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GUI Video Bridge (gui-video)

Overview

gui-video bridges the video frame format with the GUI shader pixel buffer and rendering system. It enables:

  • Converting between video frames and shader pixel buffers
  • Rendering video frames directly into GUI windows
  • Applying video effects (grayscale, invert, threshold, blend, diff) to shader buffers
  • Exporting shader buffers as video frames or BMP-ready pixel data

Import

// Direct import
guiVideo := import('gui-video')

// Or through the GUI facade (recommended)
gui := import('GUI')

Format Conversion

frameToBuffer(frame) / gui.videoFrameToBuffer(frame)

Converts a video.oak frame (RGB channel bytes) into a shader pixel buffer ({width, height, data:{packed-BGR-ints}}).

bufferToFrame(buf) / gui.videoBufferToFrame(buf)

Converts a shader pixel buffer back into a 3-channel video.oak frame.

Rendering

renderFrame(drawCtx, window, frame, ox?, oy?) / gui.videoRenderFrame(window, frame, ox?, oy?)

Draws a video frame into the GUI window at offset (ox, oy) using 1×1 fillRect calls.

renderFrameScaled(drawCtx, window, frame, ox?, oy?, scale?) / gui.videoRenderFrameScaled(window, frame, ox?, oy?, scale?)

Renders a video frame scaled by an integer factor.

Video Effects on Shader Buffers

bufferGrayscale(buf) / gui.videoBufferGrayscale(buf)

Applies luma-weighted grayscale conversion.

bufferInvert(buf) / gui.videoBufferInvert(buf)

Inverts all color channels.

bufferThreshold(buf, t?) / gui.videoBufferThreshold(buf, t?)

Binary black/white conversion based on luma threshold (default 127).

bufferBlend(bufA, bufB, alpha?) / gui.videoBufferBlend(bufA, bufB, alpha?)

Alpha-blends two buffers (default alpha 0.5).

bufferDiff(bufA, bufB) / gui.videoBufferDiff(bufA, bufB)

Per-channel absolute difference between two buffers.

Capture and Export

captureBuffer(buf) / gui.videoCaptureBuffer(buf)

Captures the current shader pixel buffer state as a video.oak frame for further processing.

frameToBmpPixels(frame) / gui.videoFrameToBmpPixels(frame)

Converts a video.oak RGB frame into the BMP pixel list expected by lib/bmp ([B, G, R] byte lists in bottom-up row order). The result can be passed directly to bmp.bmp(w, h, pixels).

Example: Shader Post-Processing

gui := import('GUI')

// Create a shader buffer and render something into it
buf := gui.shaderCreateBuffer(320, 240)
shader := gui.Shader(fn(x, y, w, h, t, u) {
    gui.rgb(int(x * 255 / w), int(y * 255 / h), 128)
})
gui.shaderRenderShaderToBuffer(buf, shader)

// Apply grayscale post-processing
grayBuf := gui.videoBufferGrayscale(buf)

// Render the processed buffer
gui.shaderRenderBuffer(window, grayBuf, 0, 0)

Example: Render a Video Frame

gui := import('GUI')
video := import('video')

// Create a test frame (red gradient)
f := video.mapPixels(video.blank(100, 100), fn(pixel, x, y) {
    [int(x * 255 / 100), 0, 0]
})

// Render at 2× scale
gui.videoRenderFrameScaled(window, f, 10, 10, 2)

Example: Export to BMP

gui := import('GUI')
bmpLib := import('bmp')
video := import('video')

f := video.blank(64, 64, 3, 128)
pixels := gui.videoFrameToBmpPixels(f)
data := bmpLib.bmp(64, 64, pixels)
// write data to file...