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Fix(posterize): Resolve incorrect vertical tiling/cropping

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The Y-axis calculation in the `posterize` function was backward for `pdf-lib`'s bottom-left origin, causing the resulting PDF tiles to display only the bottom portion of the content, leaving large empty crops.

Corrected the `y` coordinate calculation using `tileRowIndexFromBottom = rows - 1 - r` to properly map the top-to-bottom loop index to the required bottom-up positioning.
This commit is contained in:
Nishant
2025-10-14 12:20:04 +05:30
parent 0c1351adc5
commit ed2629e69b
1 changed files with 6 additions and 3 deletions
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9
src/js/logic/posterize.ts
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@@ -128,16 +128,19 @@ export async function posterize() {
const scaleX = targetWidth / tileWidth; const scaleX = targetWidth / tileWidth;
const scaleY = targetHeight / tileHeight; const scaleY = targetHeight / tileHeight;
const scale = scalingMode === 'fit' ? Math.min(scaleX, scaleY) : Math.max(scaleX, scaleY); const scale = scalingMode === 'fit' ? Math.min(scaleX, scaleY) : Math.max(scaleX, scaleY);
const scaledTileWidth = tileWidth * scale; const scaledTileWidth = tileWidth * scale;
const scaledTileHeight = tileHeight * scale; const scaledTileHeight = tileHeight * scale;
const offsetX = (targetWidth - scaledTileWidth) / 2; const offsetX = (targetWidth - scaledTileWidth) / 2;
const offsetY = (targetHeight - scaledTileHeight) / 2; const offsetY = (targetHeight - scaledTileHeight) / 2;
const tileRowIndexFromBottom = rows - 1 - r;
const overlapOffset = tileRowIndexFromBottom * overlapInPoints;
newPage.drawPage(embeddedPage, { newPage.drawPage(embeddedPage, {
x: -c * scaledTileWidth + offsetX - (c * overlapInPoints), x: -c * scaledTileWidth + offsetX - (c * overlapInPoints),
y: r * scaledTileHeight + offsetY - ((rows - 1 - r) * overlapInPoints), y: -tileRowIndexFromBottom * scaledTileHeight + offsetY + overlapOffset,
width: sourceWidth * scale, width: sourceWidth * scale,
height: sourceHeight * scale, height: sourceHeight * scale,
}); });