribute& attribute) noexcept;
WORD GetLegacyAttributes() const noexcept;
COLORREF CalculateRgbForeground(std::basic_string_view<COLORREF> colorTable,
COLORREF defaultFgColor,
COLORREF defaultBgColor) const noexcept;
COLORREF CalculateRgbBackground(std::basic_string_view<COLORREF> colorTable,
COLORREF defaultFgColor,
COLORREF defaultBgColor) const noexcept;
bool IsLeadingByte() const noexcept;
bool IsTrailingByte() const noexcept;
bool IsTopHorizontalDisplayed() const noexcept;
bool IsBottomHorizontalDisplayed() const noexcept;
bool IsLeftVerticalDisplayed() const noexcept;
bool IsRightVerticalDisplayed() const noexcept;
void SetLeftVerticalDisplayed(const bool isDisplayed) noexcept;
void SetRightVerticalDisplayed(const bool isDisplayed) noexcept;
void Invert() noexcept;
friend constexpr bool operator==(const TextAttribute& a, const TextAttribute& b) noexcept;
friend constexpr bool operator!=(const TextAttribute& a, const TextAttribute& b) noexcept;
friend constexpr bool operator==(const TextAttribute& attr, const WORD& legacyAttr) noexcept;
friend constexpr bool operator!=(const TextAttribute& attr, const WORD& legacyAttr) noexcept;
friend constexpr bool operator==(const WORD& legacyAttr, const TextAttribute& attr) noexcept;
friend constexpr bool operator!=(const WORD& legacyAttr, const TextAttribute& attr) noexcept;
bool IsLegacy() const noexcept;
bool IsBold() const noexcept;
bool IsItalic() const noexcept;
bool IsBlinking() const noexcept;
bool IsInvisible() const noexcept;
bool IsCrossedOut() const noexcept;
bool IsUnderlined() const noexcept;
bool IsOverlined() const noexcept;
bool IsReverseVideo() const noexcept;
void SetBold(bool isBold) noexcept;
void SetItalics(bool isItalic) noexcept;
void SetBlinking(bool isBlinking) noexcept;
void SetInvisible(bool isInvisible) noexcept;
void SetCrossedOut(bool isCrossedOut) noexcept;
void SetUnderline(bool isUnderlined) noexcept;
void SetOverline(bool isOverlined) noexcept;
void SetReverseVideo(bool isReversed) noexcept;
ExtendedAttributes GetExtendedAttributes() const noexcept;
TextColor GetForeground() const noexcept;
TextColor GetBackground() const noexcept;
void SetForeground(const TextColor foreground) noexcept;
void SetBackground(const TextColor background) noexcept;
void SetForeground(const COLORREF rgbForeground) noexcept;
void SetBackground(const COLORREF rgbBackground) noexcept;
void SetIndexedForeground(const BYTE fgIndex) noexcept;
void SetIndexedBackground(const BYTE bgIndex) noexcept;
void SetIndexedForeground256(const BYTE fgIndex) noexcept;
void SetIndexedBackground256(const BYTE bgIndex) noexcept;
void SetColor(const COLORREF rgbColor, const bool fIsForeground) noexcept;
void SetDefaultForeground() noexcept;
void SetDefaultBackground() noexcept;
bool BackgroundIsDefault() const noexcept;
void SetStandardErase() noexcept;
// This returns whether this attribute, if printed directly next to another attribute, for the space
// character, would look identical to the other one.
bool HasIdenticalVisualRepresentationForBlankSpace(const TextAttribute& other, const bool inverted = false) const noexcept
{
// sneaky-sneaky: I'm using xor here
// inverted is whether there's a global invert; Reverse is a local one.
// global ^ local == true : the background attribute is actually the visible foreground, so we care about the foregrounds being identical
// global ^ local == false: the foreground attribute is the visible foreground, so we care about the backgrounds being identical
const auto checkForeground = (inverted != IsReverseVideo());
return !IsAnyGridLineEnabled() && // grid lines have a visual representation
// crossed out, doubly and singly underlined have a visual representation
WI_AreAllFlagsClear(_extendedAttrs, ExtendedAttributes::CrossedOut | ExtendedAttributes::DoublyUnderlined | ExtendedAttributes::Underlined) &&
// all other attributes do not have a visual representation
(_wAttrLegacy & META_ATTRS) == (other._wAttrLegacy & META_ATTRS) &&
((checkForeground && _foreground == other._foreground) ||
(!checkForeground && _background == other._background)) &&
_extendedAttrs == other._extendedAttrs;
}
constexpr bool IsAnyGridLineEnabled() const noexcept
{
return WI_IsAnyFlagSet(_wAttrLegacy, COMMON_LVB_GRID_HORIZONTAL | COMMON_LVB_GRID_LVERTICAL | COMMON_LVB_GRID_RVERTICAL | COMMON_LVB_UNDERSCORE);
}
private:
COLORREF _GetRgbForeground(std::basic_string_view<COLORREF> colorTable,
COLORREF defaultColor) const noexcept;
COLORREF _GetRgbBackground(std::basic_string_view<COLORREF> colorTable,
COLORREF defaultColor) const noexcept;
static constexpr TextColor s_LegacyIndexOrDefault(const BYTE requestedIndex, const BYTE defaultIndex)
{
return requestedIndex == defaultIndex ? TextColor{} : TextColor{ requestedIndex, true };
}
static BYTE s_legacyDefaultForeground;
static BYTE s_legacyDefaultBackground;
WORD _wAttrLegacy;
TextColor _foreground;
TextColor _background;
ExtendedAttributes _extendedAttrs;
#ifdef UNIT_TESTING
friend class TextBufferTests;
friend class TextAttributeTests;
template<typename TextAttribute>
friend class WEX::TestExecution::VerifyOutputTraits;
#endif
};
#pragma pack(pop)
// 2 for _wAttrLegacy
// 4 for _foreground
// 4 for _background
// 1 for _extendedAttrs
static_assert(sizeof(TextAttribute) <= 11 * sizeof(BYTE), "We should only need 11B for an entire TextColor. Any more than that is just waste");
enum class TextAttributeBehavior
{
Stored, // use contained text attribute
Current, // use text attribute of cell being written to
StoredOnly, // only use the contained text attribute and skip the insertion of anything else
};
constexpr bool operator==(const TextAttribute& a, const TextAttribute& b) noexcept
{
return a._wAttrLegacy == b._wAttrLegacy &&
a._foreground == b._foreground &&
a._background == b._background &&
a._extendedAttrs == b._extendedAttrs;
}
constexpr bool operator!=(const TextAttribute& a, const TextAttribute& b) noexcept
{
return !(a == b);
}
#ifdef UNIT_TESTING
#define LOG_ATTR(attr) (Log::Comment(NoThrowString().Format( \
L#attr L"=%s", VerifyOutputTraits<TextAttribute>::ToString(attr).GetBuffer())))
namespace WEX
{
namespace TestExecution
{
template<>
class VerifyOutputTraits<TextAttribute>
{
public:
static WEX::Common::NoThrowString ToString(const TextAttribute& attr)
{
return WEX::Common::NoThrowString().Format(
L"{FG:%s,BG:%s,bold:%d,wLegacy:(0x%04x)}",
VerifyOutputTraits<TextColor>::ToString(attr._foreground).GetBuffer(),
VerifyOutputTraits<TextColor>::ToString(attr._background).GetBuffer(),
attr.IsBold(),
attr._wAttrLegacy);
}
};
}
}
#endif
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