1 files changed, 208 insertions, 0 deletions
diff --git a/src/ui/widget/export-preview.cpp b/src/ui/widget/export-preview.cpp
new file mode 100644
index 0000000..cf99258
--- /dev/null
+++ b/src/ui/widget/export-preview.cpp
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Authors:
+ *   Anshudhar Kumar Singh <anshudhar2001@gmail.com>
+ *
+ * Copyright (C) 2021 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "export-preview.h"
+
+#include "document.h"
+#include "display/cairo-utils.h"
+#include "object/sp-item.h"
+#include "object/sp-root.h"
+#include "util/preview.h"
+#include "io/resource.h"
+
+namespace Inkscape {
+namespace UI {
+namespace Dialog {
+
+/**
+ * A preview drawing object is responsible for constructing a drawing and showing it's contents
+ *
+ * On destruction it will gracefully invoke hide itself. You should destroy this object when
+ * you need to change the document object being used for the preview.
+ */
+PreviewDrawing::PreviewDrawing(SPDocument *doc)
+{
+    _document = doc;
+}
+
+PreviewDrawing::~PreviewDrawing()
+{
+    destruct();
+    _document = nullptr;
+}
+
+void PreviewDrawing::destruct()
+{
+    if (!_visionkey)
+        return;
+
+    // On exiting the document root might have gone already.
+    if (auto root = _document->getRoot()) {
+        root->invoke_hide(_visionkey);
+    }
+    _drawing.reset();
+    _visionkey = 0;
+}
+
+/**
+ * Construct the drawing, when needed
+ */
+void PreviewDrawing::construct()
+{
+    auto drawing = std::make_shared<Inkscape::Drawing>();
+    _visionkey = SPItem::display_key_new(1);
+    if (auto di = _document->getRoot()->invoke_show(*drawing, _visionkey, SP_ITEM_SHOW_DISPLAY)) {
+        drawing->setRoot(di);
+    } else {
+        drawing.reset();
+    }
+
+    if (!_shown_items.empty()) {
+        _document->getRoot()->invoke_hide_except(_visionkey, _shown_items);
+    }
+    _drawing = drawing;
+}
+
+/**
+  * Render the drawing into a cairo image surface.
+  */
+bool PreviewDrawing::render(ExportPreview *widget, uint32_t bg, SPItem *item, unsigned size, Geom::OptRect const &dbox)
+{
+    if (!_drawing || _to_destruct) {
+        if (!_construct_idle.connected()) {
+            _construct_idle = Glib::signal_timeout().connect([=]() {
+                _to_destruct = false;
+                destruct();
+                construct();
+                return false;
+            }, 100);
+        }
+        return false;
+    }
+
+    Geom::OptRect bbox = dbox;
+    DrawingItem *di = nullptr;
+
+    if (item) {
+        bbox = item->documentVisualBounds();
+        di = item->get_arenaitem(_visionkey);
+    } else if (!dbox)
+        bbox = _document->getRoot()->documentVisualBounds();
+
+    if (!bbox)
+        return true; // Force quit
+
+    // Use a callback to set the preview rendering;
+    widget->setPreview(UI::Preview::render_preview(_document, _drawing, bg, di, size, size, *bbox));
+    return true;
+}
+
+/**
+ * Limit the preview to just these items.
+ *
+ * You must call refresh after this for the change to take effect.
+ */
+void PreviewDrawing::set_shown_items(std::vector<SPItem*> &&list)
+{
+    _shown_items = std::move(list);
+    _to_destruct = true;
+}
+
+void ExportPreview::resetPixels(bool new_size)
+{
+    clear();
+    // An icon to use when the preview hasn't loaded yet
+    static Glib::RefPtr<Gdk::Pixbuf> preview_loading;
+    if (!preview_loading || new_size) {
+        using namespace Inkscape::IO::Resource;
+        preview_loading = Gdk::Pixbuf::create_from_file(get_filename(PIXMAPS, "preview_loading.svg"), size, size);
+    }
+    if (preview_loading) {
+        set(preview_loading);
+    }
+    show();
+}
+
+void ExportPreview::setSize(int newSize)
+{
+    size = newSize;
+    resetPixels(true);
+}
+
+ExportPreview::~ExportPreview()
+{
+    refresh_conn.disconnect();
+}
+
+void ExportPreview::setItem(SPItem *item)
+{
+    _item = item;
+    _dbox = {};
+}
+
+void ExportPreview::setBox(Geom::Rect const &bbox)
+{
+    if (bbox.hasZeroArea())
+        return;
+
+    _item = nullptr;
+    _dbox = bbox;
+}
+
+void ExportPreview::setDrawing(std::shared_ptr<PreviewDrawing> drawing)
+{
+    _drawing = drawing;
+}
+
+/*
+ * This is the main function which finally renders the preview.
+ * If dbox is given it will use it.
+ * if item is given and not dbox then item is used.
+ * If both are not given then we simply do nothing.
+ */
+void ExportPreview::queueRefresh()
+{
+    if (!_drawing || _render_idle.connected())
+        return;
+
+    _render_idle = Glib::signal_timeout().connect([=]() {
+        return !_drawing->render(this, _bg_color, _item, size, _dbox);
+    }, 100);
+}
+
+/**
+ * Callback when the rendering is complete.
+ */
+void ExportPreview::setPreview(Cairo::RefPtr<Cairo::ImageSurface> surface)
+{
+    if (surface) {
+        set(Gdk::Pixbuf::create(surface, 0, 0, surface->get_width(), surface->get_height()));
+        show();
+    }
+}
+
+void ExportPreview::setBackgroundColor(uint32_t bg_color)
+{
+    _bg_color = bg_color;
+}
+
+} // namespace Dialog
+} // namespace UI
+} // 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:fileencoding=utf-8:textwidth=99 :