path: root/src/display/control/canvas-item-rect.cpp

// SPDX-License-Identifier: GPL-2.0-or-later
/**
 * A class to represent a control rectangle. Used for rubberband selector, page outline, etc.
 */

/*
 * Author:
 *   Tavmjong Bah
 *
 * Copyright (C) 2020 Tavmjong Bah
 *
 * Rewrite of CtrlRect
 *
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */

#include <cairo/cairo.h>

#include "canvas-item-rect.h"
#include "display/cairo-utils.h"

#include "color.h"    // SP_RGBA_x_F
#include "inkscape.h" //
#include "ui/widget/canvas.h"
#include "display/cairo-utils.h"     // Checkerboard background.

namespace Inkscape {

/**
 * Create an null control rect.
 */
CanvasItemRect::CanvasItemRect(CanvasItemGroup *group)
    : CanvasItem(group)
{
    _name = "CanvasItemRect:Null";
    _pickable = false; // For now, nobody gets events from this class!
}

/**
 * Create a control rect. Point are in document coordinates.
 */
CanvasItemRect::CanvasItemRect(CanvasItemGroup *group, Geom::Rect const &rect)
    : CanvasItem(group)
    , _rect(rect)
{
    _name = "CanvasItemRect";
    _pickable = false; // For now, nobody gets events from this class!
    request_update();
}

/**
 * Set a control rect. Points are in document coordinates.
 */
void CanvasItemRect::set_rect(Geom::Rect const &rect)
{
    _rect = rect;
    request_update();
}

/**
 * Returns distance between point in canvas units and nearest point in rect (zero if inside rect).
 * Only valid if canvas is not rotated. (A rotated Geom::Rect yields a new axis-aligned Geom::Rect
 * that contains the original rectangle; not a rotated rectangle.)
 */
double CanvasItemRect::closest_distance_to(Geom::Point const &p)
{
    if (_affine.isNonzeroRotation()) {
        std::cerr << "CanvasItemRect::closest_distance_to: Affine includes rotation!" << std::endl;
    }

    Geom::Rect rect = _rect;
    rect *= _affine; // Convert from document to canvas coordinates. (TODO Cache this.)
    return Geom::distance(p, rect);
}

/**
 * Returns true if point p (in canvas units) is within tolerance (canvas units) distance of rect.
 * Non-zero tolerance not implemented! Is valid for a rotated canvas.
 */
bool CanvasItemRect::contains(Geom::Point const &p, double tolerance)
{
    if (tolerance != 0) {
        std::cerr << "CanvasItemRect::contains: Non-zero tolerance not implemented!" << std::endl;
    }

    Geom::Point p0 = _rect.corner(0) * _affine;
    Geom::Point p1 = _rect.corner(1) * _affine;
    Geom::Point p2 = _rect.corner(2) * _affine;
    Geom::Point p3 = _rect.corner(3) * _affine;

    // From 2geom rotated-rect.cpp
    return
        Geom::cross(p1 - p0, p - p0) >= 0 &&
        Geom::cross(p2 - p1, p - p1) >= 0 &&
        Geom::cross(p3 - p2, p - p2) >= 0 &&
        Geom::cross(p0 - p3, p - p3) >= 0;
}

/**
 * Update and redraw control rect.
 */
void CanvasItemRect::update(Geom::Affine const &affine)
{
    if (_affine == affine && !_need_update) {
        // Nothing to do.
        return;
    }

    if (_rect.area() == 0) {
        return; // Nothing to show
    }

    // Queue redraw of old area (erase previous content).
    request_redraw();

    // Get new bounds
    _affine = affine;

    // Enlarge bbox by twice shadow size (to allow for shadow on any side with a 45deg rotation).
    _bounds = _rect;
    // note: add shadow size before applying transformation, since get_shadow_size accounts for scale
    _bounds.expandBy(2 * get_shadow_size());
    _bounds *= _affine;
    _bounds.expandBy(2); // Room for stroke.

    // Queue redraw of new area
    request_redraw();

    _need_update = false;
}

/**
 * Render rect to screen via Cairo.
 */
void CanvasItemRect::render(Inkscape::CanvasItemBuffer *buf)
{
    if (!buf) {
        std::cerr << "CanvasItemRect::Render: No buffer!" << std::endl;
         return;
    }

    if (!_bounds.intersects(buf->rect)) {
        return; // Rectangle not inside buffer rectangle.
    }

    if (!_visible) {
        // Hidden
        return;
    }

    // Geom::Rect is an axis-aligned rectangle. We need to rotate it if the canvas is rotated!

    // Get canvas rotation (scale is isotropic).
    double rotation = atan2(_affine[1], _affine[0]);

    // Are we axis aligned?
    double mod_rot = fmod(rotation * M_2_PI, 1);
    bool axis_aligned = Geom::are_near(mod_rot, 0) || Geom::are_near(mod_rot, 1.0);

    // Get the points we need transformed into window coordinates.
    Geom::Point rect_transformed[4];
    for (unsigned int i = 0; i < 4; ++i) {
        rect_transformed[i] = _rect.corner(i) * _affine;
    }

    auto rect = _rect;

    using Geom::X;
    using Geom::Y;

    if (axis_aligned) {
        auto temp = _rect * _affine;
        auto min = temp.min();
        auto max = temp.max();
        auto pixgrid = Geom::Rect(
            Geom::Point(floor(min[X]) + 0.5, floor(min[Y]) + 0.5),
            Geom::Point(floor(max[X]) + 0.5, floor(max[Y]) + 0.5));
        rect = pixgrid * _affine.inverse();
    }

    buf->cr->save();
    buf->cr->translate(-buf->rect.left(), -buf->rect.top());

    if (_inverted) {
        // buf->cr->set_operator(Cairo::OPERATOR_XOR); // Blend mode operators do not have C++ bindings!
        cairo_set_operator(buf->cr->cobj(), CAIRO_OPERATOR_DIFFERENCE);
    }

    // fill background?
    if (_background && !buf->outline_overlay_pass) {
        buf->cr->save();
        Cairo::Matrix m(_affine[0], _affine[1], _affine[2], _affine[3], _affine[4], _affine[5]);
        buf->cr->transform(m);
        buf->cr->rectangle(rect.corner(0)[X], rect.corner(0)[Y], rect.width(), rect.height());
        // counter fill scaling (necessary for checkerboard pattern)
        _background->set_matrix(m);
        buf->cr->set_source(_background);
        buf->cr->fill();
        buf->cr->restore();
    }

    cairo_pattern_t *pattern = _canvas->get_background_pattern()->cobj();
    guint32 backcolor = ink_cairo_pattern_get_argb32(pattern);
    EXTRACT_ARGB32(backcolor, ab,rb,gb,bb)

    // Draw shadow first. Shadow extends under rectangle to reduce aliasing effects.
    if (_shadow_width > 0 && !_dashed) {
        // there's only one UI knob to adjust border and shadow color, so instead of using border color
        // transparency as is, it is boosted by this function, since shadow attenuates it
        const auto a = (exp(-3 * SP_RGBA32_A_F(_shadow_color)) - 1) / (exp(-3) - 1);
        buf->cr->save();

        auto affine = _affine;
        if (auto desktop = _canvas->get_desktop()) {
            rect *= desktop->doc2dt();
            affine = desktop->doc2dt() * affine;
        }
        Cairo::Matrix m(affine[0], affine[1], affine[2], affine[3], affine[4], affine[5]);
        buf->cr->transform(m);
        ink_cairo_draw_drop_shadow(buf->cr, rect, get_shadow_size(), _shadow_color, a);
        buf->cr->restore();
    }

    // Setup rectangle path
    if (axis_aligned) {

        // Snap to pixel grid
        Geom::Rect outline( _rect.min() * _affine, _rect.max() * _affine);
        buf->cr->rectangle(floor(outline.min()[X])+0.5,
                           floor(outline.min()[Y])+0.5,
                           floor(outline.max()[X]) - floor(outline.min()[X]),
                           floor(outline.max()[Y]) - floor(outline.min()[Y]));
    } else {

        // Rotated
        buf->cr->move_to(rect_transformed[0][X], rect_transformed[0][Y] );
        buf->cr->line_to(rect_transformed[1][X], rect_transformed[1][Y] );
        buf->cr->line_to(rect_transformed[2][X], rect_transformed[2][Y] );
        buf->cr->line_to(rect_transformed[3][X], rect_transformed[3][Y] );
        buf->cr->close_path();
    }
    static std::valarray<double> dashes = {4.0, 4.0};
    if (_dashed) {
        buf->cr->set_dash(dashes, -0.5);
    }
    // Draw border (stroke).
    buf->cr->set_line_width(1);
    // we maybe have painted the background, back to "normal" compositing
    
    buf->cr->set_source_rgba(SP_RGBA32_R_F(_stroke), SP_RGBA32_G_F(_stroke),
                             SP_RGBA32_B_F(_stroke), SP_RGBA32_A_F(_stroke));
    buf->cr->stroke_preserve();

    // Highlight the border by drawing it in _shadow_color.
    if (_shadow_width == 1 && _dashed) {
        buf->cr->set_dash(dashes, 3.5); // Dash offset by dash length.
        buf->cr->set_source_rgba(SP_RGBA32_R_F(_shadow_color), SP_RGBA32_G_F(_shadow_color),
                                 SP_RGBA32_B_F(_shadow_color), SP_RGBA32_A_F(_shadow_color));
        buf->cr->stroke_preserve();
    }

    buf->cr->begin_new_path(); // Clear path or get weird artifacts.

    // Uncomment to show bounds
    // Geom::Rect bounds = _bounds;
    // bounds.expandBy(-1);
    // bounds -= buf->rect.min();
    // buf->cr->set_source_rgba(1.0, 0.0, _shadow_width / 3.0, 1.0);
    // buf->cr->rectangle(bounds.min().x(), bounds.min().y(), bounds.width(), bounds.height());
    // buf->cr->stroke();

    buf->cr->restore();
}

void CanvasItemRect::set_dashed(bool dashed)
{
    if (_dashed != dashed) {
        _dashed = dashed;
        request_redraw();
    }
}

void CanvasItemRect::set_inverted(bool inverted)
{
    if (_inverted != inverted) {
        _inverted = inverted;
        request_redraw();
    }
}

void CanvasItemRect::set_shadow(guint32 color, int width)
{
    if (_shadow_color != color || _shadow_width != width) {
        _shadow_color = color;
        _shadow_width = width;
        request_redraw();
    }
}

void CanvasItemRect::set_background(guint32 background) {
    _set_background(Cairo::SolidPattern::create_rgba(SP_RGBA32_R_F(background), SP_RGBA32_G_F(background), SP_RGBA32_B_F(background), SP_RGBA32_A_F(background)));
}

void CanvasItemRect::_set_background(Cairo::RefPtr<Cairo::Pattern> background) {
    if (_background != background) {
        _background = background;
        request_redraw();
    }
}

double CanvasItemRect::get_scale() const {
    return sqrt(_affine[0] * _affine[0] + _affine[1] * _affine[1]);
}

double CanvasItemRect::get_shadow_size() const {
    // gradient drop shadow needs much more room than solid one, so inflating the size;
    // fudge factor of 6 used to make sizes baked in svg documents work as steps:
    // typical value of 2 will work out to 12 pixels which is a narrow shadow (b/c of exponential fall of)
    auto size = _shadow_width * 6;
    if (size < 0) {
        size = 0;
    }
    else if (size > 120) {
        // arbitrarily selected max size, so Cairo gradient doesn't blow up if document has bogus shadow values
        size = 120;
    }
    auto scale = get_scale();

    // calculate space for gradient shadow; if divided by 'scale' it would be zoom independent (fixed in size);
    // if 'scale' is not used, drop shadow will be getting smaller with document zoom;
    // here hybrid approach is used: "unscaling" with square root of scale allows shadows to diminish
    // more slowly at small zoom levels (so it's still perceptible) and grow more slowly at high mag (where it doesn't matter, b/c it's typically off-screen)
    return size / (scale > 0 ? sqrt(scale) : 1);
}

void CanvasItemRect::set_background_checkerboard(guint32 rgba, bool use_alpha) {
    auto pattern = ink_cairo_pattern_create_checkerboard(rgba, use_alpha);
    auto background = Cairo::RefPtr<Cairo::Pattern>(new Cairo::Pattern(pattern));
    _set_background(background);
}

} // namespace Inkscape

/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :