ePaper Display Library
Description
Basic GUI library for ePaper Displays (EPD)
OVERVIEW
EPD_Abstract:
This library can be used to build a raw screen buffer that is ready to transfer with an ePaper Display. The screen buffer will hold one bit per pixel.
The low-level communication functions with the ePaper Display (e.g. through
SPI interface) are not part of this library.
Interfaces: Raw screen buffer
The library provides functions for building GUIs on ePaper DisplaysPixel, Line, Rectangle Bitmap Text with several fonts
EPD_How_to_use:
// Display configuration
const
{
DISPLAY_WIDTH = 152,
DISPLAY_HEIGHT = 296,
DISPLAY_BUFFER_SIZE = (DISPLAY_WIDTH * DISPLAY_HEIGHT) / 8,
}
// Display Buffer, 1bit per pixel
static aDisplayBuffer{DISPLAY_BUFFER_SIZE};
// prepare ePaper Display library
catch(EPD_ScreenInit(aDisplayBuffer, DISPLAY_WIDTH, DISPLAY_HEIGHT, EPD_FLAG_ROT_LEFT));
// begin drawing within screen buffer
catch(EPD_DrawBegin());
// clear screen -> set background color WHITE
catch(EPD_Clear(EPD_COLOR_WHITE));
// draw elements: line, rectangle, bitmaps, text, ...
catch(EPD_DrawLine(DISPLAY_WIDTH/4, DISPLAY_HEIGHT/2, (DISPLAY_WIDTH*3)/4, DISPLAY_HEIGHT/2, EPD_COLOR_BLACK));
// flush screen buffer
catch(EPD_DrawEnd());
/* transfer buffer (aDisplayBuffer) to display here
* -> IO interface is not part of this library.
*/
BASIC
EPD_ScreenInit(screen{}, width, height, flags)
Provide screen buffer and prepare library for use
screen - Raw screen buffer
The buffer size in byte must be at least (width * height) / 8, because 1 bit per pixel is used. 1 byte will hold 8 pixel.
width : s32 - Screen: number of pixels
width must be a multiple of 8, because 8 pixels are grouped as 1 byte in x direction.
height : s32 - Screen: number of pixels
flags : s32 - see EPD_FLAG definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_FLAG:
Flags for EPD_ScreenInit
EPD_FLAG_OPAQUE - 0x01 | use background color as opaque
This flag can be used to optimize the amount of drawn pixels.
EPD_FLAG_ROT_LEFT - 0x02 | rotate screen left
EPD_FLAG_ROT_RIGHT - 0x04 | rotate screen right
EPD_DrawBegin()
Begin drawing to screen buffer
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_DrawEnd()
End drawing (flush screen buffer)
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_Clear(color)
Clear screen with color
color : s32 - Selected color, see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_COLOR:
Supported screen colors
EPD_COLOR_BLACK - 0
EPD_COLOR_WHITE - 1
GRAPHIC
EPD_DrawPixel(x, y, color)
Draw a pixel into the screen buffer
x : s32 - pixel position on x axis
y : s32 - pixel position on y axis
color : s32 - see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_DrawLine(x1, y1, x2, y2, color)
Draw a line into the screen buffer
x1 : s32 - line begin: pixel position on x axis
y1 : s32 - line begin: pixel position on y axis
x2 : s32 - line end: pixel position on x axis
y2 : s32 - line end: pixel position on y axis
color : s32 - see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_DrawRect(x1, y1, x2, y2, color)
Draw a rectangle into the screen buffer
x1 : s32 - corner 1: pixel position on x axis
y1 : s32 - corner 1: pixel position on y axis
x2 : s32 - corner 2: pixel position on x axis
y2 : s32 - corner 2: pixel position on y axis
The real appearance depends on the display and its configuration (e.g. axis orientation). This is not part of this library.
color : s32 - see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_DrawBitmap(bitmap{}, x, y, width, height, color)
Draw a bitmap into the screen buffer
bitmap : {} - Bitmap data buffer
Only monochrome bitmaps (1 bit per pixel, black/white) are possible. Each pixel line has to be a multiple of 8bits. Buffer size in bytes must be
at least (width * height) / 8.
x : s32 - pixel position on y axis
y : s32 - pixel position on y axis
width : s32 - number of pixel
height : s32 - number of pixel
color : s32 - see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
TEXT
Text_Abstract:
Drawing text is based on fonts. The font must be selected before drawing text is possible.
EPD_FONT:
Font selection
EPD_FONT_ARIAL_N24 - 1 | Arial Narrow 24
Character height is 24 pixel, width is character depending.
Supported Unicode characters:U+0020 to U+007F - Basic Latin U+00A0 to U+00FF - Latin-1 Supplement
EPD_FONT_ARIAL_N16 - 2 | Arial Narrow 16
Character height is 16 pixel, width is character depending.
Supported Unicode characters:U+0020 to U+005F - Basic Latin Subset U+00A0 to U+00BF - Latin-1 Subset
Currently only a subset of Basic Latin and Latin-1 characters are possible.
EPD_FONT_ARIAL_M20 - 3 | Arial Monospaced 20
Character height is 20 pixel, width is fixed to 16 pixel.
Supported Unicode characters:U+0020 to U+007F - Basic Latin U+00A0 to U+00FF - Latin-1
All fonts except EPD_FONT_ARIAL_M20 are disabled by default to save memory. Every font must be enabled through a corresponding #define. It must
set before the library itself is included (use dde/main.dde).
// Example: Enable Arial Narrow 24
#define EPD_ENABLE_FONT_ARIAL_N24 (1)
EPD_SelectFont(font)
Select font for drawing text
font : s32 - selected font, see EPD_FONT definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_DrawText(const text[], x, y, color)
Draw text
text : [] - Text buffer
x : s32 - start pixel on x axis
y : s32 - start pixel on y axis
color : s32 - Selected color, see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_GetTextExpanse(const text[], &width, &height)
Calculates the size of a text using the current font
text : [] - Text buffer
width : s32 - will hold number of required width pixels (x) upon return
height : s32 - will hold number of required height pixels (y) upon return
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EXPERT
EPD_ScreenGetDrawArea(&x, &y, &width, &height)
Get last drawn area of screen
This function can be used for partial display update. Last drawn area information is reset if EPD_DrawBegin is called.
x : s32 - will hold start pixel on x axis upon return
y : s32 - will hold start pixel on y axis upon return
width : s32 - will hold number of pixel on x axis upon return
height : s32 - will hold number of pixel on y axis upon return
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
EPD_SetBkColor(color)
Set current background color
This function can be used in combination with EPD_FLAG_OPAQUE (EPD_ScreenInit) for optimized pixel drawing. Only pixels different to selected background
color will be written.
color : s32 - Selected color, see EPD_COLOR definitions
returns : s32
OK - if successful
ERROR - if one of the following errors occurs
DEBUG
BMP280_Debug_Config:
To configure debug mode add the following macro to the main.dde file.
/**
* Use this macro to configure the debug mode:
*
* 0: No debugging
* >0: debug outputs active
*/
#define EPD_DEBUG (1)