README
¶
Foreword
This repository is fork of firelizzard18/framebuffer with module paths fixed so that it can be used in project.
About
The framebuffer library was created to have an easy way to access the pixels on the screen from the Raspberry Pi. It memory-maps the framebuffer device and provides it as a draw.Image (which is itself an image.Image). This makes it easy to use with Go's image, color and draw packages.
Right now the library only implements the RGB 565 color model, which is the default under Raspbian. Also the OS is assumed to be little endian, also the default for Raspbian.
Usage
To access the framebuffer you have to call Open and pass the device file to it. When you are done, call Close on the returned device. Note that you usually need root access for this so make sure to run your program as a super user.
Once you have a device open you can use it like a Go draw.Image (image.Image).
Here is a simple example that clears the whole screen to a dark magenta:
package main
import (
"github.com/d21d3q/framebuffer"
"image"
"image/color"
"image/draw"
)
func main() {
fb, err := framebuffer.Open("/dev/fb0")
if err != nil {
panic(err)
}
defer fb.Close()
magenta := image.NewUniform(color.RGBA{255, 0, 128, 255})
draw.Draw(fb, fb.Bounds(), magenta, image.ZP, draw.Src)
}
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type FbBitField ¶
<linux/fb.h> struct fb_bitfield
Interpretation of offset for color fields: All offsets are from the right, inside a "pixel" value, which is exactly 'bits_per_pixel' wide (means: you can use the offset as right argument to <<). A pixel afterwards is a bit stream and is written to video memory as that unmodified.
For pseudocolor: offset and length should be the same for all color components. Offset specifies the position of the least significant bit of the palette index in a pixel value. Length indicates the number of available palette entries (i.e. # of entries = 1 << length).
type FbFixScreenInfo ¶
type FbFixScreenInfo struct {
// Screen ID, e.g. "TT Builtin"
ID [16]byte
// Frame buffer mem (physical address)
SMemStart uintptr
SMemLen uint32
// Framebuffer type (see FB_TYPE_*)
Type uint32
// "Interleave for interleaved Planes"
TypeAux uint32
// ??? (see FB_VISUAL_)
Visual uint32
XPanStep uint16
YPanStep uint16
YWrapStep uint16
// Length of a line in bytes
LineLength uint32
// Memory mapped I/O (physical address)
MmioStart uintptr
MmioLen uint32
// "Indicate to driver which specific chip/card we have"
Accel uint32
// Capabilities (see FB_CAP_*)
Capabilities uint16
// contains filtered or unexported fields
}
<linux/fb.h> struct fb_fix_screeninfo
Fixed parameters of a screen
type FbVarScreenInfo ¶
type FbVarScreenInfo struct {
// Visible resolution
XRes, YRes uint32
// Virtual resolution
XResVirtual, YResVirtual uint32
// Offset from virtual to visible resolution
XOffset, YOffset uint32
// Number of bits per pixel in the buffer
BitsPerPixel uint32
// 0 = color, 1 = grayscale, >1 = FOURCC
Grayscale uint32
// Pixel format
Red, Green, Blue, Alpha FbBitField
// A value other than zero indicates a non-standard pixel format
NonStd uint32
// ??? (see FB_ACTIVATE_*)
Activate uint32
// Dimensions of picture in mm
Height, Width uint32
// Pixel clock in pico seconds
PixelClock uint32
// Time from sync to picture
LeftMargin uint32
// Time from picture to sync
RightMargin uint32
UpperMargin uint32
LowerMargin uint32
// Length of horizontal sync
HSyncLen uint32
// Length of vertical sync
VSyncLen uint32
// ??? (see FB_SYNC_*)
Sync uint32
// ??? (see FB_VMODE_*)
VMode uint32
// Angle we rotate counter clockwise
Rotate uint32
// Color space for FOURCC-based modes
ColorSpace uint32
// contains filtered or unexported fields
}
<linux/fb.h> struct fb_fix_screeninfo
Variable parameters of a screen
type FrameBuffer ¶
FrameBuffer is a wrapper around os.File that provides convenience methods for interacting with a frame buffer device.
func OpenFrameBuffer ¶
func OpenFrameBuffer(name string, flags int) (*FrameBuffer, error)
OpenFrameBuffer opens a frame buffer device.
func (*FrameBuffer) File ¶
func (fb *FrameBuffer) File() *os.File
File converts the frame buffer back to a file.
func (*FrameBuffer) FixScreenInfo ¶
func (fb *FrameBuffer) FixScreenInfo() (FbFixScreenInfo, error)
FixScreenInfo returns the fixed properties of the screen.
func (*FrameBuffer) Pixels ¶
func (fb *FrameBuffer) Pixels() ([]byte, error)
Pixels returns a byte slice memory mapped to the frame buffer.
func (*FrameBuffer) VarScreenInfo ¶
func (fb *FrameBuffer) VarScreenInfo() (FbVarScreenInfo, error)
VarScreenInfo returns the variable properties of the screen.
type Image ¶
type Image struct {
// contains filtered or unexported fields
}
func (*Image) ColorModel ¶
ColorModel returns the color model of the frame buffer.
type TTY ¶
TTY is a wrapper around os.File that provides convenience methods for interacting with a TTY.
func (*TTY) GraphicsMode ¶
GraphicsMode puts the TTY in graphics mode.
Source Files