iPAD 上的 PDFJs 模糊 PDF

Question

我正在 cordova 应用程序中处理 PDJS 视图。

一切正常，除了 pdf 有点模糊。我知道这在某种程度上是因为视网膜显示，但我如何更改此顺序如何获得正确的比例？

目前我正在尝试这个

pdfFile.getPage(data.page).then(function (page) {


    canvas.width = $('#pdfContainer').width();
    var viewport = page.getViewport(canvas.width / (page.getViewport(1).width));
    canvas.width = viewport.width;
    canvas.height = viewport.height;

    var height= $('#pdfContainer').height();



    if (canvas.height > height) {
        canvas.height = height;
        var viewport = page.getViewport(canvas.height / (page.getViewport(1).height));
        canvas.width = viewport.width;
        canvas.height = viewport.height;
    }

    var renderContext = {
        canvasContext: context,
        viewport: viewport
    };

    page.render(renderContext);
});

Answer 1

我为此所做的首先是停用图像平滑：

canvasContext = canvas.getContext('2d') as CanvasRenderingContext2D;
canvasContext.imageSmoothingEnabled = false;
canvasContext.webkitImageSmoothingEnabled = false;
canvasContext.mozImageSmoothingEnabled = false;
canvasContext.oImageSmoothingEnabled = false;

然后用 window.devicePixelRatio

乘以我找到的 devicePixelRatio

    if (window.devicePixelRatio > 1) {
        var canvasWidth = canvas.width;
        var canvasHeight = canvas.height;

        canvas.width = canvasWidth * window.devicePixelRatio;
        canvas.height = canvasHeight * window.devicePixelRatio;
        canvas.style.width = canvasWidth + "px";
        canvas.style.height = canvasHeight + "px";

        canvasContext.scale(window.devicePixelRatio, window.devicePixelRatio);
    }

这也修复了带有 Retina 显示屏的 Macbocks 的模糊效果。

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