Java：绘制缩放对象（缓冲图像和矢量图形）

Question

我想绘制包含光栅和矢量数据的缩放对象。目前，我正在绘制一个缩放的 Graphics2D 对象

protected void paintComponent(Graphics g) {

    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D) g.create();

    //Get transformation, apply scale and shifts
    at = g2d.getTransform();
    at.translate(x, y);
    at.scale(zoom, zoom);      

    //Transform Graphics2D object  
    g2d.setTransform(at);

    //Draw buffered image into the transformed object
    g2d.drawImage(img, 0, 0, this);

    //Draw line into transformed Graphics2D object
    Line2D.Double line = new Line2D.Double();
    line.x1 = (int)p1.getX();
    line.y1 = (int)p1.getY();
    line.x2 = (int)p2.getX();
    line.y2 = (int)p2.getY();

    g2d.draw(line);

    g2d.dispose();
}

不幸的是，这种方法有一些缺点（影响描边宽度，缩放图像质量较差）。

相反，我想绘制缩放对象。对于矢量数据，方法很简单：

protected void paintComponent(Graphics g) {

    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D) g.create();

    //Update affine transformation
    at = AffineTransform.getTranslateInstance(x, y);
    at = AffineTransform.getScaleInstance(zoom, zoom);

    //Transform line and draw
    Line2D.Double line = new Line2D.Double();
    line.x1 = (int)p1.getX();
    line.y1 = (int)p1.getY();
    line.x2 = (int)p2.getX();
    line.y2 = (int)p2.getY();

    g2d.draw(at.createTransformedShape((Shape)line));

    //Transform buffered image and draw ???
    g2d.draw(at.createTransformedShape((Shape)img));  //Error

    g2d.dispose();
}

但是，如何在不重新缩放 Graphics2D 对象的情况下将变换应用于缓冲图像？这个方法不行

g2d.draw(at.createTransformedShape((Shape)img));

因为栅格图像不能理解为矢量形状...

感谢您的帮助。

Answer 1

可能的解决方案可能表示栅格的仿射变换：

//Update affine transformation
at = AffineTransform.getTranslateInstance(x, y);
at = AffineTransform.getScaleInstance(zoom, zoom);

at.translate(x, y);
at.scale(zoom, zoom);      

//Create affine transformation
AffineTransformOp op = new AffineTransformOp(at,  AffineTransformOp.TYPE_NEAREST_NEIGHBOR);

//Apply transformation
BufferedImage img2 = op.filter(img, null);

//Draw image
g2d.drawImage(img2, 0, 0, this);

不幸的是，这种方法不适合缩放操作；它在计算上更昂贵。对于栅格数据（JPG，5000 x 7000 像素），一个简单的双线性插值

AffineTransformOp op = new AffineTransformOp(at,  AffineTransformOp.TYPE_BILINEAR);

大约需要 1.5 秒...相反，使用缩放 Graphics2D 对象要快得多（< 0.1 秒），图像可以实时移动和缩放。

在我看来，与栅格数据一起重新缩放对象比重新缩放 Graphics2D 对象慢....

Java：绘制缩放对象（缓冲图像和矢量图形）

Java: drawing scaled objects (buffered image and vector graphics)

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