JRViewer 显示整页图像时冻结

发布于 2024-12-21 11:39:41 字数 487 浏览 0 评论 0原文

我正在使用 JasperViewer 在 Java 桌面应用程序中显示报告。该报告由 2 页组成 - 每页代表一幅图像。

问题是，当用户在查看器内滚动页面时，会出现巨大的冻结。图像的尺寸不是很大，大约1000x1000。

图像是这样生成的：

private BufferedImage createImage(Component panel) {
    int w = (int) panel.getSize().getWidth();
    int h = (int) panel.getSize().getHeight();
    BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    Graphics2D g = bi.createGraphics();
    panel.paint(g);
    g.dispose();
    return bi;
}

原文

I am using a JasperViewer to display the report inside of a Java desktop application.
The report consists of 2 pages - each of them represents an image.

The problem is, when user scrolls the page inside the viewer, there are huge freezes.
The size of image isn't so big, about 1000x1000.

The image is generated in this way:

private BufferedImage createImage(Component panel) {
    int w = (int) panel.getSize().getWidth();
    int h = (int) panel.getSize().getHeight();
    BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    Graphics2D g = bi.createGraphics();
    panel.paint(g);
    g.dispose();
    return bi;
}

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妳是的陽光 2024-12-28 11:39:41

您有两种选择

1) 将图像作为 Icon 放置到 < a href="http://docs.oracle.com/javase/tutorial/uiswing/components/label.html" rel="nofollow">JLabel

2) 对于 Swing JComponets 是 paintComponent() paint()，

请阅读有关图形
此论坛上有大量示例（Swing 标记），

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唯憾梦倾城 2024-12-28 11:39:41

问题已解决。 JRViewer 中有一个参数：

//Maximum size (in pixels) of a buffered image that would be used by {@link JRViewer JRViewer} to render a report page.
//If rendering a report page would require an image larger than this threshold
//(i.e. image width x image height > maximum size), the report page will be rendered directly on the viewer component.
//If this property is zero or negative, buffered images will never be user to render a report page.
//By default, this property is set to 0.
public static final String VIEWER_RENDER_BUFFER_MAX_SIZE

因此，如果设置了此参数，则报告将在 JLabel 上绘制为 ImageIcon。否则，它是使用 JRGraphics2DExporter 绘制的，在处理大图像时速度要慢得多。

所以解决方案是在属性文件中设置指定的属性或使用如下方式：

 /**
 * This number represents maximum size of an image ( x*y )
 * So this value cover up to 300% zoom for an image 1000x1000 pixels
 */
public static final String MAX_PIXELS_NUMBER = "10000000";   

static {
        try {
            JRProperties.setProperty(JRViewer.VIEWER_RENDER_BUFFER_MAX_SIZE, MAX_PIXELS_NUMBER);
        } catch (Exception e) {
            System.err.println("Cannot set the VIEWER_RENDER_BUFFER_MAX_SIZE property. Reports will be rendered slowly.");
        }
    }

The issue is resolved. There is a parameter in the JRViewer:

//Maximum size (in pixels) of a buffered image that would be used by {@link JRViewer JRViewer} to render a report page.
//If rendering a report page would require an image larger than this threshold
//(i.e. image width x image height > maximum size), the report page will be rendered directly on the viewer component.
//If this property is zero or negative, buffered images will never be user to render a report page.
//By default, this property is set to 0.
public static final String VIEWER_RENDER_BUFFER_MAX_SIZE

So, if this parameter is set, the reports is drawn as an ImageIcon on a JLabel. Otherwise, it's drawn using JRGraphics2DExporter that is much more slower when working with big images.

So the solution is to set the specified property in the property file or using way like this:

 /**
 * This number represents maximum size of an image ( x*y )
 * So this value cover up to 300% zoom for an image 1000x1000 pixels
 */
public static final String MAX_PIXELS_NUMBER = "10000000";   

static {
        try {
            JRProperties.setProperty(JRViewer.VIEWER_RENDER_BUFFER_MAX_SIZE, MAX_PIXELS_NUMBER);
        } catch (Exception e) {
            System.err.println("Cannot set the VIEWER_RENDER_BUFFER_MAX_SIZE property. Reports will be rendered slowly.");
        }
    }

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