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/* ScrollBar.cpp
Copyright (c) 2024 by Daniel Yoon
Endless Sky is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later version.
Endless Sky 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, see <https://www.gnu.org/licenses/>.
*/
#include "ScrollBar.h"
#include "shader/LineShader.h"
#include "shader/PointerShader.h"
#include <algorithm>
namespace {
// Additional distance the scrollbar's tab can be selected from.
constexpr float SCROLLBAR_MOUSE_ADDITIONAL_RANGE = 5.;
}
ScrollBar::ScrollBar(float fraction, float displaySizeFraction, const Point &from, const Point &to,
float tabWidth, float lineWidth, const Color &color, const Color &innerColor) noexcept
: fraction(fraction), displaySizeFraction(displaySizeFraction), from(from), to(to),
tabWidth(tabWidth), lineWidth(lineWidth), color(color), innerColor(innerColor)
{
}
ScrollBar::ScrollBar() noexcept
: ScrollBar(0., 0., Point(), Point(),
3, 3, Color(.6), Color(.25))
{
}
void ScrollBar::Draw()
{
DrawAt(from);
}
void ScrollBar::DrawAt(const Point &from)
{
Point delta = to - this->from;
LineShader::Draw(
from,
from + delta,
lineWidth,
innerHighlighted ? innerColor : Color::Multiply(.5, innerColor)
);
Point deltaOffset = delta * displaySizeFraction;
Point offset = delta * (1 - displaySizeFraction) * fraction;
LineShader::Draw(
from + offset + deltaOffset,
from + offset,
tabWidth,
highlighted ? color : Color::Combine(.5, color, .5, innerColor)
);
PointerShader::Draw(from, Point(0., -1.), lineWidth * 3., 10.f, 5.f, fraction > 0. ? color : innerColor);
PointerShader::Draw(from + delta, Point(0., 1.), lineWidth * 3., 10.f, 5.f, fraction < 1. ? color : innerColor);
}
bool ScrollBar::Hover(int x, int y)
{
Point delta = to - from;
Point offset = delta * (1.0 - displaySizeFraction) * fraction;
// Find the distance from a point (p) to the line segment a->b
// From https://www.shadertoy.com/view/3tdSDj
constexpr auto LineSDF = [](Point a, Point b, Point p)
{
Point ab = b - a;
Point ap = p - a;
double h = std::clamp(ap.Dot(ab) / ab.LengthSquared(), 0., 1.);
double d = (ap - ab * h).Length();
return d;
};
Point a = from + offset;
Point b = a + delta * displaySizeFraction;
Point p(x, y);
highlighted = LineSDF(a, b, p) <= tabWidth + SCROLLBAR_MOUSE_ADDITIONAL_RANGE;
innerHighlighted = LineSDF(from, to, p) <= lineWidth + SCROLLBAR_MOUSE_ADDITIONAL_RANGE;
return false;
}
bool ScrollBar::Drag(double dx, double dy)
{
if(!highlighted)
return false;
Point dragVector(dx, dy);
Point thisVector = to - from;
double scalarProjectionOverLength = thisVector.Dot(dragVector) / thisVector.LengthSquared();
fraction += scalarProjectionOverLength / (1. - displaySizeFraction);
return true;
}
bool ScrollBar::Click(int x, int y, MouseButton button, int clicks)
{
if(button != MouseButton::LEFT)
return false;
Point clickPos(x, y);
if((clickPos - from).Length() < 10.)
{
fraction = std::clamp(fraction - displaySizeFraction * .6f, 0.f, 1.f);
return true;
}
if((clickPos - to).Length() < 10.)
{
fraction = std::clamp(fraction + displaySizeFraction * .6f, 0.f, 1.f);
return true;
}
if(innerHighlighted && !highlighted)
{
Point cursorVector = clickPos - from;
Point thisVector = to - from;
double scalarProjectionOverLength = thisVector.Dot(cursorVector) / thisVector.LengthSquared();
fraction = (scalarProjectionOverLength - .5) / (1. - displaySizeFraction) + .5;
highlighted = true;
}
return highlighted;
}
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