Canon' s CR2 format is included compiled with raw.
When viewing a folder with .cr2 files photoqt does not show any files choosing "All supported images". However, cr2 is supported by imagemagick and ufraw so the following simple diff makes them appear in the photoqt's window
$ cat /etc/portage/patches/media-gfx/photoqt/photoqt-support-cannon.patch
diff --git a/cplusplus/settings/fileformatsavailable.h b/cplusplus/settings/fileformatsavailable.h
index 71e2079..cdb1fdf 100644
--- a/cplusplus/settings/fileformatsavailable.h
+++ b/cplusplus/settings/fileformatsavailable.h
@@ -310,7 +310,7 @@ namespace FileFormatsHandler {
<< "*.ari" // ARRIFLEX
<< "*.arw" << "*.srf" << "*.sr2" // Sony
<< "*.bay" // Casio
- << "*.crw" << "*.crr" // Canon
+ << "*.crw" << "*.crr" << "*.cr2" // Canon
<< "*.cap" << "*.liq" << "*.eip" // Phase_one
<< "*.dcs" << "*.dcr" << "*.drf" // Kodak
<< "*.k25" << "*.kdc"
diff --git a/cplusplus/settings/fileformatsdefaultenabled.h b/cplusplus/settings/fileformatsdefaultenabled.h
index fd6d957..f59eb71 100644
--- a/cplusplus/settings/fileformatsdefaultenabled.h
+++ b/cplusplus/settings/fileformatsdefaultenabled.h
@@ -148,7 +148,7 @@ namespace FileFormatsHandler {
<< "*.ari" // ARRIFLEX
<< "*.arw" << "*.srf" << "*.sr2" // Sony
<< "*.bay" // Casio
- << "*.crw" << "*.crr" // Canon
+ << "*.crw" << "*.crr" << "*.cr2" // Canon
<< "*.cap" << "*.liq" << "*.eip" // Phase_one
<< "*.dcs" << "*.dcr" << "*.drf" // Kodak
<< "*.k25" << "*.kdc"
diff --git a/qml/settingsmanager/tabs/other/FileTypesRaw.qml b/qml/settingsmanager/tabs/other/FileTypesRaw.qml
index 54f109d..6b58458 100644
--- a/qml/settingsmanager/tabs/other/FileTypesRaw.qml
+++ b/qml/settingsmanager/tabs/other/FileTypesRaw.qml
@@ -88,7 +88,7 @@ EntryContainer {
["ARRIFLEX","*.ari"],
["Sony","*.arw","*.srf","*.sr2"],
["Casio","*.bay"],
- ["Canon","*.crw","*.crr"],
+ ["Canon","*.crw","*.crr","*.cr2"],
["Phase_one","*.cap","*.liq","*.eip"],
["Kodak","*.dcs","*.dcr","*.drf","*.k25","*.kdc"],
["Adobe","*.dng"],
Edited by Potuz V