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PhutilSpriteSheet.php
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Thu, Nov 7, 08:16

PhutilSpriteSheet.php
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<?php
/**
* NOTE: This is very new and unstable.
*/
final class PhutilSpriteSheet {
const MANIFEST_VERSION = 1;
const TYPE_STANDARD = 'standard';
const TYPE_REPEAT_X = 'repeat-x';
const TYPE_REPEAT_Y = 'repeat-y';
private $sprites = array();
private $sources = array();
private $hashes = array();
private $cssHeader;
private $generated;
private $scales = array(1);
private $type = self::TYPE_STANDARD;
private $css;
private $images;
public function addSprite(PhutilSprite $sprite) {
$this->generated = false;
$this->sprites[] = $sprite;
return $this;
}
public function setCSSHeader($header) {
$this->generated = false;
$this->cssHeader = $header;
return $this;
}
public function setScales(array $scales) {
$this->scales = array_values($scales);
return $this;
}
public function getScales() {
return $this->scales;
}
public function setSheetType($type) {
$this->type = $type;
return $this;
}
private function generate() {
if ($this->generated) {
return;
}
$multi_row = true;
$multi_col = true;
$margin_w = 1;
$margin_h = 1;
$type = $this->type;
switch ($type) {
case self::TYPE_STANDARD:
break;
case self::TYPE_REPEAT_X:
$multi_col = false;
$margin_w = 0;
$width = null;
foreach ($this->sprites as $sprite) {
if ($width === null) {
$width = $sprite->getSourceW();
} else if ($width !== $sprite->getSourceW()) {
throw new Exception(
"All sprites in a 'repeat-x' sheet must have the same width.");
}
}
break;
case self::TYPE_REPEAT_Y:
$multi_row = false;
$margin_h = 0;
$height = null;
foreach ($this->sprites as $sprite) {
if ($height === null) {
$height = $sprite->getSourceH();
} else if ($height !== $sprite->getSourceH()) {
throw new Exception(
"All sprites in a 'repeat-y' sheet must have the same height.");
}
}
break;
default:
throw new Exception("Unknown sprite sheet type '{$type}'!");
}
$css = array();
if ($this->cssHeader) {
$css[] = $this->cssHeader;
}
$out_w = 0;
$out_h = 0;
// Lay out the sprite sheet. We attempt to build a roughly square sheet
// so it's easier to manage, since 2000x20 is more cumbersome for humans
// to deal with than 200x200.
//
// To do this, we use a simple greedy algorithm, adding sprites one at a
// time. For each sprite, if the sheet is at least as wide as it is tall
// we create a new row. Otherwise, we try to add it to an existing row.
//
// This isn't optimal, but does a reasonable job in most cases and isn't
// too messy.
// Group the sprites by their sizes. We lay them out in the sheet as
// boxes, but then put them into the boxes in the order they were added
// so similar sprites end up nearby on the final sheet.
$boxes = array();
foreach (array_reverse($this->sprites) as $sprite) {
$s_w = $sprite->getSourceW() + $margin_w;
$s_h = $sprite->getSourceH() + $margin_h;
$boxes[$s_w][$s_h][] = $sprite;
}
$rows = array();
foreach ($this->sprites as $sprite) {
$s_w = $sprite->getSourceW() + $margin_w;
$s_h = $sprite->getSourceH() + $margin_h;
// Choose a row for this sprite.
$maybe = array();
foreach ($rows as $key => $row) {
if ($row['h'] < $s_h) {
// We can only add it to a row if the row is at least as tall as the
// sprite.
continue;
}
// We prefer rows which have the same height as the sprite, and then
// rows which aren't yet very wide.
$wasted_v = ($row['h'] - $s_h);
$wasted_h = ($row['w'] / $out_w);
$maybe[$key] = $wasted_v + $wasted_h;
}
$row_key = null;
if ($maybe && $multi_col) {
// If there were any candidate rows, pick the best one.
asort($maybe);
$row_key = head_key($maybe);
}
if ($row_key !== null && $multi_row) {
// If there's a candidate row, but adding the sprite to it would make
// the sprite wider than it is tall, create a new row instead. This
// generally keeps the sprite square-ish.
if ($rows[$row_key]['w'] + $s_w > $out_h) {
$row_key = null;
}
}
if ($row_key === null) {
// Add a new row.
$rows[] = array(
'w' => 0,
'h' => $s_h,
'boxes' => array(),
);
$row_key = last_key($rows);
$out_h += $s_h;
}
// Add the sprite box to the row.
$row = $rows[$row_key];
$row['w'] += $s_w;
$row['boxes'][] = array($s_w, $s_h);
$rows[$row_key] = $row;
$out_w = max($row['w'], $out_w);
}
$images = array();
foreach ($this->scales as $scale) {
$img = imagecreatetruecolor($out_w * $scale, $out_h * $scale);
imagesavealpha($img, true);
imagefill($img, 0, 0, imagecolorallocatealpha($img, 0, 0, 0, 127));
$images[$scale] = $img;
}
// Put the shorter rows first. At the same height, put the wider rows first.
// This makes the resulting sheet more human-readable.
foreach ($rows as $key => $row) {
$rows[$key]['sort'] = $row['h'] + (1 - ($row['w'] / $out_w));
}
$rows = isort($rows, 'sort');
$pos_x = 0;
$pos_y = 0;
$rules = array();
foreach ($rows as $row) {
$max_h = 0;
foreach ($row['boxes'] as $box) {
$sprite = array_pop($boxes[$box[0]][$box[1]]);
foreach ($images as $scale => $img) {
$src = $this->loadSource($sprite, $scale);
imagecopy(
$img,
$src,
$scale * $pos_x, $scale * $pos_y,
$scale * $sprite->getSourceX(), $scale * $sprite->getSourceY(),
$scale * $sprite->getSourceW(), $scale * $sprite->getSourceH());
}
$rule = $sprite->getTargetCSS();
$cssx = (-$pos_x).'px';
$cssy = (-$pos_y).'px';
$rules[$sprite->getName()] = "{$rule} {\n".
" background-position: {$cssx} {$cssy};\n}";
$pos_x += $sprite->getSourceW() + $margin_w;
$max_h = max($max_h, $sprite->getSourceH());
}
$pos_x = 0;
$pos_y += $max_h + $margin_h;
}
// Generate CSS rules in input order.
foreach ($this->sprites as $sprite) {
$css[] = $rules[$sprite->getName()];
}
$this->images = $images;
$this->css = implode("\n\n", $css)."\n";
$this->generated = true;
}
public function generateImage($path, $scale = 1) {
$this->generate();
$this->log("Writing sprite '{$path}'...");
imagepng($this->images[$scale], $path);
return $this;
}
public function generateCSS($path) {
$this->generate();
$this->log("Writing CSS '{$path}'...");
$out = $this->css;
$out = str_replace('{X}', imagesx($this->images[1]), $out);
$out = str_replace('{Y}', imagesy($this->images[1]), $out);
Filesystem::writeFile($path, $out);
return $this;
}
public function needsRegeneration(array $manifest) {
return ($this->buildManifest() !== $manifest);
}
private function buildManifest() {
$output = array();
foreach ($this->sprites as $sprite) {
$output[$sprite->getName()] = array(
'name' => $sprite->getName(),
'rule' => $sprite->getTargetCSS(),
'hash' => $this->loadSourceHash($sprite),
);
}
ksort($output);
$data = array(
'version' => self::MANIFEST_VERSION,
'sprites' => $output,
'scales' => $this->scales,
'header' => $this->cssHeader,
'type' => $this->type,
);
return $data;
}
public function generateManifest($path) {
$data = $this->buildManifest();
$json = new PhutilJSON();
$data = $json->encodeFormatted($data);
Filesystem::writeFile($path, $data);
return $this;
}
private function log($message) {
echo $message."\n";
}
private function loadSourceHash(PhutilSprite $sprite) {
$inputs = array();
foreach ($this->scales as $scale) {
$file = $sprite->getSourceFile($scale);
if (empty($this->hashes[$file])) {
$this->hashes[$file] = md5(Filesystem::readFile($file));
}
$inputs[] = $file;
$inputs[] = $this->hashes[$file];
}
$inputs[] = $sprite->getSourceX();
$inputs[] = $sprite->getSourceY();
$inputs[] = $sprite->getSourceW();
$inputs[] = $sprite->getSourceH();
return md5(implode(':', $inputs));
}
private function loadSource(PhutilSprite $sprite, $scale) {
$file = $sprite->getSourceFile($scale);
if (empty($this->sources[$file])) {
$data = Filesystem::readFile($file);
$image = imagecreatefromstring($data);
$this->sources[$file] = array(
'image' => $image,
'x' => imagesx($image),
'y' => imagesy($image),
);
}
$s_w = $sprite->getSourceW() * $scale;
$i_w = $this->sources[$file]['x'];
if ($s_w > $i_w) {
throw new Exception(
"Sprite source for '{$file}' is too small (expected width {$s_w}, ".
"found {$i_w}).");
}
$s_h = $sprite->getSourceH() * $scale;
$i_h = $this->sources[$file]['y'];
if ($s_h > $i_h) {
throw new Exception(
"Sprite source for '{$file}' is too small (expected height {$s_h}, ".
"found {$i_h}).");
}
return $this->sources[$file]['image'];
}
}

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