OledLib: OledExpansion Graphics Library in Python

[elefas GR]

OledLib

Onion Omega OledExpansion Graphics Library in Python

Intro

OledLib is a small graphics library for the OledExpansion module for Onion Omega IoT devices.

While the oledExp Python module mainly deals with writing text on screen, OledLib dives deeper into pixel precise graphics.
OledLib breaks the limit of 8 pages and 128 columns, giving access to all 128x64 pixels of the screen. It is also faster since it uses the i2c interface which is capable of sending 32 bytes of data simultaneously instead of only 1 byte (oledExp.write(byte)).

With OledLib's ability to address each pixel individually, OledExpansion becomes much more versatile and capable of rendering complex graphics.

Features

• 128x64 framebuffer, pixel-level precision.
• Up to 32 bytes sent to screen simultaneously.
• 1-bit bitmap rendering.
• DMA (Direct Memory Access) functionality to fast render a portion of the screen only.
• Special effects: rotation and scaling.

Prerequisites

Requires oledExp and onionI2C Python modules to be installed on the Onion Omega IoT device.

Demonstration

Below is a video showcasing most features of the OledLib library.

API

• clearBuffers: Clears the framebuffer (all elements to 0).
• putPixel(x, y, value): Puts the value (0 or 1) at x, y coordinates.
• putRectangle(x, y, width, height, fill): Puts a rectangle (width x height) at the specified x, y coordinates. Setting fill to True will fill the rectangle, where False will draw just the borders.
• putBitmap(x, y, bitmap): Puts a bitmap MxN array of 0s and 1s to x, y coordinates.
• translateBitmap(bitmap): Converts a MxN bitmap array where each element is a bit (0 or 1), to a byte array MxL where each element is a byte (8 bits). Bitmap array sizes can be: 0<M<128 and 0<N<64, and the translated bitmap will have sizes: 0<M<128 and 0<L<8. Useful for achieving faster rendering rates. Use before calling bitmapBlit().
• scaleBitmap(bitmap, scaleX, scaleY): Scales down the given bitmap. Each axis can scale differently by setting scaleX, scaleY. Positive integer values only.
• rotateBitmap90(bitmap): Rotates the bitmap 90 degrees.
• rotateBitmap180(bitmap): Rotates the bitmap 180 degrees.
• rotateBitmap270(bitmap): Rotates the bitmap 270 degrees.
• blit(): Renders the whole framebuffer to screen at maximum fast rate.
• pageBlit(pageNo, x, length): Renders portion of a page, (row) with length starting from x, to screen at maximum fast rate. Does not clear the framebuffer after.
• bitmapBlit(x, y, translatedBitmap): Instead of filling the whole 128x64 framebuffer it renders only the region of a translatedBitmap on the screen at x, y location, sort of Direct Memory Access (DMA). Requires the translatedBitmap from translateBitmap() as input. Does not clear the framebuffer after.

Github link:

https://github.com/pleft/omega-python-oled

[elefas GR]

Wrote some code, PerformanceDMADemo.py to measure the bitmapBlit() performance for various bitmap sizes (MxN pixels). Measures below are only for rendering one bitmap on screen each time.

Bitmap size (in pixels)	FPS
64x64	8.38996560114
32x32	27.0965993768
24x24	41.8497593639
16x16	74.5712155108
8x8	180.342651037
4x4	204.498977505
2x2	219.538968167
1x1	226.500566251

[Douglas Kryder]

@elefas-GR nice project and equally nice presentation. thanks for sharing.