php 方便水印和缩略图的图形类

                    $x_r = $i;
                    break(2);
                }
            }
        }
        for($i=$height*4-1;$i>0;$i--) {
            for($ii=$x_l;$ii<=$x_r;$ii++) {
                if(imagecolorat($im,$ii,$i) != $tm) {
                    $y_b = $i;
                    break(2);
                }
            }
        }
        $x_off = $x_l - $width*2;
        $y_off = $y_b - $height*2;
        $width = $x_r - $x_l; //精确宽度
        $height = $y_b - $y_t; //精确高度
        imagedestroy($im);

        if(isset($arg['left'])) {
            $x = (int)$arg['left'] - $x_off;
        }elseif (isset($arg['right'])){
            $x = $w - (int)$arg['right'] - $width - $x_off;
        }else {
            $x = ($w - $width)/2 - $x_off;
        }
        if(isset($arg['top'])) {
            $y = (int)$arg['top'] - $y_off + $height;
        }elseif (isset($arg['bottom'])){
            $y = $h - (int)$arg['bottom'] - $y_off;
        }else {
            $y = ($h + $height)/2 - $y_off;
        }

        imagettftext($this->im,$size,$angle,$x,$y,$color,$font,$str);