Files
crosspoint-reader-mod/lib/GfxRenderer/GfxRenderer.h
martin brook 6c3a615fac feat: add png jpeg support (#556)
## Summary
- Add embedded image support to EPUB rendering with JPEG and PNG
decoders
- Implement pixel caching system to cache decoded/dithered images to SD
card for faster re-rendering
- Add 4-level grayscale support for display
## Changes
### New Image Rendering System
- Add `ImageBlock` class to represent an image with its cached path and
display dimensions
- Add `PageImage` class as a new `PageElement` type for images on pages
- Add `ImageToFramebufferDecoder` interface for format-specific image
decoders
- Add `JpegToFramebufferConverter` - JPEG decoder with Bayer dithering
and scaling
- Add `PngToFramebufferConverter` - PNG decoder with Bayer dithering and
scaling
- Add `ImageDecoderFactory` to select appropriate decoder based on file
extension
- Add `getRenderMode()` to GfxRenderer for grayscale render mode queries
### Dithering and Grayscale
- Implement 4x4 Bayer ordered dithering for 4-level grayscale output
- Stateless algorithm works correctly with MCU block decoding
- Handles scaling without artifacts
- Add grayscale render mode support (BW, GRAYSCALE_LSB, GRAYSCALE_MSB)
- Image decoders and cache renderer respect current render mode
- Enables proper 4-level e-ink grayscale when anti-aliasing is enabled
### Pixel Caching
- Cache decoded/dithered images to `.pxc` files on SD card
- Cache format: 2-bit packed pixels (4 pixels per byte) with
width/height header
- On subsequent renders, load directly from cache instead of re-decoding
- Cache renderer supports grayscale render modes for multi-pass
rendering
- Significantly improves page navigation speed for image-heavy EPUBs
### HTML Parser Integration
- Update `ChapterHtmlSlimParser` to process `<img>` tags and extract
images from EPUB
- Resolve relative image paths within EPUB ZIP structure
- Extract images to cache directory before decoding
- Create `PageImage` elements with proper scaling to fit viewport
- Fall back to alt text display if image processing fails
### Build Configuration
- Add `PNG_MAX_BUFFERED_PIXELS=6402` to support up to 800px wide images

  ### Test Script
                                
  - Generate test EPUBs with annotated JPEG and PNG images
- Test cases cover: grayscale (4 levels), centering, scaling, cache
performance
  
## Test plan
- [x] Open EPUB with JPEG images - verify images display with proper
grayscale
- [x] Open EPUB with PNG images - verify images display correctly and no
crash
- [x] Navigate away from image page and back - verify faster load from
cache
- [x] Verify grayscale tones render correctly (not just black/white
dithering)
- [x] Verify large images are scaled down to fit screen
- [x] Verify images are centered horizontally
- [x] Verify page serialization/deserialization works with images
  - [x] Verify images rendered in landscape mode        

## Test Results
[png](https://photos.app.goo.gl/5zFUb8xA8db3dPd19)
[jpeg](https://photos.app.goo.gl/SwtwaL2DSQwKybhw7)


![20260128_231123790](https://github.com/user-attachments/assets/78855971-4bb8-441a-b207-0a292b9739f5)

![20260128_231012253](https://github.com/user-attachments/assets/f08fb63f-1b73-41d9-a25e-78232ec0c495)

![20260128_231004209](https://github.com/user-attachments/assets/06c94acc-8a06-4955-978e-6e583399478d)

![20260128_230954997](https://github.com/user-attachments/assets/49bc44d5-0f2c-416b-9199-4d680fb0f4c3)

![20260128_230945717](https://github.com/user-attachments/assets/93446da5-2e07-410c-89c9-6a21d14e5acb)

![20260128_230938313](https://github.com/user-attachments/assets/4c74c72a-3d40-4a25-b0f3-acc703f42c00)

![20260128_230925546](https://github.com/user-attachments/assets/8d8f62ee-c8fc-4f19-a12c-da29083bb766)

![20260128_230918374](https://github.com/user-attachments/assets/f007d5db-41cc-4fa6-bb22-9e767ee7b00d)


                                                                       
---

### AI Usage

Did you use AI tools to help write this code? _**< YES  >**_

---------

Co-authored-by: Matthías Páll Gissurarson <mpg@mpg.is>
Co-authored-by: Dave Allie <dave@daveallie.com>
2026-02-16 19:56:59 +11:00

132 lines
6.4 KiB
C++

#pragma once
#include <EpdFontFamily.h>
#include <HalDisplay.h>
#include <map>
#include "Bitmap.h"
// Color representation: uint8_t mapped to 4x4 Bayer matrix dithering levels
// 0 = transparent, 1-16 = gray levels (white to black)
enum Color : uint8_t { Clear = 0x00, White = 0x01, LightGray = 0x05, DarkGray = 0x0A, Black = 0x10 };
class GfxRenderer {
public:
enum RenderMode { BW, GRAYSCALE_LSB, GRAYSCALE_MSB };
// Logical screen orientation from the perspective of callers
enum Orientation {
Portrait, // 480x800 logical coordinates (current default)
LandscapeClockwise, // 800x480 logical coordinates, rotated 180° (swap top/bottom)
PortraitInverted, // 480x800 logical coordinates, inverted
LandscapeCounterClockwise // 800x480 logical coordinates, native panel orientation
};
private:
static constexpr size_t BW_BUFFER_CHUNK_SIZE = 8000; // 8KB chunks to allow for non-contiguous memory
static constexpr size_t BW_BUFFER_NUM_CHUNKS = HalDisplay::BUFFER_SIZE / BW_BUFFER_CHUNK_SIZE;
static_assert(BW_BUFFER_CHUNK_SIZE * BW_BUFFER_NUM_CHUNKS == HalDisplay::BUFFER_SIZE,
"BW buffer chunking does not line up with display buffer size");
HalDisplay& display;
RenderMode renderMode;
Orientation orientation;
bool fadingFix;
uint8_t* frameBuffer = nullptr;
uint8_t* bwBufferChunks[BW_BUFFER_NUM_CHUNKS] = {nullptr};
std::map<int, EpdFontFamily> fontMap;
void renderChar(const EpdFontFamily& fontFamily, uint32_t cp, int* x, const int* y, bool pixelState,
EpdFontFamily::Style style) const;
void freeBwBufferChunks();
template <Color color>
void drawPixelDither(int x, int y) const;
template <Color color>
void fillArc(int maxRadius, int cx, int cy, int xDir, int yDir) const;
public:
explicit GfxRenderer(HalDisplay& halDisplay)
: display(halDisplay), renderMode(BW), orientation(Portrait), fadingFix(false) {}
~GfxRenderer() { freeBwBufferChunks(); }
static constexpr int VIEWABLE_MARGIN_TOP = 9;
static constexpr int VIEWABLE_MARGIN_RIGHT = 3;
static constexpr int VIEWABLE_MARGIN_BOTTOM = 3;
static constexpr int VIEWABLE_MARGIN_LEFT = 3;
// Setup
void begin(); // must be called right after display.begin()
void insertFont(int fontId, EpdFontFamily font);
// Orientation control (affects logical width/height and coordinate transforms)
void setOrientation(const Orientation o) { orientation = o; }
Orientation getOrientation() const { return orientation; }
// Fading fix control
void setFadingFix(const bool enabled) { fadingFix = enabled; }
// Screen ops
int getScreenWidth() const;
int getScreenHeight() const;
void displayBuffer(HalDisplay::RefreshMode refreshMode = HalDisplay::FAST_REFRESH) const;
// EXPERIMENTAL: Windowed update - display only a rectangular region
// void displayWindow(int x, int y, int width, int height) const;
void invertScreen() const;
void clearScreen(uint8_t color = 0xFF) const;
void getOrientedViewableTRBL(int* outTop, int* outRight, int* outBottom, int* outLeft) const;
// Drawing
void drawPixel(int x, int y, bool state = true) const;
void drawLine(int x1, int y1, int x2, int y2, bool state = true) const;
void drawLine(int x1, int y1, int x2, int y2, int lineWidth, bool state) const;
void drawArc(int maxRadius, int cx, int cy, int xDir, int yDir, int lineWidth, bool state) const;
void drawRect(int x, int y, int width, int height, bool state = true) const;
void drawRect(int x, int y, int width, int height, int lineWidth, bool state) const;
void drawRoundedRect(int x, int y, int width, int height, int lineWidth, int cornerRadius, bool state) const;
void drawRoundedRect(int x, int y, int width, int height, int lineWidth, int cornerRadius, bool roundTopLeft,
bool roundTopRight, bool roundBottomLeft, bool roundBottomRight, bool state) const;
void fillRect(int x, int y, int width, int height, bool state = true) const;
void fillRectDither(int x, int y, int width, int height, Color color) const;
void fillRoundedRect(int x, int y, int width, int height, int cornerRadius, Color color) const;
void fillRoundedRect(int x, int y, int width, int height, int cornerRadius, bool roundTopLeft, bool roundTopRight,
bool roundBottomLeft, bool roundBottomRight, Color color) const;
void drawImage(const uint8_t bitmap[], int x, int y, int width, int height) const;
void drawIcon(const uint8_t bitmap[], int x, int y, int width, int height) const;
void drawBitmap(const Bitmap& bitmap, int x, int y, int maxWidth, int maxHeight, float cropX = 0,
float cropY = 0) const;
void drawBitmap1Bit(const Bitmap& bitmap, int x, int y, int maxWidth, int maxHeight) const;
void fillPolygon(const int* xPoints, const int* yPoints, int numPoints, bool state = true) const;
// Text
int getTextWidth(int fontId, const char* text, EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
void drawCenteredText(int fontId, int y, const char* text, bool black = true,
EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
void drawText(int fontId, int x, int y, const char* text, bool black = true,
EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
int getSpaceWidth(int fontId) const;
int getTextAdvanceX(int fontId, const char* text) const;
int getFontAscenderSize(int fontId) const;
int getLineHeight(int fontId) const;
std::string truncatedText(int fontId, const char* text, int maxWidth,
EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
// Helper for drawing rotated text (90 degrees clockwise, for side buttons)
void drawTextRotated90CW(int fontId, int x, int y, const char* text, bool black = true,
EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
int getTextHeight(int fontId) const;
// Grayscale functions
void setRenderMode(const RenderMode mode) { this->renderMode = mode; }
RenderMode getRenderMode() const { return renderMode; }
void copyGrayscaleLsbBuffers() const;
void copyGrayscaleMsbBuffers() const;
void displayGrayBuffer() const;
bool storeBwBuffer(); // Returns true if buffer was stored successfully
void restoreBwBuffer(); // Restore and free the stored buffer
void cleanupGrayscaleWithFrameBuffer() const;
// Low level functions
uint8_t* getFrameBuffer() const;
static size_t getBufferSize();
};