PHP imagetextblock Object

When generating images with PHP, proper placement of text can be difficult. The imagettftext function has served me well for various projects, but falls short when I need my text rotated, centered, right justified, etc. I used to find the bounding box every time, and use that to calculate a new position. However, this gets tedious, and makes for some overly-complex code. Thus the imagetextblock object was created.

The imagetextblock object makes rendering graphical text easier in a few different ways: Allowing the programmer to easily align the text horizontally or vertically, and specify colors in a more intuitive fashion. Rotation is also more intuitive, rotating around the point it's aligned to. Most importantly, the code is easier to understand when viewed later.

Rather than go on and on about the various features and how they work, I've created this demo to show how the various variables and functions work and how they affect the final image. Below you will find the source code to the imagetextblock object, and some sample code generated by the demo. Feel free to adjust values in the form at the left and see how the image changes. If you would like to use this in your projects, please credit me by at least leaving the credits at the top of the imagetextblock class file. Have any questions, comments, or anything else? Feel free to Contact Me.

class_imagetextblock.php
<?php // imagetextblock object // June 2007, Ben Brandt - B2Ben.com // Allows for easier creation of text on an image, simpler alignment, and simple hex or RGB color input class imagetextblock { var $image; //image resource to apply text to var $size = 10; var $angle = 0; var $x = 0; var $y = 0; var $align = 'Baseline Left'; var $color = '#000000'; var $opacity = 1.00; //Opaque = 1.0 or "100%" Totally transparent = 0.0 or "0%" var $fontfile = ''; var $text = 'Text'; function imagetextblock( $image = null ) { //Constructor function - sets image to be drawn on if( isset($image) ){ $this->image = $image; } else { //Allow image canvas not to be set, in case user just wants to find the bbox of the text $this->image = imagecreatetruecolor(1,1); //create dummy canvas } } function getcolor() { //Converts $color variable into usable color $rgb = array( 'r'=>0 , 'g'=>0 , 'b'=>0 ); $this->color = preg_replace('/^#/', '', $this->color); //remove leading pound sign $this->color = str_replace ( ' ' , '' , $this->color ); //remove spaces if( preg_match('/^[0-9a-fA-F]{6}$/',$this->color) ){ //6-character hex $rgb['r'] = hexdec( substr($this->color,0,2) ); $rgb['g'] = hexdec( substr($this->color,2,2) ); $rgb['b'] = hexdec( substr($this->color,4,2) ); } if( preg_match('/^[0-9a-fA-F]{3}$/',$this->color) ){ //3-character hex $rgb['r'] = hexdec( substr($this->color,0,1).substr($this->color,0,1) ); $rgb['g'] = hexdec( substr($this->color,1,1).substr($this->color,1,1) ); $rgb['b'] = hexdec( substr($this->color,2,1).substr($this->color,2,1) ); } if( preg_match('/^\d{1,3},\d{1,3},\d{1,3}$/',$this->color) ){ //Comma-separated list of RGB values $arr = explode ( ',' , $this->color ); $rgb['r'] = max(0,min(intval($arr[0]),255)); $rgb['g'] = max(0,min(intval($arr[1]),255)); $rgb['b'] = max(0,min(intval($arr[2]),255)); } $alpha = 0; //Completely opaque if( preg_match('/^\d+\.?\d*%$/',$this->opacity) ){ //opacity appears to be in a percentage format, such as "100.0%" $this->opacity = str_replace ( "%" , "" , $this->opacity ); $this->opacity = ($this->opacity / 100); //Convert to decimal between 0 and 1 } if( is_numeric($this->opacity) ){ //Opacity is numeric - move it within the range of 0 to 1 if outside those values $this->opacity = max(0,min($this->opacity,1)); $alpha = ((1 - $this->opacity) * 127); //convert opacity to proper alpha value (0 = opaque, 127 = transparent) } //Define the color $imgcolor = imagecolorallocatealpha($this->image,$rgb['r'],$rgb['g'],$rgb['b'],$alpha); return $imgcolor; } function new_point(){ //This function uses the alignment to determine a new x,y point to draw the text at, so it appears to be properly aligned at the user-specified x and y point //Get bounding box of un-rotated text $bbox = imagettfbbox( $this->size , 0 , $this->fontfile , $this->text ); //Determine Alignment $this->align = strtolower($this->align); $AlignPoint = array( 'x'=>0 , 'y'=>0 ); //Cartesian coordinate relative to baseline-left of text // Horizontal Alignment if( strstr ( $this->align , 'left' ) ){ $AlignPoint['x'] = ( $bbox[0] ); } if( strstr ( $this->align , 'center' ) ){ $AlignPoint['x'] = (($bbox[2] + $bbox[0])/2); } if( strstr ( $this->align , 'right' ) ){ $AlignPoint['x'] = ( $bbox[2] ); } // Vertical Alignment if( strstr ( $this->align , 'top' ) ){ $AlignPoint['y'] = ( $bbox[7] ); } if( strstr ( $this->align , 'middle' ) ){ $AlignPoint['y'] = (($bbox[1] + $bbox[7])/2); } if( strstr ( $this->align , 'baseline' ) ){ $AlignPoint['y'] = ( 0 ); } if( strstr ( $this->align , 'bottom' ) ){ $AlignPoint['y'] = ( $bbox[1] ); } //Apply rotation to our alignment point... find out where it will be after rotation $AlignPoint = $this->rotate_point( $AlignPoint['x'] , $AlignPoint['y'] , $this->angle ); //Convert specified x and y into new point $NewPoint = array( 'x'=>round($this->x - $AlignPoint['x']) , 'y'=>round($this->y - $AlignPoint['y']) ); return $NewPoint; } function rotate_point( $x , $y , $degrees , $origin_x = 0 , $origin_y = 0 ) { $rel_x = ($x-$origin_x); $rel_y = ($y-$origin_y); //x and y relative to the specified origin point //Convert to polar coordinate $radius = sqrt( pow($rel_x,2) + pow($rel_y,2) ); $angle = rad2deg(atan2((-1*$rel_y),$rel_x)); //Y is reversed to make it work with upside-down PHP Graphics coordinate system //Add rotation angle $angle += $degrees; //Convert to relative cartesian coordinate $rel_x = ( $radius * cos(deg2rad($angle)) ); $rel_y = -( $radius * sin(deg2rad($angle)) ); //Y is reversed to make it work with upside-down PHP Graphics coordinate system //Translate back to absolute coordinate $FinalPoint['x'] = ($rel_x + $origin_x); $FinalPoint['y'] = ($rel_y + $origin_y); return $FinalPoint; } function new_x() { $NewPoint = $this->new_point(); return( $NewPoint['x'] ); } function new_y() { $NewPoint = $this->new_point(); return( $NewPoint['y'] ); } function bbox(){ //Returns imagettfbbox of rotated text block //Start with the un-rotated text block... $bbox = imagettfbbox( $this->size , 0 , $this->fontfile , $this->text ); //rotate the un-rotated bounding box (the standard imagettfbbox doesn't seem to work well when rotated) $topleft = $this->rotate_point( $bbox[6] , $bbox[7] , $this->angle ); $topright = $this->rotate_point( $bbox[4] , $bbox[5] , $this->angle ); $bottomleft = $this->rotate_point( $bbox[0] , $bbox[1] , $this->angle ); $bottomright = $this->rotate_point( $bbox[2] , $bbox[3] , $this->angle ); //Translate points $newbbox = array(); $NewPoint = $this->new_point(); $newbbox[0] = round( $bottomleft['x'] + $NewPoint['x'] ); $newbbox[1] = round( $bottomleft['y'] + $NewPoint['y'] ); $newbbox[2] = round( $bottomright['x'] + $NewPoint['x'] ); $newbbox[3] = round( $bottomright['y'] + $NewPoint['y'] ); $newbbox[4] = round( $topright['x'] + $NewPoint['x'] ); $newbbox[5] = round( $topright['y'] + $NewPoint['y'] ); $newbbox[6] = round( $topleft['x'] + $NewPoint['x'] ); $newbbox[7] = round( $topleft['y'] + $NewPoint['y'] ); //Return the bounding box return $newbbox; } function top(){ //Returns topmost y-coordinate of text block $bbox = $this->bbox(); // "top" on the GD coordinate system is a smaller value than the bottom, return the minimum y-value return min( $bbox[1] , $bbox[3] , $bbox[5] , $bbox[7] ); } function bottom(){ //Returns bottom-most y-coordinate of text block $bbox = $this->bbox(); // "top" on the GD coordinate system is a smaller value than the bottom, return the maximum y-value return max( $bbox[1] , $bbox[3] , $bbox[5] , $bbox[7] ); } function left(){ //Returns left-most x-coordinate of text block $bbox = $this->bbox(); return min( $bbox[0] , $bbox[2] , $bbox[4] , $bbox[6] ); } function right(){ //Returns right-most x-coordinate of text block $bbox = $this->bbox(); return max( $bbox[0] , $bbox[2] , $bbox[4] , $bbox[6] ); } function render() { $NewPoint = $this->new_point(); imagettftext ( $this->image, $this->size, $this->angle, $NewPoint['x'] , $NewPoint['y'] , $this->getcolor() , $this->fontfile, $this->text ); } } //End imagetextblock class definition ?>