PDFBox的：写入HD图像PDF

Question

我想转换形象使用cameraa到A4 PDF

// Read image width and height 
    float imageWidth = bitmap.getWidth(); 
    float imageHeight = bitmap.getHeight(); 

    // Read page width and height ignoring the margins 
    float pageWidth = PDRectangle.A4.getWidth() - (margin_left_right * 2); 
    float pageHeight = PDRectangle.A4.getHeight() - (margin_top_bottom * 2); 

    Log.d("Image Resize", String.valueOf(imageWidth) + " x " + String.valueOf(imageHeight)); 
    Log.d("Image Resize", String.valueOf(pageWidth) + " x " + String.valueOf(pageHeight)); 

    # Image: 4160.0 x 3120.0 
    # Page: 575.27563 x 821.8898 

    Log.d("Image Resize", String.valueOf(requiredRatio)); 
    Log.d("Image Resize", String.valueOf(newImageWidth) + " x " + String.valueOf(newImageHeight)); 

    # Required ratio: 0.13828741 
    # After scaling: 575 x 431 

问题是图像大小为4160 x 3120出手，得到调整后575 x 431，看起来非常像素化。

PDF通常如何解决这个问题？在使用contentStream.drawImage()写作时，有没有办法在600 dpi处说4160 x 3120？

---

这question还支持的事实，如果写不调整大小等于图像的高度和宽度的页面，OP只能看到图像的15％，应该如何是按比例缩小而不会损失质量？

Answer 1

有一个重载drawImage()方法来做到这一点

contentStream.drawImage(PDImageXObject, float x, float y) 
contentStream.drawImage(PDImageXObject, float x, float y, float height, float width) 

通过在contentStream.drawImage()指定明确的宽度和高度，可以做到这一点。例如，如果你想显示的图像更小的4倍，但仍保留了相同的分辨率，它可以使用

scaleDownRatio = 0.25; 
pageSize = PDRectangle.A4; 

# this will draw image at bottom left corner 
PDImageXObject pageImageXObject = LosslessFactory.createFromImage(document, bitmap); 
contentStream.drawImage(pageImageXObject, 0, 0, bitmap.getWidth() * ratio, bitmap.getHeight() * ratio) 

# to center it you can use something like 
contentStream.drawImage(pageImageXObject, (pageSize.getWidth() - bitmap.getWidth() * ratio)/2, (pageSize.getHeight() - bitmap.getHeight() * ratio)/2, bitmap.getWidth() * ratio, bitmap.getHeight() * ratio)