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Use single buffer mode for EInkDisplay (#34)

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## Summary

* Frees up 48kB of statically allocated RAM in exchange for 48kB just
when grayscale rendering is needed

## Additional Context

* Upstream changes:
https://github.com/open-x4-epaper/community-sdk/pull/7
This commit is contained in:
Dave Allie
2025-12-17 00:17:49 +11:00
committed by GitHub
parent 5d68c8b305
commit c287aa03a4
5 changed files with 67 additions and 21 deletions
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51
lib/GfxRenderer/GfxRenderer.cpp
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@@ -132,13 +132,19 @@ void GfxRenderer::displayBuffer(const EInkDisplay::RefreshMode refreshMode) cons
einkDisplay.displayBuffer(refreshMode);
}
// TODO: Support partial window update
// void GfxRenderer::flushArea(const int x, const int y, const int width, const int height) const {
// const int rotatedX = y;
// const int rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x;
//
// einkDisplay.displayBuffer(EInkDisplay::FAST_REFRESH, rotatedX, rotatedY, height, width);
// }
void GfxRenderer::displayWindow(const int x, const int y, const int width, const int height) const {
// Rotate coordinates from portrait (480x800) to landscape (800x480)
// Rotation: 90 degrees clockwise
// Portrait coordinates: (x, y) with dimensions (width, height)
// Landscape coordinates: (rotatedX, rotatedY) with dimensions (rotatedWidth, rotatedHeight)
const int rotatedX = y;
const int rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x - width + 1;
const int rotatedWidth = height;
const int rotatedHeight = width;
einkDisplay.displayWindow(rotatedX, rotatedY, rotatedWidth, rotatedHeight);
}
// Note: Internal driver treats screen in command orientation, this library treats in portrait orientation
int GfxRenderer::getScreenWidth() { return EInkDisplay::DISPLAY_HEIGHT; }
@@ -164,7 +170,7 @@ int GfxRenderer::getLineHeight(const int fontId) const {
uint8_t* GfxRenderer::getFrameBuffer() const { return einkDisplay.getFrameBuffer(); }
void GfxRenderer::swapBuffers() const { einkDisplay.swapBuffers(); }
size_t GfxRenderer::getBufferSize() { return EInkDisplay::BUFFER_SIZE; }
void GfxRenderer::grayscaleRevert() const { einkDisplay.grayscaleRevert(); }
@@ -174,6 +180,35 @@ void GfxRenderer::copyGrayscaleMsbBuffers() const { einkDisplay.copyGrayscaleMsb
void GfxRenderer::displayGrayBuffer() const { einkDisplay.displayGrayBuffer(); }
/**
* This should be called before grayscale buffers are populated.
* A `restoreBwBuffer` call should always follow the grayscale render if this method was called.
*/
void GfxRenderer::storeBwBuffer() {
if (bwBuffer) {
Serial.printf("[%lu] [GFX] !! BW buffer already stored - this is likely a bug, freeing it\n", millis());
free(bwBuffer);
}
bwBuffer = static_cast<uint8_t*>(malloc(EInkDisplay::BUFFER_SIZE));
memcpy(bwBuffer, einkDisplay.getFrameBuffer(), EInkDisplay::BUFFER_SIZE);
}
/**
* This can only be called if `storeBwBuffer` was called prior to the grayscale render.
* It should be called to restore the BW buffer state after grayscale rendering is complete.
*/
void GfxRenderer::restoreBwBuffer() {
if (!bwBuffer) {
Serial.printf("[%lu] [GFX] !! BW buffer not stored - this is likely a bug\n", millis());
return;
}
einkDisplay.cleanupGrayscaleBuffers(bwBuffer);
free(bwBuffer);
bwBuffer = nullptr;
}
void GfxRenderer::renderChar(const EpdFontFamily& fontFamily, const uint32_t cp, int* x, const int* y,
const bool pixelState, const EpdFontStyle style) const {
const EpdGlyph* glyph = fontFamily.getGlyph(cp, style);