kernel-shark: Add TextBox class to KsPlot namespace

This class represents a text that is printed/drawn inside a colorful
frame.

Link: https://lore.kernel.org/linux-trace-devel/20201209134530.428368-5-y.karadz@gmail.com

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

2 files changed, 158 insertions, 0 deletions

diff --git a/src/KsPlotTools.cpp b/src/KsPlotTools.cpp
index 113a6c06..3f86f16a 100644
--- a/src/KsPlotTools.cpp
+++ b/src/KsPlotTools.cpp
@@ -97,6 +97,23 @@ void Color::setRainbowColor(int n)
 	set(r, g, b);
 }
 
+/** Alpha blending with white background. */
+void Color::blend(float alpha)
+{
+	if (alpha < 0 || alpha > 1.)
+		return;
+
+	auto lamBld = [alpha](int val) {
+		return  val * alpha + (1 - alpha) * 255;
+	};
+
+	int r = lamBld(this->r());
+	int g = lamBld(this->g());
+	int b = lamBld(this->b());
+
+	set(r, g, b);
+}
+
 /**
  * @brief Create a Hash table of Rainbow colors. The sorted Pid values are
  *	  mapped to the palette of Rainbow colors.
@@ -474,6 +491,105 @@ void Polygon::_draw(const Color &col, float size) const
 					    col.color_c_ptr(),
 					    size);
 }
+/** The created object will print/draw only the text without the frame. */
+TextBox::TextBox()
+: _text(""),
+  _font(nullptr)
+{
+	setPos(Point(0, 0));
+	_box._visible = false;
+}
+
+
+/** The created object will print/draw only the text without the frame. */
+TextBox::TextBox(ksplot_font *f)
+: _text(""),
+  _font(f)
+{
+	setPos(Point(0, 0));
+	_box._visible = false;
+}
+
+/** The created object will print/draw only the text without the frame. */
+TextBox::TextBox(ksplot_font *f, const std::string &text, const Point &pos)
+: _text(text),
+  _font(f)
+{
+	setPos(pos);
+	_box._visible = false;
+}
+
+/** The created object will print/draw only the text without the frame. */
+TextBox::TextBox(ksplot_font *f, const std::string &text, const Color &col,
+		 const Point &pos)
+: _text(text),
+  _font(f)
+{
+	_color = col;
+	setPos(pos);
+	_box._visible = false;
+}
+
+/** The created object will print/draw the text and the frame. */
+TextBox::TextBox(ksplot_font *f, const std::string &text, const Color &col,
+		 const Point &pos, int l, int h)
+: _text(text),
+  _font(f)
+{
+	setPos(pos);
+	setBoxAppearance(col, l, h);
+}
+
+/**
+ * @brief Set the position of the bottom-left corner of the frame.
+ *
+ * @param p: The coordinates of the bottom-left corner.
+ */
+void TextBox::setPos(const Point &p)
+{
+	_box.setPoint(0, p);
+}
+
+/**
+ * @brief Set the color and the dimensions of the frame.
+ *
+ * @param col: The color of the frame.
+ * @param l: The length of the frame.
+ * @param h: The height of the frame.
+ */
+void TextBox::setBoxAppearance(const Color &col, int l, int h)
+{
+	_box.setFill(true);
+	_box._color = col;
+	_box._visible = true;
+
+	if (h <= 0 && _font)
+		h = _font->height;
+
+	_box.setPoint(1, _box.getPointX(0),	_box.getPointY(0) - h);
+	_box.setPoint(2, _box.getPointX(0) + l,	_box.getPointY(0) - h);
+	_box.setPoint(3, _box.getPointX(0) + l,	_box.getPointY(0));
+}
+
+void TextBox::_draw(const Color &col, float size) const
+{
+	_box.draw();
+	if (!_font || _text.empty())
+		return;
+
+	if (_box._visible ) {
+		int bShift = (_box.getPointY(0) - _box.getPointY(1) - _font->height) / 2;
+		ksplot_print_text(_font, NULL,
+				  _box.getPointX(0) + _font->height / 4,
+				  _box.getPointY(0) - _font->base - bShift,
+				  _text.c_str());
+	} else {
+		ksplot_print_text(_font, col.color_c_ptr(),
+				  _box.getPointX(0) + _font->height / 4,
+				  _box.getPointY(0) - _font->base,
+				  _text.c_str());
+	}
+}
 
 /**
  * @brief Create a default Mark.
diff --git a/src/KsPlotTools.hpp b/src/KsPlotTools.hpp
index 6e663737..7f83af2d 100644
--- a/src/KsPlotTools.hpp
+++ b/src/KsPlotTools.hpp
@@ -47,6 +47,8 @@ public:
 
 	void setRainbowColor(int n);
 
+	void blend(float alpha);
+
 	/**
 	 * @brief Get the C struct defining the RGB color.
 	 */
@@ -304,6 +306,46 @@ public:
 };
 
 /**
+ * This class represents a text that is printed/drawn inside a colorful frame.
+ */
+class TextBox : public PlotObject {
+public:
+	TextBox();
+
+	TextBox(ksplot_font *f);
+
+	TextBox(ksplot_font *f, const std::string &text, const Point &pos);
+
+	TextBox(ksplot_font *f, const std::string &text, const Color &col,
+		const Point &pos);
+
+	TextBox(ksplot_font *f, const std::string &text, const Color &col,
+		const Point &pos, int l, int h = -1);
+
+	/** Destroy the TextBox object. Keep this destructor virtual. */
+	virtual ~TextBox() {}
+
+	/** Set the font to be used. */
+	void setFont(ksplot_font *f) {_font = f;}
+
+	/** Set the text. */
+	void setText(const std::string &t) {_text = t;}
+
+	void setPos(const Point &p);
+
+	void setBoxAppearance(const Color &col, int l, int h);
+
+private:
+	void _draw(const Color &, float size = 1.) const override;
+
+	std::string	_text;
+
+	ksplot_font	*_font;
+
+	Rectangle	_box;
+};
+
+/**
  * This class represents the graphical element of the KernelShark GUI marker.
  */
 class Mark : public PlotObject {