refactor background export treatment

Before introducing more export options later on, refactor the current
code: turn the boolean noBackground/withoutBackground/hideBackground
into an enum ExportBackgroundType exportBackground which currently can
have two values EXPORT_BACKGROUND_ALL and EXPORT_BACKGROUND_NONE.
That way we can extend the enum later on without changing call
signatures; also, enum values are hopefully self-explaining.

No change of behaviour with this commit.

src/control/XournalMain.cpp

@@ -52,10 +52,10 @@ auto migrateSettings() -> MigrateResult;
 void checkForErrorlog();
 void checkForEmergencySave(Control* control);
 
-auto exportPdf(const char* input, const char* output, const char* range, bool noBackground, bool progressiveMode)
-        -> int;
+auto exportPdf(const char* input, const char* output, const char* range, ExportBackgroundType exportBackground,
+               bool progressiveMode) -> int;
 auto exportImg(const char* input, const char* output, const char* range, int pngDpi, int pngWidth, int pngHeight,
-               bool noBackground) -> int;
+               ExportBackgroundType exportBackground) -> int;
 
 void initResourcePath(GladeSearchpath* gladePath, const gchar* relativePathAndFile, bool failIfNotFound = true);
 
@@ -235,14 +235,14 @@ void checkForEmergencySave(Control* control) {
  * @param pngDpi Set dpi for Png files. Non positive values are ignored
  * @param pngWidth Set the width for Png files. Non positive values are ignored
  * @param pngHeight Set the height for Png files. Non positive values are ignored
- * @param noBackground If true, the exported image file has transparent background
+ * @param exportBackground If EXPORT_BACKGROUND_NONE, the exported image file has transparent background
  *
  *  The priority is: pngDpi overwrites pngWidth overwrites pngHeight
  *
  * @return 0 on success, -2 on failure opening the input file, -3 on export failure
  */
 auto exportImg(const char* input, const char* output, const char* range, int pngDpi, int pngWidth, int pngHeight,
-               bool noBackground) -> int {
+               ExportBackgroundType exportBackground) -> int {
     LoadHandler loader;
 
     Document* doc = loader.loadDocument(input);
@@ -267,7 +267,7 @@ auto exportImg(const char* input, const char* output, const char* range, int png
 
     DummyProgressListener progress;
 
-    ImageExport imgExport(doc, path, format, noBackground, exportRange);
+    ImageExport imgExport(doc, path, format, exportBackground, exportRange);
 
     if (format == EXPORT_GRAPHICS_PNG) {
         if (pngDpi > 0) {
@@ -301,14 +301,14 @@ auto exportImg(const char* input, const char* output, const char* range, int png
  * @param input Path to the input file
  * @param output Path to the output file
  * @param range Page range to be parsed. If range=nullptr, exports the whole file
- * @param noBackground If true, the exported pdf file has white background
+ * @param exportBackground If EXPORT_BACKGROUND_NONE, the exported pdf file has white background
  * @param progressiveMode If true, then for each xournalpp page, instead of rendering one PDF page, the page layers are
  * rendered one by one to produce as many pages as there are layers.
  *
  * @return 0 on success, -2 on failure opening the input file, -3 on export failure
  */
-auto exportPdf(const char* input, const char* output, const char* range, bool noBackground, bool progressiveMode)
-        -> int {
+auto exportPdf(const char* input, const char* output, const char* range, ExportBackgroundType exportBackground,
+               bool progressiveMode) -> int {
     LoadHandler loader;
 
     Document* doc = loader.loadDocument(input);
@@ -319,7 +319,7 @@ auto exportPdf(const char* input, const char* output, const char* range, bool no
     GFile* file = g_file_new_for_commandline_arg(output);
 
     XojPdfExport* pdfe = XojPdfExportFactory::createExport(doc, nullptr);
-    pdfe->setNoBackgroundExport(noBackground);
+    pdfe->setExportBackground(exportBackground);
     char* cpath = g_file_get_path(file);
     string path = cpath;
     g_free(cpath);
@@ -584,11 +584,13 @@ auto on_handle_local_options(GApplication*, GVariantDict*, XMPtr app_data) -> gi
 
     if (app_data->pdfFilename && app_data->optFilename && *app_data->optFilename) {
         return exportPdf(*app_data->optFilename, app_data->pdfFilename, app_data->exportRange,
-                         app_data->exportNoBackground, app_data->progressiveMode);
+                         app_data->exportNoBackground ? EXPORT_BACKGROUND_NONE : EXPORT_BACKGROUND_ALL,
+                         app_data->progressiveMode);
     }
     if (app_data->imgFilename && app_data->optFilename && *app_data->optFilename) {
         return exportImg(*app_data->optFilename, app_data->imgFilename, app_data->exportRange, app_data->exportPngDpi,
-                         app_data->exportPngWidth, app_data->exportPngHeight, app_data->exportNoBackground);
+                         app_data->exportPngWidth, app_data->exportPngHeight,
+                         app_data->exportNoBackground ? EXPORT_BACKGROUND_NONE : EXPORT_BACKGROUND_ALL);
     }
     return -1;
 }

src/control/jobs/BaseExportJob.h

@@ -19,6 +19,12 @@
 #include "XournalType.h"
 #include "filesystem.h"
 
+/**
+ *  @brief List of types for the export of background components.
+ *  Keep the order so that one can check for intermediate types using comparsion.
+ */
+enum ExportBackgroundType { EXPORT_BACKGROUND_NONE, EXPORT_BACKGROUND_ALL };
+
 class Control;
 
 class BaseExportJob: public BlockingJob {
@@ -56,8 +62,8 @@ protected:
     class ExportType {
     public:
         string extension;
-        bool withoutBackground;
+        ExportBackgroundType exportBackground;
 
-        ExportType(string ext, bool hideBg): extension(ext), withoutBackground(hideBg) {}
+        ExportType(string ext, ExportBackgroundType exportBg): extension(ext), exportBackground(exportBg) {}
     };
 };

src/control/jobs/CustomExportJob.cpp

@@ -18,13 +18,13 @@
 
 CustomExportJob::CustomExportJob(Control* control): BaseExportJob(control, _("Custom Export")) {
     // Supported filters
-    filters[_("PDF files")] = new ExportType(".pdf", false);
-    filters[_("PDF with plain background")] = new ExportType(".pdf", true);
-    filters[_("PNG graphics")] = new ExportType(".png", false);
-    filters[_("PNG with transparent background")] = new ExportType(".png", true);
-    filters[_("SVG graphics")] = new ExportType(".svg", false);
-    filters[_("SVG with transparent background")] = new ExportType(".svg", true);
-    filters[_("Xournal (Compatibility)")] = new ExportType(".xoj", false);
+    filters[_("PDF files")] = new ExportType(".pdf", EXPORT_BACKGROUND_ALL);
+    filters[_("PDF with plain background")] = new ExportType(".pdf", EXPORT_BACKGROUND_NONE);
+    filters[_("PNG graphics")] = new ExportType(".png", EXPORT_BACKGROUND_ALL);
+    filters[_("PNG with transparent background")] = new ExportType(".png", EXPORT_BACKGROUND_NONE);
+    filters[_("SVG graphics")] = new ExportType(".svg", EXPORT_BACKGROUND_ALL);
+    filters[_("SVG with transparent background")] = new ExportType(".svg", EXPORT_BACKGROUND_NONE);
+    filters[_("Xournal (Compatibility)")] = new ExportType(".xoj", EXPORT_BACKGROUND_ALL);
 }
 
 CustomExportJob::~CustomExportJob() {
@@ -109,8 +109,8 @@ auto CustomExportJob::showFilechooser() -> bool {
  * Create one Graphics file per page
  */
 void CustomExportJob::exportGraphics() {
-    bool hideBackground = filters.at(this->chosenFilterName)->withoutBackground;
-    ImageExport imgExport(control->getDocument(), filepath, format, hideBackground, exportRange);
+    ExportBackgroundType exportBackground = filters.at(this->chosenFilterName)->exportBackground;
+    ImageExport imgExport(control->getDocument(), filepath, format, exportBackground, exportRange);
     if (format == EXPORT_GRAPHICS_PNG) {
         imgExport.setQualityParameter(pngQualityParameter);
     }
@@ -141,7 +141,7 @@ void CustomExportJob::run() {
 
         XojPdfExport* pdfe = XojPdfExportFactory::createExport(doc, control);
 
-        pdfe->setNoBackgroundExport(filters[this->chosenFilterName]->withoutBackground);
+        pdfe->setExportBackground(filters[this->chosenFilterName]->exportBackground);
 
         if (!pdfe->createPdf(this->filepath, exportRange, progressiveMode)) {
             this->errorMsg = pdfe->getLastError();

src/control/jobs/ImageExport.cpp

@@ -13,9 +13,9 @@
 #include "i18n.h"
 
 
-ImageExport::ImageExport(Document* doc, fs::path file, ExportGraphicsFormat format, bool hideBackground,
-                         PageRangeVector& exportRange):
-        doc(doc), file(std::move(file)), format(format), hideBackground(hideBackground), exportRange(exportRange) {}
+ImageExport::ImageExport(Document* doc, fs::path file, ExportGraphicsFormat format,
+                         ExportBackgroundType exportBackground, PageRangeVector& exportRange):
+        doc(doc), file(std::move(file)), format(format), exportBackground(exportBackground), exportRange(exportRange) {}
 
 ImageExport::~ImageExport() = default;
 
@@ -144,14 +144,14 @@ void ImageExport::exportImagePage(int pageId, int id, double zoomRatio, ExportGr
         return;
     }
 
-    if (page->getBackgroundType().isPdfPage() && !hideBackground) {
+    if (page->getBackgroundType().isPdfPage() && (exportBackground == EXPORT_BACKGROUND_ALL)) {
         int pgNo = page->getPdfPageNr();
         XojPdfPageSPtr popplerPage = doc->getPdfPage(pgNo);
 
         PdfView::drawPage(nullptr, popplerPage, cr, zoomRatio, page->getWidth(), page->getHeight());
     }
 
-    view.drawPage(page, this->cr, true, hideBackground);
+    view.drawPage(page, this->cr, true, exportBackground == EXPORT_BACKGROUND_NONE);
 
     if (!freeSurface(id)) {
         // could not create this file...

src/control/jobs/ImageExport.h

@@ -18,6 +18,7 @@
 
 #include "view/DocumentView.h"
 
+#include "BaseExportJob.h"
 #include "PageRange.h"
 #include "XournalType.h"
 #include "filesystem.h"
@@ -27,7 +28,6 @@ class ProgressListener;
 
 enum ExportGraphicsFormat { EXPORT_GRAPHICS_UNDEFINED, EXPORT_GRAPHICS_PDF, EXPORT_GRAPHICS_PNG, EXPORT_GRAPHICS_SVG };
 
-
 /**
  * @brief List of available criterion for determining a PNG export quality.
  * The order must agree with the corresponding listAvailableCriterion in ui/exportSettings.glade
@@ -68,7 +68,7 @@ private:
  */
 class ImageExport {
 public:
-    ImageExport(Document* doc, fs::path file, ExportGraphicsFormat format, bool hideBackground,
+    ImageExport(Document* doc, fs::path file, ExportGraphicsFormat format, ExportBackgroundType exportBackground,
                 PageRangeVector& exportRange);
     virtual ~ImageExport();
 
@@ -155,7 +155,7 @@ public:
     /**
      * Do not export the Background
      */
-    bool hideBackground = false;
+    ExportBackgroundType exportBackground = EXPORT_BACKGROUND_ALL;
 
     /**
      * The range to export

src/pdf/base/XojCairoPdfExport.cpp

@@ -24,8 +24,8 @@ XojCairoPdfExport::~XojCairoPdfExport() {
 /**
  * Export without background
  */
-void XojCairoPdfExport::setNoBackgroundExport(bool noBackgroundExport) {
-    this->noBackgroundExport = noBackgroundExport;
+void XojCairoPdfExport::setExportBackground(ExportBackgroundType exportBackground) {
+    this->exportBackground = exportBackground;
 }
 
 auto XojCairoPdfExport::startPdf(const fs::path& file) -> bool {
@@ -106,14 +106,14 @@ void XojCairoPdfExport::exportPage(size_t page) {
     DocumentView view;
 
     cairo_save(this->cr);
-    if (p->getBackgroundType().isPdfPage() && !noBackgroundExport) {
+    if (p->getBackgroundType().isPdfPage() && (exportBackground == EXPORT_BACKGROUND_ALL)) {
         int pgNo = p->getPdfPageNr();
         XojPdfPageSPtr popplerPage = doc->getPdfPage(pgNo);
 
         popplerPage->render(cr, true);
     }
 
-    view.drawPage(p, this->cr, true /* dont render eraseable */, noBackgroundExport);
+    view.drawPage(p, this->cr, true /* dont render eraseable */, exportBackground == EXPORT_BACKGROUND_NONE);
 
     // next page
     cairo_show_page(this->cr);

src/pdf/base/XojCairoPdfExport.h

@@ -11,6 +11,7 @@
 
 #pragma once
 
+#include "control/jobs/BaseExportJob.h"
 #include "control/jobs/ProgressListener.h"
 #include "model/Document.h"
 
@@ -30,7 +31,7 @@ public:
     /**
      * Export without background
      */
-    virtual void setNoBackgroundExport(bool noBackgroundExport);
+    virtual void setExportBackground(ExportBackgroundType exportBackground);
 
 private:
     bool startPdf(const fs::path& file);
@@ -59,7 +60,7 @@ private:
     cairo_surface_t* surface = nullptr;
     cairo_t* cr = nullptr;
 
-    bool noBackgroundExport = false;
+    ExportBackgroundType exportBackground = EXPORT_BACKGROUND_ALL;
 
     string lastError;
 };

src/pdf/base/XojPdfExport.cpp

@@ -7,6 +7,6 @@ XojPdfExport::~XojPdfExport() = default;
 /**
  * Export without background
  */
-void XojPdfExport::setNoBackgroundExport(bool noBackgroundExport) {
+void XojPdfExport::setExportBackground(ExportBackgroundType exportBackground) {
     // Does nothing in the base class
 }

src/pdf/base/XojPdfExport.h

@@ -14,6 +14,8 @@
 #include <string>
 #include <vector>
 
+#include "control/jobs/BaseExportJob.h"
+
 #include "PageRange.h"
 #include "XournalType.h"
 #include "filesystem.h"
@@ -31,7 +33,7 @@ public:
     /**
      * Export without background
      */
-    virtual void setNoBackgroundExport(bool noBackgroundExport);
+    virtual void setExportBackground(ExportBackgroundType exportBackground);
 
 private:
 };