1 files changed, 312 insertions, 0 deletions
diff --git a/src/display/control/canvas-item-guideline.cpp b/src/display/control/canvas-item-guideline.cpp
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+++ b/src/display/control/canvas-item-guideline.cpp
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * A class to represent a control guide line.
+ */
+
+/*
+ * Authors:
+ *   Tavmjong Bah       - Rewrite of SPGuideLine
+ *   Rafael Siejakowski - Tweaks to handle appearance
+ *
+ * Copyright (C) 2020-2022 the Authors.
+ *
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <2geom/line.h>
+
+#include "canvas-item-guideline.h"
+#include "canvas-item-ctrl.h"
+
+#include "desktop.h" // Canvas orientation so label is orientated correctly.
+#include "ui/widget/canvas.h"
+
+namespace Inkscape {
+
+/**
+ * Create a control guide line. Points are in document units.
+ */
+CanvasItemGuideLine::CanvasItemGuideLine(CanvasItemGroup *group, Glib::ustring label,
+                                         Geom::Point const &origin, Geom::Point const &normal)
+    : CanvasItem(group)
+    , _origin(origin)
+    , _normal(normal)
+    , _label(std::move(label))
+{
+    _name = "CanvasItemGuideLine:" + _label;
+    _pickable = true; // For now, everybody gets events from this class!
+
+    // Control to move guide line.
+    _origin_ctrl = make_canvasitem<CanvasItemGuideHandle>(group, _origin, this);
+    _origin_ctrl->set_name("CanvasItemGuideLine:Ctrl:" + _label);
+    _origin_ctrl->set_size_default();
+    _origin_ctrl->set_pickable(true); // The handle will also react to dragging
+    set_locked(false); // Init _origin_ctrl shape and stroke.
+}
+
+/**
+ * Sets origin of guide line (place where handle is located).
+ */
+void CanvasItemGuideLine::set_origin(Geom::Point const &origin)
+{
+    if (_origin != origin) {
+        _origin = origin;
+        _origin_ctrl->set_position(_origin);
+        request_update();
+    }
+}
+
+/**
+ * Sets orientation of guide line.
+ */
+void CanvasItemGuideLine::set_normal(Geom::Point const &normal)
+{
+    if (_normal != normal) {
+        _normal = normal;
+        request_update();
+    }
+}
+
+/**
+ * Sets the inverted nature of the line
+ */
+void CanvasItemGuideLine::set_inverted(bool inverted)
+{
+    if (_inverted != inverted) {
+        _inverted = inverted;
+        request_update();
+    }
+}
+
+/**
+ * Returns distance between point in canvas units and nearest point on guideLine.
+ */
+double CanvasItemGuideLine::closest_distance_to(Geom::Point const &p)
+{
+    // Maybe store guide as a Geom::Line?
+    auto guide = Geom::Line::from_origin_and_vector(_origin, Geom::rot90(_normal));
+    guide *= affine();
+    return Geom::distance(p, guide);
+}
+
+/**
+ * Returns true if point p (in canvas units) is within tolerance (canvas units) distance of guideLine (or 1 if tolerance is zero).
+ */
+bool CanvasItemGuideLine::contains(Geom::Point const &p, double tolerance)
+{
+    if (tolerance == 0) {
+        tolerance = 1; // Can't pick of zero!
+    }
+
+    return closest_distance_to(p) < tolerance;
+}
+
+/**
+ * Returns the pointer to the origin control (the "dot")
+ */
+CanvasItemGuideHandle* CanvasItemGuideLine::dot() const
+{
+    return _origin_ctrl.get();
+}
+
+/**
+ * Update and redraw control guideLine.
+ */
+void CanvasItemGuideLine::_update(bool)
+{
+    // Required when rotating canvas
+    _bounds = Geom::Rect(-Geom::infinity(), -Geom::infinity(), Geom::infinity(), Geom::infinity());
+
+    // Queue redraw of new area (and old too).
+    request_redraw();
+}
+
+/**
+ * Render guideLine to screen via Cairo.
+ */
+void CanvasItemGuideLine::_render(Inkscape::CanvasItemBuffer &buf) const
+{
+    // Document to canvas
+    Geom::Point const normal = _normal * affine().withoutTranslation(); // Direction only
+    Geom::Point const origin = _origin * affine();
+
+    /* Need to use floor()+0.5 such that Cairo will draw us lines with a width of a single pixel,
+     * without any aliasing. For this we need to position the lines at exactly half pixels, see
+     * https://www.cairographics.org/FAQ/#sharp_lines
+     * Must be consistent with the pixel alignment of the grid lines, see CanvasXYGrid::Render(),
+     * and the drawing of the rulers.
+     * Lastly, the origin control is also pixel-aligned and we want to visually cut through its
+     * exact center.
+     */
+    Geom::Point const aligned_origin = origin.floor() + Geom::Point(0.5, 0.5);
+
+    // Set up the Cairo rendering context
+    auto ctx = buf.cr;
+    ctx->save();
+    ctx->translate(-buf.rect.left(), -buf.rect.top()); // Canvas to screen
+    ctx->set_source_rgba(SP_RGBA32_R_F(_stroke), SP_RGBA32_G_F(_stroke),
+                         SP_RGBA32_B_F(_stroke), SP_RGBA32_A_F(_stroke));
+    ctx->set_line_width(1);
+
+    if (_inverted) {
+        // operator not available in cairo C++ bindings
+        cairo_set_operator(ctx->cobj(), CAIRO_OPERATOR_DIFFERENCE);
+    }
+
+    if (!_label.empty()) { // Render text label
+        ctx->save();
+        ctx->translate(aligned_origin.x(), aligned_origin.y());
+
+        auto desktop = get_canvas()->get_desktop();
+        ctx->rotate(atan2(normal.cw()) + M_PI * (desktop && desktop->is_yaxisdown() ? 1 : 0));
+        ctx->translate(0, -(_origin_ctrl->radius() + LABEL_SEP)); // Offset by dot radius + 2
+        ctx->move_to(0, 0);
+        ctx->show_text(_label);
+        ctx->restore();
+    }
+
+    // Draw guide.
+    // Special case: horizontal and vertical lines (easier calculations)
+
+    // Don't use isHorizontal()/isVertical() as they test only exact matches.
+    if (Geom::are_near(normal.y(), 0.0)) {
+        // Vertical
+        double const position = aligned_origin.x();
+        ctx->move_to(position, buf.rect.top()    + 0.5);
+        ctx->line_to(position, buf.rect.bottom() - 0.5);
+    } else if (Geom::are_near(normal.x(), 0.0)) {
+        // Horizontal
+        double position = aligned_origin.y();
+        ctx->move_to(buf.rect.left()  + 0.5, position);
+        ctx->line_to(buf.rect.right() - 0.5, position);
+    } else {
+        // Angled
+        Geom::Line line = Geom::Line::from_origin_and_vector(aligned_origin, Geom::rot90(normal));
+
+        // Find intersections of the line with buf rectangle. There should be zero or two.
+        std::vector<Geom::Point> intersections;
+        for (unsigned i = 0; i < 4; ++i) {
+            Geom::LineSegment side(buf.rect.corner(i), buf.rect.corner((i+1)%4));
+            try {
+                Geom::OptCrossing oc = Geom::intersection(line, side);
+                if (oc) {
+                    intersections.push_back(line.pointAt(oc->ta));
+                }
+            } catch (Geom::InfiniteSolutions const &) {
+                // Shouldn't happen as we have already taken care of horizontal/vertical guides.
+                std::cerr << "CanvasItemGuideLine::render: Error: Infinite intersections." << std::endl;
+            }
+        }
+
+        if (intersections.size() == 2) {
+            double const x0 = intersections[0].x();
+            double const x1 = intersections[1].x();
+            double const y0 = intersections[0].y();
+            double const y1 = intersections[1].y();
+            ctx->move_to(x0, y0);
+            ctx->line_to(x1, y1);
+        }
+    }
+    ctx->stroke();
+
+    ctx->restore();
+}
+
+void CanvasItemGuideLine::set_visible(bool visible)
+{
+    CanvasItem::set_visible(visible);
+    _origin_ctrl->set_visible(visible);
+}
+
+void CanvasItemGuideLine::set_stroke(uint32_t color)
+{
+    // Make sure the fill of the control is the same as the stroke
+    // of the guide-line:
+    _origin_ctrl->set_fill(color);
+    CanvasItem::set_stroke(color);
+}
+
+void CanvasItemGuideLine::set_label(Glib::ustring &&label)
+{
+    defer([=, label = std::move(label)] () mutable {
+        if (_label == label) return;
+        _label = std::move(label);
+        request_update();
+    });
+}
+
+void CanvasItemGuideLine::set_locked(bool locked)
+{
+    defer([=] {
+        if (_locked == locked) return;
+        _locked = locked;
+        if (_locked) {
+            _origin_ctrl->set_shape(CANVAS_ITEM_CTRL_SHAPE_CROSS);
+            _origin_ctrl->set_stroke(CONTROL_LOCKED_COLOR);
+            _origin_ctrl->set_fill(0x00000000);   // no fill
+        } else {
+            _origin_ctrl->set_shape(CANVAS_ITEM_CTRL_SHAPE_CIRCLE);
+            _origin_ctrl->set_stroke(0x00000000); // no stroke
+            _origin_ctrl->set_fill(_stroke);      // fill the control with this guide's color
+        }
+    });
+}
+
+//===============================================================================================
+
+/**
+ * @brief Create a handle ("dot") along a guide line
+ * @param group - the associated canvas item group
+ * @param pos   - position
+ * @param line  - pointer to the corresponding guide line
+ */
+CanvasItemGuideHandle::CanvasItemGuideHandle(CanvasItemGroup *group,
+                                             Geom::Point const &pos,
+                                             CanvasItemGuideLine* line)
+    : CanvasItemCtrl(group, CANVAS_ITEM_CTRL_SHAPE_CIRCLE, pos)
+    , _my_line(line) // Save a pointer to our guide line
+{
+}
+
+/**
+ * Return the radius of the handle dot
+ */
+double CanvasItemGuideHandle::radius() const
+{
+    return 0.5 * static_cast<double>(_width); // radius is half the width
+}
+
+/**
+ * Update the size of the handle based on the index from Preferences
+ */
+void CanvasItemGuideHandle::set_size_via_index(int index)
+{
+    double const r = static_cast<double>(index) * SCALE;
+    unsigned long const rounded_diameter = std::lround(r * 2.0); // diameter is twice the radius
+    unsigned long size = rounded_diameter | 0x1; // make sure the size is always odd
+    if (size < MINIMUM_SIZE) {
+        size = MINIMUM_SIZE;
+    }
+    defer([=] {
+        if (_width == size) return;
+        _width = size;
+        _height = size;
+        _built.reset();
+        request_update();
+        _my_line->request_update();
+    });
+}
+
+} // 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 :