crosspoint-reader-mod/chat-summaries/2026-02-09_04-43-summary.md

Sleep Screen Tweaks Implementation

Task Description

Implemented the two "Sleep Screen tweaks" from the plan:

1. Gradient fill for letterboxed areas - When a sleep screen image doesn't match the display's aspect ratio, the void (letterbox) areas are now filled with a dithered gradient sampled from the nearest ~20 pixels of the image's edge, fading toward white.
2. Fix "Fit" mode for small images - Images smaller than the 480x800 display are now scaled up (nearest-neighbor) to fit while preserving aspect ratio, instead of being displayed at native size with wasted screen space.

Changes Made

lib/GfxRenderer/GfxRenderer.cpp

• Modified drawBitmap() scaling logic: when both maxWidth and maxHeight are provided, always computes an aspect-ratio-preserving scale factor (supports both upscaling and downscaling)
• Modified drawBitmap() rendering loop: uses block-fill approach where each source pixel maps to a screen rectangle (handles both upscaling blocks and 1:1/downscaling single pixels via a unified loop)
• Applied same changes to drawBitmap1Bit() for 1-bit bitmap consistency
• Added drawPixelGray() method: draws a pixel using its 2-bit grayscale value, dispatching correctly based on the current render mode (BW, GRAYSCALE_LSB, GRAYSCALE_MSB)

lib/GfxRenderer/GfxRenderer.h

• Added drawPixelGray(int x, int y, uint8_t val2bit) declaration

lib/GfxRenderer/BitmapHelpers.cpp

• Added quantizeNoiseDither(): hash-based noise dithering that always uses noise (unlike quantize() which is controlled by a compile-time flag), used for smooth gradient rendering on the 4-level display

lib/GfxRenderer/BitmapHelpers.h

• Added quantizeNoiseDither() declaration

src/activities/boot_sleep/SleepActivity.cpp

• Removed the if (bitmap.getWidth() > pageWidth || bitmap.getHeight() > pageHeight) gate in renderBitmapSleepScreen() — position/scale is now always computed regardless of whether the image is larger or smaller than the screen
• Added anonymous namespace with:
  • LetterboxGradientData struct for edge sample storage
  • sampleBitmapEdges(): reads bitmap row-by-row to sample per-column (or per-row) average gray values from the first/last 20 pixels of the image edges
  • drawLetterboxGradients(): draws dithered gradients in letterbox areas using sampled edge colors, interpolating toward white
• Integrated gradient rendering into the sleep screen flow: edge sampling (first pass), then gradient + bitmap rendering in BW pass, and again in each grayscale pass (LSB, MSB)

Follow-up: Letterbox Fill Settings

Added three letterbox fill options and two new persisted settings:

src/CrossPointSettings.h

• Added SLEEP_SCREEN_LETTERBOX_FILL enum: LETTERBOX_NONE (plain white), LETTERBOX_GRADIENT (default), LETTERBOX_SOLID
• Added SLEEP_SCREEN_GRADIENT_DIR enum: GRADIENT_TO_WHITE (default), GRADIENT_TO_BLACK
• Added sleepScreenLetterboxFill and sleepScreenGradientDir member fields

src/CrossPointSettings.cpp

• Incremented SETTINGS_COUNT to 32
• Added serialization (read/write) for the two new fields at the end for backward compatibility

src/SettingsList.h

• Added "Letterbox Fill" menu entry (None / Gradient / Solid) in Display category
• Added "Gradient Direction" menu entry (To White / To Black) in Display category

src/activities/boot_sleep/SleepActivity.cpp

• Renamed drawLetterboxGradients → drawLetterboxFill with added solidFill and targetColor parameters
• Solid mode: uses edge color directly (no distance-based interpolation), quantized with noise dithering
• Gradient direction: interpolates from edge color toward targetColor (255 for white, 0 for black)
• renderBitmapSleepScreen reads the settings and skips edge sampling entirely when fill mode is "None"

Follow-up Items

• Test with various cover image sizes and aspect ratios on actual hardware
• Test custom images from /sleep/ directory (1-bit and multi-bit)
• Monitor RAM usage via serial during gradient rendering