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# ps_rotate

(PECL)

ps_rotate -- Sets rotation factor

## 说明

bool ps_rotate ( resource psdoc, float rot )

Sets the rotation of the coordinate system.

## 参数

`psdoc`

  Resource identifier of the postscript file as returned by ps_new().

`rot`

  Angle of rotation in degree.

## 返回值

如果成功则返回 `TRUE`，失败则返回 `FALSE`。

## 范例

例 1. Rotation of the coordinate system

`<?php
function rectangle($ps) {
ps_moveto($ps, 0, 0);
ps_lineto($ps, 0, 50);
ps_lineto($ps, 50, 50);
ps_lineto($ps, 50, 0);
ps_lineto($ps, 0, 0);
ps_stroke($ps);
}
$ps = ps_new();
if (!ps_open_file($ps, "rotation.ps")) {
print "Cannot open PostScript file\n";
exit;
}
ps_set_info($ps, "Creator", "rotation.php");
ps_set_info($ps, "Author", "Uwe Steinmann");
ps_set_info($ps, "Title", "Rotation example");
ps_set_info($ps, "BoundingBox", "0 0 596 842");
$psfont = ps_findfont($ps, "Helvetica", "", 0);
ps_begin_page($ps, 596, 842);
ps_set_text_pos($ps, 100, 100);
ps_save($ps);
ps_translate($ps, 100, 100);
ps_rotate($ps, 45);
rectangle($ps);
ps_restore($ps);
ps_setfont($ps, $psfont, 8.0);
ps_show($ps, "Text without rotation");
ps_end_page($ps);
ps_delete($ps);
?>`

The above example illustrates a very common way of rotating a graphic (in this case just a rectangle) by simply rotating the coordinate system. Since the graphic's coordinate system assumes (0,0) to be the origin, the page coordinate system is also translated to place the graphics not on the edge of the page. Pay attention to the order of ps_translate() and ps_rotate(). In the above case the rectancle is rotated around the point (100, 100) in the untranslated coordinate system. Switching the two statements has a completely different result.

In order to output the following text at the original position, all modifications of the coordinate system are encapsulated in ps_save() and ps_restore().

## 参见

ps_scale()
ps_translate()

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