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Re-factor the showCanvas function, reducing function calls during rendering

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This commit is contained in:
Jonas Jenwald 2023-03-31 10:02:17 +02:00
parent 6858dae1c3
commit 92cf183f56
1 changed files with 6 additions and 7 deletions
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13
web/pdf_page_view.js
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@ -945,17 +945,16 @@ class PDFPageView {
// Keep the canvas hidden until the first draw callback, or until drawing // Keep the canvas hidden until the first draw callback, or until drawing
// is complete when `!this.renderingQueue`, to prevent black flickering. // is complete when `!this.renderingQueue`, to prevent black flickering.
canvas.hidden = true; canvas.hidden = true;
let isCanvasHidden = true;
const hasHCM = !!( const hasHCM = !!(
this.pageColors?.background && this.pageColors?.foreground this.pageColors?.background && this.pageColors?.foreground
); );
const showCanvas = function (isLastShow) { let showCanvas = isLastShow => {
// In HCM, a final filter is applied on the canvas which means that // In HCM, a final filter is applied on the canvas which means that
// before it's applied we've normal colors. Consequently, to avoid to have // before it's applied we've normal colors. Consequently, to avoid to have
// a final flash we just display it once all the drawing is done. // a final flash we just display it once all the drawing is done.
if (isCanvasHidden && (!hasHCM || isLastShow)) { if (!hasHCM || isLastShow) {
canvas.hidden = false; canvas.hidden = false;
isCanvasHidden = false; showCanvas = null; // Only invoke the function once.
} }
}; };
@ -1014,7 +1013,7 @@ class PDFPageView {
}; };
const renderTask = this.pdfPage.render(renderContext); const renderTask = this.pdfPage.render(renderContext);
renderTask.onContinue = function (cont) { renderTask.onContinue = function (cont) {
showCanvas(false); showCanvas?.(false);
if (result.onRenderContinue) { if (result.onRenderContinue) {
result.onRenderContinue(cont); result.onRenderContinue(cont);
} else { } else {
@ -1024,7 +1023,7 @@ class PDFPageView {
renderTask.promise.then( renderTask.promise.then(
function () { function () {
showCanvas(true); showCanvas?.(true);
renderCapability.resolve(); renderCapability.resolve();
}, },
function (error) { function (error) {
@ -1032,7 +1031,7 @@ class PDFPageView {
// a black canvas if rendering was cancelled before the `onContinue`- // a black canvas if rendering was cancelled before the `onContinue`-
// callback had been invoked at least once. // callback had been invoked at least once.
if (!(error instanceof RenderingCancelledException)) { if (!(error instanceof RenderingCancelledException)) {
showCanvas(true); showCanvas?.(true);
} }
renderCapability.reject(error); renderCapability.reject(error);
} }