结合3图像与透明度 - Combining 3 images with transparency

我正在做这个项目，我想把3张图片合并成一张。

目前为止的工作是使每个图像(jpg)透明。但是在将它们合并成新的png图像后，透明度就消失了。

代码如下:

function CreateMyCoolOutfitBaby () {
    $Outfitwidth = 250;
    $Outfitheight = 350;
    $newoutfit = imagecreatetruecolor($Outfitwidth, $Outfitheight); // create empty new image
    $dress = imagecreatefromstring(file_get_contents("http://images180.affili.net/001089/c/bb9c33888aae07d839b6724e31f462bc.jpg"));
    imagealphablending($dress, true);
    $white = imagecolorallocate($dress, 255, 255, 255);
    imagecolortransparent($dress, $white);
    $bag = imagecreatefromstring(file_get_contents("http://images180.affili.net/000698/6/40afc9ed65a94177635d1c7675fd3756.jpg"));
    imagealphablending($bag, true);
    $white = imagecolorallocate($bag, 255, 255, 255);
    imagecolortransparent($bag, $white);
    $shoe = imagecreatefromstring(file_get_contents("http://images180.affili.net/000389/4/4482beed9a949f895debe13d9dd28704.jpg"));
    imagealphablending($shoe, true);
    $white = imagecolorallocate($shoe, 255, 255, 255);
    imagecolortransparent($shoe, $white);


    imagealphablending($newoutfit,true); //on each new layer.
    // UN-COMMENT THIS PARAGRAPH TO SEE SINGLE FILES BEING TRANSPARENT
    //header('Content-Type: image/png');
    //imagepng($dress); // output to the browser
    //imagepng($bag); // output to the browser
    //imagepng($shoe); // output to the browser
    // WORKS TILL HERE :)

    // get with and height from images
    $Dresswidth = imagesx($dress);  $Bagwidth = imagesx($bag);  $Shoewidth = imagesx($shoe);    
    $Dressheight = imagesy($dress); $Bagheight = imagesy($bag); $Shoeheight = imagesy($shoe);

    // Calc Dress Position (middle)
    $DressPosWidth  = ( ( $Outfitwidth / 2 )  - ( $Dresswidth / 2 ) );
    $DressPosHeight = ( ( $Outfitheight / 2 ) - ( $Dressheight / 2 ) );
    // Calc Bag Position (right beside dress)
    $BagPosWidth    = ( ( $Outfitwidth / 2 )  - ( $Bagwidth / 2 ) + 60 ); // place bag in middle but more to the right
    $BagPosHeight = ( ( $Outfitheight / 2 ) - ( $Bagheight / 2 ) );
    // Calc Shoe Position (middle under dress)
    $ShoePosWidth   = ( ( $Outfitwidth / 2 )  - ( $Shoewidth / 2 ) );
    $ShoePosHeight = ( ( $Outfitheight / 2 ) - ( $Shoeheight / 2 ) + 100); // place further down
    // merge images together
    imagecopy($newoutfit,$dress,$DressPosWidth,$DressPosHeight,0,0,$Dresswidth,$Dressheight);
    imagealphablending($newoutfit,true);
    imagecopy($newoutfit,$bag,$BagPosWidth,$BagPosHeight,0,0,$Bagwidth,$Bagheight);
    imagealphablending($newoutfit,true);
    imagecopy($newoutfit,$shoe,$ShoePosWidth,$ShoePosHeight,0,0,$Shoewidth,$Shoeheight);
    imagealphablending($newoutfit,true);
    // make sure alpha is saved
    imagesavealpha($newoutfit, true);
    imagealphablending($newoutfit, true);
    // output to browser
    header('Content-Type: image/png');
    imagepng($newoutfit); // output to the browser
    imagedestroy($newoutfit);
}

所以单个图像的透明度工作良好。就在$newoutfit被放出来的时候，我得到了一个黑色的背景，图像又回到了白色的背景…

我能做什么?

使用imagecopymerge():

修复此问题

<?php
CreateMyCoolOutfitBaby ();
function CreateMyCoolOutfitBaby () {
    $Outfitwidth = 250;
    $Outfitheight = 350;
    $newoutfit = imagecreatetruecolor($Outfitwidth, $Outfitheight); // create empty new image
    imagealphablending($newoutfit, true);
    $black = imagecolorallocate($newoutfit, 0, 0, 0);imagecolortransparent($newoutfit, $black); // Making it transparent
    $dress = imagecreatefromstring(file_get_contents('http://example.com/dress.jpg'));
    imagealphablending($dress, true);
    $white = imagecolorallocate($dress, 255, 255, 255);
    imagecolortransparent($dress, $white);
    $bag = imagecreatefromstring(file_get_contents('http://example.com/bag.jpg'));
    imagealphablending($bag, true);
    $white = imagecolorallocate($bag, 255, 255, 255);
    imagecolortransparent($bag, $white);
    $shoe = imagecreatefromstring(file_get_contents('http://example.com/shoe.jpg'));
    imagealphablending($shoe, true);
    $white = imagecolorallocate($shoe, 255, 255, 255);
    imagecolortransparent($shoe, $white);
    // get with and height from images
    $Dresswidth = imagesx($dress);  $Bagwidth = imagesx($bag);  $Shoewidth = imagesx($shoe);    
    $Dressheight = imagesy($dress); $Bagheight = imagesy($bag); $Shoeheight = imagesy($shoe);

    // Calc Dress Position (middle)
    $DressPosWidth  = ( ( $Outfitwidth / 2 )  - ( $Dresswidth / 2 ) );
    $DressPosHeight = ( ( $Outfitheight / 2 ) - ( $Dressheight / 2 ) );
    // Calc Bag Position (right beside dress)
    $BagPosWidth    = ( ( $Outfitwidth / 2 )  - ( $Bagwidth / 2 ) + 60 ); // place bag in middle but more to the right
    $BagPosHeight = ( ( $Outfitheight / 2 ) - ( $Bagheight / 2 ) );
    // Calc Shoe Position (middle under dress)
    $ShoePosWidth   = ( ( $Outfitwidth / 2 )  - ( $Shoewidth / 2 ) );
    $ShoePosHeight = ( ( $Outfitheight / 2 ) - ( $Shoeheight / 2 ) + 100); // place further down
    // merge images together
    imagecopymerge($newoutfit,$dress,$DressPosWidth,$DressPosHeight,0,0,$Dresswidth,$Dressheight,100);
    imagealphablending($newoutfit,true);
    imagecopymerge($newoutfit,$bag,$BagPosWidth,$BagPosHeight,0,0,$Bagwidth,$Bagheight,100);
    imagealphablending($newoutfit,true);
    imagecopymerge($newoutfit,$shoe,$ShoePosWidth,$ShoePosHeight,0,0,$Shoewidth,$Shoeheight,100);
    imagealphablending($newoutfit,true);
    header('Content-Type: image/png');
    imagepng($newoutfit); // output to the browser
    imagedestroy($newoutfit);
}