java 使用 AffineTransform 将形状缩放/转换为给定的矩形
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Scaling/Translating a Shape to a given Rectangle using AffineTransform
提问by Pierre
I'm trying to scale/translate a java.awt.Shapewith AffineTransformin order to draw it in a defined bounding Rectangle.
我正在尝试缩放/翻译 java.awt。使用AffineTransform塑造形状，以便在定义的边界矩形中绘制它。
Moreover, I want to paint it in a drawing Area having a 'zoom' parameter.
此外，我想在具有“缩放”参数的绘图区域中绘制它。
I tried various concatenations of AffineTransform but I couldn't find the correct sequence. For example, the following solution was wrong:
我尝试了 AffineTransform 的各种串联，但找不到正确的序列。例如，以下解决方案是错误的：
double zoom=(...);/* current zoom */
Rectangle2D viewRect=(...)/** the rectangle where we want to paint the shape */
Shape shape=(...)/* the original shape that should fit in the rectangle viewRect */
Rectangle2D bounds=shape.getBounds2D();
double ratioW=(viewRect.getWidth()/bounds.getWidth());
double ratioH=(viewRect.getHeight()/bounds.getHeight());
AffineTransform transforms[]=
{
AffineTransform.getScaleInstance(zoom, zoom),
AffineTransform.getTranslateInstance(-bounds.getX(),-bounds.getY()),
AffineTransform.getTranslateInstance(viewRect.getX(),viewRect.getY()),
AffineTransform.getScaleInstance(ratioW, ratioH)
};
AffineTransform tr=new AffineTransform();
for(int i=0;i< transforms.length;++i)
{
tr.concatenate(transforms[i]);
}
Shape shape2=tr.createTransformedShape(shape);
graphics2D.draw(shape2);
Any idea about the correct AffineTransform ?
知道正确的 AffineTransform 吗？
Many thanks
非常感谢
Pierre
皮埃尔
回答by trashgod
Note that AffineTransformtransformations are concatenated "in the most commonly useful way", which may be regarded as last in, first-outorder. The effect can be seen in this example. Given the sequence below, the resulting Shapeis first rotated, then scaled and finally translated.
需要注意的是AffineTransform转换串接“中最常用的方式”，这可以看作是最后的，先出的顺序。在这个例子中可以看到效果。给定下面的序列，结果Shape首先旋转，然后缩放，最后平移。
at.translate(SIZE/2, SIZE/2);
at.scale(60, 60);
at.rotate(Math.PI/4);
return at.createTransformedShape(...);
回答by Pierre
Inspired by trashgod's answer, the correct sequence was:
受垃圾神的回答启发，正确的顺序是：
AffineTransform transforms[]=
{
AffineTransform.getScaleInstance(zoom, zoom),
AffineTransform.getTranslateInstance(viewRect.getX(),viewRect.getY()),
AffineTransform.getScaleInstance(ratioW, ratioH),
AffineTransform.getTranslateInstance(-bounds.getX(),-bounds.getY())
};
AffineTransform tr=new AffineTransform();
for(int i=0;i< transforms.length;++i)
{
tr.concatenate(transforms[i]);
}
