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@@ -249,6 +249,55 @@ function binarySearchFirstItem(items, condition) {
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return minIndex; /* === maxIndex */
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return minIndex; /* === maxIndex */
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}
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}
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+/**
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+ * Approximates float number as a fraction using Farey sequence (max order
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+ * of 8).
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+ * @param {number} x - Positive float number.
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+ * @returns {Array} Estimated fraction: the first array item is a numerator,
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+ * the second one is a denominator.
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+ */
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+function approximateFraction(x) {
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+ // Fast paths for int numbers or their inversions.
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+ if (Math.floor(x) === x) {
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+ return [x, 1];
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+ }
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+ var xinv = 1 / x;
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+ var limit = 8;
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+ if (xinv > limit) {
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+ return [1, limit];
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+ } else if (Math.floor(xinv) === xinv) {
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+ return [1, xinv];
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+ }
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+
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+ var x_ = x > 1 ? xinv : x;
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+ // a/b and c/d are neighbours in Farey sequence.
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+ var a = 0, b = 1, c = 1, d = 1;
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+ // Limiting search to order 8.
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+ while (true) {
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+ // Generating next term in sequence (order of q).
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+ var p = a + c, q = b + d;
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+ if (q > limit) {
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+ break;
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+ }
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+ if (x_ <= p / q) {
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+ c = p; d = q;
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+ } else {
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+ a = p; b = q;
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+ }
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+ }
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+ // Select closest of the neighbours to x.
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+ if (x_ - a / b < c / d - x_) {
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+ return x_ === x ? [a, b] : [b, a];
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+ } else {
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+ return x_ === x ? [c, d] : [d, c];
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+ }
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+}
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+
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+function roundToDivide(x, div) {
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+ var r = x % div;
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+ return r === 0 ? x : Math.round(x - r + div);
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+}
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+
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/**
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/**
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* Generic helper to find out what elements are visible within a scroll pane.
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* Generic helper to find out what elements are visible within a scroll pane.
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*/
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*/
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@@ -1186,7 +1235,7 @@ var PDFPageView = (function PDFPageViewClosure() {
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var outputScale = getOutputScale(ctx);
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var outputScale = getOutputScale(ctx);
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if (PDFJS.useOnlyCssZoom) {
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if (PDFJS.useOnlyCssZoom) {
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- var actualSizeViewport = viewport.clone({ scale: CSS_UNITS });
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+ var actualSizeViewport = viewport.clone({scale: CSS_UNITS});
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// Use a scale that will make the canvas be the original intended size
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// Use a scale that will make the canvas be the original intended size
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// of the page.
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// of the page.
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outputScale.sx *= actualSizeViewport.width / viewport.width;
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outputScale.sx *= actualSizeViewport.width / viewport.width;
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@@ -1207,10 +1256,12 @@ var PDFPageView = (function PDFPageViewClosure() {
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}
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}
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}
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}
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- canvas.width = (Math.floor(viewport.width) * outputScale.sx) | 0;
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- canvas.height = (Math.floor(viewport.height) * outputScale.sy) | 0;
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- canvas.style.width = Math.floor(viewport.width) + 'px';
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- canvas.style.height = Math.floor(viewport.height) + 'px';
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+ var sfx = approximateFraction(outputScale.sx);
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+ var sfy = approximateFraction(outputScale.sy);
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+ canvas.width = roundToDivide(viewport.width * outputScale.sx, sfx[0]);
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+ canvas.height = roundToDivide(viewport.height * outputScale.sy, sfy[0]);
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+ canvas.style.width = roundToDivide(viewport.width, sfx[1]) + 'px';
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+ canvas.style.height = roundToDivide(viewport.height, sfy[1]) + 'px';
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// Add the viewport so it's known what it was originally drawn with.
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// Add the viewport so it's known what it was originally drawn with.
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canvas._viewport = viewport;
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canvas._viewport = viewport;
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