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Always enable smoothing when rendering downscaled image

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and rely on the Interpolate flag only when the image is upscaled.
Fixes #16273.
This commit is contained in:
Calixte Denizet 2024-04-02 14:57:29 +02:00
parent d1f494d68c
commit b511878ba7
1 changed files with 9 additions and 9 deletions
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18
src/display/canvas.js
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@ -913,6 +913,14 @@ function composeSMask(ctx, smask, layerCtx, layerBox) {
} }
function getImageSmoothingEnabled(transform, interpolate) { function getImageSmoothingEnabled(transform, interpolate) {
// In section 8.9.5.3 of the PDF spec, it's mentioned that the interpolate
// flag should be used when the image is upscaled.
// In Firefox, smoothing is always used when downscaling images (bug 1360415).
if (interpolate) {
return true;
}
const scale = Util.singularValueDecompose2dScale(transform); const scale = Util.singularValueDecompose2dScale(transform);
// Round to a 32bit float so that `<=` check below will pass for numbers that // Round to a 32bit float so that `<=` check below will pass for numbers that
// are very close, but not exactly the same 64bit floats. // are very close, but not exactly the same 64bit floats.
@ -921,15 +929,7 @@ function getImageSmoothingEnabled(transform, interpolate) {
const actualScale = Math.fround( const actualScale = Math.fround(
(globalThis.devicePixelRatio || 1) * PixelsPerInch.PDF_TO_CSS_UNITS (globalThis.devicePixelRatio || 1) * PixelsPerInch.PDF_TO_CSS_UNITS
); );
if (interpolate !== undefined) { return scale[0] <= actualScale && scale[1] <= actualScale;
// If the value is explicitly set use it.
return interpolate;
} else if (scale[0] <= actualScale || scale[1] <= actualScale) {
// Smooth when downscaling.
return true;
}
// Don't smooth when upscaling.
return false;
} }
const LINE_CAP_STYLES = ["butt", "round", "square"]; const LINE_CAP_STYLES = ["butt", "round", "square"];