kotatogram/lib_ui
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Add Images::GenerateShadow.

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This commit is contained in:
John Preston 2021-10-19 19:58:03 +04:00
parent aa16cd0c16
commit 48ebd65323
2 changed files with 53 additions and 0 deletions
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47
ui/image/image_prepare.cpp
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@ -878,6 +878,53 @@ QImage GenerateLinearGradient(
return result;
}
QImage GenerateShadow(
int height,
int topAlpha,
int bottomAlpha,
QColor color) {
Expects(topAlpha >= 0 && topAlpha < 256);
Expects(bottomAlpha >= 0 && bottomAlpha < 256);
Expects(height * style::DevicePixelRatio() < 65536);
const auto base = (uint32(color.red()) << 16)
| (uint32(color.green()) << 8)
| uint32(color.blue());
const auto premultiplied = (topAlpha == bottomAlpha) || !base;
auto result = QImage(
QSize(1, height * style::DevicePixelRatio()),
(premultiplied
? QImage::Format_ARGB32_Premultiplied
: QImage::Format_ARGB32));
if (topAlpha == bottomAlpha) {
color.setAlpha(topAlpha);
result.fill(color);
return result;
}
constexpr auto kShift = 16;
constexpr auto kMultiply = (1U << kShift);
const auto values = std::abs(topAlpha - bottomAlpha);
const auto rows = uint32(result.height());
const auto step = (values * kMultiply) / (rows - 1);
const auto till = rows * uint32(step);
Assert(result.bytesPerLine() == sizeof(uint32));
auto ints = reinterpret_cast<uint32*>(result.bits());
if (topAlpha < bottomAlpha) {
for (auto i = uint32(0); i != till; i += step) {
*ints++ = base | ((topAlpha + (i >> kShift)) << 24);
}
} else {
for (auto i = uint32(0); i != till; i += step) {
*ints++ = base | ((topAlpha - (i >> kShift)) << 24);
}
}
if (!premultiplied) {
result = std::move(result).convertToFormat(
QImage::Format_ARGB32_Premultiplied);
}
return result;
}
void prepareCircle(QImage &img) {
Assert(!img.isNull());

6
ui/image/image_prepare.h
View file

@ -40,6 +40,12 @@ namespace Images {
const std::vector<QColor> &colors,
int rotation = 0);
[[nodiscard]] QImage GenerateShadow(
int height,
int topAlpha,
int bottomAlpha,
QColor color = QColor(0, 0, 0));
[[nodiscard]] const std::array<QImage, 4> &CornersMask(
ImageRoundRadius radius);
[[nodiscard]] std::array<QImage, 4> PrepareCorners(