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/*
* qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
* Copyright (C) 2026 Danilo M. <danix@danix.xyz>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "avatar.h"
#include <QCryptographicHash>
#include <QLinearGradient>
#include <QLineF>
#include <QPainter>
#include <QPainterPath>
namespace {
QString twoFrom(const QString &text)
{
const QString trimmed = text.trimmed();
if (trimmed.size() >= 2)
return trimmed.left(2).toUpper();
if (trimmed.size() == 1)
return (trimmed + trimmed).toUpper();
return QString();
}
} // namespace
namespace Avatar {
QString initialsFor(const QString &displayName, const QString &address,
const QString &accountLabel)
{
const QStringList words = displayName.split(QLatin1Char(' '),
Qt::SkipEmptyParts);
if (words.size() >= 2) {
return (words.at(0).left(1) + words.at(1).left(1)).toUpper();
}
if (words.size() == 1) {
const QString one = twoFrom(words.at(0));
if (!one.isEmpty())
return one;
}
// No usable name. The local part and the domain each give one letter,
// which never degrades to a single letter the way the local part alone
// would, and never reads as a truncated word.
const int at = address.indexOf(QLatin1Char('@'));
if (at > 0) {
const QString local = address.left(at).trimmed();
const QString domain = address.mid(at + 1).trimmed();
if (!local.isEmpty() && !domain.isEmpty())
return (local.left(1) + domain.left(1)).toUpper();
}
// An address with no `@` is still something to show.
const QString bare = twoFrom(address);
if (!bare.isEmpty())
return bare;
const QString account = twoFrom(accountLabel);
if (!account.isEmpty())
return account;
// Nothing at all. Two characters regardless, so the shape never breaks.
return QStringLiteral("??");
}
Fill fillFor(const QString &displayName, bool isBusinessSender)
{
// The list first: it is the user's explicit override and must beat the
// heuristic, or a listed sender could never be pinned.
if (isBusinessSender)
return Fill::TwoTone;
return displayName.trimmed().isEmpty() ? Fill::TwoTone : Fill::Identicon;
}
QColor colourFor(const QString &address)
{
// The same construction TagColors::colourFor() uses for a tag with nothing
// configured: hashed so it is stable, at a fixed saturation and lightness
// so it cannot come out neon and cannot lose its contrast with the
// initials. The lightness differs from that function's deliberately: a
// chip carries dark text, a squircle carries white.
const QByteArray digest =
QCryptographicHash::hash(address.toUtf8(), QCryptographicHash::Md5);
const int hue = static_cast<quint8>(digest.at(0)) * 360 / 256;
return QColor::fromHsl(hue, 110, 95);
}
QPixmap pixmapFor(const QString &seed, const QString &initials, Fill fill,
int side, const QFont &font)
{
QPixmap pixmap(side, side);
pixmap.fill(Qt::transparent);
const QByteArray digest =
QCryptographicHash::hash(seed.toUtf8(), QCryptographicHash::Md5);
const QColor base = colourFor(seed);
QPainter painter(&pixmap);
painter.setRenderHint(QPainter::Antialiasing, true);
// The squircle. A rounded rect at ~30% of the side reads as one without
// needing a superellipse, and clipping to it means neither fill has to
// know the shape.
QPainterPath squircle;
squircle.addRoundedRect(QRectF(0, 0, side, side), side * 0.3, side * 0.3);
painter.setClipPath(squircle);
if (fill == Fill::Identicon) {
// A 5x5 grid, mirrored about the vertical axis, so only the left
// three columns come from the hash: 15 cells, one bit each, which is
// two bytes of the digest. Symmetry is what makes the shape read as a
// deliberate mark rather than as noise.
painter.fillRect(QRect(0, 0, side, side), base.darker(220));
const qreal cell = qreal(side) / 5.0;
for (int col = 0; col < 3; ++col) {
for (int row = 0; row < 5; ++row) {
const int bit = col * 5 + row;
const bool on =
(static_cast<quint8>(digest.at(bit / 8)) >> (bit % 8)) & 1;
if (!on)
continue;
painter.fillRect(QRectF(col * cell, row * cell, cell, cell),
base);
const int mirrored = 4 - col;
painter.fillRect(
QRectF(mirrored * cell, row * cell, cell, cell), base);
}
}
// The veil. Without it the initials sit on whatever the pattern
// happens to do behind them, which is the classic legibility failure
// this fill invites. Tune the opacity against the real font before
// calling it done.
painter.fillRect(QRect(0, 0, side, side), QColor(0, 0, 0, 77));
} else {
// Two related hues split at an angle, both from the hash. The field
// behind the letters stays large and flat, which is the whole reason
// this fill exists beside the identicon.
const int angle = static_cast<quint8>(digest.at(1)) * 360 / 256;
QLineF axis = QLineF::fromPolar(side, angle);
axis.translate(side / 2.0, side / 2.0);
QLinearGradient gradient(axis.p2(), axis.p1());
gradient.setColorAt(0.0, base);
gradient.setColorAt(0.499, base);
gradient.setColorAt(0.5, base.darker(135));
gradient.setColorAt(1.0, base.darker(135));
painter.fillRect(QRect(0, 0, side, side), gradient);
}
// The letters. White with a soft shadow rather than a computed contrast
// colour: the fills are generated at a fixed lightness precisely so one
// choice works for all of them.
QFont letters = font;
letters.setBold(true);
letters.setPixelSize(qMax(8, int(side * 0.36)));
painter.setFont(letters);
painter.setPen(QColor(0, 0, 0, 120));
painter.drawText(QRect(1, 1, side, side), Qt::AlignCenter, initials);
painter.setPen(Qt::white);
painter.drawText(QRect(0, 0, side, side), Qt::AlignCenter, initials);
return pixmap;
}
} // namespace Avatar
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