diff --git a/CHANGELOG.md b/CHANGELOG.md
index cfe7ad694d9b777edb94b1aa1eb6c684e693d263..a0afeb2ed9465563fc7bf9868bb8dc21ba5eb3ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,11 @@ current (development)
### Screen
- Feature: Add `Box::IsEmpty()`.
+- Feature: Color transparency
+ - Add `Color::RGBA(r,g,b,a)`.
+ - Add `Color::HSVA(r,g,b,a)`.
+ - Add `Color::Blend(Color)`.
+ - Add `Color::IsOpaque()`
### Util
- Feature: Support arbitrary `Adapter` for `ConstStringListRef`. See #843.
diff --git a/include/ftxui/screen/color.hpp b/include/ftxui/screen/color.hpp
index 52f699b5e59e41026f1b1f6ed6a67ff285752b1d..1489dca634982cd31efee4b2ce6e21f63c070239 100644
--- a/include/ftxui/screen/color.hpp
+++ b/include/ftxui/screen/color.hpp
@@ -29,10 +29,16 @@ class Color {
Color(Palette16 index); // Implicit conversion from index to Color.
Color(Palette256 index); // Implicit conversion from index to Color.
// NOLINTEND
- Color(uint8_t red, uint8_t green, uint8_t blue);
+ Color(uint8_t red, uint8_t green, uint8_t blue, uint8_t alpha = 255);
static Color RGB(uint8_t red, uint8_t green, uint8_t blue);
static Color HSV(uint8_t hue, uint8_t saturation, uint8_t value);
+ static Color RGBA(uint8_t red, uint8_t green, uint8_t blue, uint8_t alpha);
+ static Color HSVA(uint8_t hue,
+ uint8_t saturation,
+ uint8_t value,
+ uint8_t alpha);
static Color Interpolate(float t, const Color& a, const Color& b);
+ static Color Blend(const Color& lhs, const Color& rhs);
//---------------------------
// List of colors:
@@ -310,6 +316,7 @@ class Color {
bool operator!=(const Color& rhs) const;
std::string Print(bool is_background_color) const;
+ bool IsOpaque() const { return alpha_ == 255; }
private:
enum class ColorType : uint8_t {
@@ -322,6 +329,7 @@ class Color {
uint8_t red_ = 0;
uint8_t green_ = 0;
uint8_t blue_ = 0;
+ uint8_t alpha_ = 0;
};
inline namespace literals {
diff --git a/include/ftxui/screen/pixel.hpp b/include/ftxui/screen/pixel.hpp
index 0a58a389802d6bf5f78167691700159eeb8f6621..7545d1ef8873f3b64a1842c675a10748b6062e71 100644
--- a/include/ftxui/screen/pixel.hpp
+++ b/include/ftxui/screen/pixel.hpp
@@ -38,7 +38,7 @@ struct Pixel {
// The graphemes stored into the pixel. To support combining characters,
// like: a?, this can potentially contain multiple codepoints.
- std::string character = " ";
+ std::string character = "";
// Colors:
Color background_color = Color::Default;
diff --git a/src/ftxui/dom/clear_under.cpp b/src/ftxui/dom/clear_under.cpp
index a18510dfae0032a101fc309602546740c1ad22cd..81dc2bfce14524bc385b9c67a2a2b993dd0347c9 100644
--- a/src/ftxui/dom/clear_under.cpp
+++ b/src/ftxui/dom/clear_under.cpp
@@ -23,6 +23,7 @@ class ClearUnder : public NodeDecorator {
for (int y = box_.y_min; y <= box_.y_max; ++y) {
for (int x = box_.x_min; x <= box_.x_max; ++x) {
screen.PixelAt(x, y) = Pixel();
+ screen.PixelAt(x, y).character = " "; // Consider the pixel written.
}
}
Node::Render(screen);
diff --git a/src/ftxui/dom/color.cpp b/src/ftxui/dom/color.cpp
index 238ccca63664ca9a1cdecdf6739c381d9d20e4a8..431d522eb6ab34af5078b099c1848d134cd2753a 100644
--- a/src/ftxui/dom/color.cpp
+++ b/src/ftxui/dom/color.cpp
@@ -19,9 +19,18 @@ class BgColor : public NodeDecorator {
: NodeDecorator(std::move(child)), color_(color) {}
void Render(Screen& screen) override {
- for (int y = box_.y_min; y <= box_.y_max; ++y) {
- for (int x = box_.x_min; x <= box_.x_max; ++x) {
- screen.PixelAt(x, y).background_color = color_;
+ if (color_.IsOpaque()) {
+ for (int y = box_.y_min; y <= box_.y_max; ++y) {
+ for (int x = box_.x_min; x <= box_.x_max; ++x) {
+ screen.PixelAt(x, y).background_color = color_;
+ }
+ }
+ } else {
+ for (int y = box_.y_min; y <= box_.y_max; ++y) {
+ for (int x = box_.x_min; x <= box_.x_max; ++x) {
+ Color& color = screen.PixelAt(x, y).background_color;
+ color = Color::Blend(color, color_);
+ }
}
}
NodeDecorator::Render(screen);
@@ -36,9 +45,18 @@ class FgColor : public NodeDecorator {
: NodeDecorator(std::move(child)), color_(color) {}
void Render(Screen& screen) override {
- for (int y = box_.y_min; y <= box_.y_max; ++y) {
- for (int x = box_.x_min; x <= box_.x_max; ++x) {
- screen.PixelAt(x, y).foreground_color = color_;
+ if (color_.IsOpaque()) {
+ for (int y = box_.y_min; y <= box_.y_max; ++y) {
+ for (int x = box_.x_min; x <= box_.x_max; ++x) {
+ screen.PixelAt(x, y).foreground_color = color_;
+ }
+ }
+ } else {
+ for (int y = box_.y_min; y <= box_.y_max; ++y) {
+ for (int x = box_.x_min; x <= box_.x_max; ++x) {
+ Color& color = screen.PixelAt(x, y).foreground_color;
+ color = Color::Blend(color, color_);
+ }
}
}
NodeDecorator::Render(screen);
@@ -46,6 +64,7 @@ class FgColor : public NodeDecorator {
Color color_;
};
+
} // namespace
/// @brief Set the foreground color of an element.
diff --git a/src/ftxui/dom/dbox.cpp b/src/ftxui/dom/dbox.cpp
index 92971c81fe67bc120651ec867e831e8577019753..a75321550437a85be6ff1b31302940a34550c495 100644
--- a/src/ftxui/dom/dbox.cpp
+++ b/src/ftxui/dom/dbox.cpp
@@ -46,6 +46,57 @@ class DBox : public Node {
child->SetBox(box);
}
}
+
+ void Render(Screen& screen) override {
+ if (children_.size() <= 1) {
+ return Node::Render(screen);
+ }
+
+ const int width = box_.x_max - box_.x_min + 1;
+ const int height = box_.y_max - box_.y_min + 1;
+ std::vector<Pixel> pixels(size_t(width * height));
+
+ for (auto& child : children_) {
+ child->Render(screen);
+
+ // Accumulate the pixels
+ Pixel* acc = pixels.data();
+ for (int x = 0; x < width; ++x) {
+ for (int y = 0; y < height; ++y) {
+ auto& pixel = screen.PixelAt(x + box_.x_min, y + box_.y_min);
+ acc->background_color =
+ Color::Blend(acc->background_color, pixel.background_color);
+ acc->automerge = pixel.automerge || acc->automerge;
+ if (pixel.character == "") {
+ acc->foreground_color =
+ Color::Blend(acc->foreground_color, pixel.background_color);
+ } else {
+ acc->blink = pixel.blink;
+ acc->bold = pixel.bold;
+ acc->dim = pixel.dim;
+ acc->inverted = pixel.inverted;
+ acc->underlined = pixel.underlined;
+ acc->underlined_double = pixel.underlined_double;
+ acc->strikethrough = pixel.strikethrough;
+ acc->hyperlink = pixel.hyperlink;
+ acc->character = pixel.character;
+ acc->foreground_color = pixel.foreground_color;
+ }
+ ++acc;
+
+ pixel = Pixel();
+ }
+ }
+ }
+
+ // Render the accumulated pixels:
+ Pixel* acc = pixels.data();
+ for (int x = 0; x < width; ++x) {
+ for (int y = 0; y < height; ++y) {
+ screen.PixelAt(x + box_.x_min, y + box_.y_min) = *acc++;
+ }
+ }
+ }
};
} // namespace
diff --git a/src/ftxui/screen/color.cpp b/src/ftxui/screen/color.cpp
index a70ec87249a0d56703a30462a88bea324a9bfb30..546241f7319f05f0e6d4e92107108536cfc72403 100644
--- a/src/ftxui/screen/color.cpp
+++ b/src/ftxui/screen/color.cpp
@@ -73,13 +73,15 @@ Color::Color() = default;
/// @ingroup screen
Color::Color(Palette1 /*value*/) : Color() {}
-/// @brief Build a transparent using Palette16 colors.
+/// @brief Build a color using the Palette16 colors.
/// @ingroup screen
-Color::Color(Palette16 index) : type_(ColorType::Palette16), red_(index) {}
+Color::Color(Palette16 index)
+ : type_(ColorType::Palette16), red_(index), alpha_(255) {}
-/// @brief Build a transparent using Palette256 colors.
+/// @brief Build a color using Palette256 colors.
/// @ingroup screen
-Color::Color(Palette256 index) : type_(ColorType::Palette256), red_(index) {
+Color::Color(Palette256 index)
+ : type_(ColorType::Palette256), red_(index), alpha_(255) {
if (Terminal::ColorSupport() >= Terminal::Color::Palette256) {
return;
}
@@ -93,9 +95,14 @@ Color::Color(Palette256 index) : type_(ColorType::Palette256), red_(index) {
/// @param red The quantity of red [0,255]
/// @param green The quantity of green [0,255]
/// @param blue The quantity of blue [0,255]
+/// @param alpha The quantity of alpha [0,255]
/// @ingroup screen
-Color::Color(uint8_t red, uint8_t green, uint8_t blue)
- : type_(ColorType::TrueColor), red_(red), green_(green), blue_(blue) {
+Color::Color(uint8_t red, uint8_t green, uint8_t blue, uint8_t alpha)
+ : type_(ColorType::TrueColor),
+ red_(red),
+ green_(green),
+ blue_(blue),
+ alpha_(alpha) {
if (Terminal::ColorSupport() == Terminal::Color::TrueColor) {
return;
}
@@ -136,7 +143,20 @@ Color::Color(uint8_t red, uint8_t green, uint8_t blue)
/// @ingroup screen
// static
Color Color::RGB(uint8_t red, uint8_t green, uint8_t blue) {
- return {red, green, blue};
+ return RGBA(red, green, blue, 255);
+}
+
+/// @brief Build a Color from its RGBA representation.
+/// https://en.wikipedia.org/wiki/RGB_color_model
+/// @param red The quantity of red [0,255]
+/// @param green The quantity of green [0,255]
+/// @param blue The quantity of blue [0,255]
+/// @param alpha The quantity of alpha [0,255]
+/// @ingroup screen
+/// @see Color::RGB
+// static
+Color Color::RGBA(uint8_t red, uint8_t green, uint8_t blue, uint8_t alpha) {
+ return {red, green, blue, alpha};
}
/// @brief Build a Color from its HSV representation.
@@ -145,9 +165,10 @@ Color Color::RGB(uint8_t red, uint8_t green, uint8_t blue) {
/// @param h The hue of the color [0,255]
/// @param s The "colorfulness" [0,255].
/// @param v The "Lightness" [0,255]
+/// @param alpha The quantity of alpha [0,255]
/// @ingroup screen
// static
-Color Color::HSV(uint8_t h, uint8_t s, uint8_t v) {
+Color Color::HSVA(uint8_t h, uint8_t s, uint8_t v, uint8_t alpha) {
uint8_t region = h / 43; // NOLINT
uint8_t remainder = (h - (region * 43)) * 6; // NOLINT
uint8_t p = (v * (255 - s)) >> 8; // NOLINT
@@ -155,16 +176,28 @@ Color Color::HSV(uint8_t h, uint8_t s, uint8_t v) {
uint8_t t = (v * (255 - ((s * (255 - remainder)) >> 8))) >> 8; // NOLINT
// clang-format off
- switch (region) { // NOLINT
- case 0: return Color(v,t,p); // NOLINT
- case 1: return Color(q,v,p); // NOLINT
- case 2: return Color(p,v,t); // NOLINT
- case 3: return Color(p,q,v); // NOLINT
- case 4: return Color(t,p,v); // NOLINT
- case 5: return Color(v,p,q); // NOLINT
- } // NOLINT
+ switch (region) { // NOLINT
+ case 0: return Color(v,t,p, alpha); // NOLINT
+ case 1: return Color(q,v,p, alpha); // NOLINT
+ case 2: return Color(p,v,t, alpha); // NOLINT
+ case 3: return Color(p,q,v, alpha); // NOLINT
+ case 4: return Color(t,p,v, alpha); // NOLINT
+ case 5: return Color(v,p,q, alpha); // NOLINT
+ } // NOLINT
// clang-format on
- return {0, 0, 0};
+ return {0, 0, 0, alpha};
+}
+
+/// @brief Build a Color from its HSV representation.
+/// https://en.wikipedia.org/wiki/HSL_and_HSV
+///
+/// @param h The hue of the color [0,255]
+/// @param s The "colorfulness" [0,255].
+/// @param v The "Lightness" [0,255]
+/// @ingroup screen
+// static
+Color Color::HSV(uint8_t h, uint8_t s, uint8_t v) {
+ return HSVA(h, s, v, 255);
}
// static
@@ -235,6 +268,14 @@ Color Color::Interpolate(float t, const Color& a, const Color& b) {
interp(a_b, b_b)); //
}
+/// @brief Blend two colors together using the alpha channel.
+// static
+Color Color::Blend(const Color& lhs, const Color& rhs) {
+ Color out = Interpolate(float(rhs.alpha_) / 255.F, lhs, rhs);
+ out.alpha_ = lhs.alpha_ + rhs.alpha_ - lhs.alpha_ * rhs.alpha_ / 255;
+ return out;
+}
+
inline namespace literals {
Color operator""_rgb(unsigned long long int combined) {
diff --git a/src/ftxui/screen/screen.cpp b/src/ftxui/screen/screen.cpp
index 1a272baaa9cd3a6fb07c5a339178bdd4e013df7a..a04914a0a48725032f0aee61df7f5caa4691c7b0 100644
--- a/src/ftxui/screen/screen.cpp
+++ b/src/ftxui/screen/screen.cpp
@@ -423,7 +423,11 @@ std::string Screen::ToString() const {
if (!previous_fullwidth) {
UpdatePixelStyle(this, ss, *previous_pixel_ref, pixel);
previous_pixel_ref = &pixel;
- ss << pixel.character;
+ if (pixel.character.empty()) {
+ ss << " ";
+ } else {
+ ss << pixel.character;
+ }
}
previous_fullwidth = (string_width(pixel.character) == 2);
}