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fix: Align double FAST_REFRESH image rendering with upstream PR #957

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Reorder refresh branches so image+AA pages always use the double
FAST_REFRESH technique instead of occasionally falling through to
HALF_REFRESH when the refresh counter expires. Image pages no longer
count toward the full refresh cadence. Remove experimental Method B
toggle (USE_IMAGE_DOUBLE_FAST_REFRESH / displayWindow).

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
cottongin
2026-02-19 14:30:10 -05:00
parent c8ba4fe973
commit ad282cadfe
1 changed files with 12 additions and 38 deletions
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50
src/activities/reader/EpubReaderActivity.cpp
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@@ -22,11 +22,6 @@
#include "util/BookmarkStore.h"
#include "util/Dictionary.h"
// Image refresh optimization strategy:
// 0 = Use double FAST_REFRESH technique (default, feels snappier)
// 1 = Use displayWindow() for partial refresh (experimental)
#define USE_IMAGE_DOUBLE_FAST_REFRESH 0
namespace {
// pagesPerRefresh now comes from SETTINGS.getRefreshFrequency()
constexpr unsigned long skipChapterMs = 700;
@@ -1022,13 +1017,8 @@ void EpubReaderActivity::saveProgress(int spineIndex, int currentPage, int pageC
void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int orientedMarginTop,
const int orientedMarginRight, const int orientedMarginBottom,
const int orientedMarginLeft) {
// Determine if this page needs special image handling
bool pageHasImages = page->hasImages();
bool useAntiAliasing = SETTINGS.textAntiAliasing;
// Force half refresh for pages with images when anti-aliasing is on,
// as grayscale tones require half refresh to display correctly
bool forceFullRefresh = pageHasImages && useAntiAliasing;
// Force special handling for pages with images when anti-aliasing is on
bool imagePageWithAA = page->hasImages() && SETTINGS.textAntiAliasing;
page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
@@ -1048,42 +1038,26 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
}
renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
// Check if half-refresh is needed (either entering Reader or pages counter reached)
if (pagesUntilFullRefresh <= 1) {
renderer.displayBuffer(HalDisplay::HALF_REFRESH);
pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
} else if (forceFullRefresh) {
// OPTIMIZATION: For image pages with anti-aliasing, use fast double-refresh technique
// to reduce perceived lag. Only when pagesUntilFullRefresh > 1 (screen already clean).
if (imagePageWithAA) {
// Double FAST_REFRESH with selective image blanking (pablohc's technique):
// HALF_REFRESH sets particles too firmly for the grayscale LUT to adjust.
// Instead, blank only the image area and do two fast refreshes.
int imgX, imgY, imgW, imgH;
if (page->getImageBoundingBox(imgX, imgY, imgW, imgH)) {
int screenX = imgX + orientedMarginLeft;
int screenY = imgY + orientedMarginTop;
LOG_DBG("ERS", "Image page: fast double-refresh (page bbox: %d,%d %dx%d, screen: %d,%d %dx%d)", imgX, imgY, imgW,
imgH, screenX, screenY, imgW, imgH);
renderer.fillRect(imgX + orientedMarginLeft, imgY + orientedMarginTop, imgW, imgH, false);
renderer.displayBuffer(HalDisplay::FAST_REFRESH);
#if USE_IMAGE_DOUBLE_FAST_REFRESH == 0
// Method A: Fill blank area + two FAST_REFRESH operations
renderer.fillRect(screenX, screenY, imgW, imgH, false);
renderer.displayBuffer(HalDisplay::FAST_REFRESH);
page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
renderer.displayBuffer(HalDisplay::FAST_REFRESH);
#else
// Method B (experimental): Use displayWindow() for partial refresh
renderer.displayBuffer(HalDisplay::FAST_REFRESH);
page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
renderer.displayWindow(screenX, screenY, imgW, imgH, HalDisplay::FAST_REFRESH);
#endif
} else {
LOG_DBG("ERS", "Image page but no bbox, using standard half refresh");
renderer.displayBuffer(HalDisplay::HALF_REFRESH);
}
pagesUntilFullRefresh--;
// Double FAST_REFRESH handles ghosting for image pages; don't count toward full refresh cadence
} else if (pagesUntilFullRefresh <= 1) {
renderer.displayBuffer(HalDisplay::HALF_REFRESH);
pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
} else {
// Normal page without images, or images without anti-aliasing
renderer.displayBuffer();
pagesUntilFullRefresh--;
}