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Refactor the getTempCanvas function in pdf_thumbnail_view.js to a factory, in preparation for ES6 conversion of the thumbnail related code

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This patch intends to simplify future ES6 refactoring of the thumbnail code, since the current code isn't going to work well together with proper `Class`es.
This commit is contained in:
Jonas Jenwald 2017-05-30 15:50:37 +02:00
parent e51718711b
commit 92529e2b11
2 changed files with 48 additions and 35 deletions
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74
web/pdf_thumbnail_view.js
View File

@ -32,35 +32,52 @@ var THUMBNAIL_CANVAS_BORDER_WIDTH = 1; // px
* but increases the overall memory usage. The default value is false.
*/
const TempImageFactory = (function TempImageFactoryClosure() {
let tempCanvasCache = null;
return {
getCanvas(width, height) {
let tempCanvas = tempCanvasCache;
if (!tempCanvas) {
tempCanvas = document.createElement('canvas');
tempCanvasCache = tempCanvas;
}
tempCanvas.width = width;
tempCanvas.height = height;
// Since this is a temporary canvas, we need to fill it with a white
// background ourselves. `_getPageDrawContext` uses CSS rules for this.
if (typeof PDFJSDev === 'undefined' ||
PDFJSDev.test('MOZCENTRAL || FIREFOX || GENERIC')) {
tempCanvas.mozOpaque = true;
}
let ctx = tempCanvas.getContext('2d', { alpha: false, });
ctx.save();
ctx.fillStyle = 'rgb(255, 255, 255)';
ctx.fillRect(0, 0, width, height);
ctx.restore();
return tempCanvas;
},
destroyCanvas() {
let tempCanvas = tempCanvasCache;
if (tempCanvas) {
// Zeroing the width and height causes Firefox to release graphics
// resources immediately, which can greatly reduce memory consumption.
tempCanvas.width = 0;
tempCanvas.height = 0;
}
tempCanvasCache = null;
},
};
})();
/**
* @class
* @implements {IRenderableView}
*/
var PDFThumbnailView = (function PDFThumbnailViewClosure() {
function getTempCanvas(width, height) {
var tempCanvas = PDFThumbnailView.tempImageCache;
if (!tempCanvas) {
tempCanvas = document.createElement('canvas');
PDFThumbnailView.tempImageCache = tempCanvas;
}
tempCanvas.width = width;
tempCanvas.height = height;
// Since this is a temporary canvas, we need to fill the canvas with a white
// background ourselves. `_getPageDrawContext` uses CSS rules for this.
if (typeof PDFJSDev === 'undefined' ||
PDFJSDev.test('MOZCENTRAL || FIREFOX || GENERIC')) {
tempCanvas.mozOpaque = true;
}
var ctx = tempCanvas.getContext('2d', {alpha: false});
ctx.save();
ctx.fillStyle = 'rgb(255, 255, 255)';
ctx.fillRect(0, 0, width, height);
ctx.restore();
return tempCanvas;
}
/**
* @constructs PDFThumbnailView
* @param {PDFThumbnailViewOptions} options
@ -358,7 +375,8 @@ var PDFThumbnailView = (function PDFThumbnailViewClosure() {
var MAX_NUM_SCALING_STEPS = 3;
var reducedWidth = canvas.width << MAX_NUM_SCALING_STEPS;
var reducedHeight = canvas.height << MAX_NUM_SCALING_STEPS;
var reducedImage = getTempCanvas(reducedWidth, reducedHeight);
var reducedImage = TempImageFactory.getCanvas(reducedWidth,
reducedHeight);
var reducedImageCtx = reducedImage.getContext('2d');
while (reducedWidth > img.width || reducedHeight > img.height) {
@ -405,11 +423,13 @@ var PDFThumbnailView = (function PDFThumbnailViewClosure() {
},
};
PDFThumbnailView.cleanup = function() {
TempImageFactory.destroyCanvas();
};
return PDFThumbnailView;
})();
PDFThumbnailView.tempImageCache = null;
export {
PDFThumbnailView,
};

9
web/pdf_thumbnail_viewer.js
View File

@ -104,14 +104,7 @@ var PDFThumbnailViewer = (function PDFThumbnailViewerClosure() {
},
cleanup: function PDFThumbnailViewer_cleanup() {
var tempCanvas = PDFThumbnailView.tempImageCache;
if (tempCanvas) {
// Zeroing the width and height causes Firefox to release graphics
// resources immediately, which can greatly reduce memory consumption.
tempCanvas.width = 0;
tempCanvas.height = 0;
}
PDFThumbnailView.tempImageCache = null;
PDFThumbnailView.cleanup();
},
/**