5.2. Esteettömyys

Some users may need specific support because of e.g. some visual impairment. USB braille displays are detected automatically (not serial displays connected via a serial-to-USB converter), but most other accessibility features have to be enabled manually. On machines that support it, the boot menu emits beeps when it is ready to receive keystrokes. It beeps once on BIOS systems, and beeps twice on UEFI systems. Some boot parameters can then be appended to enable accessibility features (see also Kohta 5.1.7, ”Käynnistysruutu”). Note that on most architectures the boot loader interprets your keyboard as a QWERTY keyboard.

5.2.1. Installer front-end

The Debian installer supports several front-ends for asking questions, with varying convenience for accessibility: notably, text uses plain text while newt uses text-based dialog boxes. The choice can be made at the boot prompt, see the documentation for DEBIAN_FRONTEND in Kohta 5.3.2, ”Debianin asentimen parametrit”.

5.2.2. USB pistekirjoitusnäytöt

USB pistekirjoitusnäyttöjen pitäisi tunnistua automaattisesti. Tällöin automaattisesti valitaan asentimen tekstikäyttöliittymä ja asennetaan kohdejärjestelmään tuki pistekirjoitusnäytölle. Pelkkä näppäimen Enter painallus käynnistysvalikossa siis riittää. Kun brltty on käynnistynyt, voidaan pistekirjoitustaulukko valita asetusvalikosta. Ohjeita pistekirjoitusnäyttöjen näppäinoikoteista löytyy brltty:n webbisivulta.

5.2.3. Sarjaportin pistekirjoitusnäytöt

Serial braille displays cannot safely be automatically detected (since that may damage some of them). You thus need to append the brltty=driver,port boot parameter to tell brltty which driver and port it should use. driver should be replaced by the two-letter driver code for your terminal (see the BRLTTY manual). port should be replaced by the name of the serial port the display is connected to, ttyS0 is the default, ttyUSB0 can be typically used when using a serial-to-USB converter. A third parameter can be provided, to choose the name of the braille table to be used (see the BRLTTY manual); the English table is the default. Note that the table can be changed later by entering the preference menu. A fourth parameter can be provided to pass parameters to the braille driver, such as protocol=foo which is needed for some rare models. Documentation on key bindings for braille devices is available on the brltty website.

5.2.4. Software Speech Synthesis

Support for software speech synthesis is available on all installer images which have the graphical installer, i.e. all netinst, CD and DVD images, and the netboot gtk variant. It can be activated by selecting it in the boot menu by typing s Enter. The textual version of the installer will then be automatically selected, and support for software speech synthesis will be automatically installed on the target system.

If several sound cards are detected, you will be prompted to press Enter when you hear speech from the desired sound card.

The first question (language) is spoken in english, and the remainder of installation is spoken in the selected language (if available in espeak).

The default speech rate is quite slow. To make it faster, press CapsLock+6. To make it slower, press CapsLock+5. The default volume should be medium. To make it louder, press CapsLock+2. To make it quieter, press CapsLock+1. To get more details on the browsing shortcuts, see the Speakup guide. To just accept the default answer for a question, simply press Enter at the prompt. To provide an empty answer for a question, type ! at the prompt. To get back to the previous question, type < at the prompt.

5.2.5. Puhesyntetisaattorilaitteet

Support for hardware speech synthesis devices is available on all installer images which have the graphical installer, i.e. all netinst, CD and DVD images, and the netboot gtk variant. You thus need to select a Graphical install entry in the boot menu.

Puhesyntetisaattorilaitteita ei voi automaattisesti tunnistaa. On siis lisättävä käynnistysvalitsin speakup.synth=driver josta speakup tietää mitä ajuria tulee käyttää. driver tulee korvata laitteen ajurikoodilla (katso drive code list). Tällöin automaattisesti valitaan asentimen tekstiversio ja asennetaan kohdejärjestelmään tuki puhesyntetisaattorilaitteelle.

5.2.6. Lisälaittekortit

Jotkin esteettömyyslaitteet ovat lisälaitekortteja jotka asennetaan tietokoneen sisään ja lukevat tekstiä suoraan näyttömuistista. Jotta ne toimisivat on tuki ruutupuskurille poistettava käytöstä käynnistysvalitsimella vga=normal fb=false. Tämä toisaalta pienentää käytettävissä olevien kielten määrää.

Haluttaessa voidaan käynnistyslataimen tekstiversio aktivoida ennen käynnistystarkentimen lisäämistä kirjoittamalla h Enter.

5.2.7. Suurikonstrastinen teema

For users with low vision, the installer can use a high-contrast color theme that makes it more readable. To enable it, you can use the Accessible high contrast entry from the boot screen with the d shortcut, or append the theme=dark boot parameter.

5.2.8. Zoom

For users with low vision, the graphical installer has a very basic zoom support: the Control++ and Control+- shortcuts increase and decrease the font size.

5.2.9. Expert install, rescue mode, automated install

Expert, Rescue, and Automated installation choices are also available with accessibility support. To access them, one has to first enter the Advanced options submenu from the boot menu by typing a. When using a BIOS system (the boot menu will have beeped only once), this has to be followed by Enter ; for UEFI systems (the boot menu will have beeped twice) that must not be done. Then, to enable speech synthesis, s can optionally be pressed (followed again by Enter on BIOS systems but not on UEFI systems). From there, various shortcuts can be used: x for expert installation, r for rescue mode, or a for automated installation. Again these need to be followed by Enter when using a BIOS system.

The automated install choice allows to install Debian completely automatically by using preseeding, whose source can be entered after accessibility features get started. Preseeding itself is documented in Liite B, Asennuksen automatisointi valmiilla vastauksilla.

5.2.10. Accessibility of the installed system

Documentation on accessibility of the installed system is available on the Debian Accessibility wiki page.