1 files changed, 249 insertions, 0 deletions
diff --git a/src/ui/cursor-utils.cpp b/src/ui/cursor-utils.cpp
new file mode 100644
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--- /dev/null
+++ b/src/ui/cursor-utils.cpp
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cursor utilities
+ *
+ * Copyright (C) 2020 Tavmjong Bah
+ *
+ * The contents of this file may be used under the GNU General Public License Version 2 or later.
+ *
+ */
+
+#include <iomanip>
+#include <sstream>
+#include <unordered_map>
+#include <boost/functional/hash.hpp>
+
+#include "cursor-utils.h"
+
+#include "document.h"
+#include "preferences.h"
+
+#include "display/cairo-utils.h"
+
+#include "helper/pixbuf-ops.h"
+
+#include "io/file.h"
+#include "io/resource.h"
+
+#include "object/sp-object.h"
+#include "object/sp-root.h"
+
+#include "util/units.h"
+
+using Inkscape::IO::Resource::SYSTEM;
+using Inkscape::IO::Resource::ICONS;
+
+namespace Inkscape {
+
+// SVG cursor unique ID/key
+typedef std::tuple<std::string, std::string, std::string, guint32, guint32, double, double, bool, int> Key;
+
+struct KeyHasher {
+    std::size_t operator () (const Key& k) const { return boost::hash_value(k); }
+};
+
+/**
+ * Loads an SVG cursor from the specified file name.
+ *
+ * Returns pointer to cursor (or null cursor if we could not load a cursor).
+ */
+Glib::RefPtr<Gdk::Cursor>
+load_svg_cursor(Glib::RefPtr<Gdk::Display> display,
+                Glib::RefPtr<Gdk::Window> window,
+                std::string const &file_name,
+                guint32 fill,
+                guint32 stroke,
+                double fill_opacity,
+                double stroke_opacity)
+{
+    // GTK puts cursors in a "cursors" subdirectory of icon themes. We'll do the same... but
+    // note that we cannot use the normal GTK method for loading cursors as GTK knows nothing
+    // about scalable SVG cursors. We must locate and load the files ourselves. (Even if
+    // GTK could handle scalable cursors, we would need to load the files ourselves inorder
+    // to modify CSS 'fill' and 'stroke' properties.)
+
+    Glib::RefPtr<Gdk::Cursor> cursor;
+
+    // Make list of icon themes, highest priority first.
+    std::vector<std::string> theme_names;
+
+    // Set in preferences
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    Glib::ustring theme_name = prefs->getString("/theme/iconTheme", prefs->getString("/theme/defaultIconTheme", ""));
+    if (!theme_name.empty()) {
+        theme_names.push_back(theme_name);
+    }
+
+    // System
+    theme_name = Gtk::Settings::get_default()->property_gtk_icon_theme_name();
+    theme_names.push_back(theme_name);
+
+    // Our default
+    theme_names.emplace_back("hicolor");
+
+    // quantize opacity to limit number of cursor variations we generate
+    fill_opacity   = std::floor(std::clamp(fill_opacity,   0.0, 1.0) * 100) / 100;
+    stroke_opacity = std::floor(std::clamp(stroke_opacity, 0.0, 1.0) * 100) / 100;
+
+    const auto enable_drop_shadow = prefs->getBool("/options/cursor-drop-shadow", true);
+
+    // Find the rendered size of the icon.
+    int scale = 1;
+    bool cursor_scaling = false;
+#ifndef GDK_WINDOWING_QUARTZ
+    // Default cursor size (get_default_cursor_size()) fixed to 32 on Quartz. Cursor scaling handled elsewhere.
+
+    cursor_scaling = prefs->getBool("/options/cursorscaling"); // Fractional scaling is broken but we can't detect it.
+    if (cursor_scaling) {
+        scale = window->get_scale_factor(); // Adjust for HiDPI screens.
+    }
+#endif
+    static std::unordered_map<Key, Glib::RefPtr<Gdk::Cursor>, KeyHasher> cursor_cache;
+    Key cursor_key;
+
+    const auto cache_enabled = prefs->getBool("/options/cache_svg_cursors", true);
+    if (cache_enabled) {
+        // construct a key
+        cursor_key = std::make_tuple(std::string(theme_names[0]), std::string(theme_names[1]), file_name, fill, stroke, fill_opacity, stroke_opacity, enable_drop_shadow, scale);
+        if (auto cursor = cursor_cache[cursor_key]) {
+            return cursor;
+        }
+    }
+
+    // Find theme paths.
+    auto screen = display->get_default_screen();
+    auto icon_theme = Gtk::IconTheme::get_for_screen(screen);
+    auto theme_paths = icon_theme->get_search_path();
+
+    // Loop over theme names and paths, looking for file.
+    Glib::RefPtr<Gio::File> file;
+    std::string full_file_path;
+    for (auto theme_name : theme_names) {
+        for (auto theme_path : theme_paths) {
+            full_file_path = Glib::build_filename(theme_path, theme_name, "cursors", file_name);
+            // std::cout << "Checking: " << full_file_path << std::endl;
+            file = Gio::File::create_for_path(full_file_path);
+            if (file->query_exists()) break;
+        }
+        if (file->query_exists()) break;
+    }
+
+    if (!file->query_exists()) {
+        std::cerr << "load_svg_cursor: Cannot locate cursor file: " << file_name << std::endl;
+        return cursor;
+    }
+
+    bool cancelled = false;
+    std::unique_ptr<SPDocument> document;
+    document.reset(ink_file_open(file, &cancelled));
+
+    if (!document) {
+        std::cerr << "load_svg_cursor: Could not open document: " << full_file_path << std::endl;
+        return cursor;
+    }
+
+    SPRoot *root = document->getRoot();
+    if (!root) {
+        std::cerr << "load_svg_cursor: Could not find SVG element: " << full_file_path << std::endl;
+        return cursor;
+    }
+
+    // Set the CSS 'fill' and 'stroke' properties on the SVG element (for cascading).
+    SPCSSAttr *css = sp_repr_css_attr(root->getRepr(), "style");
+
+    std::stringstream fill_stream;
+    fill_stream << "#"
+                << std::setfill ('0') << std::setw(6)
+                << std::hex << (fill >> 8);
+    std::stringstream stroke_stream;
+    stroke_stream << "#"
+                  << std::setfill ('0') << std::setw(6)
+                  << std::hex << (stroke >> 8);
+
+    sp_repr_css_set_property(css, "fill",   fill_stream.str().c_str());
+    sp_repr_css_set_property(css, "stroke", stroke_stream.str().c_str());
+    sp_repr_css_set_property_double(css, "fill-opacity",   fill_opacity);
+    sp_repr_css_set_property_double(css, "stroke-opacity", stroke_opacity);
+    root->changeCSS(css, "style");
+    sp_repr_css_attr_unref(css);
+
+    if (!enable_drop_shadow) {
+        // turn off drop shadow, if any
+        Glib::ustring shadow("drop-shadow");
+        auto objects = document->getObjectsByClass(shadow);
+        for (auto&& el : objects) {
+            if (auto val = el->getAttribute("class")) {
+                Glib::ustring cls = val;
+                auto pos = cls.find(shadow);
+                if (pos != Glib::ustring::npos) {
+                    cls.erase(pos, shadow.length());
+                }
+                el->setAttribute("class", cls);
+            }
+        }
+    }
+
+    // Check for maximum size
+    // int mwidth = 0;
+    // int mheight = 0;
+    // display->get_maximal_cursor_size(mwidth, mheight);
+    // int normal_size = display->get_default_cursor_size();
+
+    auto w = document->getWidth().value("px");
+    auto h = document->getHeight().value("px");
+    // Calculate the hotspot.
+    int hotspot_x = root->getIntAttribute("inkscape:hotspot_x", 0); // Do not include window scale factor!
+    int hotspot_y = root->getIntAttribute("inkscape:hotspot_y", 0);
+
+    Geom::Rect area(0, 0, cursor_scaling ? w * scale : w, cursor_scaling ? h * scale : h);
+    int dpi = 96 * scale;
+    // render document into internal bitmap; returns null on failure
+    if (auto ink_pixbuf = std::unique_ptr<Inkscape::Pixbuf>(sp_generate_internal_bitmap(document.get(), area, dpi))) {
+       if (cursor_scaling) {
+            // creating cursor from Cairo surface rather than pixbuf gives us opportunity to set device scaling;
+            // what that means in practice is we can prepare high-res image and it will be used as-is on
+            // a high-res display; cursors created from pixbuf are up-scaled to device pixels (blurry)
+            auto surface = ink_pixbuf->getSurface();
+            if (surface && surface->cobj()) {
+                cairo_surface_set_device_scale(surface->cobj(), scale, scale);
+                cursor = Gdk::Cursor::create(display, surface, hotspot_x, hotspot_y);
+            }
+            else {
+                std::cerr << "load_svg_cursor: failed to get surface for: " << full_file_path << std::endl;
+            }
+        }
+        else {
+            // original code path when cursor scaling is turned off in preferences
+            auto pixbuf = Glib::wrap(ink_pixbuf->getPixbufRaw(), true);
+
+            if (pixbuf) {
+                cursor = Gdk::Cursor::create(display, pixbuf, hotspot_x, hotspot_y);
+            }
+        }
+    } else {
+        std::cerr << "load_svg_cursor: failed to create pixbuf for: " << full_file_path << std::endl;
+    }
+
+    // Explicit delete required for SPDocument to be freed
+    // see https://gitlab.com/inkscape/inkscape/-/issues/2723
+    delete document.release();
+
+    if (cache_enabled) {
+        cursor_cache[cursor_key] = cursor;
+    }
+
+    return cursor;
+}
+
+} // Namespace
+
+/*
+  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 :