Working with a virtual grid
Create a new image, with a real width/height (ex: 600x800), but also a grid width/height (ex: 10x10). Then you can give images a virtual size and virtual position. I'll try to make it step by step to make you understand what I mean.
First of all, we need an environment for this.
class imageGrid
{
private $realWidth;
private $realHeight;
private $gridWidth;
private $gridHeight;
private $image;
public function __construct($realWidth, $realHeight, $gridWidth, $gridHeight)
{
$this->realWidth = $realWidth;
$this->realHeight = $realHeight;
$this->gridWidth = $gridWidth;
$this->gridHeight = $gridHeight;
// create destination image
$this->image = imagecreatetruecolor($realWidth, $realHeight);
// set image default background
$white = imagecolorallocate($this->image, 255, 255, 255);
imagefill($this->image, 0, 0, $white);
}
public function __destruct()
{
imagedestroy($this->image);
}
public function display()
{
header("Content-type: image/png");
imagepng($this->image);
}
}
$imageGrid = new imageGrid(800, 600, 10, 10);
$imageGrid->display();
This will give us a beautiful white square. Then, we need a grid to display images. Because that's perhaps difficult to imagine, let's display it.
public function demoGrid()
{
$black = imagecolorallocate($this->image, 0, 0, 0);
imagesetthickness($this->image, 3);
$cellWidth = ($this->realWidth - 1) / $this->gridWidth; // note: -1 to avoid writting
$cellHeight = ($this->realHeight - 1) / $this->gridHeight; // a pixel outside the image
for ($x = 0; ($x <= $this->gridWidth); $x++)
{
for ($y = 0; ($y <= $this->gridHeight); $y++)
{
imageline($this->image, ($x * $cellWidth), 0, ($x * $cellWidth), $this->realHeight, $black);
imageline($this->image, 0, ($y * $cellHeight), $this->realWidth, ($y * $cellHeight), $black);
}
}
}
By calling :
$imageGrid = new imageGrid(800, 600, 10, 10);
$imageGrid->demoGrid();
$imageGrid->display();
We can see :
Now, we want to know how to write a rectangle of 3x4, and paste it to (2,5) in our virtual measures. We need to search how to get real sizes and positions of our rectangle.
public function demoPutSquare($sizeW, $sizeH, $posX, $posY)
{
// Cell width
$cellWidth = $this->realWidth / $this->gridWidth;
$cellHeight = $this->realHeight / $this->gridHeight;
// Conversion of our virtual sizes/positions to real ones
$realSizeW = ($cellWidth * $sizeW);
$realSizeH = ($cellHeight * $sizeH);
$realPosX = ($cellWidth * $posX);
$realPosY = ($cellHeight * $posY);
// Getting top left and bottom right of our rectangle
$topLeftX = $realPosX;
$topLeftY = $realPosY;
$bottomRightX = $realPosX + $realSizeW;
$bottomRightY = $realPosY + $realSizeH;
// Displaying rectangle
$red = imagecolorallocate($this->image, 100, 0, 0);
imagefilledrectangle($this->image, $topLeftX, $topLeftY, $bottomRightX, $bottomRightY, $red);
}
By calling :
$imageGrid = new imageGrid(800, 600, 10, 10);
$imageGrid->demoGrid();
$imageGrid->demoPutSquare(3, 4, 2, 5);
$imageGrid->display();
We get a square of 3x4 positionned at (2,5) in our grid :
Now let's get it more seriousely, we have good measures so we can paste an image.
public function putImage($img, $sizeW, $sizeH, $posX, $posY)
{
// Cell width
$cellWidth = $this->realWidth / $this->gridWidth;
$cellHeight = $this->realHeight / $this->gridHeight;
// Conversion of our virtual sizes/positions to real ones
$realSizeW = ceil($cellWidth * $sizeW);
$realSizeH = ceil($cellHeight * $sizeH);
$realPosX = ($cellWidth * $posX);
$realPosY = ($cellHeight * $posY);
// Copying the image
imagecopyresampled($this->image, $img, $realPosX, $realPosY, 0, 0, $realSizeW, $realSizeH, imagesx($img), imagesy($img));
}
By calling :
$imageGrid = new imageGrid(800, 600, 10, 10);
$imageGrid->demoGrid();
$img = imagecreatefromjpeg("ninsuo.jpg");
$imageGrid->putImage($img, 3, 4, 2, 5);
$imageGrid->display();
We get :
That way we have a picture in the good place, but we lost the aspect ratio. Let's add a method to resize correctly our image.
public function resizePreservingAspectRatio($img, $targetWidth, $targetHeight)
{
$srcWidth = imagesx($img);
$srcHeight = imagesy($img);
$srcRatio = $srcWidth / $srcHeight;
$targetRatio = $targetWidth / $targetHeight;
if (($srcWidth <= $targetWidth) && ($srcHeight <= $targetHeight))
{
$imgTargetWidth = $srcWidth;
$imgTargetHeight = $srcHeight;
}
else if ($targetRatio > $srcRatio)
{
$imgTargetWidth = (int) ($targetHeight * $srcRatio);
$imgTargetHeight = $targetHeight;
}
else
{
$imgTargetWidth = $targetWidth;
$imgTargetHeight = (int) ($targetWidth / $srcRatio);
}
$targetImg = imagecreatetruecolor($targetWidth, $targetHeight);
imagecopyresampled(
$targetImg,
$img,
($targetWidth - $imgTargetWidth) / 2, // centered
($targetHeight - $imgTargetHeight) / 2, // centered
0,
0,
$imgTargetWidth,
$imgTargetHeight,
$srcWidth,
$srcHeight
);
return $targetImg;
}
And just before :
imagecopyresampled($this->image, $img, $realPosX, $realPosY, 0, 0, $realSizeW, $realSizeH, imagesx($img), imagesy($img));
We put :
$img = $this->resizePreservingAspectRatio($img, $realSizeW, $realSizeH);
This look like this :
We now have a full functionnal class to make your job.
class imageGrid
{
private $realWidth;
private $realHeight;
private $gridWidth;
private $gridHeight;
private $image;
public function __construct($realWidth, $realHeight, $gridWidth, $gridHeight)
{
$this->realWidth = $realWidth;
$this->realHeight = $realHeight;
$this->gridWidth = $gridWidth;
$this->gridHeight = $gridHeight;
// create destination image
$this->image = imagecreatetruecolor($realWidth, $realHeight);
$black = imagecolorallocate($this->image, 0, 0, 0);
imagecolortransparent($this->image, $black);
}
public function __destruct()
{
imagedestroy($this->image);
}
public function display()
{
header("Content-type: image/png");
imagepng($this->image);
}
public function putImage($img, $sizeW, $sizeH, $posX, $posY)
{
// Cell width
$cellWidth = $this->realWidth / $this->gridWidth;
$cellHeight = $this->realHeight / $this->gridHeight;
// Conversion of our virtual sizes/positions to real ones
$realSizeW = ceil($cellWidth * $sizeW);
$realSizeH = ceil($cellHeight * $sizeH);
$realPosX = ($cellWidth * $posX);
$realPosY = ($cellHeight * $posY);
$img = $this->resizePreservingAspectRatio($img, $realSizeW, $realSizeH);
// Copying the image
imagecopyresampled($this->image, $img, $realPosX, $realPosY, 0, 0, $realSizeW, $realSizeH, imagesx($img), imagesy($img));
}
public function resizePreservingAspectRatio($img, $targetWidth, $targetHeight)
{
$srcWidth = imagesx($img);
$srcHeight = imagesy($img);
$srcRatio = $srcWidth / $srcHeight;
$targetRatio = $targetWidth / $targetHeight;
if (($srcWidth <= $targetWidth) && ($srcHeight <= $targetHeight))
{
$imgTargetWidth = $srcWidth;
$imgTargetHeight = $srcHeight;
}
else if ($targetRatio > $srcRatio)
{
$imgTargetWidth = (int) ($targetHeight * $srcRatio);
$imgTargetHeight = $targetHeight;
}
else
{
$imgTargetWidth = $targetWidth;
$imgTargetHeight = (int) ($targetWidth / $srcRatio);
}
$targetImg = imagecreatetruecolor($targetWidth, $targetHeight);
imagecopyresampled(
$targetImg,
$img,
($targetWidth - $imgTargetWidth) / 2, // centered
($targetHeight - $imgTargetHeight) / 2, // centered
0,
0,
$imgTargetWidth,
$imgTargetHeight,
$srcWidth,
$srcHeight
);
return $targetImg;
}
}
We can now play with it to see if it works :
$imageGrid = new imageGrid(800, 400, 12, 2);
$blue = imagecreatefrompng("cheers_blue.png");
$imageGrid->putImage($blue, 6, 2, 0, 0);
imagedestroy($blue);
$green = imagecreatefrompng("cheers_green.png");
$imageGrid->putImage($green, 2, 1, 6, 0);
imagedestroy($green);
$red = imagecreatefrompng("cheers_red.png");
$imageGrid->putImage($red, 2, 1, 8, 0);
imagedestroy($red);
$yellow = imagecreatefrompng("cheers_yellow.png");
$imageGrid->putImage($yellow, 2, 1, 10, 0);
imagedestroy($yellow);
$purple = imagecreatefrompng("cheers_purple.png");
$imageGrid->putImage($purple, 3, 1, 6, 1);
imagedestroy($purple);
$cyan = imagecreatefrompng("cheers_cyan.png");
$imageGrid->putImage($cyan, 3, 1, 9, 1);
imagedestroy($cyan);
$imageGrid->display();
Personnally, I prefer the one without preserving aspect ratio :-)
Cheers! (eh, enjoy I would say!)
