16568932cf
Pre-scaling (critical fix): - Add pre-scaling to fit display dimensions (480x800) before dithering to prevent post-downsampling artifacts that destroy dithering patterns - Use fixed-point (16.16) math for sub-pixel accurate scaling - Implement area averaging for smooth downsampling Dithering improvements: - Add Atkinson dithering (75% error diffusion) for cleaner results - Add Floyd-Steinberg dithering option with serpentine scanning - Keep clustered-dot halftone and Bayer as compile-time options Image adjustments: - Add brightness, contrast, and gamma adjustments for better visibility - Adjust RGB to grayscale conversion (25-50-25) to reduce blue darkness Other changes: - Fix MCU block indexing bug for correct picojpeg buffer access - Pre-generate cover BMP when EPUB is loaded for faster sleep screen
60 lines
1.3 KiB
C++
60 lines
1.3 KiB
C++
#pragma once
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#include <FS.h>
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enum class BmpReaderError : uint8_t {
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Ok = 0,
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FileInvalid,
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SeekStartFailed,
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NotBMP,
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DIBTooSmall,
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BadPlanes,
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UnsupportedBpp,
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UnsupportedCompression,
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BadDimensions,
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ImageTooLarge,
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PaletteTooLarge,
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SeekPixelDataFailed,
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BufferTooSmall,
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OomRowBuffer,
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ShortReadRow,
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};
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class Bitmap {
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public:
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static const char* errorToString(BmpReaderError err);
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explicit Bitmap(File& file) : file(file) {}
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~Bitmap();
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BmpReaderError parseHeaders();
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BmpReaderError readRow(uint8_t* data, uint8_t* rowBuffer, int rowY) const;
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BmpReaderError rewindToData() const;
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int getWidth() const { return width; }
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int getHeight() const { return height; }
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bool isTopDown() const { return topDown; }
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bool hasGreyscale() const { return bpp > 1; }
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int getRowBytes() const { return rowBytes; }
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private:
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static uint16_t readLE16(File& f);
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static uint32_t readLE32(File& f);
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File& file;
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int width = 0;
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int height = 0;
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bool topDown = false;
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uint32_t bfOffBits = 0;
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uint16_t bpp = 0;
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int rowBytes = 0;
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uint8_t paletteLum[256] = {};
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// Floyd-Steinberg dithering state (mutable for const methods)
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mutable int16_t* errorCurRow = nullptr;
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mutable int16_t* errorNextRow = nullptr;
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mutable int lastRowY = -1; // Track row progression for error propagation
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};
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