使用transform.matrix和矩形.bounds绘制actionscript位图

发布于 2024-12-09 10:36:43 字数 417 浏览 1 评论 0原文

我正在尝试从对象中获取部分位图，但我得到了不同的值：

object.transform.matrix.tx and object.transform.matrix.ty

v/s

object.getBounds(object.parent).x and object.getBounds(object.parent).y

我不确定在绘制位图数据时应该使用哪些值：

bitmapdata.draw(object, <matrix>);

要添加矩阵的 a、b、c、d 分量，请使用以下方法： 1,0,0,1（或身份）。那么有人可以解释一下在哪些场景中matrix.tx和matrix.ty与边界坐标不同吗？

原文

I am trying to get a partial bitmap from an object but I am getting different values from:

object.transform.matrix.tx and object.transform.matrix.ty

v/s

object.getBounds(object.parent).x and object.getBounds(object.parent).y

I am not sure which ones should I use while drawing the bitmapdata:

bitmapdata.draw(object, <matrix>);

To add the a,b,c,d components of matrix are 1,0,0,1 (or identity). So Can someone explain in which scenarios are matrix.tx and matrix.ty different from bounds coordinates?

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七秒鱼° 2024-12-16 10:36:43

如果没有应用其他转换，object.transform.matrix.tx 等于 object.x（y 相同）。如果您将某些内容绘制到负坐标，则object的x和y属性不会改变。

object.x = 300;
object.y = 300;
object.graphics.beginFill(0);
object.graphics.drawCircle(0,0,100);

本例中绘制的圆的边界矩形将从-100,-100开始，但对象的中心仍位于父对象的300,300处坐标空间。现在getBounds指的是对象的区域。该区域的坐标被转换为父级的空间，并且恰好是200,200。

父坐标空间中的矩阵平移和边界何时不同？
几乎总是，仅当对象的边界（在其自己的坐标空间中）从 0,0 开始时，它们才相同。

文档中的 getBounds 示例。我无法告诉你应该使用哪一个，这取决于你需要在哪里绘制对象，但你没有提到所需的位置。

object.transform.matrix.tx is equals to object.x if no other transformation is applied (same for y). If you draw something to the negative coordinates, the x and y properties of object don't change.

object.x = 300;
object.y = 300;
object.graphics.beginFill(0);
object.graphics.drawCircle(0,0,100);

The bounding rect of the circle drawn in this example would start at -100,-100 but the object's center is still at 300,300 in the parent's coordinate space. Now getBounds refers to the area of the object. The area's coordinates are converted to the parent's space and happen to be 200,200.

When are matrix translations and bounds in the parent's coordinate space different?
Almost always, they are only the same if the object's bound (in it's own coordinate space) start at 0,0.

This is partly covered by the example of getBounds in the documentation. I can't tell you which one should use, it depends on where you need to draw the object, but you haven't mentioned the desired position.

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