QuickSnapshot plugin added to xournal++.

Add a 'saveAs' dialog function for the Lua api

Fixed the QuickScreenshot plugin to work with scrot (gnome-screenshot polluted the xournalpp window)

Fixed the comments in QuickScreenshot/main.lua to reflect current changes.

Fixed formatting in QuickScreenshot files and luapi_application.h

plugins/QuickScreenshot/main.lua

@@ -0,0 +1,112 @@
+-- The QuickScreenshot plugin:
+--
+-- Allows the user to save a region to disk as png image.
+-- To be used so that users can save various diagrams, etc
+-- to their directory of choice; useful when creating a lot
+-- of diagrams for presentation.
+--
+-- TODO:
+--  o Support for Windows and macOS is missing. To add support
+--    you must edit the functions 'existsUtility' and 'go' to
+--    use the right system programs.
+--
+
+-- Returns 'true' if the system utility exists;
+-- returns 'false' otherwise. This is a dangerous function,
+-- since the argument to popen is not sanitized.
+-- The programmer must ensure that the argument to
+-- existsUtility() is sanitized (not malicious).
+function existsUtility(utility)
+  if operatingSystem == "Windows" then
+    -- Windows not supported yet.
+  elseif operatingSystem == "Darwin" then
+    -- macOS not supported yet.
+  else
+    local f = assert(io.popen("command -v " .. utility))
+    local s = assert(f:read('*a'))
+    f:close()
+    return s ~= ""
+  end
+end
+
+-- Return one of "Windows", "Linux", "Darwin", "FreeBSD",
+-- "OpenBSD" or "NetBSD", etc.
+function findOS()
+  if package.config:sub(1,1) == '\\' then
+    return "Windows"
+  else
+    local f = assert(io.popen("uname -s", 'r'))
+    local s = assert(f:read('*a'))
+    f:close()
+    return s
+  end
+end
+
+-- Register all Toolbar actions and intialize all UI stuff
+function initUi()
+  ref = app.registerUi({["menu"] = "QuickScreenshot", ["callback"] = "go", ["accelerator"] = "<Shift><Alt>t"});
+  operatingSystem = findOS() -- What's the operating system?
+end
+
+-- This is the callback that gets executed when the user
+-- activates the plugin via the menu or hotkey.
+--
+-- This function calls 'app.saveAs' to create
+-- a "Save As" dialog for the user to choose the
+-- filename where the image should reside. Then
+-- it executes a screenshot utility to capture the
+-- region the user selects.
+function go()
+  local windowsUtilities = {} -- list of windows programs here
+  local macUtilities = {} -- list of macOS programs here
+  local elseUtilities = -- list of programs for other systems
+    { "scrot --overwrite --select --silent "
+-- gnome-screenshot behaves oddly (pollutes the window)
+-- the line is added here to be indicative of what
+-- adding another utility looks like.
+--
+--  , "gnome-screenshot --area --file="
+    }
+
+  -- Different operating systems have different
+  -- screenshot utilities, so we check the OS here
+  if operatingSystem == "Windows" then
+    app.msgbox("Windows not supported yet.", {[1] = "OK"})
+  elseif operatingSystem == "Darwin" then
+    app.msgbox("macOS not supported yet.", {[1] = "OK"})
+  else
+    -- This becomes true if at least one screenshot
+    -- utility is available on the system
+    local foundUtility = false
+    -- Check utility availability and use it
+    for i,command in ipairs(elseUtilities) do
+      utilityName = command:match("%S+")
+      if existsUtility(utilityName) then
+        local tmpFilename = os.tmpname()
+        local runCommand = assert(io.popen(command .. tmpFilename .. " &"))
+        runCommand:read('*all')
+        runCommand:close()
+
+        -- Launch the "Save As" dialog
+        local filename = app.saveAs()
+        if not filename then
+          os.remove(tmpFilename)
+          return
+        end
+
+        os.rename(tmpFilename, filename)
+        foundUtility = true
+        break
+      end
+    end
+    -- No utility available on the system, inform the user
+    if not foundUtility then
+      print("Missing screenshot utility.")
+      print("Please install one of:")
+      for i,command in ipairs(elseUtilities) do
+        print(command:match("%S+"))
+      end
+      return
+    end
+  end
+end

plugins/QuickScreenshot/plugin.ini

@@ -0,0 +1,15 @@
+[about]
+## Author / Copyright notice
+author=Debbie Reynolds
+
+description=Capture a region of the screen and save to PNG, or other.
+
+## If the plugin is packed with Xournal++, use
+## <xournalpp> then it gets the same version number
+version=<xournalpp>
+
+[default]
+enabled=false
+
+[plugin]
+mainfile=main.lua

src/plugin/luapi_application.h

@@ -9,6 +9,7 @@
  * @license GNU GPLv2 or later
  */
 
+#include <cstring>
 #include <map>
 
 #include "control/Control.h"
@@ -19,6 +20,43 @@
 #include "XojMsgBox.h"
 using std::map;
 
+/**
+ * Create a 'Save As' native dialog and return as a string
+ * the filepath of the location the user chose to save.
+ */
+static int applib_saveAs(lua_State* L) {
+    GtkFileChooserNative* native;
+    gint res;
+    int args_returned = 0;  // change to 1 if user chooses file
+
+    // Create a 'Save As' native dialog
+    native = gtk_file_chooser_native_new(_("Save file"), nullptr, GTK_FILE_CHOOSER_ACTION_SAVE, nullptr, nullptr);
+
+    // If user tries to overwrite a file, ask if it's OK
+    gtk_file_chooser_set_do_overwrite_confirmation(GTK_FILE_CHOOSER(native), TRUE);
+    // Offer a suggestion for the filename
+    gchar* default_filename = g_strconcat(_("Untitled"), ".png", nullptr);
+    gtk_file_chooser_set_current_name(GTK_FILE_CHOOSER(native), default_filename);
+
+    // Wait until user responds to dialog
+    res = gtk_native_dialog_run(GTK_NATIVE_DIALOG(native));
+
+    // Return the filename chosen to lua
+    if (res == GTK_RESPONSE_ACCEPT) {
+        char* filename = static_cast<char*>(gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(native)));
+
+        lua_pushlstring(L, filename, strlen(filename));
+        g_free(static_cast<gchar*>(filename));
+        args_returned = 1;
+    }
+
+    // Destroy the dialog and free memory
+    g_object_unref(native);
+    g_free(default_filename);
+
+    return args_returned;
+}
+
 /**
  * Example:
  * app.msgbox("Test123", {[1] = "Yes", [2] = "No"})
@@ -201,6 +239,7 @@ static const luaL_Reg applib[] = {{"msgbox", applib_msgbox},
                                   {"uiAction", applib_uiAction},
                                   {"uiActionSelected", applib_uiActionSelected},
                                   {"changeCurrentPageBackground", applib_changeCurrentPageBackground},
+                                  {"saveAs", applib_saveAs},
 
                                   // Placeholder
                                   //	{"MSG_BT_OK", nullptr},