Printer and Recording Medium

The disclosure discloses a printer including an operation device, a display device, and a controller. The controller executes a condition deciding process, a determining process, a first mode switching process, and a second mode switching process. In the condition deciding process, printable conditions in a length and a width direction are decided. In the determining process, it is determining whether contents after the edit operation satisfy the printable conditions. In the first mode switching process, the operation mode is switched from a real-time preview mode to a text input mode in the case that the printable conditions are not satisfied. In the second mode switching process, the operation mode is returned from the text input mode to the real-time preview mode in the case that the printable conditions are satisfied after the operation mode is switched to the text input mode.