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84a0a62988
Make framebuffer font documentation match reality Expose glyph cache size as a configuration option svn path=/trunk/netsurf/; revision=10871
202 lines
7.3 KiB
Plaintext
202 lines
7.3 KiB
Plaintext
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Usage Instructions for Framebuffer NetSurf 2nd October 2010
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This document provides usage instructions for the Framebuffer version of
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NetSurf.
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Framebuffer NetSurf has been tested on Ubuntu and Debian.
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Overview
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========
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What it is
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----------
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The NetSurf framebuffer front end is primarily intended for kiosk
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and embedded applications where there is insufficient Operating
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System support for a full graphical windowing environment.
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The framebuffer frontend features:
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* A trivial occluded rectangle window management toolkit
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* Font handling system using either:
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- A trivial internal monochrome bitmap glyph set.
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- An interface to fully anti-aliased glyphs using libfreetype 2
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* Uses libnsfb to provide transparent support for:
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- Numerous surface providers allowing usage on Linux, X, SDL, VNC
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and any mapped linear memory region.
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- Surface depths of 8, 16, 24 and 32bpp
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- Optimised software plotters for lines, rectangles, polygons,
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arbitrary ellipses (including circles), cubic and quadratic
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splines, font glyphs and 32bpp RGBA bitmaps.
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- Abstracted input handling.
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What it is not
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--------------
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The framebuffer frontend is not a replacement for full native
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ports. It lacks functionality and flexibility compared to such
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implementations.
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Limitations include:
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- Single window interface.
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- No tabbed interface.
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- Expects to control the entire plotting surface.
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- No ability to re-size a surface after initialisation.
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- Inflexible input character mapping.
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- Limited history view.
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In addition it should be noted support for some libnsfb surfaces has
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been implemented purely for debugging functionality (SDL
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especially) and is not intended to replace native surface
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handlers.
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If a high level windowing system is available then a native NetSurf
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frontend is almost certainly a better choice than attempting to use
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the framebuffer frontend.
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If there is a graphical environment which supports GTK then using
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the GTK frontend is a vastly superior choice. The framebuffer
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frontend will appear exceptionally limited on such capable systems.
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Configuring
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===========
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Several resources are set at *compile* time and are not changeable at
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run time such as the icon bitmaps, the font system to use and what
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default surface to use. Refer to the BUILDING-Framebuffer document
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for details.
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Toolkit Options
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---------------
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The trivial toolkit has some configuration parameters allowing the
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user to alter specific aspects of the UI. All the sizes are in
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surface pixels however that is mapped.
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fb_furniture_size
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This is the size allowed for the scroll bar elements.
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fb_toolbar_size
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The height of the toolbar.
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fb_toolbar_layout
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The layout of the toolbar, layout uses a string to define buttons
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type and position each character adds an element to the toolbar:
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b - back
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l - local history
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f - forward
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s - stop
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r - refresh
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u - url bar expands to fit remaining space
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t - throbber/activity indicator
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c - close the current window
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The default layout is "blfsrut" there should be no more than a
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single url bar entry. If the option is set to the empty string (no
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spaces permitted) the toolbar is disabled altogether.
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fb_osk
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Whether the on screen keyboard should be enabled for input.
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Framebuffer Surface
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-------------------
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There are four command line switches which override compiled in
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defaults these are:
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-f <handler>
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Selects a surface handler to pass to libnsfb instead of the
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default. (e.g. x, sdl, mem, linux)
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-b <depth>
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Selects the pixel depth to pass to libnsfb instead of the
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compiled in default. (one of 8, 16, 24, 32)
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-w <width>
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Selects the surface width to pass to libnsfb instead of the
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compiled in default.
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-h <height>
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Selects the surface height to pass to libnsfb instead of the
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compiled in default.
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As with any NetSurf frontend run-time configuration is read from a
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"Choices-fb" file. This file is a simple key:value list. In addition
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to the standard values supported by the NetSurf core there are a
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number of values to control specific aspects of the framebuffer
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version.
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The libnsfb surface parameters are controlled with:
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fb_refresh - The refresh rate (for physical displays)
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fb_depth - The depth (in bits per pixel) of the surface
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fb_device - The path to the device (for physical displays)
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fb_input_devpath - The path to the input devices (for linux input layer)
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fb_input_glob - The input device selection glob (for linux input layer)
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window_width - The width of the framebuffer
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window_height - The height of the framebuffer
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The defaults are for 800 by 600 pixels at 16bpp and 70Hz refresh rate.
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The documentation of libnsfb should be consulted for further
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information about supported surfaces and their configuration.
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Fonts
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-----
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If the compile time option is set to use the freetype font system
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then several configuration options are available. If the simple
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bitmap glyphs are used none of these options apply.
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Font faces are provided for the css default styles of sans serif,
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serif, monospace, cursive and fantasy. Only the sans serif
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non-italic normal weight font is required to exist, If any of the
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other faces are missing the sans serif font will be used instead.
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The compiled in default font file paths are specified within the
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build time Makefile.config. The default faces is the truetype DejaVu
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font set in the directory /usr/share/fonts/truetype/ttf-dejavu/
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The font glyphs are, by default, rendered as 256 level transparency
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which gives excellent visual results even on small font sizes.
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The font selection may be changed by placing truetype font files
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in the resources path. The resource files will be the generic names
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sans_serif.ttf, sans_serif_bold.ttf etc.
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The font system is configured at run-time by several options:
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fb_font_monochrome
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This option causes the renderer to use monochrome glyph
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rendering. This method of rendering is much less visually
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appealing and while faster to plot it is slower to render.
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fb_font_cachesize
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This option sets the number of kilobytes of memory set aside for
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caching the rendered glyphs. This caching significantly improves
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the performance of using the freetype rendering system. It is set
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to 2048 by default (2 Megabytes of memory) which impiracle testing
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shows to be a suitable value for the seven default faces.
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The remaining options control the files to be used for font faces. The
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font file name options will override both the compiled in paths and
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files found in the resource path.
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fb_face_sans_serif - The sans serif face
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fb_face_sans_serif_bold - The bold sans serif face
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fb_face_sans_serif_italic - The italic sans serif face
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fb_face_sans_serif_italic_bold - The bold italic sans serif face.
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fb_face_serif - The serif font
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fb_face_serif_bold - The bold serif font
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fb_face_monospace - The monospaced font
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fb_face_monospace_bold - The bold monospaced font
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fb_face_cursive - The cursive font
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fb_face_fantasy - The fantasy font
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